Re: [time-nuts] optically excite a quartz crystal?

2014-04-21 Thread J. Forster
No. There is just a little rectangular quartz wafer. No plating.

In fact, post WWII, when many ham transmitters were 'rock bound' (ie:
crystal conteolled) it was common pratice to regrind mil surplus rystals
to move them into the ham banda.

Apparently, some were also etched using a cleanser called Whink, which
contains a flourine compound.

Also, some advocated applying graphite from a pencil lead was used to
decrease the frequency.

If the crystal ativity was low, they were taken appart and cleaned.



-John

==




 I'm puzzling over this statement.  The FT-243's I have seen have a spring
 that squishes the quartz blank between the electrodes.  They aren't plated
 onto the quartz, but they are still in intimate mechanical and electrical
 contact.

 -Chuck Harris

 Bob Camp wrote:
 Hi

 The WWII era FT-243 is one example of a crystal that has the active
 portion of the
 electrodes separated from the resonator by an air gap. There are lots of
 similar
 holders from that era that do pretty much the same thing. Non-contacting
 electrodes are not very new.

 Bob
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Re: [time-nuts] optically excite a quartz crystal?

2014-04-21 Thread J. Forster
The etching referred to was by post-war hams,

-John

===



 Hi

 Early in the WWII era, quartz blanks were not commonly etched after begin
 ground / polished to frequency. This left debris on the surface of the
 blank. The net result was that the resonators failed after a period of
 time in the field, especially under damp conditions. The problem got so
 bad that it actually threatened the ability to communicate in 1942. A
 fairly high level team looked into the issue and etching of blanks (and a
 few other mods) were made a mandatory part of all crystals suppled to the
 government. Ammonium bi-flouride and water was the most common etchant in
 that era. There are a number of papers about the whole deal in the FCS,
 and many stories told by those who were part of the changes.

 Bob


 On Apr 21, 2014, at 10:10 AM, J. Forster j...@quikus.com wrote:

 No. There is just a little rectangular quartz wafer. No plating.

 In fact, post WWII, when many ham transmitters were 'rock bound' (ie:
 crystal conteolled) it was common pratice to regrind mil surplus rystals
 to move them into the ham banda.

 Apparently, some were also etched using a cleanser called Whink, which
 contains a flourine compound.

 Also, some advocated applying graphite from a pencil lead was used to
 decrease the frequency.

 If the crystal ativity was low, they were taken appart and cleaned.



 -John

 ==




 I'm puzzling over this statement.  The FT-243's I have seen have a
 spring
 that squishes the quartz blank between the electrodes.  They aren't
 plated
 onto the quartz, but they are still in intimate mechanical and
 electrical
 contact.

 -Chuck Harris

 Bob Camp wrote:
 Hi

 The WWII era FT-243 is one example of a crystal that has the active
 portion of the
 electrodes separated from the resonator by an air gap. There are lots
 of
 similar
 holders from that era that do pretty much the same thing.
 Non-contacting
 electrodes are not very new.

 Bob
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Re: [time-nuts] Software for use HP 82350B gpib card.

2014-04-14 Thread J. Forster
FWIW, the HP GPIB cards are only really useful with a complete HP system
that runs HP special software in a complete computer controlled
instrument.

If that is not your intent, get a NI or compatible card. It'll be far
easier in the long run.

YMMV,

-John

===



 Hi,

 I need any software to work with HP5335a or hp 5370B witch work with the
 82350B gpib card.
 Timelab only works with national instruments IEEE488.2 compatible devices.
 Can anyone help?

 Rui Martins

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Re: [time-nuts] Frequency of LC Tank.

2014-04-11 Thread J. Forster
At resonance, an LC looks pure resistive.

For a parallel LC, sample the voltage across the LC and the drive current,
and tweek the frequency until they are in-phase.

For a series LC, sample the voltage across the L or C and tweek as above.

If you want to do it analog, dither the frequency a bit. With the
quardature of the sweep signal as reference for a lock-in. The output of
thye L-I is the tuning signal. (Roughly Pound Locking)

YMMV,

-John

===


 Hi all,

 I'm thinking about an upcoming project, if this is off topic please
 disregard or contact me off list. :)

 I have a large LC tank, with a very lossy inductor. Being driven by a
 pulse width push pull driver, that is digitally controlled. The driver
 circuit will couple through a N:1 transformer. I need to be able to
 adjust the push/pull driver frequency to match the frequency of the tank
 circuit. (See frequency/time is involved :) ) The tank components can
 vary and are not adjustable, so the drive frequency needs to vary.

 I'm thinking some sort of a phase detector may be the way to go. I'm
 just not sure were to sample the V and I signals to look for phase
 differences, or where to get a good clean reference from.

 So the question is, when actively driving a tank circuit, how do you
 know you are driving it with the same frequency ad the same phase it
 naturally oscillates at.

 Any thoughts, suggestions, or readily available papers you guy could
 point me to?

 Thanks!
 Dan
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Re: [time-nuts] Frequency of LC Tank.

2014-04-11 Thread J. Forster
That's why you want to look for the phase of the tank impedance. The phase
goes through zero at resonance. It is far more precise. The steepness of
the phase v. frequency plot is steep w/ a high Q circuit...  flatter w/ a
low Q tank. Either way, it does go through zero at resonance.

The phase v. freq looks kinda like this:

Phase:
  /\
-/  \  /---Freq
 \/

^ resonance



The dither sweep, amplituse measurement, lock-in will tune the oscillator
to maximize the amplituse.

Either on should pretty much steer you to resonance.

-John

==





 I have a large LC tank, with a very lossy inductor. ...

 So the question is, when actively driving a tank circuit, how do you
 know
 you are driving it with the same frequency ad the same phase it
 naturally
 oscillates at.

 If it's lossy, the peak will be broad so tuning the driving frequency
 won't
 be critical.

 How about just measuring the amplitude and tune for a max?  I'm thinking
 of
 something like a diode and R/C filter feeding an ADC.


 --
 These are my opinions.  I hate spam.



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[time-nuts] New England Ham - Electronic Flea Market Dates * April * update]

2014-04-04 Thread J. Forster
 Original Message 
Subject: [BARC-List] [Flea@MIT] New England Ham - Electronic Flea Market
Dates * April * update
From:New England Area  Ham - Electronic Flea Market f...@mit.edu
Date:Thu, April 3, 2014 3:05 pm
To:  f...@mit.edu
--

New England Area   Ham - Electronic Flea Market  ***  DATES ***  2014 P 1
of 2

All events are Ham Radio/ Electronic related except ~_~

***
2014Contact 
Source
~~~

6 Apr Framingham MA FARA @Keefe Tech $5@9 $25/T@7:30  Bev N1LOO 508 626
2012  +

12,13 Apr Wakefield MA Photographica @AmericalCtr ~photo~  John 781 592
2553 F

12 Apr Windsor CT VR+C Mus 115 Pierson LN @8AM Outdoor John 860 673 0518

12 Apr Montreal PQ MARC @StIgnatiusCh $5@9 $8/T@8:15  James 514 990
1965 W

13 Ap Manchester CT NEWS V/UHFConf @Baymount@8 I84x63 MarkK1MAP 413 566
8118 W+

19 Apr S.Portland ME PAWA @AmLegion $6@8 $10/T@6:30 Bryce K1GAX 207 415
0498 W+

20 Apr  Cambridge MA   FLEA at MITMitch 617 253
3776 F
   Third Sunday April thru October

26 Ap Gales Ferry CT RANSON Auction @FireHs $2@9Gary WT1SND 860 884
4218 W+

26 Apr Brookline NH NEARC Antique $5@8:30 $10@7:30Bruce 603 772
7516 F+

27 Ap Middletown NY OCARA @CommCtr $7@9 $12Sell   Neil AC2O 914 490
2001 F

2,3 May Deerfield NH NEARfest XV @FG Mike K1TWF 978 250
1235 R

10 May E Greenbush NY EGARA @FireCo $6@8 $6/T@6  Tom KC2FCP 518 272
1494 W

18 May  Cambridge MA   FLEA at MITMitch 617 253
3776 F

31 May Goshen CT SBARC @FG Rt63  Marc K1CTT 860 672
2659 A+

1 June Bethpage NY LIMARC @Briarcliffe   Dave AK1NS 516 312
8745 A+

7 June Hermon ME PSARA @8 @HS TG@6:30   Jerry K1GUP 207 848
3400 W

7 June Windsor CT VR+C Mus 115 Pierson LN @8AM Outdoor John 860 673 0518

8 June Queens NY HoSARC  Stephen WB2KDG 718 898
5599 A+

***
LAST UPDATE 4-2-14 de W1GSL http://swapfest.usP 1
   List is normally updated twice a month - look for the latest version
***
Additions/ Corrections via e-Mail   w1...@mit.edu  - SUBSCRIBE
   US Mail  W1GSL POB 397082 MIT Br Cambridge MA
02139
(c)2014 W1GSL unlimited reproduction permitted in entirety





New England Area  Ham - Electronic  Flea Market  ***  DATES  ***   2014 
P2 of 2
***
2014Contact 
Source
~~~

15 June  Cambridge MA  FLEA at MITMitch 617 253
3776 F
   Third Sunday April thru October

21 June Newington CT NARL @StMarySch Quentin KB1EWM 860 383
8203 A+

18,19 July Hartford CT ARRL Nat Conv 100th Anv. 860 594
0200 W

20 July  Cambridge MA  FLEA at MITMitch 617 253
3776 F

9 Aug Milo ME PARC @AmLegion  George WA1JMM 207 441
6112 A+

17 August  Cambridge MAFLEA at MITMitch 617 253
3776 F

24 Aug Adams MA NoBARC @BoweFld $5@9 $10S@8 Eric KA1SUN 413 743
9975 F+

6 Sept Windsor CT VR+C Mus 115 Pierson LN @8AM Outdoor John 860 673 0518

7 Sept Ballston Spa NY SCRACES @FG $10@7  Darlene N2XQG 518 587
2385 W+

14 Sept Newtown CT CARA @TownHall$5@8:30 $10/TG $15/T Ron AB1RJ 203 938
7007  +

20 Sept Forestdale RI RIAFMRS @VFW $5/Sp@8   Pete AA1PL 401 639
4484 T

21 Sept  Cambridge MA  FLEA at MITMitch 617 253
3776 F

27 Sept Brookline NH NEARC Antique $5@8:30 $10@7:30   Bruce 603 772
7516 F+

5 Oct Queens NY HoSARC   Stephen WB2KDG 718 898
5599 W+

10,11 Oct Deerfield NH NEARfest XVI @FG  Mike K1TWF 978 250 1235

12 Oct Meriden CT Nutmeg @Sheraton  was Wallingford  John N1GNV 203 440 4973

18,19 Oct Wakefield MA Photographica @AmericalCtr ~photo~  John 781 592 2553

18 Oct Longueuil PQ CRA-RS $10/T@7 $7@9   Martin VE2DNF 405 466
2810 R+

19 Oct  Cambridge MA   FLEA at MITMitch 617 253
3776 F

25 Oct Gales Ferry CT TCARC Auction @FireCo @10Darryl WA1DD 860 443
7799 T

26 Oct Hicksville NY LIMARC @Levittown HallRichie K2KNB 516 694
4937 A

***
LAST UPDATE 4-2-14 de W1GSL http://swapfest.us   P 2 of 2
   List is 

Re: [time-nuts] Airraft Ping Timing

2014-03-25 Thread J. Forster
Yes, and there was an early military positioning system, roughly 1960s /
1970s that worked on Dopplar also. The name escapes me at the moment.

-John

=



 This is how ELT locating satellites work (when not relaying the newer GPS
 data bursts).  Several on another list I watch suggested this pretty early
 on and I guess INMARSAT got the message.  I'd be curious to know if AFRCC
 pointed INMARSAT in that direction.

 Really shows the value of precise and stable time references!




 Date: Mon, 24 Mar 2014 16:06:14 -0700 (PDT)
 From: J. Forsterj...@quikus.com
 To:time-nuts@febo.com
 Subject: [time-nuts] Airraft Ping Timing
 Message-ID:
   13855.12.226.214.5.1395702374.squir...@popaccts.quikus.com
 Content-Type: text/plain;charset=iso-8859-1

 According to a report on FOX, INMARSAT was able to determine the Malasia
 Air followed the southern traectory from the Dopplar of the pings. They
 verified their model by tracking other planes.

 -John

 =

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Re: [time-nuts] Airraft Ping Timing

2014-03-25 Thread J. Forster
Could well be. I never saw the bird, of course. The portable ground
station was roughly the same size as an OD Manpak radio of the period and
read out Lat/Long on LED digital readouts. In retrospect, it may have been
in the early 1980s.

-John

==


 Hi,

 Yes, and there was an early military positioning system, roughly 1960s /
 1970s that worked on Dopplar also. The name escapes me at the moment.

 I think it is Transit.
 See http://en.wikipedia.org/wiki/Transit_(satellite)

 Greetings,
 Pieter.


 -John

 =



 This is how ELT locating satellites work (when not relaying the newer
 GPS
 data bursts).  Several on another list I watch suggested this pretty
 early
 on and I guess INMARSAT got the message.  I'd be curious to know if
 AFRCC
 pointed INMARSAT in that direction.

 Really shows the value of precise and stable time references!




 Date: Mon, 24 Mar 2014 16:06:14 -0700 (PDT)
 From: J. Forsterj...@quikus.com
 To:time-nuts@febo.com
 Subject: [time-nuts] Airraft Ping Timing
 Message-ID:
 13855.12.226.214.5.1395702374.squir...@popaccts.quikus.com
 Content-Type: text/plain;charset=iso-8859-1

 According to a report on FOX, INMARSAT was able to determine the
 Malasia
 Air followed the southern traectory from the Dopplar of the pings. They
 verified their model by tracking other planes.

 -John

 =

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Re: [time-nuts] Airraft Ping Timing

2014-03-25 Thread J. Forster
Certainly, if it's a bent-pipe repeater, that makes extracting the Dopplar
a whole lot easier. Furthermore, since it's unlikely that the missing
plane was the only signal, you can essentially do a differential Dopplar
measurement against other sorces, stationary or moving in a know
trajectory.

-John

==



 On Mon, Mar 24, 2014 at 06:15:57PM -0700, Chris Albertson wrote:
 Yes, word is that they were able to determine the Doppler shift in the
 plane's signal.  I'm surprised this was even recorded but it must have
 been
 in the satellite's telemetry downlink.   Projecting radial velocity and
 constraining it to be close to the earth's surface, I guess determines
 one
 path and the direction on it.


   Perhaps some of the readers here are unaware that the INMARSAT
 F3 in question is a bent pipe repeater in both directions.   It takes a
 C band uplink from the ground and turns it around to L band, and turns L
 band uplinks around to a C band downlink.

   It has 8 spot beams, and one regional beam.   Channelization of
 the uplink and downlink bandwidth and an board switch matrix allows
 various allocations of frequencies and bandwidth to the 9 beams varying
 with load and demand.

   There is no on satellite signal demodulation/modulation or
 protocol processing  for the classic AERO signals to/from the plane ...
 that is ALL done on ground at the GES (in Perth Australia AFAIK).

   This would make it possible for INMARSAT (and others in the
 region tasked with monitoring such things) to capture the actual
 repeated RF from the plane and digitize it - this happens in the ground
 equipment as part of the normal processing anyway - and dumping it to a
 disk array somewhere is certain to be going on, either both inside
 INMARSAT at the GES or at least at other (less public)  sites such as
 Alice Springs.   The C band downlinks are global beams BTW and can
 be received anywhere that sees the satellite.

   As such the quality of the recovered Doppler and other signal
 parameters is very much a function of the stability of the various LOs
 (and sample clocks)  involved, which I believe can correctly be presumed
 to be really high grade both in space and certainly on the ground. AES
 (plane) timing and frequency may be less good, but it is more or less
 locked to the L band downlink timing and frequency signals as reference.

   The newer INMARSAT F4 birds do have DSP processing on the
 satellite, but apparently NOT used for demodulating and processing the
 various control channel signals on the satellite - but just for doing
 beam forming and power allocation for the 120 spot beams these birds
 support.   This of course would impact delay through the satellite
 for precision timing and ranging.

   But so far there are no reports that the F4 POR satellite was
 involved. The high gain antennas on the AES (plane) are fairly
 directional and if they were in use there might not be a lot of signal
 seen on the POR bird.   Not sure if those pings would have been sent
 via a low gain antenna on the AES, but I suspect normally not.

 --
   Dave Emery N1PRE/AE, d...@dieconsulting.com  DIE Consulting, Weston, Mass
 02493
 An empty zombie mind with a forlorn barely readable weatherbeaten
 'For Rent' sign still vainly flapping outside on the weed encrusted pole -
 in
 celebration of what could have been, but wasn't and is not to be now
 either.

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[time-nuts] Airraft Ping Timing

2014-03-24 Thread J. Forster
According to a report on FOX, INMARSAT was able to determine the Malasia
Air followed the southern traectory from the Dopplar of the pings. They
verified their model by tracking other planes.

-John

=

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Re: [time-nuts] Aircraft ping timing

2014-03-22 Thread J. Forster
I'm not so sure it is worth much as parts, except possibly on the black
market. I believe the aircraft industry is big on tracking every part,
cradle to grave. After all an under spec bolt can cause a very expensive
crash.

YMMV,

-John

==



 In retrospect it is kind of crazy that fleet owners will put tracking
 devices on $100K semi trucks and cranes yet $100 million aircraft have to
 rely upon 60 year old technology (Transponders) and ACARS to keep track of
 them. I don't question the utility of TCAS and Transponders, it is just
 the issue of not tracking such a valuable asset that is kind of crazy. Can
 you imagine how much an aircraft like that is worth in spare parts alone?
 -on the world market. If I were an insurer I would be asking questions of
 the industry.

 Orbcomm is kind of troublesome.

 There is a tracking service used mostly by helicopters, which of course
 are notorious for falling off the radar due to low altitude. It is
 Iridium based.

 http://us.spidertracks.com/

 I've used or have know users various satellite messaging services over
 the years. Iridium is good. I was a Globcomm customer, but it was not
 reliable. A friend was on Orbcomm and it had issues as well. 

 --
 Joe Leikhim


 Leikhim and Associates

 Communications Consultants

 Oviedo, Florida

 jleik...@leikhim.com

 407-982-0446

 WWW.LEIKHIM.COM

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Re: [time-nuts] Aircraft ping timing

2014-03-19 Thread J. Forster
It depends on how accurately the bird can measure the round-trip time:

1 us  = ca 500'
10 us = ca 1 mile
100us = ca 10 miles
1 ms  = ca 100 miles

The arcs are loci of constant round trip time, projected on the globe.

-John

===




 My question was on what would be the expected accuracy of the circle's
 radius.

 Antonio I8IOV

Messaggio originale
Da: b...@iaxs.net
Data: 20/03/2014 1.21

They only got one ping from INMARSAT at 64E above the Indian Ocean.
There was no other ping to triangulate the position.

One ping projects a circle on the Earth. The maximum flying range of the
plane determined the ends of the NE and SE arcs of that circle.

The news only gets stranger as time goes on.

Bill Hawkins


-Original Message-
From: iov...@inwind.it
Sent: Wednesday, March 19, 2014 6:46 PM

Those who say the missing aircraft should be searched along the two
corridors, what measurement are they relying on? I think it is a one-way
measurement of time-stamped pings, which implies good synchronization of
clocks between a geosynchronous satellite and a moving aircraft. Antonio
I8IOV




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Re: [time-nuts] 3.0GHz Channel 3 installation in Agilent 53132A counter

2014-03-18 Thread J. Forster
Jim,

You were looking for a 0 Ohm resistor.

Sometimes HP did not, in fact, insert a 0 Ohm resistor component in later
revs of some PCBs. They just added the default 0 Ohmers in etch, between
two vias. Then, if someone wanted to open the link, the etch was cut. I
guess it saved a couple of pennies.

-John

===


 Further checking the service manual indicates that the main board  treats
 pins 9 and 10 of the ribbon cable as CH3code1 and CH3 code2 respectively
 so
 perhaps it's using these as identifiers and it might be worth checking
 that
 those signals are as expected. The prescaler board schematic shows 9 as
 being  connected to +12V and 10 to ground.
 If you don't have access to the component level service manual let me know
 and I'll send you a copy.

 Regards

 Nigel
 GM8PZR




 In a message dated 18/03/2014 18:20:09 GMT Standard Time,
 jsrobb...@earthlink.net writes:

 I hope  this is not too OT.



 I have acquired a 3.0GHz original Channel 3  board for my Agilent 53132A
 counter.  When installed, it reads four  times (4x) the actual frequency.
 I'm wondering if anyone has any experience  with such an installation and
 can
 point me to some setup item or zero ohm  resistor I'm supposed to install.
 All that the manual says is to have it  done by the factory.  That will
 cost
 me more than the board  itself.  Many thanks.



 Jim  Robbins

 N1JR

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Re: [time-nuts] LORAN C 89700 on the air starting Monday

2014-03-01 Thread J. Forster
Paul,

Do you know if this is a prelude to continuous service?

-John

===


 Wildwood will be on air from approximately 1400 on 02 March until 1400 on
 04
 March
 Regards
 Paul
 WB8TSL
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[time-nuts] New England Ham - Electronic Fleamarket Dates * March * update]

2014-03-01 Thread J. Forster
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Re: [time-nuts] New WWVB modulation format receivers

2014-02-22 Thread J. Forster
Carrier extraction by squareing does not work well at all in a high noise
environment. The BPSK limits the narowness of the IF BW.

If you rule out modelling the data stream, and phase switching the signal
before the IF, you have to go w/ something like a Costas Loop.

-John

=


 Hi Paul,

 Without digging through the archives, I'll rely on your memory of that
 past thread!

 The scheme of using the doubler relied on the 100 kHz carrier recovery
 relied on the fact that the 200 kHz bandpass filters, being based on
 quartz crystals, was extremely narrow - on the order of fractions of
 Hz.  This effectively made them frequency-selective integrators (not the
 right word, but you get the idea...) and they were effectively immune to
 noise pulses as they simply could not react quickly.

 IIRC - and I'll have to review my old notes - I used the first 200 kHz
 crystal as a series element and then passed it to a source-follower and
 then a bipolar amplifier with ridiculous gain (e.g. grounded emitter,
 high collector resistance) to form a limiter - and then ran it through
 another 200 kHz crystal and JFET/limiter. It took a couple of seconds
 for the outputs of the two limiters to saturate due to the narrow
 bandwidth and it was extremely tolerant of amplitude variations.  There
 was a phase shift with different amplitude levels, but since, on an FM
 microwave link the amplitude wasn't going to change much, that - and the
 phase shift related to temperature - was inconsequential.

 On this simple recover scheme you could remove the input carrier for
 nearly a second (or blot it out with noise) and there would be almost no
 measurable effect on the output, aside from a phase shift of a few 10's
 of degrees which quickly rectified itself once the signal was returned.
 Had added some better tuning of the resonators I could have likely
 minimized this.  (I happened to have these 200 kHz HC-6 style units in
 my semi-large collection of 40-80's vintage crystals.)

 The trick to replicating such a filter would be to find a suitable
 bandpass filter for the doubled frequency - in this case, a 120.005 kHz
 crystal (or thereabouts) - but it should be practical to convert the
 previously-filtered 60 kHz signal to a frequency for which a suitable
 crystal could be located.

 The 60.003 kHz crystal to which I referred was a bandpass filter rather
 than an oscillator:  The TRF units found in WWVB clocks use these since
 most standard 60.000 kHz units end up being low in frequency when used
 in this sort of mode and they are a bit tricky to pull this far.

 Rather than try to find such a crystal I would probably throw together a
 Tayloe commutating mixer with RC lowpass filtering with a time
 constant of a hundred milliseconds or so - this, filter/mixer being
 clocked at the nominal 60 kHz receive signal.

 I would then follow it with another commutating mixer to translate the
 quadrature signal to any convenient frequency (say, audio - no doubt
 available from the 4060 or 4040 counter I'd be using!) where I would
 then do my frequency doubling and then follow it by yet another
 extremely narrow filter - this time, using an 8-capacitor SCF where I
 could set the detection bandwidth to a tiny fraction of 1 Hz just using
 a bunch of electrolytics!  It should be easy to set the carrier
 detection bandwidth to be a fraction of the information bandwidth so
 that reliable carrier recovery can be maintained under any conditions
 under which the BPSK data could be recovered.

 (An example of an 8-capacitor Roanoake type SCF may be seen here:
 http://ka7oei.com/emm2a_scf.html  )

 This recovered (and slightly filtered) signal, divided-by-two, could
 then be used to synchronously demodulate the original
 frequency-converted signal, at which point one should have a reasonable
 representation of the phase (and amplitude) of the transmitted signal -
 albeit, delayed by a fairly consistent amount.

 Of course, all of this could be done by throwing a 16 bit A/D and DSP
 chip at it, but sometimes there's a simple pleasure in doing it with a
 bunch of 4000 CMOS and a few op-amps, handing the recovered baseband off
 to a PIC or Arduino only at the very end!

 * * *

 Many years ago I built a WWVB carrier recovery circuit using just a
 single-stage LC bandpass filter (to get rid of the VLF powerhouses) and
 an NE565 phase detector along with a 6 MHz VCXO divided down to 60 kHz
 as the comparison.  What amazed me was that even with the practically
 nonexistant filtering in front of the '565 (you really couldn't see the
 60 kHz carrier with the oscilloscope) that '565 would always find its
 way into lock over time - and then it would stay firmly there owing to
 that effect that occurs in which the effective loop bandwidth seems to
 decrease once lock has been achieved.  (WWVB's 45 degree phase shift
 ID would always throw it for a loop, though - pun intended!)

 73,

 Clint
 KA7OEI


 Date: Thu, 20 Feb 2014 22:10:26 -0500
 From: 

Re: [time-nuts] software-defined WWVB receivers

2014-02-22 Thread J. Forster
I was monitoring WWVB against a good local standard and evaluating 60kHz
'seeing' 30 years ago. Sometimes it is beautifully quiet, after a storm
front went through as I remember, at other times it's absolute hash...  to
the point that the HP 117A would not even hold lock.

-John

=


 The randomness of WWVB propagation require incredibly long measurements
 to get an interesting degree of accuracy compared to a GPS driven
 solution.

 The WWVB signal does respond nicely to solar flares if measurements are
 integrated
 over one minute.  Check out the VLF monitoring stuff on my web page.

 On 02/21/2014 12:06 PM, John Seamons wrote:
 As a starting point: Here's an extension of the SAQrx PC sound card
 receiver that supports 192 KHz sample-rate sound cards. Enough to get
 you WWVB.
 https://sites.google.com/site/swljo30tb

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 --
   Chuck Forsberg WA7KGX   c...@omen.com   www.omen.com
 Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc  The High Reliability Software
 10255 NW Old Cornelius Pass Portland OR 97231   503-614-0430

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Re: [time-nuts] WWVB antennas

2014-02-22 Thread J. Forster
I doubt that a 'fractal antenna' is going to do very well at 60 kHz in a
size small enough to fit in a wrist watch.

YMMV,

-John

==


 Google 'fractal antenna'.  Fractal Antennas are a relatively recent (late
 1980's to mid-1990's) discovery/invention.  I have read that they are
 approximately 20% more efficient than normal antennas.

  Jim, KG4FXV



 From: d0ct0r t...@patoka.org
To: Discussion of precise time and frequency measurement
 time-nuts@febo.com
Sent: Saturday, February 22, 2014 12:54 AM
Subject: Re: [time-nuts] WWVB antennas


I am impressed by Casio engineers who created tiny antenna for my wrist
 watch. I don't know how, but that Pathfinder able to catch and decode 60
 khz wwvb in noisy city environment. And it did even better when i was 500
 km north !

:40, Alexander Pummer wrote:
 here are the other 60kHz transmitters:
 http://www.ka7oei.com/wwvb_antenna.html

 U.S. based WWVB transmitter.  As described, it
           could also be used for theUK-based 60 kHz MSF
 http://en.wikipedia.org/wiki/Time_from_NPL    MSF signal  formerly
 the Rugby clock*    *and the
 Japanese 60 kHz JJY  http://en.wikipedia.org/wiki/JJY_
 _our fiend in Australia most likely*_  _*receive the JapaneseWWVB
 73
 KJ6HUN
 Alex
 _*//*_






 On 2/21/2014 12:21 PM, Robert Roehrig wrote:
 John Forster said:

 WWVB is hard to detect w/ a 3-foot diameter HP shielded loop w/
 integral
 preamp  2 stages of mechanical filters. (HP 117A). The other half of
 the
 time it was undetectable. Paul S uses a loop that is much larger.

 I am near Chicago and I have 2 60 kHz antennas. One is a ferrite
 rod type and the other a 5  foot diameter loop. Both are tuned
 and feed identical 2 transistor preamp. The loop does work better.
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-- WBW,

V.P.
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Re: [time-nuts] WWVB antennas

2014-02-22 Thread J. Forster
You are about 1/4 the distance away. Inverse square law.

-John

===




 On 2/21/14, 2:21 PM, Robert Roehrig wrote:
 John Forster said:

 WWVB is hard to detect w/ a 3-foot diameter HP shielded loop w/
 integral
 preamp  2 stages of mechanical filters. (HP 117A). The other half of
 the
 time it was undetectable. Paul S uses a loop that is much larger.

 I am near Chicago and I have 2 60 kHz antennas. One is a ferrite
 rod type and the other a 5  foot diameter loop. Both are tuned
 and feed identical 2 transistor preamp. The loop does work better.

 I am in San Antonio, TX, and I use a Pixelsat untuned loop. It receives
 WWVB just fine. It also receives pretty much everything from DC-20MHz
 just fine.

 --
 Brian Lloyd, WB6RQN/J79BPL
 706 Flightline Drive
 Spring Branch, TX 78070
 br...@lloyd.com
 +1.916.877.5067
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Re: [time-nuts] New WWVB modulation format receivers (NOT)

2014-02-21 Thread J. Forster
Well, I used to be able to see LORAN pulses w/ a 3-inch diameter loop and
a Tek 7000-series 'scope.

WWVB is hard to detect w/ a 3-foot diameter HP shielded loop w/ integral
preamp  2 stages of mechanical filters. (HP 117A). The other half ogf the
time it was undetectable.

Paul S uses a loop that is much larger.

-John

===



 I have an OpenHPSDR Hermes and it has no problem receiving WWVB;
 however, since I live in Fort Collins - Colorado, part of the success
 might just be the strong signal. I wonder if I could just stick a piece
 of wire into one of the channel inputs of a 192Khz sample rate audio
 interface (especially if it had a good low noise mic preamp) and decode
 WWVB from baseband audio!

 John
 AC0ZG


 On 2/20/2014 9:55 PM, wb6bnq wrote:
 Hi Zim,

 With but a very few exceptions most broadband Amateur radfio
 trancievers do not do well below 500 KHz even though many allow for
 tuning below 500 KHz.

 BillWB6BNQ



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Re: [time-nuts] New WWVB modulation format receivers (NOT)

2014-02-21 Thread J. Forster
500 GHz ? Really? How? Even counting 100 GHz is pushing it.

You mean MHz, no?

-John

==



 Well if we are talking about $50 then you have my attention.


 No I am not afraid to use a soldering iron.  Amateur radio is not my main
 interest here.  I have the same compulsion many of you out there seem to
 have, that if I can get more accuracy I want it.  I get that content smile
 on my face when my counter reads a string of zeroes on a measurement that
 is supposed to do just that.

 I am doing a lot better than 1 ppm right now.  I have my counter and
 signal generator agreeing within about 1 Hz at over 500 GHz.  When I get
 one beat in 10 seconds against 20 MHz WWV I have 5 ppb I think.  I am
 close to that but it gets sticky using 20 MHz to communicate, plus the
 signal is only available in my location for a few hours on most days.

 I am doing similar things with voltage but you can't communicate voltage
 over the radio so I don't have that kind of agreement, more like 50 ppm.

 It's all in fun; I have no legitimate need for this accuracy.

 Bob




 On Friday, February 21, 2014 10:26 AM, Chris Albertson
 albertson.ch...@gmail.com wrote:

 On Fri, Feb 21, 2014 at 9:47 AM, Bob Albert bob91...@yahoo.com wrote:
 I looked on line and it seems that these receivers are available for
 about $150 and up.  A little out of my price range right now but I'll
 keep my eyes open.

 Watch the thread on this list about the Arduino based GPSDO.  I think
 you can get the price down to $50.  If all you need is something to
 calibrate frequency counter then all you need is  9 to 10 digit
 accuracy

 I'm going to do this just to prove it can be done for a low two figure
 price.  But first I have to find a decent crystal oscillator that does
 not use up 1/2 of my $40 budget.

 If you want ultimate precision that you need a good GPS antenna in a
 good location,  A high-end timing mode GPS receiver and a high-end
 double oven quartz oscillator.  The cost adds up.   But I think if you
 relax the specifications and shoot only for 9 to 10 digits you can
 greatly reduce the price.


 --

 Chris Albertson
 Redondo Beach, California
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Re: [time-nuts] New WWVB modulation format receivers (NOT)

2014-02-20 Thread J. Forster
Paul Swed posted a working, mostly analog, design here maybe 6 months ago.

-John

=


 Am Wed, 19 Feb 2014 22:45:56 -0800
 schrieb Richard (Rick) Karlquist rich...@karlquist.com:



 On 2/19/2014 9:10 PM, John Marvin wrote:
  I guess my question is who has the right to grant exclusive
  rights for the ability to decode a very simple protocol? Was a
  patent actually granted for this?
 
  John
 

 They have exclusive rights to the IP core for their IC.
 I guess someone else could design their own IC...

 Rick

 Well, if someone comes up with a circuit, I could check how much chip
 area that would consume in a 250nm SiGe BiCMOS... Shouldn't be out of
 range for a serious time nut ;-)

 Florian
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Re: [time-nuts] New WWVB modulation format receivers (NOT)

2014-02-20 Thread J. Forster
At least on the Atlantic coast, the WWVB signal levels jump all over the
place, certainly 40 dB and maybe more.  If a receiver cannot deal w/ that
w/o losing lock, it's nearly useless.

OTOH, LORAN was always a whopping signal.

-John





 Chuck thats easy. Because I could make it work. :-)
 That said there was a post on time-nuts about LORAN C receiver in
 software.
 I responded and have had the great pleasure of communicating with Matthias
 over the last two weeks. I have learned a lot already and he in return has
 a tested LORAN C receiver.
 So with some luck just maybe I can become smart enough to do a better
 design in software on a $15 micro. You still need the RF frontend section
 that I released quite a while ago to time-nuts.
 Regards
 Paul
 WB8TSL



 On Thu, Feb 20, 2014 at 4:02 PM, Chuck Harris cfhar...@erols.com wrote:

 At 60KHz, it shouldn't be out of range of most
 general purpose CPU's, and even the most pathetic DSP.

 Why bother with a hardware solution when software can
 do it more easily?

 -Chuck Harris


 Florian Teply wrote:

 Well, if someone comes up with a circuit, I could check how much chip
 area that would consume in a 250nm SiGe BiCMOS... Shouldn't be out of
 range for a serious time nut ;-)

 Florian
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Re: [time-nuts] New WWVB modulation format receivers (NOT)

2014-02-20 Thread J. Forster
The large amplitude swings happen on a very short time scale too.
Certainly 1 second at times.

-John




 Totally agree with you John as I learned. I knew it was a variable but I
 have seen nights that were crazy and do fit your 40 db. I redesigned the
 AGC to account for that in the fr front end actually.
 Regards
 Paul


 On Thu, Feb 20, 2014 at 4:34 PM, J. Forster j...@quikus.com wrote:

 At least on the Atlantic coast, the WWVB signal levels jump all over the
 place, certainly 40 dB and maybe more.  If a receiver cannot deal w/
 that
 w/o losing lock, it's nearly useless.

 OTOH, LORAN was always a whopping signal.

 -John

 



  Chuck thats easy. Because I could make it work. :-)
  That said there was a post on time-nuts about LORAN C receiver in
  software.
  I responded and have had the great pleasure of communicating with
 Matthias
  over the last two weeks. I have learned a lot already and he in return
 has
  a tested LORAN C receiver.
  So with some luck just maybe I can become smart enough to do a better
  design in software on a $15 micro. You still need the RF frontend
 section
  that I released quite a while ago to time-nuts.
  Regards
  Paul
  WB8TSL
 
 
 
  On Thu, Feb 20, 2014 at 4:02 PM, Chuck Harris cfhar...@erols.com
 wrote:
 
  At 60KHz, it shouldn't be out of range of most
  general purpose CPU's, and even the most pathetic DSP.
 
  Why bother with a hardware solution when software can
  do it more easily?
 
  -Chuck Harris
 
 
  Florian Teply wrote:
 
  Well, if someone comes up with a circuit, I could check how much
 chip
  area that would consume in a 250nm SiGe BiCMOS... Shouldn't be out
 of
  range for a serious time nut ;-)
 
  Florian
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Re: [time-nuts] New WWVB modulation format receivers (NOT)

2014-02-19 Thread J. Forster
Wouldn't that be nice!

They implement a new format which destroys much of the installed
infrastructure, then don't actually produce the 'better replacement'.

How very LORAN!

-John

==



 It may be true that WWVB is sending out a new
 format, but the receivers for it don't seem to
 exist.  The exclusive rights are held by this
 company, which is clearly on hold while it
 tries to find a customer who will pay for a
 wafer run:

 http://eversetclocks.com/

 I've seen this sort of thing many times before.
 Don't be surprised if this goes the way of
 AM stereo, etc.

 Does anyone have any positive news about this?

 Rick
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Re: [time-nuts] Now For Something Completely Different...GPS Security

2014-02-14 Thread J. Forster
You should not denigrate PhotoMultiplier tubes.

They are virtually perfect, almost noiseless, detectors. With the right
photocathode, they are capable of QEs 50%, spectral response from the VUV
to near IR, and dark counts 1 PPS, with maximum count rates 10 MPPS.
Thay can easily have current gains of 10E+6

-John



 Thanks, John
 It's quite clear that at least one far eastern nation, need I name it?
 is going for domination of space, meanwhile feinting with such useless
 stuff as old rotted carriers and the like, nothing up my sleeve, trick
 the first, meanwhile building its own gps fleet, hardened i'll bet, and
 reaching for the moon. DMSP's are OLD stuff (they use pm tubes to get
 that sensitivity; we've looked at both fires and lightning with them for
 more than 30 yrs if I remember right???
 Don

 John C. Westmoreland, P.E.
 Hello Again Time Nuts,

 Sorry - first time I went to that site it was 'OK' but then I see it
 requires registration - here's the story:

 Regards,
 John W.

  February 13, 2014 7:22 pm
 GPS pioneer warns on network's security

 By Sam Jones and Carola Hoyos
  [image: Europe --- This image is a composite of hundreds of pictures
 made
 by the Defense Meteorological Satellite Program (DMSP), which currently
 operates four satellites carrying the Operational Linescan System (OLS)
 in
 low-altitude polar orbits. Three of these satellites record nighttime
 data.
 The DMSP-OLS has a unique capability to detect low levels of
 visible-near
 infrared (VNIR) radiance at night. With the OLS 'VIS' band data it is
 possible to detect clouds illuminated by moonlight, plus lights from
 cities, towns, industrial sites, gas flares, and ephemeral events such
 as
 fires and lightning-illuminated clouds](c)NASA

 The Global Positioning System helps power everything from in-car satnavs
 and smart bombs to bank security and flight control, but its founder has
 warned that it is more vulnerable to sabotage or disruption than ever
 before - and politicians and security chiefs are ignoring the risk.

 Impairment of the system by hostile foreign governments, cyber criminals
 -
 or even regular citizens - has become a matter of national security,
 according to Colonel Bradford Parkinson, who is hailed as the architect
 of
 modern navigation http://www.nae.edu/55030.aspx.

-
 https://twitter.com/intent/tweet?url=http%3A%2F%2Fwww.ft.com%2Fcms%2Fs%2F0%2Ffadf1714-940d-11e3-bf0c-00144feab7de.htmltext=GPS%20pioneer%20warns%20on%20network%E2%80%99s%20security%20-%20FT.comoriginal_referer=http%3A%2F%2Fwww.ft.com%2Fintl%2Fcms%2Fs%2F0%2Ffadf1714-940d-11e3-bf0c-00144feab7de.htmlrelated=fttheworldvia=FT
-
 http://www.facebook.com/sharer.php?u=http%3A%2F%2Fwww.ft.com%2Fcms%2Fs%2F0%2Ffadf1714-940d-11e3-bf0c-00144feab7de.htmlt=GPS%20pioneer%20warns%20on%20network%E2%80%99s%20security%20-%20FT.com+|+US%20%26%20Canada
-
 https://plus.google.com/share?url=http%3A%2F%2Fwww.ft.com%2Fcms%2Fs%2F0%2Ffadf1714-940d-11e3-bf0c-00144feab7de.html
-
 http://www.linkedin.com/shareArticle?mini=trueurl=http%3A%2F%2Fwww.ft.com%2Fcms%2Fs%2F0%2Ffadf1714-940d-11e3-bf0c-00144feab7de.htmltitle=GPS%20pioneer%20warns%20on%20network%E2%80%99s%20security%20-%20FT.com+|+US%20%26%20Canadasummary=Crucial+navigation+system+vulnerable+to+attacksource=Financial%20Times

 More
 ON THIS STORY

- In depth Cyber warfare http://www.ft.com/indepth/cyber-warfare
- Analysis Eyes in the
 skyhttp://www.ft.com/cms/s/0/b42e4e34-0bfa-11e3-8840-00144feabdc0.html
- N Korea jams signals on Seoul
 flightshttp://www.ft.com/cms/s/0/aa557dd4-944f-11e1-bb47-00144feab49a.html
- Growth in cyber attacks
 'unprecedented'http://www.ft.com/cms/s/0/ab3c847a-7e1a-11e3-b409-00144feabdc0.html
- Academy warns on solar
 superstormhttp://www.ft.com/cms/s/0/f30d9e54-7067-11e2-ab31-00144feab49a.html

 ON THIS TOPIC

- Sochi is a cyber war zone, experts
 warnhttp://www.ft.com/cms/s/0/08895c6e-92ae-11e3-8018-00144feab7de.html
- Security chiefs warn over cyber
 defencehttp://www.ft.com/cms/s/0/fd93a898-8e4b-11e3-98c6-00144feab7de.html
- Cyber criminals 'targeting share
 prices'http://www.ft.com/cms/s/0/4a063b34-8de6-11e3-ba55-00144feab7de.html
- Target was not sole cyber attack
 victimhttp://www.ft.com/cms/s/0/5e183dfe-7fb1-11e3-94d2-00144feabdc0.html

 IN US  CANADA

- Obama walks into Asia tensions
 crossfirehttp://www.ft.com/cms/s/0/97d7c088-8edd-11e3-98c6-00144feab7de.html
- Think-tank proposes sovereign debt
 forumhttp://www.ft.com/cms/s/0/19a993fc-7ec1-11e3-8642-00144feabdc0.html
- Democrats prove barrier to Obama on
 tradehttp://www.ft.com/cms/s/0/fcc7adfe-7b9c-11e3-a2da-00144feabdc0.html
- US Midwest thaws after 'polar
 vortex'http://www.ft.com/cms/s/0/563f20ec-7981-11e3-b381-00144feabdc0.html

 If we don't watch out and we aren't prepared, then countries could be
 denied everything from 'navigation' to 'precision weapon delivery', Mr
 Parkinson warned.

 We have to make it more robust ... our 

Re: [time-nuts] Now For Something Completely Different...GPS Security

2014-02-14 Thread J. Forster
There was a lot of work done on GEN III NV devices. They use GaAs
photocathodes w/ high QE. The same photocathode works for PMTs.

Detecting single photons is duck soup w/ a PMT. With modest cooling, you
can get the dark count down to 1/minute or better.

-John

=


 On Fri, Feb 14, 2014 at 7:45 AM, J. Forster j...@quikus.com wrote:

 You should not denigrate PhotoMultiplier tubes.

 They are virtually perfect, almost noiseless, detectors. With the right
 photocathode, they are capable of QEs 50%, spectral response from the
 VUV
 to near IR, and dark counts 1 PPS, with maximum count rates 10 MPPS.
 Thay can easily have current gains of 10E+6


 Really? I used to work on photon-counting systems for photometric
 astronomy. As I recall, the best quantum efficiency I had ever seen was
 around 21%. Which cathode material are you talking about?

 Conversely I remember working on current amps for photodiodes. The
 photodiodes I was playing with had QEs of 90% but, of course, they had no
 current gain. Detecting individual photoelectrons is a challenge.

 Yeah, PM tubes are very cool devices, especially if you cool them to
 reduce
 the emission of thermal electrons. ;-)

 --
 Brian Lloyd, WB6RQN/J79BPL
 706 Flightline Drive
 Spring Branch, TX 78070
 br...@lloyd.com
 +1.916.877.5067



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Re: [time-nuts] How to open solder-sealed OCXOs?

2014-02-02 Thread J. Forster
IMO, the easiest way (non-destructive too!0 is with a high wattage iron or
250 W gun, solder wick or a solder sucker, and an X-Acto knife.

Start in the middle of one side. Heat the joint area and suck out as much
of the solder from the joint area as you can. Slip the knife in the joint
and pry gently after sucking to prevent any residual solder from bridging
the gap. when that area has cooled, move left or right and work your way
around the can. Eventually, when almost all the solder is out, gentle
prying at the joint will pop the top off.

Work slowly and patriently and you'll be able to resolder the can just
about as new.

-John

==






 What's the best way to open an OCXO in the typical solder-sealed tinned
 steel can?  I don't mind destroying the can itself, as long as the innards
 are not harmed. The goal is to run some experiments with thermal impedance
 as discussed here last week, and to ovenize parts of the EFC controller
 for
 better stability.

 Cheers!
 --Stu
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Re: [time-nuts] How to open solder-sealed OCXOs?

2014-02-02 Thread J. Forster
In general, I sandwich the solder wick between the joint and the iron. In
such a joint, the solder is mostly at the edge of the joint:


==OO --- Solder bead
  ===

You don't really want to heat the thing so the solder flows into the joint
more deeply.

-John




 One thing about soldering that many people don't know is
 that the solder is attracted to the hottest part of the joint.

 If you apply the soldering iron to the side of the can, the
 solder will be sucked down into the can, leaving a gap where
 the lid meets the can...

 So, if you want to solder a can shut neatly, apply the soldering
 iron so that it bridges the gap between the lid and the can, and
 apply the solder to the leading edge of the soldering iron just
 where the iron meets the can/lid.

 Also, avoid using eutectic solders (63/37) for any soldering job
 where you want to make a smooth fillet.  Eutectic solders have
 a single melt temperature, with no slush zone, and as such they
 are either fully melted, or not.  They don't thicken and build
 like non-eutectic solder (60/40)

 -Chuck Harris

 J. Forster wrote:
 IMO, the easiest way (non-destructive too!0 is with a high wattage iron
 or
 250 W gun, solder wick or a solder sucker, and an X-Acto knife.

 Start in the middle of one side. Heat the joint area and suck out as
 much
 of the solder from the joint area as you can. Slip the knife in the
 joint
 and pry gently after sucking to prevent any residual solder from
 bridging
 the gap. when that area has cooled, move left or right and work your way
 around the can. Eventually, when almost all the solder is out, gentle
 prying at the joint will pop the top off.

 Work slowly and patriently and you'll be able to resolder the can just
 about as new.

 -John
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[time-nuts] WARNING: MALWARE LINK Re: RE(1): shack

2014-01-29 Thread J. Forster
MALWARE LINK.

-John





 http://conseilax.u.info.bro.html

 ---=-=-=-=-=-=-=-=-=-=-=-=-=--

 From: B Riches 1/29/2014 9:58:05 PM
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Re: [time-nuts] Mini Circuits RF TX question

2014-01-28 Thread J. Forster
Corby,

I'd email or call mini-circuits.

-John

==


 Hi,

 Does anyone know where to find the primary inductance value for Mini
 Circuits RF Transformers?

 I need to know so I can pick one to resonate with a particular capacitor
 at 5Mhz.


 Thanks,

 Corby

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Re: [time-nuts] fast edge, rise time.

2013-12-26 Thread J. Forster
Can you say more about your application? What does your load look like?
What pulse shape? There are well-known solutiuons for most problems.

As Jim said, a lot depends on the energy you need per pulse. What works
for a few mJ will not work for MJ

BTW, SCRs probably switch a lot faster than thyratrons. Years ago, I
cobbled up a high-current SCR pulser with a few thousand uF cap and stud
mounted SCR. It would drive enough current through a length of hook up
wire so that the wire would jump off the desk when pulsed.

-John

=



 On 26 December 2013 16:07, ct1dmk ct1...@gmail.com wrote:
 Hello,

 I'm willing to generate a pulse (of some few hundred volts)
 by discharging a capacitor into a pulse transformer

 There are probably more modern approaches, but a thryatron is one
 possibility. Shame I put on in the dump a few months ago. Maybe though
 they are more suitable for higher voltages.

 Dave
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Re: [time-nuts] fast edge, rise time.

2013-12-26 Thread J. Forster
There are very fast pulsers, some in NIM, that use a charged coax line and
Hg relay to calibrate Pulse Height analyzers. The line length sets the
pulse length; the charging voltage, the pulse height.

-John





 Years ago I had a cousin who ran a civilian calibration lab. For
 calibrating
 scopes, etc, for rise time he used a mercury wetted relay which he claimed
 had nearly instant rise time and no bounce. Seems that he used a resistive
 divider and the mercury relay shunted a portion of the divider. With very
 small inductances and capacitance to slow things down it would seem to be
 very fast.

 Al, k9si, retired



 The target is 4ns, while ideas seemed to be clear at some point, now I'm
 having doubts if better to use a MOSFET or a bipolar transistor
 as the switch element. Experiments with MOSFETs presented me some
 difficulties charging the gate capacitance having some trouble to
 achieve something in the 4ns region. Well 4ns seems hard whatever device
 anyway.

 I would be happy to receive some comments/ideas that may pop out of your
 heads.
 Thanks.


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Re: [time-nuts] fast edge, rise time.

2013-12-26 Thread J. Forster
Are only the amplitude and rep rate variable, or do you vary the width too?

-John

=




 Many thanks to all for the nice tips.

 I may narrow down by saying a few more specs as suggested.
 The pulse would see a somehow unknown load but for a start I
 was suggested to have my source with 50ohm impedance so worst
 case would be a short circuit and therefore the pulse would be a current
 pulse
 and would have some 10Amp. Pulse length about 100ns so only some 0.5mJ
 energy that would die inside the pulse source( this would be the worst
 case).
 The 100us repetition rate make a a very small duty cycle of 1/1000 so
 average power
 maximum 5W.

 Since the amplitude and timing parameters are to be controlled (pulse
 timing come from an FPGA) I really need a solution using that trivial
 switching element fet or bipolar (and can't really do a more exotic
 scheme if I cant electronically control the parameters) also I must use
 a transformer because these short pulse are to be superimposed to
 another voltage and a transformer becomes very handy to do that. I
 interrupt the wire and insert the secondary there to add the pulses.

 The challenge I'm facing is on the device either RF FET or Biplolar tr
 etc. and
 surrounding circuits, transformer, etc. this to achieve the 4ns (or 5ns).
 (the transformer I have in mind is something very similar to those
 transformers
 on the final stages of HF/VHF ham radio amps, coax cables and ferrite
 cores)
 any suggestion regarding devices etc ?...

 Thanks for all comments.

 Luis Cupido.
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Re: [time-nuts] No E-mails

2013-12-19 Thread J. Forster
The server has appeared to be spastic at times, suddenly sending out a
burst of messages, some new, some old, interspersed by nothing.

YMMV,

-John





 Hi,

 seems to me that the server is OK but minimum activity from the people.

 Rgds Ernie.




 -Original Message-
 From: dzorbini dzorb...@netscape.net
 To: time-nuts time-nuts@febo.com
 Sent: Thu, Dec 19, 2013 7:19 pm
 Subject: [time-nuts] No E-mails


 Hello: haven't received any messages for your site past few days, I've
 been
 eading all the comments and questions for years now nothing.
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Re: [time-nuts] MS3106R10SL-4S connector question

2013-12-10 Thread J. Forster
No. Wrong shape.

-John

==



 Wouldn't this be a pin-extractor?

 -Don









 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of Bob Stewart
 Sent: Monday, December 09, 2013 8:53 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] MS3106R10SL-4S connector question

 Take a look at eBay auction 261315795465.  It's a mil-spec connector and I
 don't see any way for the connector pins to come out.  It looks like it's
 probably pressure tight.  You can see the blue plastic pin in the third
 picture.  It's almost like it has something to do with the rubber strain
 relief/enviro shield, but I dunno what.

 Bob





 From: J. Forster j...@quikus.com
To: Bob Stewart b...@evoria.net; Discussion of precise time and
 frequency
 measurement time-nuts@febo.com
Sent: Monday, December 9, 2013 8:33 PM
Subject: Re: [time-nuts] MS3106R10SL-4S connector question


If the contacts are loose and individually extractable/insertable, the
 pin
is probably a dummy pin to substitute for the more expensive brass/gold
pins. This is so the rubber does not distorted over time.

-John


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Re: [time-nuts] MS3106R10SL-4S connector question

2013-12-10 Thread J. Forster
If you are using both wires of a two-pin connector the question is moot.

There are exquisitely detailed docs on connector assembly out there, both
from the manufacturers and agencies like NASA. They include everything
from tool settings, proper locators, to assembly torques.

IMO, unless you are building a spacecraft or somesuch, solder in your
wires, assemble the connector, and be happy.

You can spend years learning about mil connectors.

YMMV,

-John

==


 Thanks Robert.  So, am I right in thinking that you insert the small end
 from the connector side of the rubber grommet and pull it through until
 the thick part just touches the narrowed place in the grommet?  They have
 it sized to imply that.  Are there any assembly documents on the net that
 lay it out in a straightforward manner?  I couldn't find anything related
 to the plastic pin.  Note that this is for future info.  I've assembled my
 connector with 2 wires and given it my blessing.  =)

 Bob





 From: Robert Atkinson robert8...@yahoo.co.uk
To: j...@quikus.com j...@quikus.com; Discussion of precise time and
 frequency measurement time-nuts@febo.com
Sent: Tuesday, December 10, 2013 12:27 PM
Subject: Re: [time-nuts] MS3106R10SL-4S connector question


Hi,
John is correct. The plastic pin is used when a contact position is not
 wired. You put the unwired pin in first and then insert the plastic pin
 behind it, thick end first. It replaces the wire to seal that individual
 hole and also maintain correct seal pressure on the other wires. Blue for
 #16 pins, Red for #20. Not required if you don't need a full
 environmental seal.

Robert G8RPI. CEng, MRAeS, EASA licenced avionics engineer. (i.e. this is
 a definitive answer, I can certify that one of these is correctly
 installed on an aircraft :-)


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Re: [time-nuts] Hp5061A K15 distribution amp

2013-12-09 Thread J. Forster
Is this a rebadged 5087A?

-John




 10 MHz 6 output amps, 1 input amp. Matches 5061A Cs standard.
 fs, contact me off list please.
 Don
 --
 The power of accurate observation is commonly called cynicism by those
 who have not got it.
  -George Bernard Shaw
 --
 Dr. Don Latham AJ7LL
 Six Mile Systems LLC
 17850 Six Mile Road
 POB 134
 Huson, MT, 59846
 VOX 406-626-4304
 Skype: buffler2
 www.lightningforensics.com
 www.sixmilesystems.com


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Re: [time-nuts] MS3106R10SL-4S connector question

2013-12-09 Thread J. Forster
If the contacts are loose and individually extractable/insertable, the pin
is probably a dummy pin to substitute for the more expensive brass/gold
pins. This is so the rubber does not distorted over time.

-John
=


 I got a GPS Source splitter recently and since my little Adafruit doesn't
 have enough power to run it I got an MS3016R connector to hook up external
 power.  What I can't figure out is what is that blue plastic pin for that
 comes in the package?

 Bob - AE6RV
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Re: [time-nuts] MS3106R10SL-4S connector question

2013-12-09 Thread J. Forster
It's what I said. A blanking pin for the hole in the rubber seal, except
that it's only for the seal, not the whole connector.

-John




 Take a look at ebay auction 261315795465.  It's a mil-spec connector and I
 don't see any way for the connector pins to come out.  It looks like it's
 probably pressure tight.  You can see the blue plastic pin in the third
 picture.  It's almost like it has something to do with the rubber strain
 relief/enviro shield, but I dunno what.

 Bob





 From: J. Forster j...@quikus.com
To: Bob Stewart b...@evoria.net; Discussion of precise time and
 frequency measurement time-nuts@febo.com
Sent: Monday, December 9, 2013 8:33 PM
Subject: Re: [time-nuts] MS3106R10SL-4S connector question


If the contacts are loose and individually extractable/insertable, the
 pin
is probably a dummy pin to substitute for the more expensive brass/gold
pins. This is so the rubber does not distorted over time.

-John


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Re: [time-nuts] Man killed in quartz crystal accident

2013-11-26 Thread J. Forster
Far more people are killed and injured every year by car crashes and
smoking than by all civilian incidents, or even atomic warfare, in
history.

-John

===

 This quartz crystal accident is a canary in the coal mine that
 demonstrates how poor safety and regulations often work in the real world.
  What I feel is a bigger concern is the similar risks we have with our
 aging Nuclear reactors. Many are over twenty-five years past their
 intended life.
 The problem is today they are paid for, and the government insures them,
 so they are very profitable. The question is do any of the safety
 officials and inspectors really have the authority to close them when they
 become inherently unsafe? I don't think so. I think they will run until
 one catastrophically fails. I think government oversight is far to often
 an illusion.

 Thomas Knox



 Date: Tue, 26 Nov 2013 00:51:49 -0500
 From: n...@verizon.net
 To: time-nuts@febo.com
 Subject: Re: [time-nuts] Man killed in quartz crystal accident

 I oncecancelled my purchase of a home when I found a sign nearby
 indicating an
 underground high pressure gas transmission line. These days they're
 probably
 removing the signs.

 Let's hope the government doesn't decide that precise timekeeping is of
 strategic value and not permitted amongst ordinary people.


 On 11/25/2013 11:49 PM, Joe Leikhim wrote:
  If you really want to lose sleep, think about those old rusty 24 inch
 gas
  mains running under your neighborhood like in San Bruno California.
 The
  warning signs were present there as well.
 
  Now thanks to Homeland Security you can't find accurate gas
 transmission maps
  on-line unless you are cleared. So if you are buying a house in a
 particular
  neighborhood, do some walking around looking for signs of buried
 facilities.
 

 ___
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Re: [time-nuts] Man killed in quartz crystal accident

2013-11-26 Thread J. Forster
It's a matter of perception of risk.

Opponents of nuclear power have successfully propagandized risks out of
all proportion compared to other risks.

There are many more rational things to worry about, including a rogue
state or terror group acquiring CW, BW. And, CW and BW are much easier to
make/get than nuclear stuff. If you can brew beer, you can make crude BW
agents. Furthermore BW spreads by itself.

The world has not really seen a serious BW incident AFAIK, but antibiotic
resistant strains are rampant in US healthcare. A serious BW attack would
make those issues seem trivial.

Furthermore, nuclear materials can be detected pretty easily. AFAIK, there
are no readily available detectors for virii or bacteria.

Scientists do nobody any favors by overblowing some risks to fit their
political agenda.

-John

===



 So throw caution to the wind because other things kill people?  100% of
 people die from something.  So we shouldn't try to keep from killing
 bystanders because they are going to die anyway?  Sounds a bit sociopathic
 to me.

 Doc

 Sent from mobile

 On Nov 26, 2013, at 7:34 AM, J. Forster j...@quikus.com wrote:

 Far more people are killed and injured every year by car crashes and
 smoking than by all civilian incidents, or even atomic warfare, in
 history.

 -John

 ===

 This quartz crystal accident is a canary in the coal mine that
 demonstrates how poor safety and regulations often work in the real
 world.
 What I feel is a bigger concern is the similar risks we have with our
 aging Nuclear reactors. Many are over twenty-five years past their
 intended life.
 The problem is today they are paid for, and the government insures
 them,
 so they are very profitable. The question is do any of the safety
 officials and inspectors really have the authority to close them when
 they
 become inherently unsafe? I don't think so. I think they will run until
 one catastrophically fails. I think government oversight is far to
 often
 an illusion.

 Thomas Knox



 Date: Tue, 26 Nov 2013 00:51:49 -0500
 From: n...@verizon.net
 To: time-nuts@febo.com
 Subject: Re: [time-nuts] Man killed in quartz crystal accident

 I oncecancelled my purchase of a home when I found a sign nearby
 indicating an
 underground high pressure gas transmission line. These days they're
 probably
 removing the signs.

 Let's hope the government doesn't decide that precise timekeeping is
 of
 strategic value and not permitted amongst ordinary people.


 On 11/25/2013 11:49 PM, Joe Leikhim wrote:
 If you really want to lose sleep, think about those old rusty 24 inch
 gas
 mains running under your neighborhood like in San Bruno California.
 The
 warning signs were present there as well.

 Now thanks to Homeland Security you can't find accurate gas
 transmission maps
 on-line unless you are cleared. So if you are buying a house in a
 particular
 neighborhood, do some walking around looking for signs of buried
 facilities.

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Re: [time-nuts] Crude Survey Technique

2013-11-22 Thread J. Forster
If the telescope on your transit can go to your lattitude, sight Polaris
and you're done after a simple calculation.

-John




  Stephen -


  [time-nuts] Crude Survey Technique



  Thanks for describing your method. I am learning a lot. here is agovt web
 site that will give the compass correction for any long and lat. Here in
 KS the magnetic pole is about 2.3 degrees to the east.

 Once all the ideas are in, I will put together a summary.

 I have a number of the required tools, compass, several T-bolts,
 surveyor's transit, tall poles, laser level, and bulls-eye levels.
 So with all of these good ideas I am sure I will get it right. It will be
 interesting to cross check the various methods.

 It also occurred to me that I could buy a 3 ft length of hardened steel
 shafting, wrap a couple of dozen turns of # 6 around it and then connect
 it to a big lead acid battery via a 200 Amp fuse. Should result in a 3 ft
 long compass needle. You only get to use the fuse once though!

 Thanks to all  -john



 -Original Message-
 From: time-nuts-request time-nuts-requ...@febo.com
 To: time-nuts time-nuts@febo.com
 Sent: Fri, Nov 22, 2013 6:29 am
 Subject: time-nuts Digest, Vol 112, Issue 75


 Send time-nuts mailing list submissions to
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 When replying, please edit your Subject line so it is more specific
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 Today's Topics:

1. Re: Motorola M12+ (Azelio Boriani)
2. Re: Isolation achieved by opamp based isoamp? (Bruce Griffiths)
3. Re: DMTD: Mixer DC offset will result in time offset at
   zero-crossing detector out? (Bruce Griffiths)
4. Re: Crude Survey Technique (Stephan Sandenbergh)
5. Re: Strange 100ns jumps on Motorola M12+T (Bob Camp)
6. Re: DMTD: Mixer DC offset will result in time offset at
   zero-crossing detector out? (Stephan Sandenbergh)


 --

 Message: 1
 Date: Fri, 22 Nov 2013 11:45:17 +0100
 From: Azelio Boriani azelio.bori...@screen.it
 To: Discussion of precise time and frequency measurement
   time-nuts@febo.com
 Subject: Re: [time-nuts] Motorola M12+
 Message-ID:
   cal8xpmppu6e2g90veafkzmdqvpmse+ql+uxr6+rcvhuueyd...@mail.gmail.com
 Content-Type: text/plain; charset=ISO-8859-1

 Strange item... it has an M12+ and a supporting board full of
 components. Protocol translation from 12-channel to 8-channel? The
 link to the PDF file returns a 404.

 On Fri, Nov 22, 2013 at 9:32 AM, Pascual Arbona Lopez
 p.arb...@securimar.com wrote:
 I am wondering if this is a sustitute of  the original oncore VP
 receiver for
 the Z3801 -Z3805. (E-pay 281161070304 )
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 --

 Message: 2
 Date: Sat, 23 Nov 2013 00:18:50 +1300
 From: Bruce Griffiths bruce.griffi...@xtra.co.nz
 To: Discussion of precise time and frequency measurement
   time-nuts@febo.com
 Subject: Re: [time-nuts] Isolation achieved by opamp based isoamp?
 Message-ID: 528f3d9a.5090...@xtra.co.nz
 Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 Stephan Sandenbergh wrote:
 Something that would be interesting to know is if certain opamps are
 better
 suited toward S12 isolation than others. I guess at the expense of noise
 floor and 1/f corner one could cascade two opamps to improve the S12
 isolation further.


 The flicker noise corner of an opamp may be lower than you think.
 Current feedback opamps may have higher flicker noise corners than volt
 feedback opamps
 As soon as you are looking at frequencies of 100MHz you are probably
 left
 with the discrete options in any way.

 There are 1GHz and 10GHz opamps available.

 Bruce

 On 22 November 2013 11:45, Stephan
 Sandenberghssandenbe...@gmail.comwrote:


 Thanks for the spec. I suspected that it would be in that ball park.

 The discrete transistor type amplifiers achieve around 120dB or more at
 10MHz. But, they are a lot more effort to implement than the opamp
 designs.

 I believe the transformer in this case is for ground loop isolation
 rather
 than S12 isolation.


 On 21 November 2013 20:20, Charles
 Steinmetzcsteinm...@yandex.comwrote:


 Corby wrote:

   This opamp buffer has 80-90db isolation.


 That is typical at 5 to 10 MHz *if* (i) all of the splitting is done
 on
 the input side (i.e., each output has its own op amp), and (ii) the
 splitter and all of the construction (grounds, shielding, etc.) is
 done
 correctly.

 If any splitting is 

Re: [time-nuts] Crude Survey Technique

2013-11-22 Thread J. Forster
, no need to bog the list down
 with this.

 Didier KO4BB
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 --

 Message: 6
 Date: Fri, 22 Nov 2013 11:19:51 -0600
 From: Brian Lloyd br...@lloyd.com
 To: j...@quikus.com j...@quikus.com,  Discussion of precise time
   and frequency measurement time-nuts@febo.com
 Subject: Re: [time-nuts] Crude Survey Technique
 Message-ID:
   CAE3hgTdk3+g-hjik8EkgSf6TuXxtVqHxUF3zKzGrNZ_HFi=v...@mail.gmail.com
 Content-Type: text/plain; charset=ISO-8859-1

 On Friday, November 22, 2013, J. Forster wrote:

 If the telescope on your transit can go to your lattitude, sight Polaris
 and you're done after a simple calculation.


 This is the simplest high-accuracy solution. Celestial navigation is your
 friend.

 A magnetic compass is the simplest solution. Magnetic variation is found
 on
 all VFR aviation navigation charts.

 2 degrees is an interesting number. It seems either too accurate or not
 accurate enough for most applications I can think of.

 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts



 --
 Brian Lloyd, WB6RQN/J79BPL
 706 Flightline Drive
 Spring Branch, TX 78070
 br...@lloyd.com
 +1.916.877.5067


 --

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 **


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Re: [time-nuts] Crude Survey Technique

2013-11-21 Thread J. Forster
For something that crude, I'd consider taking a sight on Polaris. If you
note the time and do the math, you can probably do better than your
bounds.

Also, there is almost certainly an app somewhere to do the math for you. I
think tha reeuction info was in Bowditch or the Nautical Almanac.

FWIW,

-John

===





 In message 8d0b5020292d91e-cc0-4b...@webmail-vm026.sysops.aol.com,
 johncroos@
 aol.com writes:

 I wish to establish a north south line on my property to an
accuracy of +/- 2 degrees.

 First of all, at that level of precision you will have to decide what
 you mean by north south ?

 Magnetic ?  Geodetic ?  (if so: Which Datum ?)  Meridian ?

 The base line would be 300 ft

 So your east-west precision needs to be tan(2)*300ft = 10.5 ft.

 I don't think you can do that with a single band GPS.

 If you can locate suitable landmarks, you may be able to do with
 the arial photograph on maps.google.com (or similar servce) but
 you need to get coordinates figured out (not trivial!)

 I would raise a pole or other marker at one end (N or S), calculate
 when a suitable celestial object crosses your designated line and
 that to triangulate the opposite end.

 --
 Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
 p...@freebsd.org | TCP/IP since RFC 956
 FreeBSD committer   | BSD since 4.3-tahoe
 Never attribute to malice what can adequately be explained by
 incompetence.
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Re: [time-nuts] Crude Survey Technique

2013-11-21 Thread J. Forster
The INS has to be 'aligned' before takeoff.

Remember, the earth is spinning on an axis, and the INS's platform is
stable in Inertial space.  If you know the INS is sitting on the ground
(or even deep in a mine shaft) it's just trig. Nothing external needed,
not even stars.

-John





 The simplest ones do it by difference in position from one fix to another.
 no need for a map for True North, just trig. For Magnetic North you need a
 map with variation data. More advanced units have magnetic sensors and
 accelerometers. An interesting question that I once spent some hours
 discussing in a pub (bar) about 20 years ago is how does an inertial
 navigation unit determine True North without the aircraft moving? No
 magnetic sensors, just a self contained black box. We know it did it
 because we had just finished installing one and watched it do it. We
 worked it out after a few pints ;-) Hint, it takes longer the closer to
 the pole you are. For Magnetic headings you still need a table of
 variations. At least one common aircraft inertial nav unit has magvar
 tables that are several years out of date with the OEM (well current IP
 owner, they bought out the real OEM) say it's not possible to update them!

 Robert G8RPI.




 
  From: Neville Michie namic...@gmail.com
 To: Discussion of precise time and frequency measurement
 time-nuts@febo.com
 Sent: Thursday, 21 November 2013, 21:46
 Subject: Re: [time-nuts] Crude Survey Technique


 How do the car mounted GPS guidance devices find North?
 Is it by deciding which direction you are moving on the map that they have
 stored?
 It is amazing how quickly they show the orientation of the map/your
 direction of travel.
 Do they have a sensor to register when you turn a corner?
 What they do does not seem possible from just a series of position fixes.
 cheers,
 Neville Michie





 On 22/11/2013, at 7:45 AM, tmil...@skylinenet.net wrote:

 If you want true north, set up a camera that has time or bulb shutter at
 the south end of your property. Put in a marker stake. take a time
 exposure at night with the camera facing north. If you expose for about
 30 minutes, you will get a landscape with the stars rotating around the
 north star. You can then mark the north location on your property under
 the north star.

 A compass siting can give the mag north.

 
 From: time-nuts-boun...@febo.com time-nuts-boun...@febo.com on behalf
 of Brian Lloyd br...@lloyd.com
 Sent: Thursday, November 21, 2013 2:04 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Crude Survey Technique

 On Thu, Nov 21, 2013 at 12:52 PM, johncr...@aol.com wrote:

 I wish to establish a north south line on my property to an accuracy of
 +/- 2 degrees.
 Could this be done by loading a T-bolt, Antenna, Power source, and
 laptop
 into my
 little red wagon? The idea being to find two positions several hundred
 ft
 apart where either LH or T-bolt Mon report the same latitude? Will
 either
 of these programs report to sufficient accuracy? The base line would be
 300
 ft, though more is possible.I realizes that the T-bolt is not a survey
 device, but I can spend several hours fixing each position if required.


 True north or magnetic north? In any case, a good lensatic compass and
 knowing your magnetic variation should easily get you to within 2
 degrees
 and is a lot easier than doing a survey with your GPS.


 --
 Brian Lloyd, WB6RQN/J79BPL
 706 Flightline Drive
 Spring Branch, TX 78070
 br...@lloyd.com
 +1.916.877.5067
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 CONFIDENTIALITY NOTICE: The information contained in this electronic
 message is confidential information intended for the use of the
 individual or entity named above. If the reader of this message is not
 the intended recipient, or an employee or agent responsible for
 delivering this electronic message to the intended recipient, you are
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 is strictly prohibited. If this message contains non-public personal
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Re: [time-nuts] Crude Survey Technique

2013-11-21 Thread J. Forster
FWIW, my Garmin Nuvie 40 (el cheapo) only takes moving maybe 10' to get a
rough compass direction. I doubt it has any gyro or accelerometers.

-John

===


 Hi Neville:

 Most low cost hand held and car GPS receivers can only display direction
 based on changes in position.
 While on vacation in Japan I was using a hand held Garmin 12-channel GPS,
 but when standing still the compass did not
 work, I needed to run a block to get a bearing.
 My Honda van GPS includes a gyroscope so it know you have turned even in
 an urban canyon where there may not be enough
 satellites visible to get a fix.

 Have Fun,

 Brooke Clarke
 http://www.PRC68.com
 http://www.end2partygovernment.com/2012Issues.html

 Neville Michie wrote:
 How do the car mounted GPS guidance devices find North?
 Is it by deciding which direction you are moving on the map that they
 have stored?
 It is amazing how quickly they show the orientation of the map/your
 direction of travel.
 Do they have a sensor to register when you turn a corner?
 What they do does not seem possible from just a series of position
 fixes.
 cheers,
 Neville Michie





 On 22/11/2013, at 7:45 AM, tmil...@skylinenet.net wrote:

 If you want true north, set up a camera that has time or bulb shutter
 at the south end of your property. Put in a marker stake. take a time
 exposure at night with the camera facing north. If you expose for about
 30 minutes, you will get a landscape with the stars rotating around the
 north star. You can then mark the north location on your property under
 the north star.

 A compass siting can give the mag north.

 
 From: time-nuts-boun...@febo.com time-nuts-boun...@febo.com on behalf
 of Brian Lloyd br...@lloyd.com
 Sent: Thursday, November 21, 2013 2:04 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Crude Survey Technique

 On Thu, Nov 21, 2013 at 12:52 PM, johncr...@aol.com wrote:

 I wish to establish a north south line on my property to an accuracy
 of
 +/- 2 degrees.
 Could this be done by loading a T-bolt, Antenna, Power source, and
 laptop
 into my
 little red wagon? The idea being to find two positions several hundred
 ft
 apart where either LH or T-bolt Mon report the same latitude? Will
 either
 of these programs report to sufficient accuracy? The base line would
 be 300
 ft, though more is possible.I realizes that the T-bolt is not a survey
 device, but I can spend several hours fixing each position if
 required.

 True north or magnetic north? In any case, a good lensatic compass and
 knowing your magnetic variation should easily get you to within 2
 degrees
 and is a lot easier than doing a survey with your GPS.


 --
 Brian Lloyd, WB6RQN/J79BPL
 706 Flightline Drive
 Spring Branch, TX 78070
 br...@lloyd.com
 +1.916.877.5067
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Re: [time-nuts] Crude Survey Technique

2013-11-21 Thread J. Forster
As I said before, the RA and Dec of Polaris is well known.

Spherical trig and the Siderial Time will give you the offset from the
true pole in Az and El.

With corrections for refraction, this is good to better than an arc-second.

-John

==




 On Thu, Nov 21, 2013 at 12:45 PM,  tmil...@skylinenet.net wrote:
 If you want true north, set up a camera that has time or bulb shutter at
 the south end of your property. Put in a marker stake. take a time
 exposure at night with the camera facing north. If you expose for about
 30 minutes, you will get a landscape with the stars rotating around the
 north star. You can then mark the north location on your property under
 the north star.

 I vote this suggestion as the winner.  The north ster is offset a
 little from the pole but if will make an arc like the others and you
 can find it's center.  This method could get you to better than a
 degree..
 --

 Chris Albertson
 Redondo Beach, California
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Re: [time-nuts] Isolation achieved by opamp based isoamp?

2013-11-21 Thread J. Forster
A good transformer has very high CMRR. The purpose of the interwinding
shield is to prevent CM on the input swide, coupling through to the buffer
input, and yes, it should be well grounded. However, even if the shield is
not perfectly grounded, it greatly reduces the interwinding coupling
capacitance. Model it as a C-L reactive voltage divider.

-John

=



 One thing to keep in mind is that isolation through shielding usually
 results in much greater capacitance to ground (actually to the shield)
 from
 both input and output windings.

 Therefore, the actual isolation in practice is totally driven by how good
 the ground to the shield is.

 At RF, any inductance in series with the shield's connection to ground
 will
 degrade the isolation. Not a problem at 60Hz, but certainly a problem as
 the frequency gets higher.

 Didier KO4BB




 On Thu, Nov 21, 2013 at 8:28 AM, J. Forster j...@quikus.com wrote:

 Looking quickly at the prints on the site, the isolation is provided by
 the transformer, not the active circuitry. The transistors/op-amps are
 just buffers for the output.

 That means that the isolation is determined, for the most part, by the
 transformer design, so:

  A bifilar wound torroid would have relatively poor isolation,
  Two windings on opposite ends of a ferrite rod much better.

 Some (power line) ultra-isolation transformers have a shield between the
 primary and secondary, and I don't see any reason that could not be done
 at RF. The objective is, of course, to minimize the capacitance between
 the windings. Topaz got 0.001 pF on a 1 kW unit as I remember.

 -John

 =






  Hi,
 
  I'm curious about the level of isolation that is achieved by an opamp
  based
  isoamp. I'm referring to ones described here on Bruce Griffiths' page:
  http://www.ko4bb.com/~bruce/IsolationAmplifiers.html
 
  Anyone has a number for this?
 
  I've tried googling it, but the results are mostly filled with the
 other
  kind of iso amplifier where isolation refers to galvanic isolation.
 
  Regards,
 
  Stephan.
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Re: [time-nuts] Isolation achieved by opamp based isoamp?

2013-11-21 Thread J. Forster
Looking quickly at the prints on the site, the isolation is provided by
the transformer, not the active circuitry. The transistors/op-amps are
just buffers for the output.

That means that the isolation is determined, for the most part, by the
transformer design, so:

 A bifilar wound torroid would have relatively poor isolation,
 Two windings on opposite ends of a ferrite rod much better.

Some (power line) ultra-isolation transformers have a shield between the
primary and secondary, and I don't see any reason that could not be done
at RF. The objective is, of course, to minimize the capacitance between
the windings. Topaz got 0.001 pF on a 1 kW unit as I remember.

-John

=






 Hi,

 I'm curious about the level of isolation that is achieved by an opamp
 based
 isoamp. I'm referring to ones described here on Bruce Griffiths' page:
 http://www.ko4bb.com/~bruce/IsolationAmplifiers.html

 Anyone has a number for this?

 I've tried googling it, but the results are mostly filled with the other
 kind of iso amplifier where isolation refers to galvanic isolation.

 Regards,

 Stephan.
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Re: [time-nuts] Loran

2013-11-14 Thread J. Forster
What's the signal strength like?

-John

===



 Oh that is indeed interesting that they are moving forward.
 The GRI is 89700.
 SRS700 locked and looking good.
 Just brought the Austron 2100 and 2100F on line.
 The 2100 is tied to the local RB and the f is tied to the HP3801.
 The SRS700 looks at the RB.
 I pulled the Austron 2000 out of the rack several months ago.
 Needed the space.
 Regards
 Paul
 WB8TSL. Near Boston.


 On Thu, Nov 14, 2013 at 2:41 PM, Tom Van Baak t...@leapsecond.com wrote:

  Well lets see. Just warming up the srs700.
  UrsaNav must have received some support $
  Regards
  Paul
  WB8TSL

 Paul,

 See below, via Adobe OCR on a JPG press release:

 ---

 From: UrsaNav Press Contact
 Sent: Thursday, November 14, 2013 10:31 AM
 Subject: UrsaNav Accepts eLoran Transmitter from Nautel

 UrsaNav News Release November 14, 2013

 Two Companies - One Dream

 UrsaNav Accepts Delivery of First Production Nautel NlAO eLoran
 Transmitter

 Bedford, Massachusetts, USA.- After extensive Final Acceptance Testing
 at
 Nautel's Hackett's Cove, NS facility, UrsaNav has accepted delivery of
 the
 first production NL40 Loran-C and Enhanced Loran (eLoran) transmitter.
 This
 seventh generation Loran transmitter technology is the culmination of
 over
 six years of collaborative development between the two companies.

 The transmitter successfully met or exceeded all of the requirements of
 the u.s. Coast Guard Specification of the Transmitted Loran-C Signal.
 Testing was conducted into a simulated antenna matching the
 characteristics
 of a u.s. Coast Guard standard 625-foot Top-Loaded Monopole. The
 NL-Series transmitters are capable of transmitting Loran-C, eLoran,
 Chayka,
 and eChayka in any combination at power levels exceeding one megawatt.
 They
 are qualified for today, and prepared for tomorrow.

 UrsaNav's President, Charles Schue, shown accepting the transmitter from
 Nautel's President, Peter Conlon, commented: Resilient PNT begins with
 complementary technologies, layered one upon the other in such a way
 that
 the user is ensured improved continuity of operations over a sole-source
 solution. eLoran is the terrestrial coprimary complement to GNSS, and
 our
 technology makes eLoran the most economical, efficient, and wide-area
 alternative when GNSS is not available.

 UrsaNav provides the world's most advanced solutions for Low Frequency
 Alternative Positioning, Navigation, Timing, and Data, including
 high-performance eLoran Receiver, Command and Control, and Differential
 Loran technology. We are the exclusive, global, reseller of Nautel's
 industry-leading, high-power, Low Frequency transmitters for
 Loran/eLoran
 and Chayka/eChayka.

 ---
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[time-nuts] It's About Time :)

2013-10-09 Thread J. Forster
From another list:

http://www.youtube.com/watch?v=9CpsPgXyIm8

-John

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[time-nuts] [Fwd: [Boatanchors] FW: [ndblist] WWVB etc]

2013-10-08 Thread J. Forster
FORWARDED:

Sorry, I could not resist!!

73,
Billl, WA2DVU
Cape May
---

WWVB has been sold to Clear Channel

http://www.lownoiserecords.com/wwv_the_tick.html

-

-John

===



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Re: [time-nuts] How hard is it to detect a GPS Jammer?

2013-10-07 Thread J. Forster
On spacecraft hardware, even though something is a bit old, it does make
sense to use it.

Space qualifying a piece of hardware is very, very expensive, because it
requires a lot of shake and bake plus thermal vaccuum and other things.

Furthermore, there are always unknowns.

Do YOU really want to see a Billion dollar mission go wrong, because you
used a new, unproven, design of Cammand Receiver or Sequencer?

In my view, if you are going into the unknown, you want to use the best
available, tested and proven, stuff you can get whereever you can.

Remember, many of the launch vehicles still used were made in the 1950s or
1960s, and sat in a missile silo somewhere, as ICBMs for 30+ years. Until
fairly recently, the Atlas used sub-mini vacuum tubes.

I'm not against inovation, but it's not necessarily about saving a few
bucks when older gear is used.

YMPV,

-John

===




 On 10/7/13 7:46 AM, Collins, Graham wrote:

 Indeed, the inexpensive DVB-T dongles are showing up in many places
 including as David noted, decoding GPS.


 The AMSAT Fun Cube Dongle is a very capable and interesting device.
 Interestingly it uses the same Elonics E4000 front end chip that many
 of the inexpensive DVB-T devices do. Apparently Elonics is no longer
 in business and the inexpensive DVB-T devices using this chip are
 becoming less common. The DVB-T devises using the R820T chip are
 becoming the preferable versions when those with the E4000 cannot be
 found. I wonder if the Fun Cube Dongle will be likewise changed
 (perhaps it already has).


 This illustrates is the fundamental problem with leveraging cheap
 consumer or government surplus gear.  The hacker community moves much
 slower than the commercial one, so you wind up with projects requiring
 things that are no longer sold.  It's particularly endemic in the
 amateur radio community where we are always repurposing something that
 hasn't been made for 30 years.  But it makes it hard for the new
 entrant, who doesn't have a box full of old MASTR-II VHF radios or Bell
 202 modems or whatever sitting around.

 But the existence of that gear in some folks's garages tends to ossify
 the development.  How many Bell 202 modems are still in use? But VHF
 packet radio is 202 compatible, because every product made for the last
 30 years was compatible with the 202.  Not because it's inherently good,
 but because you want to be compatible with the other people, and there's
 a sort of rolling compatibility.

 (Amateur radio is not the only instance of this. The Scientific
 Spaceflight community is the same.  We love to use spares from previous
 missions to reduce costs, but that brings along the need to be
 compatible with the interfaces of those spares.  As a result,
 MIL-STD-1553B Notice 2 or Notice 4 is still used on spacecraft, even if
 it's not the most appropriate, lowest power, etc.)


 For a particularly interesting example, look at the plethora of versions
 of the WRT-54G WiFi router popular with hackers; there's about 50
 versions listed on the DD-WRt website.  Some of he versions  are
 amenable to dropping in a new OS and/or software, others are not, and
 still others are modifiable (as in cutting traces, soldering, adding
 parts and/or connectors) to put in new software.

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Re: [time-nuts] NIST off-line

2013-10-01 Thread J. Forster
What did you expect? It's the Washington Monument strategy...  again. Just
like the 'sequester'.

When you take a lollypop away from a kid, it kicks and screams and tries
to make as much fuss as possible. Sometimes, just letting the kicking and
screaming go on is the best way to teach a badly spoilt child things are
not really as bad as it imagines.

YMMWV,

-John

===



 NIST is off-line due to the shutdown.

 http://www.nist.gov/pml/div688
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Re: [time-nuts] time-nuts Digest, Vol 111, Issue 2

2013-10-01 Thread J. Forster
I would really like someone to justify the shutting off of an automated
system.

And, why not WWV and WWVB also?

If there had not been a bill for the DoD, would GPS have been shut off also?

-John

==

 What a load of crap; shut down the NIST web-based system that is
 self-running and costs zero dollars as a punitive measure to kill us for
 someone else's boondoggle.

 Robert L. (Bob) Burchett
 Certified Communications Engineer
 Enterprise Electronics
 Contractors License 522372
 22826 Mariposa Ave.
 Torrance CA 90502
 310.534.4456
 bob.burch...@eeontheweb.com


 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of time-nuts-requ...@febo.com
 Sent: Tuesday, October 01, 2013 2:04 PM
 To: time-nuts@febo.com
 Subject: time-nuts Digest, Vol 111, Issue 2

 Send time-nuts mailing list submissions to
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 Re: Contents of time-nuts digest...


 Today's Topics:

1. NIST off-line (David McGaw)
2. Re: NIST off-line (Tom Minnis)
3. Re: NIST off-line (paul swed)
4. Re: NIST off-line (Brian Inglis)
5. Re: NIST off-line (Jim Lux)
6. Re: NIST off-line (Brooke Clarke)
7. Re: NIST off-line (J. Forster)
8. Re: NIST off-line (Tom Van Baak)
9. Re: NIST off-line (Alan Melia)


 --

 Message: 1
 Date: Tue, 01 Oct 2013 13:13:16 -0400
 From: David McGaw n1...@alum.dartmouth.org
 To: Discussion of precise time and frequency measurement
   time-nuts@febo.com
 Subject: [time-nuts] NIST off-line
 Message-ID: 524b02ac.2020...@alum.dartmouth.org
 Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 NIST is off-line due to the shutdown.

 http://www.nist.gov/pml/div688


 --

 Message: 2
 Date: Tue, 01 Oct 2013 10:45:08 -0700
 From: Tom Minnis tom_min...@att.net
 To: David McGaw n1...@alum.dartmouth.org,   Discussion of precise
   time and frequency measurement time-nuts@febo.com
 Subject: Re: [time-nuts] NIST off-line
 Message-ID: 524b0a24.5060...@att.net
 Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 WWV is still ticking
 Tom


 On 10/1/2013 10:13 AM, David McGaw wrote:
 NIST is off-line due to the shutdown.

 http://www.nist.gov/pml/div688
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 --

 Message: 3
 Date: Tue, 1 Oct 2013 14:09:30 -0400
 From: paul swed paulsw...@gmail.com
 To: tom_min...@att.net, Discussion of precise time and frequency
   measurement time-nuts@febo.com
 Subject: Re: [time-nuts] NIST off-line
 Message-ID:
   CAD2JfAiCJXV=7yr7s-ZgvREa2FvTAu_X8rnC_ov7Akp6QUZi=g...@mail.gmail.com
 Content-Type: text/plain; charset=ISO-8859-1

 Yes but wwvb is on a AA battery it will run out. :-)


 On Tue, Oct 1, 2013 at 1:45 PM, Tom Minnis tom_min...@att.net wrote:

 WWV is still ticking
 Tom



 On 10/1/2013 10:13 AM, David McGaw wrote:

 NIST is off-line due to the shutdown.

 http://www.nist.gov/pml/div688
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 --

 Message: 4
 Date: Tue, 01 Oct 2013 12:49:55 -0600
 From: Brian Inglis brian.ing...@systematicsw.ab.ca
 To: time-nuts@febo.com
 Subject: Re: [time-nuts] NIST off-line
 Message-ID: 524b1953.1060...@systematicsw.ab.ca
 Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 It could well if the electrical utility bills are not paid for a few
 months!

 On 2013-10-01 12:09, paul swed wrote:
 Yes but wwvb is on a AA battery it will run out. :-)


 On Tue, Oct 1, 2013 at 1:45 PM, Tom Minnis tom_min...@att.net wrote:

 WWV is still ticking
 Tom



 On 10/1/2013 10:13 AM, David McGaw wrote:

 NIST is off-line due to the shutdown.

 http://www.nist.gov/pml/div688
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Re: [time-nuts] Pulsars make a GPS for the cosmos

2013-09-29 Thread J. Forster
There really is no such thing as a 'bright' pulsar. They are something
like 16 Mag at best. This is not exactly naked eye.

-John

===





 b...@evoria.net said:
 Just to satisfy my curiosity: what's easiest to detect galactic pulse
 emitter (regardless of type), and what's the minimum setup to reliably
 look
 at it, whether it's just during night time, or whatever.  Just seeking
 perspective, I haven't just won the lottery.

 An optical astronomy-nut friend says that you can see pulsars (or at least
 some of them) in the visible.  The setup is a spinning disk with holes in
 it.
  Adjust the speed of rotation until it beats with the pulsar.

 I think you need a small telescope for the bright pulsars.  Clearly within
 the budget and skills of a not-very-nut, but probably takes at least a
 somewhat-nut to think it is cool enough to do.

 

 Re nighttime...  One of the advantages of radio astronomy is that it works
 during the day and when it is cloudy, an interesting bargaining chip when
 fighting for funds.


 --
 These are my opinions.  I hate spam.



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Re: [time-nuts] Pulsars make a GPS for the cosmos

2013-09-28 Thread J. Forster
A couple of points:

Pulsars are pretty faint and the only solution to that is antenna
aperture. We looked at that while doing SETI a ways back. Receivers are
now quite close to the theoretical limit as far as noise temperatuse.
There is very little room for improvement.

Pulsars are not infrinitely stable. They slowly decay, and, worse,
randomly undergto 'star quakes' which upset their timing. This was proven
in the 1960s.

Best,

-John




 On 9/28/13 7:32 AM, Hal Murray wrote:

 jim...@earthlink.net said:
 Scrolling down, it looks like they're getting a whopping 0.5 dB SNR on
 the Crab Nebula pulsar.

 How much of the noise comes from local sources vs thermal or galactic?


 These are amateurs, so they're probably not using cryocooled receivers:
 a good part of the noise is kTB noise in the receiver.


 I'm missing the scale factor for the big picture.  How big a volume does
 this
 work over before I have to start counting fringes or something like
 that?
 Wiki says the longest one is 8.5 seconds.  That's small even on the
 scale of
 the Solar system.

 You also get direction, so for a navigation system, you can figure out
 where you are.

 Time wise, you'd have to count ticks.


 Is there some trick I'm missing?  Are there lots and lots of pulsars at
 different frequencies so I can beat them against each other to make
 larger
 synthetic fringes?

 Are X-ray or gamma-ray pulsars (much) slower?



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Re: [time-nuts] Pulsars make a GPS for the cosmos

2013-09-28 Thread J. Forster
Yes, but to use them for interstellar navigation, as suggested, when the
propagation delays are 10,000 years or more complicates things.

What is contemplated is comparing the clocks, as they were thousands of
years ago, where they were thousands of years ago, with largely unknown
motions. You can't have a central coordinating facility that sends out
correction signals, because of the propagation delays.

Essentially you are cherry picking the data. Never mind the technical
problems with monitoring many pulsars in many different directions.

There is a similar problem with some early SETI searches. There is really
no 0,0,0 for the universe, AFAIK. Which Doppler effects do you remove?
Some? All? None?

My solution was to use the coordinate system, wherein the 3 degree K
background was the same in all directions as a standard of rest, but who
knows if that is a correct choice?

-John

=



 Pulsars are not infrinitely stable. They slowly decay, and, worse,
 randomly undergto 'star quakes' which upset their timing. This was
 proven
 in the 1960s.

 John,

 You are correct, but it is a simple opportunity rather than a major
 problem. The solution is to monitor multiple pulsar sources. Not only can
 you detect the quakes, but you can precisely measure their magnitude as
 well. Once a quake is detected the new phase and/or frequency offset for
 that source can be entered into the ensemble equation, and you move
 forward as if nothing happened.

 Exactly the same thing happens at home when you monitor multiple quartz
 oscillators. You need more than one or two; three or four is better.
 Confidence grows according to the number of oscillators. N-1 oscillators
 help you detect any abnormality in 1.

 This is not unlike what happens with GPS SV as they come in and out of
 reception. Easy to detect; easily solved.

 And the same solution is used for UTC, where more than 300 clocks
 participate. Phase or frequency jumps (quakes) are easily identified and
 excluded from the ensemble mean. The mean is safe and the N-1 clocks can
 be used to precisely measure the anomaly in 1 clock.

 /tvb

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Re: [time-nuts] Pulsars make a GPS for the cosmos

2013-09-28 Thread J. Forster
From what I remember, with the 1000' Aricebo dish and pretty good LNA,
there were a literal handful of RF photons per pulse...  less than 10
maybe.

-John

===


 Just to satisfy my curiosity: what's easiest to detect galactic pulse
 emitter (regardless of type), and what's the minimum setup to reliably
 look at it, whether it's just during night time, or whatever.  Just
 seeking perspective, I haven't just won the lottery.

 Bob
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Re: [time-nuts] Pulsars make a GPS for the cosmos

2013-09-28 Thread J. Forster
The sune is hugely bright in the RF.

I've been able to see it at 2.2 GHz with nothing more than a horn a foot
or so across and a receiver w/ a NF of maybe 8 dB (cavity preselector 
mixer  IFA...   ACL SR-209).

There was a noticable difference between pointing at the sun and in
another direction.

During a SETI search, when 80-odd foot dish was pointed at the sun, the
preamp was completely saturated sat about 1421 MHz.

-John

=


 Hi

 If you are on the surface of the earth, you face the sun from time to
 time. That creates some issues that you would not have in a deep space
 setting. In deep space you don't have to correct for all sorts of orbital
 issues as well. This is one of those - not so easy here - sort of things.

 Bob


 On Sep 28, 2013, at 6:55 PM, Bob Stewart b...@evoria.net wrote:

 Just to satisfy my curiosity: what's easiest to detect galactic pulse
 emitter (regardless of type), and what's the minimum setup to reliably
 look at it, whether it's just during night time, or whatever.  Just
 seeking perspective, I haven't just won the lottery.

 Bob
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Re: [time-nuts] FCC politics vs their engineers...

2013-09-17 Thread J. Forster
It is hard to imagine a more stupid or more dangerous way of making
decisions than by putting those decisions in the hands of people who pay
no price for being wrong. - Thomas Sowell

YMMV,

-John

===



 Was it not always so?? Remember the politicians pay the bills not the
 engineers!
 Alan
 G3NYK

 - Original Message -
 From: Eric Williams wd6...@gmail.com
 To: Discussion of precise time and frequency measurement
 time-nuts@febo.com
 Sent: Tuesday, September 17, 2013 7:04 PM
 Subject: Re: [time-nuts] FCC politics vs their engineers...


 He tells me with some bitterness that politics triumphed over
 all of the objections of the engineering staff to LS and that this
 is not the first time that this has happened.

 That's how we ended up with Challenger and Columbia.


 On Tue, Sep 17, 2013 at 6:46 AM, Michael Baker mp...@clanbaker.org
 wrote:

 Time-Nutters--

 Jim wrote:
 snip
  That's why the FCC granted a conditional waiver
  of the rules.  It was politically expedient, and I would
  imagine that the engineers at the FCC thought there's
  no way they'll be able to demonstrate no interference

 Charles wrote:
 snip
  The Commission not only thought LS would demonstrate
  non-interference, it put its thumb on the scale until the
  public outcry became too loud to ignore (the GPS interests
  took forever to wake up -- that didn't happen until all of
  the comment periods were long closed).  It just didn't
  matter what the staff engineers thought -- which is
  business  as usual at the FCC.
 --**--

 A friend of mine was one of the FCC lead supervisory engineers
 that was involved in the LS fiasco.  He tells me that there were
 technical reports, evaluation summaries and strong opinions
 offered by the engineering staff that provided a number of
 reasons why the LS project should be denied.  He tells me that
 most of these engineering studies got buried and ignored.
 He tells me with some bitterness that politics triumphed over
 all of the objections of the engineering staff to LS and that this
 is not the first time that this has happened.

 Mike Baker
 Gainesville, FL  USA

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[time-nuts] Lightning Strike Site

2013-09-09 Thread J. Forster
FYI:

http://thunderstorm.vaisala.com/explorer.html

-John

===

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Re: [time-nuts] SDR Radio Opinion- Next Question...

2013-08-07 Thread J. Forster
The trend to add more and more fearures to electronic gadgets is a real
pain, IMO.

I have a Garmin Nuvi and you basically have to do a royal flush of every
stored parameter to simply clear the 'trail of bread crumbs'.

The thing has so many modes that it is really annoying to use and there
seems to be no way of turning unwanted features off. For example, if you
simply want to pan the display, likely as not the address of where you
touched will pop up.

Furthermore, the positions are not reliable. If you are close too, but not
on, a road, or are on the sidewalk going against traffic, like AutoCAD it
will 'snap' to where it thinks you should be. Off road mode is better.

YMMV,

-John

===



 Got some examples?  Without specific you risk sounding like some old guy
 says to days music is no good the old stuff was better  Which of course
 was every year for the last three hundred years.

 But it could be that much software is poorly designed. It is so easy now
 to
 write something and publish it so many people do and the markethas to
 decide what's good and not.  But you can't talk about generalities. So
 which specific software don't you like.

 One thing about Open Source SDR software, if you don't like it, you can
 change it.




 On Wed, Aug 7, 2013 at 8:25 AM, Burt I. Weiner b...@att.net wrote:

 Chris and all,

 It seems to me that a lot of the new software is being developed by
 people
 who don't live in the real world or don't use the end product in the
 real
 world - or maybe not at all.  Maybe I'm just old and senile, but a lot
 of
 the stuff I'm seeing is not intuitive, stable or even consistent.

 Is the State of The Art exceeding the state of the need?

 Burt, K6OQK


 --

 Chris Albertson
 Redondo Beach, California
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Re: [time-nuts] Heads up: Mark C. Stephens...

2013-08-05 Thread J. Forster
I wish there were a way of blocking all Chinese ISPs. I'm sick of Dr Oz
and similar incessant crap.

YMMV,

-John

=


 Hi

 I run the same sort of stuff, and have the same sort of problems from time
 to time. At one point all of Germany was unable to send me email …

 Bob

 On Aug 5, 2013, at 6:55 AM, Mark C. Stephens ma...@non-stop.com.au
 wrote:

 Yikes! I wish I had known earlier.
 Is it just SORBS or SpamCop, SpamHaus and WPBL as well?

 As remedial action I have turned off SORBS blocking.
 Really, sorry about this Bob, John, please resend, as I do value your
 correspondence even if SORBS led you to believe otherwise.


 --marki

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of Bob Camp
 Sent: Monday, 5 August 2013 8:31 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Heads up: Mark C. Stephens...

 Hi

 I had the same problem with some stuff I tried to send Mark.

 Bob

 On Aug 5, 2013, at 5:29 AM, John Miles j...@miles.io wrote:

 Mark, I'm having trouble replying to your email, as your ISP is using
 a spam blacklist (SORBS) that blocks the SMTP servers used by the
 largest American cable ISP.  Do you have another ISP you can use to
 receive email?



 -- john, KE5FX

 Miles Design LLC



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Re: [time-nuts] Heads up: Mark C. Stephens...

2013-08-05 Thread J. Forster
If you mean Comcast, I can well see their point.

Over half the malware spam I get comes from Comcast and Comcastbussiness.
Just because they are big, does not mean they should be given an exemption
from being responsible.

YMMV,

-John





 I agree with John, you can't go around blocking America's largest cable
 ISP!
 We have err opted out of using SORBS now.

 -marki

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of MailLists
 Sent: Monday, 5 August 2013 8:43 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Heads up: Mark C. Stephens...

 Good luck delisting a DNSBL listed IP (block) from those crusaders...
 Back some time there was a piss contest between some of those blacklists
 on which one would blacklist the whole internet faster.
 In the mean time different security providers bought up some of those
 rabid blacklists to power their antispam offerings, usually bundled
 with a security appliance.
 If you get caught in their web, you'll have a tough time to get delisted,
 usually denied with some puerile pretext, from obtuse criteria up to pure
 blackmail.

 On 8/5/2013 12:29 PM, John Miles wrote:
 Mark, I'm having trouble replying to your email, as your ISP is using
 a spam blacklist (SORBS) that blocks the SMTP servers used by the
 largest American cable ISP.  Do you have another ISP you can use to
 receive email?



 -- john, KE5FX

 Miles Design LLC



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Re: [time-nuts] Low cost GPS for model aircraft

2013-08-05 Thread J. Forster
This chatter about model aircraft GPS got me to wondering if there now
off-the-shelf flight control systems for model planes that will do nav
and/or attitude control? I know there are mini-gyros, but I think they are
only good enough for attitude control.

Last time I was into this, if you lost radio contact the model was gone or
had crashed..

-John





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Re: [time-nuts] Low cost GPS for model aircraft

2013-08-05 Thread J. Forster
Wow! IR horizon sensors for pitch and roll model aircraft! That is neat.

Thanks,

-John

==



 There are quite a few off the shelf model aircraft controllers. As you can
 imagine, those based on GPS and/or MEMS IMUs are not terrifically high
 performing. That said, I have seen very promising results from thermopile
 based systems - good discussion in the link below

 http://paparazzi.enac.fr/wiki/Sensors/IR

 They do tend to break down on overcast or cloudy days when the contrast
 between the sky and the ground is minimal.

 Andy Bardagjy
 bardagjy.com


 On Mon, Aug 5, 2013 at 10:14 AM, J. Forster j...@quikus.com wrote:

 This chatter about model aircraft GPS got me to wondering if there now
 off-the-shelf flight control systems for model planes that will do nav
 and/or attitude control? I know there are mini-gyros, but I think they
 are
 only good enough for attitude control.

 Last time I was into this, if you lost radio contact the model was gone
 or
 had crashed..

 -John

 



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[time-nuts] SDR Radio Opinion ?

2013-08-05 Thread J. Forster
Has anyone played with this thing?

http://microsat.com.pl/product_info.php?products_id=35

If you add a laptop, is the thing a complete radio? It seems to be far too
cheap to believe.

-John

===

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[time-nuts] SDR Radio Opinion- Next Question

2013-08-05 Thread J. Forster
OK. Thanks everybody. Can you please reccomend a make/model?

I'd like something like:

75 to 1300 MHz
USB
Ability to function as a crude SA.
Not crawling w/ birdies or aliasing issues.
Will run on Win XP.
Demod selecttable for all modes at all frequencies.
In a package, rather than a loose PCB.
$150

Prefer:

SMA rather than RCA or F
Receiver and SW from same vendor.

Suggestions, please.

Thanks,

-John

===

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Re: [time-nuts] [TestEquipTrader] SDR Radio Opinion- Next Question

2013-08-05 Thread J. Forster
The 240-420 MHz gap is a killer for me. Much of my interest lies in that
band.

Also, I'd much prefer a 20 MHz plus SA function.

-John

==




 For that money, look for a used Funcube Dongle.
 The new Funcube Dongle Pro+ is just under 200 USD but it goes down to
 150 kHz and up to 1.9 GHZ, with a gap from 240 to 420 MHz. Might be
 worth the extra money for you.
 You will be able to see 96 kHz wide as a spectrum analyzer with either
 model of the Funcube; if you want to see wider than that, you'll need to
 look for an rtl2832 based receiver..which will see about 1 MHz wide if I
 remember.

 http://www.funcubedongle.com/

 On 8/5/2013 5:52 PM, J. Forster wrote:

 OK. Thanks everybody. Can you please reccomend a make/model?

 I'd like something like:

 75 to 1300 MHz
 USB
 Ability to function as a crude SA.
 Not crawling w/ birdies or aliasing issues.
 Will run on Win XP.
 Demod selecttable for all modes at all frequencies.
 In a package, rather than a loose PCB.
 $150

 Prefer:

 SMA rather than RCA or F
 Receiver and SW from same vendor.

 Suggestions, please.

 Thanks,

 -John

 ===

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Re: [time-nuts] SDR Radio Opinion- Next Question

2013-08-05 Thread J. Forster
I assume you mean XP?

Several reasons:

Used Thinkpads that will run XP are cheap and plentiful.
I hate Vista and Win 7...
I'm interested in a turnkey tool, not SW 'elegance', etc.

-John

==



 On Mon, Aug 5, 2013 at 2:52 PM, J. Forster j...@quikus.com wrote:

 OK. Thanks everybody. Can you please reccomend a make/model?


 Will run on Win XP.


 The above seems an odd requirement.   Why?

 --

 Chris Albertson
 Redondo Beach, California



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Re: [time-nuts] SDR Radio Opinion- Next Question

2013-08-05 Thread J. Forster
If the windo can be slid under SW control, that's enough.  Flat, in this
context is something like +/- 6 dB...  non-critical. I want to be able to
see spurs, etc. I don't need much dynamic range either.

-John

===



 Just be aware that they're not wideband units.  The sampling rate defines
 the bandwidth of any sample, and the fact that it's 8 bits limits the
 resolution.  So, you can essentially look at up to a 2MHz slice anywhere
 you want within 64MHz to 1.7GHz.  Of course, you could move your center
 frequency to move the window.  As to whether they have a flat response?  I
 can't tell you.  If you get a European consumer unit, you'll probably get
 one with a Belling-Lee connector.  I don't know if anyone has written SA
 software for one, yet.  When I was playing with mine, SDRSharp was pretty
 much the software standard.  I've never tried to use mine for anything
 other than an FM radio.  If I had a B-L adapter I'd be able to check some
 samples from my Tracking Generator, but it's not something I've ever
 looked into.  Look on ebay for rtl2832 to find out what's most readily
 available

 Bob






 From: J. Forster j...@quikus.com
To: hp_agilent_equipm...@yahoogroups.com; tekscop...@yahoogroups.com
Cc: Time-nuts@febo.com; testequiptra...@yahoogroups.com;
 armyrad...@yahoogroups.com
Sent: Monday, August 5, 2013 4:52 PM
Subject: [time-nuts] SDR Radio Opinion- Next Question


OK. Thanks everybody. Can you please reccomend a make/model?

I'd like something like:

75 to 1300 MHz
USB
Ability to function as a crude SA.
Not crawling w/ birdies or aliasing issues.
Will run on Win XP.
Demod selecttable for all modes at all frequencies.
In a package, rather than a loose PCB.
$150

Prefer:

SMA rather than RCA or F
Receiver and SW from same vendor.

Suggestions, please.

Thanks,

-John

===

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Re: [time-nuts] SDR Radio Opinion- Next Question

2013-08-05 Thread J. Forster
 Hi John,

 I don't think you quite got it yet.  All of those types of Dongles
 have no frontend filtering and no gain control (AGC).

Oh, I'm all too familiar w/ SAs without YIG preselectors. That's why I've
always preferred AILtech to HP.

 Basically it is a
 diode (so to speak) looking at the spectrum from DC to Daylight, even
 though they have a limited range.

Understood. But, there are Image Rejection Mixers.

 So, yes, there will be birdies and
 aliasing issues.  There is no software from a unit's manufacturer for
 the All Frequency observation mode that Amateur radio and other
 hobbyists are using it for.

What I'm looking for is something like the W-J, ACL, or CEI ELINT
receivers, in digital form, and much cheaper. I just would like to play
with one a bit.

 Aside from all that , they do come in a plastic case and there is some
 excelent control software, notably Simon Browns HDSDR,  that can control
 a number of these types of umits.  As for spectrum software, the best
 one is Spectrum Labs which can take I/Q input.  See the respective web
 sites for more information.  Both of these packages are FREE.

Free is good! LoL.

 http://www.hdsdr.de/hardware.html   The SDR software hardware page

 http://www.qsl.net/dl4yhf/spectra1.htmlThe Spectrum Lab software.

 BillWB6BNQ

Thanks,

-John



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Re: [time-nuts] [hp_agilent_equipment] SDR Radio Opinion ?

2013-08-05 Thread J. Forster
About $100.

-John

=


 On 08/05/2013 04:56 PM, J. Forster wrote:


 Has anyone played with this thing?

 http://microsat.com.pl/product_info.php?products_id=35

 If you add a laptop, is the thing a complete radio? It seems to be far
 too
 cheap to believe.

 -John

 ===

 It may or may not be cheap. The price I see is 280.00 PLN. What the heck
 are PLN? What's that in US dollars?

 --doug, WA2SAY
 --
 Blessed are the peacemakers..for they shall be shot at from both sides.
 --A.M.Greeley




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[time-nuts] Radio Shack GPS Module

2013-08-02 Thread J. Forster
In looking around the local Radio Shack a few days ago, I notices a silver
dollar sized GPS module w/ patch antenna for use in home brew robots. The
thing is supposedly good to 5 Meters and costs about $55. It appears to
have a serial ASCII interface.

There is nothing obvious on the RS website. Does anybody have any info on
the unit?

Best,

-John

===

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Re: [time-nuts] Story in the Economist about GPS jamming

2013-07-30 Thread J. Forster
I'm unconvinced Clarke's Law is operative here.

A more appropriate model is the Swiss Army Knife...  a single tool to be
all things to all people. In reality, such a tool or program does nothing
very well. Examples abound.

YMMV,

-John

=



 Any competent engineer could have told the powers that be that a satellite
 system based in LEO has a relatively high risk profile from the
 Universe/hostile activity/spoofing and jamming

 Yes GPS is/was oversold.

 Trouble is Clarkes law applies here (any sufficiently advanced technology
 is indistinguishable from magic).  And this applies double to the
 technological illiterates in DC

 See Sen 'Tubes' Stevens for the canonical example

 Sent from my iPhone

 On Jul 29, 2013, at 12:46 PM, J. Forster j...@quikus.com wrote:

 It seems to me that GPS has been oversold as the be all, end all system
 that made all other systems obsolete and GPS has become all but an
 indespensible utility.

 Reports like this, could well be used to promote a backup, like LORAN or
 eLORAN, just as public buildings have backup generators.

 YMMV,

 -John

 ==



 http://www.economist.com/news/international/21582288-satellite-positioning-data-are-vitalbut-signal-surprisingly-easy-disrupt-out?fsrc=scn/tw/te/pe/outofsight

-Bill





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Re: [time-nuts] Story in the Economist about GPS jamming

2013-07-30 Thread J. Forster
I think the largest concern about jamming is for civilian uses, rather
than military, mainly because military receivers are designed and built to
be more immune. Also, military systems are far more likely to have good
grade INS.

Furthermore, there are probably a couple of orders of magnitude more
civilian systems in use.

-John

==



 Exactly what do you mean by ... based in LEO has a relatively high risk
 profile from the Universe/hostile activity/spoofing and jamming...?

 Other than a LOS, in a jammers immediate area, GPS is not subject to
 jamming, and for the critical users, ie, the DOD, very difficult to jam,
 even in a LOS.

 The LEO makes it harder to jam since the received signal strength is
 higher
 than would be practical from GeoSync orbit, not easier,  as is implied my
 Mr. McGraths comment.

 Lester B Veenstra  MØYCM K1YCM W8YCM
 les...@veenstras.com

 US Postal Address:
 5 Shrine Club Drive
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Re: [time-nuts] GPS Spoofing

2013-07-29 Thread J. Forster
Well, OK, but I never saw a small, $500 box that could be put on pleasure
boats, etc. and directly read out Lat/Long. Such things were available at
the local boating store for LORAN.

-John

==.




 John, Omega did make it into the 'uP age' I briefly got involved in the
 80's and my first patent was for using DSPs and software radio for an
 Omega development . The key thing was Omega was genuinely world wide
 from a small chain of transmitters and one of the important users had to
 do their navigation while staying underwater for weeks on end, even
 Loran had limitations never mind satellite.

 It might be the answer the mystery Collins Ru posting here, I remember
 similar items in airborne Omega receivers, the omega carrier frequencies
 were low but the receiver bandwidths were measured in mHz and phase
 error was critical hence the boxes I saw included similar references.

 Its rather painful to see all the warnings about GPS made 30 years ago
 having to be re addressed. I suspect Loran will not get a big revival,
 the important development since the '80s is probably cheap MEMS inertial
 measurement sensors that give a user a secure cheap independent
 accessory to integrate with GPS etc. Its not an alternative but a rather
 useful thing to merge into a system to help deal with spoofing or other
 signal loss, this page from Analog Devices shows prices and performance:

 http://www.analog.com/en/mems-sensors/mems-inertial-measurement-units/products/index.html#iSensor_MEMS_Inertial_Measurement_Units

 There are other opportunistic navigation systems that try (tried?) other
 approaches such as Peter Duffett-Smith's Cursor system which I think is
 now in the hands of CSR.

 Regards
 David


 --

 Message: 1
 Date: Sun, 28 Jul 2013 15:24:30 -0700 (PDT)
 From: J. Forster j...@quikus.com

 Subject: Re: [time-nuts] GPS Spoofing

 I'm not so convinced about this:

 OMEGA was the primary means of radio navigation, world wide, from 1976
 to
 1997. .

 There was LORAN-C, after all.

 And Omega was a CW, phase difference system, LORAN a pulse system.

 AFAIK, Omega never really made it into the uP age; LORAN certainly did.

 -John

 ===



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Re: [time-nuts] GPS Spoofing

2013-07-29 Thread J. Forster
From what I've been told privately and off the record, the vacuum was not
filled with political gas.

YMMV,

-John

=



[snip]
 Indeed, all of this was gone over *many* times in the 80's. Those involved
 were *very* knowledgeable about all of these systems and their weaknesses.
 None of the decisions we are living with were made in a vacuum or without
 a lot of discussion.

 Bob


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Re: [time-nuts] GPS Spoofing- oops

2013-07-29 Thread J. Forster
Oops:

From what I've been told privately and off the record, the vacuum was not
a vacuum, but was filled with political gas.

Sorry,

-John

==



 From what I've been told privately and off the record, the vacuum was not
 filled with political gas.

 YMMV,

 -John

 =



 [snip]
 Indeed, all of this was gone over *many* times in the 80's. Those
 involved
 were *very* knowledgeable about all of these systems and their
 weaknesses.
 None of the decisions we are living with were made in a vacuum or
 without
 a lot of discussion.

 Bob


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Re: [time-nuts] GPS Spoofing

2013-07-29 Thread J. Forster
Prohibition never works. It's been tried with booze, drugs, pay sex, and
guns, at least, and failed every time.

If people want something badly enough, they will get it.

Ask yourself, is the collateral damage worth it?

MMV,

-John

=





 We've been discussing both GNSS denial/spoofing vs Loran denial/spoofing
 and the relative difficulty of doing same to determine which system is
 most survivable

 That being said the penalty for using the truck stop/spy shop GPS should
 be in the hundreds of thousands per day and carry serious jail time. As
 most of them are easily capable of affecting a square mile as if you look
 at the specs from their Chinese suppliers.

 If you want to keep your boss from finding that you spent more than
 allocated time eating lunch just wrap the antenna in Al foil



 Sent from my iPhone

 On Jul 29, 2013, at 1:12 AM, Fuqua, Bill L wlfuq...@uky.edu wrote:

  The idea behind GPS spoofing is that one or several surface antennas
 and sources could be set up in such a way that they would produce
 believable position data that would take a vessel off course. The
 problem with this concept is that the person in charge of the GPS
 spoofing hardware has to know exactly where the vessel is at all times
 to start with and other vessels some distance away, and not very far
 from the target vessel would get contradicting signals from the virtual
 satellites.
 Software could be used to detect changes in position data that is
 inconsistent with present course and recent data. And in most cases
 there would be a period of very inconsistent signals from satellites and
 more obvious, signal strengths.
 Another way to limit spoofing is to use directional antennas that
 prevent reception from near horizon signals. Or detect low angle signals
 and sound the alarm or implement a means of ignoring those sources.
 The problem very high tech systems are often defeated by low tech
 solutions. Successful GPS spoofing would be very high tech.
 Many high tech systems that the government had developed in the past
 have been defeated by low tech methods. An example is the microwave
 system that is intended to turn back rioters by inducing burning pain.
 It was defeated by using thick wooden shields which absorbed the RF
 energy.
 Human resourcefulness and determination often defeats technology in low
 tech ways. And the more complex a system is the easier it is to defeat.
 “The more they overtake the plumbing the easier it is to stop up the
 drain.”
 Most discussions have been about wireless spoofing. However, the most
 reliable way to do it would be an “inside job” where a device would
 be put on board and patched in the antenna lead. The correct GPS data
 would be received by the device and then it would produce a virtual
 constellation of satellites that would direct the vessel off course.
 However, the programmer would have to know the course that the pilot
 intended to take in the first place if his goal is to
 take the vessel to a different destination.
 73
 Bill wa4lav
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Re: [time-nuts] Story in the Economist about GPS jamming

2013-07-29 Thread J. Forster
It seems to me that GPS has been oversold as the be all, end all system
that made all other systems obsolete and GPS has become all but an
indespensible utility.

Reports like this, could well be used to promote a backup, like LORAN or
eLORAN, just as public buildings have backup generators.

YMMV,

-John

==



 http://www.economist.com/news/international/21582288-satellite-positioning-data-are-vitalbut-signal-surprisingly-easy-disrupt-out?fsrc=scn/tw/te/pe/outofsight

 -Bill





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Re: [time-nuts] GPS Spoofing

2013-07-28 Thread J. Forster
The point about the duty cycle being low is correct. And, there are
commercial linear power amps, like the used ones made by ENI and others,
that can easily put out 1 kW plus narrow pulses.

Furthermore, the pulse generator is trivial to make with a Rb, 3 or more
Tektronix DD501s, a simple OR gate and a gated oscillator at about 100
kHz. I've cobbled up that setup several times as a LORAN-A simulator.

The main difficulty is getting a reasonable match to an efficient antenna
at 100 kHz.

-John

=



 Hi

 Since it's a pulse system, and you get to position your pulse for maximum
 effect, I don't see any reason to generate CW power. Simply mimic the
 lowest power slave in the chain. There's very little redundancy with
 Loran, so spoofing one station will mess it up. No need to mask the entire
 chain. At most you would need to hit two low power slaves.

 Math wise:

 Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and you
 have problems in a harbor. You would need to play a bit to see weather a
 pulse every so often does the trick or not. Is that 20 db below the slave
 or not ? You'd have to play with it. It's in that range. A spoof that says
 they are on the other side of the world isn't going to work. One that says
 you are on the north side of the channel (when you are on the south side)
 is what would work.

 Power within a pulse set at a  5:1 duty cycle. For a 50,000 us GRI you
 have another 50:1. For longer GRI's you might add another 2:1. Net is a
 peak to average ratio of 250-1000 to 1. Put another way, a 500W pulse is ~
 1 average.

 Power at 100 KHz = what's in a fairly cheap switching power supply. Plug
 it into the wall. A couple hundred watts (or even KW) pulse is cheap. Say
 you have 120W out of the wall (or a car battery). If the math above is
 correct and you can run 80% efficiency, that's a pretty powerful pulse.
 It's probably cheaper to generate something at 50:1 rather than the whole
  200:1. A 5KW is a *lot* of RF, even into a simple antenna.

 Antenna - there's a couple ways to do that. All of them are tradeoffs
 (size / cost / power). The cheap way is to use a wire that's already
 there…. Since you don't need to propagate (near field), the antenna
 efficiency could be higher than you would think for some antennas.

 Is it easier than that with some smarts involved in the pulse - probably
 yes. Do the smarts raise the hardware cost significantly? - you'd have to
 build a few and find out. What really drives this or that Loran receiver
 nuts? I'm quite sure you could work that out with one to play with.

 Am I gong into the Loran-C jammer business? No, so don't contact me off
 list to buy one. The point is not *have* I built one, but could one be
 built easily.


 Bob


 On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk
 wrote:

 In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp
 writes:

 I'm not talking about taking out Loran-C over the entire North
 Atlantic.
 The target is a harbor sized area. For that, you certainly do not need
 a
 600' antenna or megawatts of power.

 No, you need about 600W (continuous) and a loop-antenna about 5m in
 diameter.

 Do the math, It's not as easy as you think.

 --
 Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
 p...@freebsd.org | TCP/IP since RFC 956
 FreeBSD committer   | BSD since 4.3-tahoe
 Never attribute to malice what can adequately be explained by
 incompetence.

 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] GPS Spoofing

2013-07-28 Thread J. Forster
Not so at all.

What I described is a simple means to make a receiver see different GRIs
and TDs than what it might see off the air. The system can accurately set
any GRI in 1 uS increments and any one of several TDs to 1 uS also. That
is hardly a jammer.

Furthermore, if the Tek DD501s were replaced by something like BNC
programmable Digital Delays, you could change the received position over
time.

-John





 I've just been catching up on this thread.

 The subject says GPS Spoofing, but most of the replies seem to revolve
 around jamming. Not the same thing.

 Just a thought...

 Rob

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of J. Forster
 Sent: 28 July 2013 20:06
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] GPS Spoofing

 The point about the duty cycle being low is correct. And, there are
 commercial linear power amps, like the used ones made by ENI and others,
 that can easily put out 1 kW plus narrow pulses.

 Furthermore, the pulse generator is trivial to make with a Rb, 3 or more
 Tektronix DD501s, a simple OR gate and a gated oscillator at about 100
 kHz.
 I've cobbled up that setup several times as a LORAN-A simulator.

 The main difficulty is getting a reasonable match to an efficient antenna
 at
 100 kHz.

 -John

 =



 Hi

 Since it's a pulse system, and you get to position your pulse for
 maximum effect, I don't see any reason to generate CW power. Simply
 mimic the lowest power slave in the chain. There's very little
 redundancy with Loran, so spoofing one station will mess it up. No
 need to mask the entire chain. At most you would need to hit two low
 power
 slaves.

 Math wise:

 Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that and
 you have problems in a harbor. You would need to play a bit to see
 weather a pulse every so often does the trick or not. Is that 20 db
 below the slave or not ? You'd have to play with it. It's in that
 range. A spoof that says they are on the other side of the world isn't
 going to work. One that says you are on the north side of the channel
 (when you are on the south side) is what would work.

 Power within a pulse set at a  5:1 duty cycle. For a 50,000 us GRI you
 have another 50:1. For longer GRI's you might add another 2:1. Net is
 a peak to average ratio of 250-1000 to 1. Put another way, a 500W
 pulse is ~
 1 average.

 Power at 100 KHz = what's in a fairly cheap switching power supply.
 Plug it into the wall. A couple hundred watts (or even KW) pulse is
 cheap. Say you have 120W out of the wall (or a car battery). If the
 math above is correct and you can run 80% efficiency, that's a pretty
 powerful pulse.
 It's probably cheaper to generate something at 50:1 rather than the
 whole
  200:1. A 5KW is a *lot* of RF, even into a simple antenna.

 Antenna - there's a couple ways to do that. All of them are tradeoffs
 (size / cost / power). The cheap way is to use a wire that's already
 there.. Since you don't need to propagate (near field), the antenna
 efficiency could be higher than you would think for some antennas.

 Is it easier than that with some smarts involved in the pulse -
 probably yes. Do the smarts raise the hardware cost significantly? -
 you'd have to build a few and find out. What really drives this or
 that Loran receiver nuts? I'm quite sure you could work that out with
 one
 to play with.

 Am I gong into the Loran-C jammer business? No, so don't contact me
 off list to buy one. The point is not *have* I built one, but could
 one be built easily.


 Bob


 On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk
 wrote:

 In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp
 writes:

 I'm not talking about taking out Loran-C over the entire North
 Atlantic.
 The target is a harbor sized area. For that, you certainly do not
 need a 600' antenna or megawatts of power.

 No, you need about 600W (continuous) and a loop-antenna about 5m in
 diameter.

 Do the math, It's not as easy as you think.

 --
 Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
 p...@freebsd.org | TCP/IP since RFC 956
 FreeBSD committer   | BSD since 4.3-tahoe
 Never attribute to malice what can adequately be explained by
 incompetence.

 ___
 time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.




 ___
 time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
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Re: [time-nuts] GPS Spoofing

2013-07-28 Thread J. Forster
I'm not so convinced about this:

OMEGA was the primary means of radio navigation, world wide, from 1976 to
1997. .

There was LORAN-C, after all.

And Omega was a CW, phase difference system, LORAN a pulse system.

AFAIK, Omega never really made it into the uP age; LORAN certainly did.

-John

===






 The Helix coils are 25' high and have a 6' high relay:
 http://www.haikuvalley.com/History/OMEGA-NAVIGATION-SYSTEM/8839335_kzKJLd#!i=2042047390k=QJbHKzM/


 --marki


 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of Bob Camp
 Sent: Monday, 29 July 2013 7:05 AM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] GPS Spoofing

 Hi

 So in this case we're talking about horrible to even more horrible in
 terms of efficiency. I'll freely grant that a 600' tower over a really
 good ground plane (like say the sea) is going to be way more efficient
 than anything I'd come up with. The same thing would apply to a matching
 network made of coils you can stand up inside compared to anything I'd
 make.

 Totally off topic - In the lobby of Continental Electronics they used to
 have this typical transmitter sitting there. You sort of wondered why.
 After looking at it you figured out the little ant down in the bottom was
 a person. Yes, the coils and stuff in Omega transmitters were *big*.

 Bob

 On Jul 28, 2013, at 4:23 PM, Tom Miller tmil...@skylinenet.net wrote:

 You can't use efficient antenna and 100 kHz in the same sentence.
 Oh, wait...


 - Original Message - From: J. Forster j...@quikus.com
 To: Discussion of precise time and frequency measurement
 time-nuts@febo.com
 Sent: Sunday, July 28, 2013 3:06 PM
 Subject: Re: [time-nuts] GPS Spoofing


 The point about the duty cycle being low is correct. And, there are
 commercial linear power amps, like the used ones made by ENI and
 others, that can easily put out 1 kW plus narrow pulses.

 Furthermore, the pulse generator is trivial to make with a Rb, 3 or
 more Tektronix DD501s, a simple OR gate and a gated oscillator at
 about 100 kHz. I've cobbled up that setup several times as a LORAN-A
 simulator.

 The main difficulty is getting a reasonable match to an efficient
 antenna at 100 kHz.

 -John

 =



 Hi

 Since it's a pulse system, and you get to position your pulse for
 maximum effect, I don't see any reason to generate CW power. Simply
 mimic the lowest power slave in the chain. There's very little
 redundancy with Loran, so spoofing one station will mess it up. No
 need to mask the entire chain. At most you would need to hit two low
 power slaves.

 Math wise:

 Wavelength is 10,000 ft / 3,000M. Throw things off by ~10% of that
 and you have problems in a harbor. You would need to play a bit to
 see weather a pulse every so often does the trick or not. Is that 20
 db below the slave or not ? You'd have to play with it. It's in that
 range. A spoof that says they are on the other side of the world
 isn't going to work. One that says you are on the north side of the
 channel (when you are on the south side) is what would work.

 Power within a pulse set at a  5:1 duty cycle. For a 50,000 us GRI
 you have another 50:1. For longer GRI's you might add another 2:1.
 Net is a peak to average ratio of 250-1000 to 1. Put another way, a
 500W pulse is ~
 1 average.

 Power at 100 KHz = what's in a fairly cheap switching power supply.
 Plug it into the wall. A couple hundred watts (or even KW) pulse is
 cheap. Say you have 120W out of the wall (or a car battery). If the
 math above is correct and you can run 80% efficiency, that's a pretty
 powerful pulse.
 It's probably cheaper to generate something at 50:1 rather than the
 whole
  200:1. A 5KW is a *lot* of RF, even into a simple antenna.

 Antenna - there's a couple ways to do that. All of them are tradeoffs
 (size / cost / power). The cheap way is to use a wire that's already
 there Since you don't need to propagate (near field), the antenna
 efficiency could be higher than you would think for some antennas.

 Is it easier than that with some smarts involved in the pulse -
 probably yes. Do the smarts raise the hardware cost significantly? -
 you'd have to build a few and find out. What really drives this or
 that Loran receiver nuts? I'm quite sure you could work that out with
 one to play with.

 Am I gong into the Loran-C jammer business? No, so don't contact me
 off list to buy one. The point is not *have* I built one, but could
 one be built easily.


 Bob


 On Jul 28, 2013, at 1:29 PM, Poul-Henning Kamp p...@phk.freebsd.dk
 wrote:

 In message dab33aef-98ef-4503-89a7-657f0d25a...@rtty.us, Bob Camp
 writes:

 I'm not talking about taking out Loran-C over the entire North
 Atlantic.
 The target is a harbor sized area. For that, you certainly do not
 need a 600' antenna or megawatts of power.

 No, you need about 600W (continuous) and a loop-antenna about 5m in
 diameter.

 Do

Re: [time-nuts] GPS Spoofing

2013-07-27 Thread J. Forster
About 25 years ago, I bought a bunch of LORAN-C receiver boards at the
Appelco bankrupcy auction. Despite zero doc, I got a couple running.

They had to 8085 uPs, one to compute the TDs and a second,on a daughter
board, to compute Lat/Long. The unit would repeatably hit my location w/in
a couple of hundred feet.

A trivial uP in a box could easily subtract the GPS and LORAN positions
and sound an alarm if they differed by more than a set limit, and sound an
alarm.

Furthermore, I suspect the cost to operate a set of worldwide LORAN chains
is far less than launching a single GPS bird.

-John

==



 LORAN can be good to 60 ft.


 On 7/27/13 12:21 AM, Jim Lux wrote:
 On 7/26/13 8:45 PM, J. Forster wrote:
 I gather from the article, the GPS position was spoofed and the
 autopilot,
 in bringing it back to where it was supposed to be, actually took it
 off
 course.

 There are places where a few hundred feet makes a big difference,
 viz. the
 Costa Concordia.

 IMO, this is a very convincing reason for something like LORAN.

 I think it's a convincing argument for a captain who pays attention to
 the other navigation instruments and doesn't blindly follow the GPS.

 It's also a convincing argument that shipboard
 automation/autopilot/autocontrol vendors need to make more
 sophisticated software (which I suspect they do, particularly on 200+
 foot ships.. I would imagine that there are some aspects of this demo
 that are contrived.)  The ship making and driving business is pretty
 unregulated. It's all about what the owner of the ship is willing to
 pay (or what he needs to get liability insurance, if he wants).
 There's nothing even remotely like DO-178 for shipboard stuff.

 The folks doing stabilized oil rigs probably have sophisticated
 systems, but they're also using IMUs and other stuff. Ditto for high
 value things (oil tankers, warships).  Molasses tankers? They're
 probably lucky to have a functioning compass and some old charts.


 I'm not sure, though, that looking at the big picture, whether your
 tax dollars are better spent on LORAN, or on some other precision
 navigation method or on making jam resistant GPS receivers (which do,
 in fact exist, and make use of things like direction of arrival of the
 signal..)

 Note that a GPS system with 3 antennas (as is common in systems that
 use GPS to derive attitude/orientation) would be extremely difficult
 to spoof, and would be VERY inexpensive to implement. Either the
 carrier phases and code phases are consistent for all the received
 signals or they're not.  A jamming signal coming from the wrong
 direction will not have the right direction of arrival relative to the
 platform orientation.  One wrong signal might be tolerable (multipath,
 etc.) but with a multi satellite fix, I suspect it would be hard to do
 it.

 Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but
 that's getting to be a bit noticeable.


 For what it's worth, I don't know that LORAN has the performance to
 avoid a Costa Concordia type foul up (assuming they were crazy enough
 to do the near pass in the fog, so visual navigation didn't work)

 I seem to recall that LORAN had 1/4 nmi kinds of accuracy.  it would
 get you to the channel or mouth of the harbor, but not get you into
 your berth. You might be familiar with the local propagation anomalies
 and get better accuracy with experience in your local waters.







 -John

 =



 I boat?  The backup is a competent captain.  He'd see the compass
 heading
 move and quickly disengage the autopilot.   I had a boat for years
 I'd
 notice a 5 degree change.  Mine was a sailboat so I'd be more
 sensitive to
 heading changes than a power boater but still the human is the backup.

 Most autopilots don't directly follow GPS, they use GPS to determine a
 heading, follow it then use GPS to detect drift and re-compute the
 heading.
   the heading would be held by a compass sensor in a low-cost setup
 or in a
 larger setup a lazer ring gyro backed up by a compass. So a
 spoofed
 GPS
 would cause the autopilot to think there was a bigger crooswnd or
 current
 and make a bigger heading change.

 I bet you could hijack a drone not a manned vehicle the pilot is
 trained
 to
 monitor the automation and he'd very quickly turn it off thinking it
 was
 broken.






 On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote:

 Prof. Humphry from Texas just reported being able to spoof GPS in the
 Med
 and take over the nav system of a luxury yacht. He's done this before
 with
 a drone in the US.

 LORAN as a backup, at least?

 -John

 ==



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 To unsubscribe, go to
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 --

 Chris Albertson
 Redondo Beach, California



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 time-nuts mailing list

Re: [time-nuts] GPS Spoofing

2013-07-27 Thread J. Forster
People screw up. Period. The Costa Concordia, that Talgo train driver in
Spain, pilots fly into the ground as in San Francisco, just to name a few.

IMO, putting all one's eggs in the GPS basket is simply foolish,
especially when a continuous cross-check with an independant nav system
can be implemented, probably for lest cost than a dinner at the Captain's
Table.

I was a guest on the bridge of a ship as it went through the Straights of
Gibralter and the Captain was using RADAR, Peloris sights, and multiple
lookouts. Suspenders and a belt.

The modern supertankers and container ships probably don't do that. The
highly automated ships don't carry a lot of crew.

-John

=




 As a (former) Naval Officer, I will tell you that a competent mariner
 should always be using and cross-checking /all /sources -- GPS, radar,
 dead reconing, /looking out the window/, and even celestial in open ocean.

 (I frequently had to remind my junior officers that nobody ever ran
 aground or collided with another ship from spending too much time
 looking out the window.  Way too easy to get their heads stuck in the
 radar or the GPS map.

 73,
 Jim
 wb4...@amsat.org

 On 7/27/2013 9:43 AM, Scott McGrath wrote:
 Key here is how does the captain know that GPS is no longer providing an
 accurate fix?   You need 2 or more independent systems to cross check
 each other.

 Sent from my iPhone

 On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote:

 On 7/26/13 8:45 PM, J. Forster wrote:
 I gather from the article, the GPS position was spoofed and the
 autopilot,
 in bringing it back to where it was supposed to be, actually took it
 off
 course.

 There are places where a few hundred feet makes a big difference, viz.
 the
 Costa Concordia.

 IMO, this is a very convincing reason for something like LORAN.
 I think it's a convincing argument for a captain who pays attention to
 the other navigation instruments and doesn't blindly follow the GPS.

 It's also a convincing argument that shipboard
 automation/autopilot/autocontrol vendors need to make more
 sophisticated software (which I suspect they do, particularly on 200+
 foot ships.. I would imagine that there are some aspects of this demo
 that are contrived.)  The ship making and driving business is pretty
 unregulated. It's all about what the owner of the ship is willing to
 pay (or what he needs to get liability insurance, if he wants).
 There's nothing even remotely like DO-178 for shipboard stuff.

 The folks doing stabilized oil rigs probably have sophisticated
 systems, but they're also using IMUs and other stuff. Ditto for high
 value things (oil tankers, warships).  Molasses tankers? They're
 probably lucky to have a functioning compass and some old charts.


 I'm not sure, though, that looking at the big picture, whether your tax
 dollars are better spent on LORAN, or on some other precision
 navigation method or on making jam resistant GPS receivers (which do,
 in fact exist, and make use of things like direction of arrival of the
 signal..)

 Note that a GPS system with 3 antennas (as is common in systems that
 use GPS to derive attitude/orientation) would be extremely difficult to
 spoof, and would be VERY inexpensive to implement.  Either the carrier
 phases and code phases are consistent for all the received signals or
 they're not.  A jamming signal coming from the wrong direction will not
 have the right direction of arrival relative to the platform
 orientation.  One wrong signal might be tolerable (multipath, etc.) but
 with a multi satellite fix, I suspect it would be hard to do it.

 Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but
 that's getting to be a bit noticeable.


 For what it's worth, I don't know that LORAN has the performance to
 avoid a Costa Concordia type foul up (assuming they were crazy enough
 to do the near pass in the fog, so visual navigation didn't work)

 I seem to recall that LORAN had 1/4 nmi kinds of accuracy.  it would
 get you to the channel or mouth of the harbor, but not get you into
 your berth. You might be familiar with the local propagation anomalies
 and get better accuracy with experience in your local waters.






 -John

 =



 I boat?  The backup is a competent captain.  He'd see the compass
 heading
 move and quickly disengage the autopilot.   I had a boat for years
 I'd
 notice a 5 degree change.  Mine was a sailboat so I'd be more
 sensitive to
 heading changes than a power boater but still the human is the
 backup.

 Most autopilots don't directly follow GPS, they use GPS to determine
 a
 heading, follow it then use GPS to detect drift and re-compute the
 heading.
   the heading would be held by a compass sensor in a low-cost setup
 or in a
 larger setup a lazer ring gyro backed up by a compass. So a
 spoofed
 GPS
 would cause the autopilot to think there was a bigger crooswnd or
 current
 and make a bigger heading change.

 I bet you could hijack

Re: [time-nuts] GPS Spoofing

2013-07-27 Thread J. Forster
The failure rate does not matter a whole lot, if you or a loved one are
killed or injured.

How much comfort is it to a victim, if 1 person, or 5 million people,
survived ?

Failure rates only really matter to actuaries and insurance companies.

-John

=



 What is the failure rate?   The number of failures does not matter unless
 we know the total number of attempts.

 Do 1% of the ships that leave a harbor to become involved in an accident
 or
 is  it more like one in one ten million?

 I'd bet there are tens of thousands of cases of GPS failures where the
 user
 said to himself darn, it's broken turned the thing off and went on his
 way.




 On Sat, Jul 27, 2013 at 1:51 AM, Robert Atkinson
 robert8...@yahoo.co.ukwrote:

 It seems you can't rely on the human backup. The UK Marine accident
 Investigation Branch Has recorded numerous accidents due to poor
 lookout.
 See
 http://www.maib.gov.uk/cms_resources.cfm?file=/KarinSchepersReportWeb.pdf
 http://www.maib.gov.uk/cms_resources.cfm?file=/CoastalIsle.pdf
 http://www.maib.gov.uk/cms_resources.cfm?file=/Beaumont.pdf
 http://www.maib.gov.uk/cms_resources.cfm?file=/Seagate_ReportWeb.pdf
 for recent examplesThe other problem is that AIS, a significant
 anti-collision aid, relies on GPS and is susceptable to spoofing.

 Robert G8RPI.


 
  From: Chris Albertson albertson.ch...@gmail.com
 To: j...@quikus.com; Discussion of precise time and frequency
 measurement
 time-nuts@febo.com
 Sent: Saturday, 27 July 2013, 4:18
 Subject: Re: [time-nuts] GPS Spoofing


 I boat?  The backup is a competent captain.  He'd see the compass
 heading
 move and quickly disengage the autopilot.   I had a boat for years  I'd
 notice a 5 degree change.  Mine was a sailboat so I'd be more sensitive
 to
 heading changes than a power boater but still the human is the backup.

 Most autopilots don't directly follow GPS, they use GPS to determine a
 heading, follow it then use GPS to detect drift and re-compute the
 heading.
 the heading would be held by a compass sensor in a low-cost setup or in
 a
 larger setup a lazer ring gyro backed up by a compass. So a spoofed
 GPS
 would cause the autopilot to think there was a bigger crooswnd or
 current
 and make a bigger heading change.

 I bet you could hijack a drone not a manned vehicle the pilot is trained
 to
 monitor the automation and he'd very quickly turn it off thinking it was
 broken.






 On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote:

  Prof. Humphry from Texas just reported being able to spoof GPS in the
 Med
  and take over the nav system of a luxury yacht. He's done this before
 with
  a drone in the US.
 
  LORAN as a backup, at least?
 
  -John
 
  ==
 
 
 
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Re: [time-nuts] GPS Spoofing

2013-07-27 Thread J. Forster
When Cape Cod LORAN was functional, I could easily see the pulses with a
few turn coil maybe a foot in diameter, roughly resonated, and a scope.

-John

==



 Key

 Problem with GPS is its easy to spoof on one level and have a complete
 denial of service on the other.   Out in California a while back a
 malfunctioning TV distribution amplifier jammed a major harbor and
 surrounding almost 25 sq miles affected all because of a 49.95 TV amp had
 a problem.  The military receivers had the same problem

 LORAN is virtually jam proof unless you have a very powerful transmitter

 Sent from my iPhone

 On Jul 27, 2013, at 11:17 AM, Michael Perrett mkperr...@gmail.com wrote:

 I have seen a lot of differing opinions on GPS Spoofing and using back
 up
 systems on this thread. Most pretty good, but a couple off the mark a
 bit.

 Here are a couple of comments on GPS Spoofing.

   - There are anti-spoofing GPS receivers available - to authorized
   users. Typically DOD. Most, if not all, military receivers utilize the
   encrypted P-Code, while civilians must use the more vulnerable clear
 text
   C/A code. The P-Code signals are very difficult to spoof unless you
 have
   a-pirori knowledge. The newer satellites (GPS III) will have an even
 more
   robust AS methodology.
  - Note: beware of P-Code, or Military, receivers available on eBay.
  They are useless without the encryption keys distributed by the US
  Government.
  - In the (near?) future there will be four civilian GPS Signals:
 The
   government is in the process of fielding three new signals designed
 for
   civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A
 or
   C/A at L1, will continue broadcasting in the future, for a total of
 four
   civil GPS signals. Users must upgrade their equipment to benefit from
 the
   new signals. ref
   http://www.gps.gov/systems/gps/modernization/civilsignals/
   - Receivers utilizing the new civilian GPS frequencies can solve the
 GPS
   equations from more than one frequency and see if any one signal is
 being
   spoofed. The new civilian frequencies will be more spoof resistant.

 Comments on using inertial measurement units (IMUs) to back up GPS.

   - Current IMUs with even a good drift rate of say, 1 degree per
 hour,
   available for around a few thousand dollars, will be off 60 nautical
 miles
   after an hour of uncorrected operation. That can be reduced by other
 sensor
   inputs (GPS, LORAN, pit-log or what ever you have), but the navigation
   solution will eventually degrade to the accuracy of the external
 sensor. If
   my memory serves me for a really deep pocket navigator (having tens to
   hundreds of thousands of dollars, and a large amount of available
 mounting
   space) IMUs with drift rates of up to a thousand times less can be
   purchased (that's ,001 miles per hour, or around a couple of meters
 per
   hour), think submarines, etc.

 Using a dual sensor navigation system (or timing system! ), such as
 GPS/eLORAN, would obviously make the system so much more robust.

 Michael / K7HIL

 On Sat, Jul 27, 2013 at 6:43 AM, Scott McGrath scmcgr...@gmail.com
 wrote:

 Key here is how does the captain know that GPS is no longer providing
 an
 accurate fix?   You need 2 or more independent systems to cross check
 each
 other.

 Sent from my iPhone

 On Jul 27, 2013, at 12:21 AM, Jim Lux jim...@earthlink.net wrote:

 On 7/26/13 8:45 PM, J. Forster wrote:
 I gather from the article, the GPS position was spoofed and the
 autopilot,
 in bringing it back to where it was supposed to be, actually took it
 off
 course.

 There are places where a few hundred feet makes a big difference,
 viz.
 the
 Costa Concordia.

 IMO, this is a very convincing reason for something like LORAN.

 I think it's a convincing argument for a captain who pays attention to
 the other navigation instruments and doesn't blindly follow the GPS.

 It's also a convincing argument that shipboard
 automation/autopilot/autocontrol vendors need to make more
 sophisticated
 software (which I suspect they do, particularly on 200+ foot ships.. I
 would imagine that there are some aspects of this demo that are
 contrived.)
 The ship making and driving business is pretty unregulated. It's all
 about
 what the owner of the ship is willing to pay (or what he needs to get
 liability insurance, if he wants).  There's nothing even remotely like
 DO-178 for shipboard stuff.

 The folks doing stabilized oil rigs probably have sophisticated
 systems,
 but they're also using IMUs and other stuff. Ditto for high value
 things
 (oil tankers, warships).  Molasses tankers? They're probably lucky to
 have
 a functioning compass and some old charts.


 I'm not sure, though, that looking at the big picture, whether your
 tax
 dollars are better spent on LORAN, or on some other precision
 navigation
 method or on making jam resistant GPS receivers (which do, in fact
 exist,
 and make use of things like direction of arrival

Re: [time-nuts] Agilent / HP 117A on eBay...

2013-07-26 Thread J. Forster
On mine, the side arms are insulated at the bottom and the conduit screws
directly into the Tee at the top. That makes the shield symmetric about
ground at the vertical post.

-John

===


 the side loops are insulated at the top to prevent forming aa shorted
 turn. It's a loop antenna that works on the magnetic field component of
 the incoming wave, rather than the electric field, like a whip. So, if
 you put a bunch of turns inside the loop of conduit, a complete loop of
 conduit will be a shorted secondary.

 J. Forster
 The HP 117A antenna is a circular shielded loop, about 1 meter or 3' in
 diameter. I never bothered to measure it. It looks to be made out of
 roughly 1 OD aluminum electrical conduit components, a Tee at the top
 and
 a pull box at the bottom. There are three conduit sections, one a
 diameter
 that goes vertically from the bottom pull box to the top Tee. There are
 a
 pair of semicirllas, one on each side.  The two side loop halved are
 insulated from the pull box as I remember.

 There is a picture in the 117A manual on the Agilent site, but no
 dimensions I saw. It is a crummy scan. The loop dimensions may be in a
 catalog of the period.

 It'd be fairly easy to replicate w/ a hand conduit bender, IMO.

 -John

 



 I never bothered


 Hi Pete, I have a 14 diameter choke ring GPS L1 with a big spike on
 the
 top of it, on the peak of the roof :)

 That certainly gets some stares!

 As the HP antenna is VLF, is the Antenna Huge?

 I can't reliably get WWVB in Australia.
 Lots of fading etcetera, or I'd be in there like a shot :)

 We do have a beer called VB hmmm..

 --marki

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]
 On
 Behalf Of Pete Lancashire
 Sent: Friday, 26 July 2013 10:50 AM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Agilent / HP 117A on eBay...

 I still would like to find one of the HP antenna's just for the looks.
 Even the 10509A with 13CW4's .. ok the FET version would be better.

 At least give those passing by something else to point at :-)

 -pete




 On Thu, Jul 25, 2013 at 7:09 AM, Burt I. Weiner b...@att.net wrote:

 I always wanted on, but with the intention of using it.  To bad it's
 now useless now with the new WWVB format, otherwise I'd buy it.
 Antennas I got.

 Burt, K6OQK

 At 06:14 AM 7/25/2013, time-nuts-requ...@febo.com wrote

  Would this box work with the new WWVB format?
 
 
  On 07/25/2013 04:07 AM, Mark C. Stephens wrote:
 
  Oh my gosh, a 117A has popped up on eBay!
  Looks in pretty good condition given its age...
 
  Seller claims the antenna will be listed shortly!
 
  Item # 281141315740
 
 
  --marki


 Burt I. Weiner Associates
 Broadcast Technical Services
 Glendale, California  U.S.A.
 b...@att.net
 www.biwa.cc
 K6OQK
 __**_
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 --
 Neither the voice of authority nor the weight of reason and argument
 are as significant as experiment, for thence comes quiet to the mind.
 De Erroribus Medicorum, R. Bacon, 13th century.
 If you don't know what it is, don't poke it.
 Ghost in the Shell


 Dr. Don Latham AJ7LL
 Six Mile Systems LLP
 17850 Six Mile Road
 POB 134
 Huson, MT, 59846
 VOX 406-626-4304
 Skype: buffler2
 www.lightningforensics.com
 www.sixmilesystems.com





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[time-nuts] GPS Spoofing

2013-07-26 Thread J. Forster
Prof. Humphry from Texas just reported being able to spoof GPS in the Med
and take over the nav system of a luxury yacht. He's done this before with
a drone in the US.

LORAN as a backup, at least?

-John

==



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Re: [time-nuts] HP 117 from ebay

2013-07-26 Thread J. Forster
IMO, it is unlikely you will be able to form the loop by hand on a
mandrel. I'd suggest a commercial conduit bender for that trade size
conduit and work your way along the tubing a few inches at a time.

-John

===






  
 List,
  
 I bought one of them for several reasons besides
 that I really wanted it.
  
 1.  There is
 plenty of real estate to install Paul’s demod circuit.
  
 2.  It is
 large enough so the nuvistors can be replaced with dual gate mosfets (I
 have
 lots of them). Also sometimes replacement nuvistors can be obtained on
 ebay for
 a reasonable amount.
  
 3.  If
 needed, I believe most of the divider circuits can be relatively easily
 replaced with IC’s.
  
 However the first thing I will do before firing it
 up (figuratively or literally) is to replace all the electrolytic caps.
  
 I’m not interested in buying the antenna as there
 are numerous vlf antenna circuits with preamps for 60 KHz on the net. 
 One suggestion I found interesting was the
 idea of filling your tubing with wet sand then using a truck tire to bend
 the
 loop. Where to borrow a truck tire? It didn’t say.
  
 Regards,
  
 Perrier


 
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Re: [time-nuts] GPS Spoofing

2013-07-26 Thread J. Forster
I gather from the article, the GPS position was spoofed and the autopilot,
in bringing it back to where it was supposed to be, actually took it off
course.

There are places where a few hundred feet makes a big difference, viz. the
Costa Concordia.

IMO, this is a very convincing reason for something like LORAN.

-John

=



 I boat?  The backup is a competent captain.  He'd see the compass heading
 move and quickly disengage the autopilot.   I had a boat for years  I'd
 notice a 5 degree change.  Mine was a sailboat so I'd be more sensitive to
 heading changes than a power boater but still the human is the backup.

 Most autopilots don't directly follow GPS, they use GPS to determine a
 heading, follow it then use GPS to detect drift and re-compute the
 heading.
  the heading would be held by a compass sensor in a low-cost setup or in a
 larger setup a lazer ring gyro backed up by a compass. So a spoofed
 GPS
 would cause the autopilot to think there was a bigger crooswnd or
 current
 and make a bigger heading change.

 I bet you could hijack a drone not a manned vehicle the pilot is trained
 to
 monitor the automation and he'd very quickly turn it off thinking it was
 broken.






 On Fri, Jul 26, 2013 at 8:41 AM, J. Forster j...@quikus.com wrote:

 Prof. Humphry from Texas just reported being able to spoof GPS in the
 Med
 and take over the nav system of a luxury yacht. He's done this before
 with
 a drone in the US.

 LORAN as a backup, at least?

 -John

 ==



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 --

 Chris Albertson
 Redondo Beach, California



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Re: [time-nuts] Agilent / HP 117A on eBay...

2013-07-25 Thread J. Forster
The HP 117A antenna is a circular shielded loop, about 1 meter or 3' in
diameter. I never bothered to measure it. It looks to be made out of
roughly 1 OD aluminum electrical conduit components, a Tee at the top and
a pull box at the bottom. There are three conduit sections, one a diameter
that goes vertically from the bottom pull box to the top Tee. There are a
pair of semicirllas, one on each side.  The two side loop halved are
insulated from the pull box as I remember.

There is a picture in the 117A manual on the Agilent site, but no
dimensions I saw. It is a crummy scan. The loop dimensions may be in a
catalog of the period.

It'd be fairly easy to replicate w/ a hand conduit bender, IMO.

-John





I never bothered


 Hi Pete, I have a 14 diameter choke ring GPS L1 with a big spike on the
 top of it, on the peak of the roof :)

 That certainly gets some stares!

 As the HP antenna is VLF, is the Antenna Huge?

 I can't reliably get WWVB in Australia.
 Lots of fading etcetera, or I'd be in there like a shot :)

 We do have a beer called VB hmmm..

 --marki

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of Pete Lancashire
 Sent: Friday, 26 July 2013 10:50 AM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Agilent / HP 117A on eBay...

 I still would like to find one of the HP antenna's just for the looks.
 Even the 10509A with 13CW4's .. ok the FET version would be better.

 At least give those passing by something else to point at :-)

 -pete




 On Thu, Jul 25, 2013 at 7:09 AM, Burt I. Weiner b...@att.net wrote:

 I always wanted on, but with the intention of using it.  To bad it's
 now useless now with the new WWVB format, otherwise I'd buy it.
 Antennas I got.

 Burt, K6OQK

 At 06:14 AM 7/25/2013, time-nuts-requ...@febo.com wrote

  Would this box work with the new WWVB format?
 
 
  On 07/25/2013 04:07 AM, Mark C. Stephens wrote:
 
  Oh my gosh, a 117A has popped up on eBay!
  Looks in pretty good condition given its age...
 
  Seller claims the antenna will be listed shortly!
 
  Item # 281141315740
 
 
  --marki


 Burt I. Weiner Associates
 Broadcast Technical Services
 Glendale, California  U.S.A.
 b...@att.net
 www.biwa.cc
 K6OQK
 __**_
 time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
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Re: [time-nuts] eLoran announcement in the UK

2013-07-17 Thread J. Forster
Do you have any idea of the transmitter power/antenna gain?

The relatively low power of the UK 60 kHz is strong enough to interfere w/
WWVB in MA, so I'm wondering if the UK eLORAN might be usably strong.

-John

===




 Not the first time this has been mentioned but another confirmation of
 the GPS alternative and eLoran stations to be rolled out across UK

 http://eandt.theiet.org/news/2013/jul/eloran-rollout.cfm?utm_source=Adestrautm_campaign=E%26T%20News%20fortinightly%20-AUTOMATION%20VERSION-%20membersutm_medium=Newsletters-E%26T%20Newsutm_content=E%26T%20News%20-%20Membersutm_term=http%3A%2F%2Feandt.theiet.org%2Fnews%2F2013%2Fjul%2Feloran-rollout.cfmutm_contact=17085095

 /A navigation system resilient to GPS jamming will be installed along
 the south and east coast of the UK, it was announced today./

 /Following approval by the Department for Transport, seven differential
 eLoran stations will be installed to provide alternative position,
 navigation and timing (PNT) information to ensure that ships equipped
 with eLoran receivers can navigate safely in the event of GPS failure in
 one of the busiest shipping regions in the world./

 /The GPS signals most ships rely on are vulnerable to both deliberate
 and accidental jamming, which is causing increasing concern because of
 the wide availability of GPS jammers online for as little as £30 that
 are capable of causing complete outages across all receivers currently
 on the market./

 /The rollout, led by the General Lighthouse Authorities (GLAs) of the UK
 and Ireland, is the first in the world to deploy this technology for
 shipping companies operating both passenger and cargo services./

 . etc

 Regards
 David

 (I've designed  built off air standards for 60kHz MSF, 198kHz BBC
 radio4 and GPS so it looks another project just added to the DO list)

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Re: [time-nuts] eLoran announcement in the UK

2013-07-17 Thread J. Forster
On a smaller scale, my two Austron 2100Fs are sitting, patiently waiting

Has anyone had success in the US locking a standard LORAN-C
receiver/antenna onto the European stations lately?

-John

=


 I find this interesting.

 The military is also rekindling an interest in HF communications.  It
 seems that they are worried that satellite communications are vulnerable.

 A story I heard was that one fellow (a ham and book reseller) spent 10
 year buying up surplus Collins 5 kW transmitters from the government.

 He had the warehouse space and equipment to handle heavy stuff.

 Now there is a run on his stock by, guess who, the military.

 Brian

 On 7/17/2013 17:06, Iain Young wrote:
 On 17/07/13 17:27, David wrote:

 Not the first time this has been mentioned but another confirmation of
 the GPS alternative and eLoran stations to be rolled out across UK

 http://eandt.theiet.org/news/2013/jul/eloran-rollout.cfm?utm_source=Adestrautm_campaign=E%26T%20News%20fortinightly%20-AUTOMATION%20VERSION-%20membersutm_medium=Newsletters-E%26T%20Newsutm_content=E%26T%20News%20-%20Membersutm_term=http%3A%2F%2Feandt.theiet.org%2Fnews%2F2013%2Fjul%2Feloran-rollout.cfmutm_contact=17085095


 Now this will be interesting. My -understanding- is that eLORAN is
 backwards compatible with LORAN-C, (So an old LORAN receiver will
 still receive the eLORAN signals, you just wont get the extra features
 [low rate data transmissions, timing built in, rather than relying on
 TOC etc])

 Now if only they'd stop playing with Anthorn during the day at the
 moment, I could do some more tests. Ah well, I'll get to it later,
 it'll be cooler then anyway!


 Iain

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Re: [time-nuts] Lead acid battery noise levels

2013-07-11 Thread J. Forster
It's a compromise. NiCds are quiet, but they have to be recharged and can
have high self-discharge rates and grow whiskers internally.

If I were building a one-off or a few amps, and Hg batteries were
plentiful in the stockroom, I might well use them also.

In the PAR 113 the NiCd pack has to be replaced pretty often. The unit is
either in battery charge or operate mode. They do not 'float charge'. If
you get them used, the battery was not even wirth testing. Digi-Key would
make up replacements for $100-$150, but that was a while ago.

I don't know if you can noise model a battery as an ideal voltage source
in series w/ a Thevenin Equivalent, and use the Thevenin resistance in
SQR(4KTBR), but it seems at least plausible.

This would explain why bigger batteries reported;y have lower noise, at
least in part.

-John






 A long time ago, when I was concerned about a phase noise issue, I found
 an
 old NBS article. It was on measuring phase noise and included a schematic
 of
 an ultra-low noise amplifier. In that amplifier they used Mercury
 batteries.
 I also glanced at the referenced article, stating NiCad is the lowest
 noise,
 and, NiCads were available for a long time, yet they used Mercury.
 Regards
 - Mike

 Mike B. Feher, EOZ Inc.
 89 Arnold Blvd.
 Howell, NJ, 07731
 732-886-5960 office
 908-902-3831 cell


 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of David Kirkby
 Sent: Thursday, July 11, 2013 10:25 AM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Lead acid battery noise levels

 On 11 July 2013 05:47, Mark Spencer mspencer12...@yahoo.ca wrote:
 Eric:

  http://tf.nist.gov/general/pdf/1133.pdf

 discusses the noise levels of various batteries.

 Regards
 Mark S


 Sod's Law comes into play here. From a quick read of that, it seems NiCd
 are
 best, but they are being phased out. I was told they were banned in
 Europe,
 but I don't know if that is true. I'm pretty sure I've seen NiCd tools in
 the local DIY store, so I doubt it is true.

 Dave
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Re: [time-nuts] Lead acid battery noise levels

2013-07-11 Thread J. Forster
Yeah! In spades. And there really are no good substitutes. I have a number
of instruments from ESI, GR and others that are pretty much doorstops w/o
them.

The solution the camera people use, the silver cells, are not available in
the larger sizes for instruments AFAIK.

-John

===




 But Hg batteries are So Moot! We're simply not allowed to have them or
 make them. Nanny won't have them in the house.
 I have a couple of Accutron clocks that would love to see a mercury cell.

 ed breya
 Second attempt at emailing again:

 NiCd batteries should have the lowest noise for their size due to low
 resistance, but if you look at ever-lower frequency, the Hg should be
 superior since it has the most stable voltage with time and
 temperature. Drift (including self-discharge) and temperature
 variation response can appear as very low frequency noise independent
 of the other noise sources and operating conditions. Hg batteries are
 so stable that they were commonly used as voltage references or to
 power small circuits without any additional regulation needed.

 Ed



  Mike Feher wrote:

 A long time ago, when I was concerned about a phase noise issue, I found
 an
 old NBS article. It was on measuring phase noise and included a
 schematic of
 an ultra-low noise amplifier. In that amplifier they used Mercury
 batteries.
 I also glanced at the referenced article, stating NiCad is the lowest
 noise,
 and, NiCads were available for a long time, yet they used Mercury.
 Regards
 - Mike
  










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 --
 Neither the voice of authority nor the weight of reason and argument
 are as significant as experiment, for thence comes quiet to the mind.
 De Erroribus Medicorum, R. Bacon, 13th century.
 If you don't know what it is, don't poke it.
 Ghost in the Shell


 Dr. Don Latham AJ7LL
 Six Mile Systems LLP
 17850 Six Mile Road
 POB 134
 Huson, MT, 59846
 VOX 406-626-4304
 Skype: buffler2
 www.lightningforensics.com
 www.sixmilesystems.com


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Re: [time-nuts] How dangerous if a Rb lamp broken?

2013-07-10 Thread J. Forster
Public perceptions of risk change with time.

In WWII, Radium dial watches, aircraft instruments, dial and switch
markings, were ubiquitous. But so were explosives, bombs, bayonettes, and
a bunch of other things. So people didn't have the luxury of concerns over
minor things.

Now that is not so.

-John

===



 I just tried calling your cell because you seem to be the legitimate
 person to ask.   I don't read all the time-nuts postings but has anyone
 ever
 brought up the most logical aspect of ionizing radiation for the group:
 the
 radium dial wrist watch? or are they all too young to have experienced
 that?
 I think I got one for Christmas when I was 12 or 13.   I'm still here at
 74!
 I do think that all reflector's are at their best when they are
 entertaining---maybe not exactly on topic!

 Regards,

 Lee MushelI live about 20 miles from the Mississippi and 50 miles
 north
 of the Illinois border.   We simply try to enjoy life, our garden, our
 flowers, our dogs and our cats.  Best to stay away from neighbors and
 social
 media!


 - Original Message -
 From: Mike Feher mfe...@eozinc.com
 To: 'Discussion of precise time and frequency measurement'
 time-nuts@febo.com
 Sent: Wednesday, July 10, 2013 7:00 AM
 Subject: Re: [time-nuts] How dangerous if a Rb lamp broken?


 You must really be a legend in your own mind, and now, a
 self-proclaimed
 time-nuts cop.  -

 Mike B. Feher, EOZ Inc.
 89 Arnold Blvd.
 Howell, NJ, 07731
 732-886-5960 office
 908-902-3831 cell




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