On Wed, 1 Feb 2012 09:27:30 -0800
Chris Albertson albertson.ch...@gmail.com wrote:
I thought it might be interresting but then found out you need to buy
$2,000+ worth of hardware for even start experimenting.Open Source
SDR needs to run on a common affordable platform or it will never
On Thu, 02 Feb 2012 00:50:39 +0100
Magnus Danielson mag...@rubidium.dyndns.org wrote:
I have not seen any such papers yet. Do you have any pointers or hints
what to search for?
Let me see... yes, here it is:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA497270
Thanks!
Printed and ready
On Thu, 02 Feb 2012 01:22:07 +0100
Magnus Danielson mag...@rubidium.dyndns.org wrote:
On 01/02/12 19:12, Attila Kinali wrote:
I guestimate, that the RF/ADC part would cost somewhere between
100 to 200 USD in parts. The big uncertainty here is the FPGA.
I have no clue how much logic space
On Thu, 2 Feb 2012 11:41:17 +1100
Tristan Steele tristan.ste...@gmail.com wrote:
I have been looking at SDR GPS reception for a while, and have a number of
ideas as to how to go about this process. My first point of call is the
layout of a board using a MAX2769B (1) receiver chip attached
OK, got it: no need to lock the receiver clock to birds to get stable data
(e.g. Oncore+Cs) but the clock can be locked to birds to get even better
data and obtain for free a reference clock (TBolt). The use of a stable
clock (not locked to birds) feeding the receiver can show the various
errors
Great plot :)
I've a dump of the SPI transfers during a night taken with the logic
analyzer... but have found no time yet to process the dump to extract
the transfers. Of course it is easier to take it from the serial port
data :)
The adjustment looks quite closely related to the
I forgot... have you had the opportunity to check if the difference
between the two DDS programming words is the same in all cases? All my
readings leds to 1400.00x Hz, I've not looked at it but probably the
difference in DDS counts is constant.
Regards,
Javier
El 02/02/2012 10:13, Javier
On Wed, 01 Feb 2012 21:53:16 -0800
Jim Lux jim...@earthlink.net wrote:
You don't need the ADC: you just need a limiter/comparator.
Yes, but this degrades sensitivity quite a lot.
You don't need insane sampling rates. Think in terms of subharmonic
sampling.
This requires that you have an
I think I've seen comments about making 32 KHz from 10 MHz in a PIC or AVR.
tvb has this web page, but I don't see a 32 KHz option:
http://www.leapsecond.com/pic/picdiv.htm
Hal,
Yes, I have a PIC divider that takes 5 or 10 MHz input and
outputs a 32.768 kHz square wave with minimal jitter
If I want to decode a GPS signal, do I have to know (or figure out) the
frequency of the local oscillator? Or does it drop out of the calculations,
somehow?
--
These are my opinions, not necessarily my employer's. I hate spam.
___
time-nuts
Thanks guys!
Updated Elio's picture with the additional info John provided.
Revised picture posted here...
http://www.xertech.net/FE5680A/FE-5680A_annotated_2.jpg
Let me know if I got anything wrong. Elio, feel free to update your
original if you want to keep control of it.
-Rex
On
ggg*fitting has two listings NEW and USED. Bought a NEW hoping to get a
better unit. Based on tests unit has run at least three years. Also has dent
on case.Recommend we stay away from this one. Is a marketing ploy. Will
ship it back to day. There are other choices out there. Do not need to
I modified my previous pinout image adding some more info (thanks to John
and Rex for their suggestions):
you can find them at the following addresses:
JPG format (1.4MB):
http://www.rhodiatoce.com/pics/time-nuts/FE-5680A/FE-5680A_annotated_001.jpg
Editable Adobe photoshop format (40MB):
Hi Tom,
I'm interested in that divider. Actually, insterested in knowing how it
works, not in the .HEX file.
Breseham's algorith works but has inherent jitter and I've found no other
solutions for situations like that.
I'd live to know how it is done.
Thank you,
Roberto EB4EQA
Hello all,
I have acquired some FEI modules that have seen better days, but look
like they might be repairable. I've looked in the ko4bb and BAMA
manuals archives without success - is there any chance anyone on the
list has any information on these units please?
FE-1050-D Frequency Time
I would disagree. The traffic on the FE-5680A took some of the group's
bandwidth only in the recent weeks in coincidence with the appearance of cheap
units on the auction site. Why to force time-nuts to jump to and fro one group
and another?
I have only been a member of the time-nuts group for
You are welcome to upload it to my manuals pages
www.ko4bb.com/manuals
Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things...
-Original Message-
From: Bob Bownes bow...@gmail.com
Sender: time-nuts-boun...@febo.com
Date: Wed, 1 Feb 2012 12:41:19
To: Discussion
Magnus,
How do they compare in price to the receivers we normally use for timing?
Do you see any advantage for a timing receiver to fix faster than once per
second?
Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things...
-Original Message-
From: Magnus
I would disagree. The traffic on the FE-5680A took some of the group's
bandwidth only in the recent weeks in coincidence with the
appearance of cheap
units on the auction site. Why to force time-nuts to jump to and fro
one group
and another?
And some of us will not use yahoo lists, based
Me too. I think that this is a transient that will surely decay... and
that also is leading to several constructive sub-threads that are not
directly related with the FE-5680A but nevertheless very interesting and
very time-nut related. I'm not interested to subscribe another list
that
No new groups please, the Rb thread is interesting for time-nuts, and
I don't see the need.
73 - Marco IK1ODO
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I dont want to have to take loads of groups to keep up with the expertise
available on this Group. The answer to bandwidth in my case is the DELETE
key, and it would be less if there was not the continued use of
quoted-quoted quotes :-)) Even if you quote one its worth knocking the tail
off
I created a spam filter for anything with 5680
so I don't see all those posts.
On 02/02/2012 08:57 AM, Rich (Buckeye) wrote:
I have only been a member of the time-nuts group for a short
while. It seems like 75% of the posts here have to do with the
I indeed created a filter to send them to another folder so I keep both
and have all about the 5680A grouped.
On 02/02/2012 16:07, Mike Naruta AA8K wrote:
I created a spam filter for anything with 5680
so I don't see all those posts.
On 02/02/2012 08:57 AM, Rich (Buckeye) wrote:
I have
On 2/2/12 1:49 AM, Hal Murray wrote:
If I want to decode a GPS signal, do I have to know (or figure out) the
frequency of the local oscillator? Or does it drop out of the calculations,
somehow?
Yes, it comes out in the calculations.
That's why you need 4 satellites. You solve for x,y,z
Hi Roberto,
The motivation for this, I assume most list members know, is to
drive cheap quartz stepper motor clocks with precise 32 kHz
frequency, one derived from an atomic or GPS 10 MHz.
The 10 MHz to 32 kHz PIC divider I wrote uses a sort of binary
leap year algorithm to adjust the digital
On 2/2/12 1:28 AM, Attila Kinali wrote:
On Wed, 01 Feb 2012 21:53:16 -0800
Jim Luxjim...@earthlink.net wrote:
You don't need the ADC: you just need a limiter/comparator.
Yes, but this degrades sensitivity quite a lot.
You don't need insane sampling rates. Think in terms of subharmonic
I managed to take a photo at the scope screen showing the 1 pps pulse
from an old FE-5680A (the one that does not need the 5V and does not
output the oscillator signal - just the 1pps).
Exposure was 30 sec, F9. The signal was barely visible with naked eye,
and some jittering is present. The room
If anyone wants all the FE5580A mail to go to one place make a filter
in you email reader. Tell it to place anything sent from the TN list
with FE5680 in the hearer or text to go into a special folder or
otherwise be tagged as fe5680 related.
I think this happens all the time -- people talk
Amazing... there is always something to learn from TVB. Now I'll try to
derive a 2.048MHz G.703-13 clock from a 10MHz clock. I suspect that the
procedure is similar, even if 2048KHz is not quite a power of 2.
On Thu, Feb 2, 2012 at 4:35 PM, Tom Van Baak t...@leapsecond.com wrote:
Hi Roberto,
and here's another photo of the pulse from one of the newer breed of
FE-5680A that require the 5V.
Taken with a Sony Cybershot H5, 8 sec exposure, 'scope is an elderly Tektronix
2252
http://dl.dropbox.com/u/1690159/1PPS_1%20FE-5680E.jpg
John H.
On 2 Feb 2012, at 15:50, Alberto di
I have only been a member of the time-nuts group for a short while. It
seems like 75% of the posts here have to do with the FE-5680A Rubidium
Frequency Standards and there use and modification. This seems like the
most popular subject and takes up allot of the group's bandwidth.
Hi Rich,
Odd. Did Tektronix mark it Fluke PM3082? :)
It is nice to know that the current generation of digital cameras can
be used for this application. It is too bad that the image has so
much noise.
On Thu, 2 Feb 2012 16:27:03 +, John Howell j...@howell61.f9.co.uk
wrote:
and here's
Staying on the topic of the thread, I also found the list clogging
up with fixes for a cheap rubidium device (wouldn't call it a
standard).
Outlook told me that there were 10,350 messages in the time-nuts
folder since it was archived at the end of 2010. I used Find for
5680 and got 900 messages,
Azelio,
2.048 MHz has a cycle period of just 488.28125 ns so a PIC/AVR is (far) too
slow to use the same trick I did on the low frequency 32 kHz.
I think you'll have to use a PLL for that one. How about a 16 kHz compare rate:
10 MHz / 625 = 16000 Hz = 2.048 MHz / 128
/tvb
- Original
Yes, shortly after having sent out the message I realized that I was, as
usual, too fast. I'm aware that a simple microprocessor can't be used but a
Spartan3 can be involved. Then another problem: the 2.048MHz is about 1/5
of the 10MHz so it is not possible. Sofar the way out is: dividing the
On Thu, 02 Feb 2012 07:49:53 -0800
Jim Lux jim...@earthlink.net wrote:
[Limiting / Downmixing converter]
Yes, if you need lots o'bits, but a single bit sampler with wide
bandwidth is easy (which is why they do it). It's basically a D-latch
at the end of the amplifier/limiter chain.
Yes,
My frustration is that there is very little information or discussion as to
the performance of the device, ultimately some may want to use it in their
shop as thee reference, and to make that possible more performance data
would be nice. It may be the best they have.
Bert Kehren
In a
Not odd but my mistake, I took a picture on both 'scopes and the Fluke gave
marginally better results, the text referred to the wrong one. Sorry for the
confusion.
On 2 Feb 2012, at 16:43, David wrote:
Odd. Did Tektronix mark it Fluke PM3082? :)
It is nice to know that the current
Hi Roberto:
By changing the timer count dynamically it's possible to lower the jitter to
one timer count. See:
http://www.prc68.com/I/PClock.shtml#BA
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/Brooke4Congress.html
Roberto Barrios wrote:
Hi Tom,
I'm
If I want to decode a GPS signal, do I have to know (or figure out) the
frequency of the local oscillator? Or does it drop out of the
calculations,
somehow?
Yes, it comes out in the calculations.
That's why you need 4 satellites. You solve for x,y,z and local clock
offset. (and, in
On Thu, 02 Feb 2012 10:49:22 -0800
Hal Murray hmur...@megapathdsl.net wrote:
Yes, it comes out in the calculations.
That's why you need 4 satellites. You solve for x,y,z and local clock
offset. (and, in reality you also have to solve for xdot,ydot,zdot, and
fdot)
I thought the 4th
One can do many things with a small micro having programmable logic cells, such
as the Cypress PSOC. For grins I worked out (via spreadsheet) how to use the
PSOC digital divider blocks and the built-in clock PLL to get from 10MHz to
2.048MHz in a fairly precise manner. The scheme uses a divider
t...@leapsecond.com said:
I'm not sure how well a multi-level leap year algorithm relates Breseham's
algorithm. I tracked down his 1965 plotter article. There might be common
ground there.
It's the same math as a DDS.
If Breseham would land exactly on a grid point after N steps, a DDS will
Filed my comments. They should be available online in a day or so.
Thanks for the word.
*** REPLY SEPARATOR ***
On 01-Feb-12 at 18:12 John Darwin Powers wrote:
Group the following material may be out of context of the normal
subject matter, but take notice
Is anyone prepared to comment on the relative performance of the FE-5680A
compared with the LPROs?
Bruce Hunter, KG6OJI
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and
I found this homebrew GPS receiver project recently:
http://www.holmea.demon.co.uk/GPS/Main.htm
No custom specialized chips that are unavailable in small quantities, or which
will go obsolete in a few months. I think the best solution for the open
source GPS community is to design open source
Yes, if you need lots o'bits, but a single bit sampler with wide
bandwidth is easy (which is why they do it). It's basically a D-latch
at the end of the amplifier/limiter chain.
Yes, but you lose IIRC about 3dB of performance compared to a 2bit ADC.
Only if you get the gain right.
A
Hi Roberto:
By changing the timer count dynamically it's possible to lower the jitter to
one timer count. See:
http://www.prc68.com/I/PClock.shtml#BA
Have Fun,
Brooke Clarke
Hi Brooke,
You're a fellow PIC guy; let me explain.
Correct, that method works with a modest interrupt rate to
Is anyone prepared to comment on the relative performance of the FE-5680A
compared with the LPROs?
Bruce Hunter, KG6OJI
I would be interested in such comments too. I judiciously refrained myself
from buying an FE-5680A because I own nine LPROs.
Antonio I8IOV
Some info...
Its tempting to attach an LED to the /LOCK signal on the DB9.
However this signal is very weak and the LED does not seem very bright
and PPS signal does not pulse...Hmm
Internally the /LOCK pin is connected the 74AC240 buffer, but with an
LED helping to keep the signal voltage high
I did the same thing when I first tested mine. I mounted the regulator and a
pair of SMA jacks right to the board it came with using the big board copper as
the heat sink for the regulator. I didn't want to build a driver for the LED
so I wired it directly (with resistor, of course). Dim and
I thought the 4th satellite was needed to determine the time. Wouldn't
it take a 5th satellite to also determine the frequency of the local clock?
Not really. There are two ways to get the postion and time derivatives. One
is to either use two fixes which give you each a (x,y,z,t) tuple,
On Thu, Feb 2, 2012 at 12:21 PM, Tom Van Baak t...@leapsecond.com wrote:
I'm curious how a 10 MHz-driven high-end DDS would generate
32 kHz with the lowest possible jitter?
I wonder if your 32K diver could be improved if it used interpolation.
In other words use an analog output. So at
Now I'm thinking that starting with a first run of 8 cycles at 500nS + 2
cycles at 400nS to be repeated for 10 times and then inserting 2 cycles of
400nS, a first approximation of my 2.048MHz can be done. Maybe with a
deltaF/F of 10 at -4 for tau 1 second but it can be done. In the very long
run
I've used an LED direct to the lock output.
330R resistor in series and the other end of the LED to the +5V rail.
Works fine for me, but then, I'm not interested in the 1PPS (actually not
even sure my bricks have that feature).
Rob Kimberley
-Original Message-
From:
Hi Tom:
I like the leap year idea. Does this fit into one of the 8-pin PICs?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/Brooke4Congress.html
Tom Van Baak wrote:
Hi Roberto:
By changing the timer count dynamically it's possible to lower the jitter to
OK for the PSOC example. At the moment I can try on a Spartan3 because I
already have a board with the OCXO. The Spartan3 has the so called DCM, a
digital clock generator that can multiply an input clock using its DDL
digital delay line.
On Thu, Feb 2, 2012 at 8:13 PM, Hal Murray
YMMV but, if there's any chance of a PPS output it'll be arriving at pin
2 of the 74AC240 buffer.
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On Thu, 02 Feb 2012 15:05:49 -0500
Daniel Schultz n8...@usa.net wrote:
I found this homebrew GPS receiver project recently:
http://www.holmea.demon.co.uk/GPS/Main.htm
No custom specialized chips that are unavailable in small quantities, or which
will go obsolete in a few months. I think
On Thu, 02 Feb 2012 12:15:41 -0800
Hal Murray hmur...@megapathdsl.net wrote:
Yes, if you need lots o'bits, but a single bit sampler with wide
bandwidth is easy (which is why they do it). It's basically a D-latch
at the end of the amplifier/limiter chain.
Yes, but you lose IIRC about
On Thu, Feb 2, 2012 at 6:42 AM, shali...@gmail.com wrote:
Magnus,
How do they compare in price to the receivers we normally use for timing?
Do you see any advantage for a timing receiver to fix faster than once per
second?
This thread got started when someone asked if an analog PLL would
Hi
They are pretty similar units.
They are both within about 7x10^-12 to 1.5x10^11 at one second. Both are
within about 1 to 3x10^-12 at 100 seconds. Good samples of both will get
much better than that out past 100 seconds. Bad samples of each, not so
much. You would have to test a pretty good
On Thu, 02 Feb 2012 12:46:01 -0800
bob grant bobgr...@fastmail.fm wrote:
Some info...
Its tempting to attach an LED to the /LOCK signal on the DB9.
However this signal is very weak and the LED does not seem very bright
and PPS signal does not pulse...Hmm
Internally the /LOCK pin is
Years ago (in the 80's) I needed to lock a homebrew DDS to an accurate,
stable 10 MHz reference (a good TCXO in this case) that was set to
WWV/H. Considering that the DDS was clocked at 2^24 Hz (16.777216 MHz)
this was slightly awkward, but I did it using standard HC and 4000 logic.
The
No doubt, the correct way to generate accurate clocks from an accurate
10MHz is by PLLs. There are DDS too, then there is a strange method that
uses a sort of dual (triple? Quadruple? ...) modulus. The advantage is that
you don't need another oscillator (the PLL needs a VCO) or the (co)sine
lookup
Hence the need for a 100PPS from a Motorola, the 800Hz from a uBlox, the
10KHz from the Jupiter T, the 10MHz from the CW12 (the WI version, recently
developed thanks to the time-nuts list).
Anyway I still think that an analog GPSDO 1PPS based can be done. Maybe not
the best accuracy can be
The LEDs are common garden variety, tied to +5V and inline with 1k8...I
was expecting 2ma or so.
Note, whereas the PPS signal is buffered the LOCK signal for the DB9 is
not passed though the 74ACT240 buffer.
On Thu, Feb 2, 2012, at 11:10 PM, Attila Kinali wrote:
On Thu, 02 Feb 2012 12:46:01
... since the analogs went dark.
Are you near any Class-A or low-power stations? Those are still permitted to
broadcast NTSC signals. What's in their vertical interval would be a separate
question, though.
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Bob wrote:
They [FE-5680A and LPRO] are pretty similar units.
[much good stuff snipped.]
Another Rb unit that has been available on the surplus market for
$50-100 in the past is the FRS-C. How do folks here feel they
compare to the FE-5680A and LPRO?
Best regards,
Charles
OK for the PSOC example. At the moment I can try on a Spartan3 because I
already have a board with the OCXO. The Spartan3 has the so called DCM, a
digital clock generator that can multiply an input clock using its DDL
digital delay line.
The original context was keeping wall clock time. In
At 03:20 AM 2/2/2012, Javier Herrero wrote:
I forgot... have you had the opportunity to check if the difference
between the two DDS programming words is the same in all cases? All
my readings leds to 1400.00x Hz, I've not looked at it but probably
the difference in DDS counts is constant.
So
Remarkably, the simplest and still one of the best GPSDO I've tested was the
10 kHz Jupiter and analog PLL-based standard by James Miller. It performed
superbly. It's the 4th GPSDO at: http://www.leapsecond.com/pages/gpsdo/
In hindsight, that doesn't seem too surprising.
I'm not a Juniper
Bob,
WOW!
Thanks for the very comprehensive report.
Bruce, KG6OJI
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It's possible to use Bresenham with two integers 10,000,000 and 32,768 but I
found no way to perform all the 24-bit calculations on an 8-bit PIC quick
enough. Removing the GCD often helps but in this case the accumulator
remains 3-bytes wide.
To generate 32 kHz you have to toggle a pin and
On Thu, Feb 2, 2012 at 12:21, Tom Van Baak t...@leapsecond.com wrote:
It's possible to use Bresenham with two integers 10,000,000 and
32,768 but I found no way to perform all the 24-bit calculations
on an 8-bit PIC quick enough. Removing the GCD often helps
but in this case the accumulator
On 2/2/12 12:05 PM, Daniel Schultz wrote:
I found this homebrew GPS receiver project recently:
http://www.holmea.demon.co.uk/GPS/Main.htm
No custom specialized chips that are unavailable in small quantities, or which
will go obsolete in a few months. I think the best solution for the open
On 2/2/12 9:39 AM, Attila Kinali wrote:
On Thu, 02 Feb 2012 07:49:53 -0800
Jim Luxjim...@earthlink.net wrote:
[
There is a sampling rate around 38-39 MHz that works out nicely for all
three bands (actually, any rate in that range probably works..I haven't
looked).. It helps that the 3 GPS
Thank you Bob! I just tried removing the lock indicator LED on my three
5680A units and sure enough, in every case, there was the 1 PPS (+5V, 1
usec, rise/fall time ~100 ns) just as if it had always been there.
As a reminder, this and much else useful lore is now collected at the
ongoing
On 1/29/2012 5:52 PM, J. L. Trantham wrote:
I seem to recall seeing this (or perhaps for the 'non-II' units) in the past
but can't seem to find it.
Can anyone point me to the pin outs and interconnects for these units?
Thanks in advance.
Joe
On Thu, Feb 2, 2012 at 7:16 PM, Hal Murray hmur...@megapathdsl.net wrote:
It's possible to use Bresenham with two integers 10,000,000 and 32,768
but I
found no way to perform all the 24-bit calculations on an 8-bit PIC quick
enough. Removing the GCD often helps but in this case the
On 3 Feb, 2012, at 05:07 , Hal Murray wrote:
I thought the 4th satellite was needed to determine the time. Wouldn't
it take a 5th satellite to also determine the frequency of the local clock?
Not really. There are two ways to get the postion and time derivatives. One
is to either use two
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