Am Fri, 21 Feb 2014 11:42:05 -0800 (PST)
schrieb Bob Albert bob91...@yahoo.com:
Oops yes I goofed, it's 500 MHz. 500 GHz is beyond state of the art
I would think.
Depends on your circuit development skills. Bipolars with gain at
500GHz are in principle possible, both in III/V-semiconductors
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
I ran across these units
http://www.conwin.com/time-frequency_references-gps_disciplined-gps_references.html
and I found some references from a few years ago in the time-nuts
archives, but I can't find any data on phase noise, etc. for the
disciplined output.
The data sheet/user manual/etc
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
=
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
=
Or just put it on a VNA and characterize it
I would be happy to.
Lester B Veenstra MØYCM K1YCM W8YCM
les...@veenstras.com
US Postal Address:
5 Shrine Club Drive
HC84 Box 89C
Keyser WV 26726
GPS: 39.336826 N 78.982287 W (Google)
GPS: 39.33682 N 78.9023741 W (GPSDO)
Telephones:
Home:
I need some help with a 'noob' question regarding some practical examples in
some of the NIST literature. When attempting to compare two clocks, I'm a bit
confused on the subject of exactly how to use my counter to compare a delayed
clock relative to another. Or perhaps I should just say
On 2/22/14 5:17 AM, Jimmy Burrell wrote:
I need some help with a 'noob' question regarding some practical
examples in some of the NIST literature. When attempting to compare
two clocks, I'm a bit confused on the subject of exactly how to use
my counter to compare a delayed clock relative to
Hi
On some counters, if both inputs arrive at exactly the same time, they get very
confused. The normal approach is to offset one by a few hundred ns or so. The
exact offset is fairly non-critical. It’s real value depends entirely on the
amount of drift you expect to see over the time period
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
On 2/20/14, 8:51 PM, Bob Camp wrote:
Hi
You can get parts in the 18 bit and up range for not a whole lot of money
with rational sample rates for a WWVB receiver. Analog Devices and Linear
Tech both make some interesting looking parts. They get you into the =100 db
dynamic range area.
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
On 2/20/14, 10:35 PM, Graeme Zimmer wrote:
I have a Kenwood TS-940S transceiver that can receive 60 kHz but I
have never heard anything
Where are you? It must be deaf as a post.
Most ham receivers that purport to have coverage down there really
don't. I thought my Flex 5000 should hear
On 2/20/14, 11:08 PM, John Marvin wrote:
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
Sorry for comming late to the party...
This may be relevant:
http://phk.freebsd.dk/loran-c/CW/
The basic idea is that you use a high-rate ADC, something like 1MS/s
and then you average into for instance a 1msec = 1.000 samples circular
buffer.
That gives you a very narrow comb filter
Claims on antenna efficiency at these frequencies are fairly meaningless (as
always) in that a normal antenna efficiency would be less than 1% !!
Alan
G3NYK
- Original Message -
From: JIM FARLEY jimfar...@att.net
To: t...@patoka.org; Discussion of precise time and frequency
On 2/20/14, 11:35 PM, Hal Murray wrote:
Can somebody give me a lesson in the tradeoffs between number of bits and
sampling rate?
Sure, the Shannon-Hartley Theorem. See:
http://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem
--
Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring
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
In August 2011 there was a brief mention on Time-Nuts of DDMTD's which
led me to The P. Moreira and I. Darwazeh paper Digital femtosecond
time difference circuit for CERN’s timing system. I'm hoping that
someone can explain one item mentioned in this paper for me. For those
not familiar
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
Jim, Bob,
we just had the pleasure of doing exactly this aligned-1PPS measurement two
days ago. I had to measure the difference (noise) of two units that were locked
to the same source. To jump ahead, the difference was 0ns +/- about 500ps noise
range.
We used an HP 5335, no problem, it
Hi
When you do any of these delay line based gizmos, you get some very strange
outputs. Flip flops go metastable, edges don’t quite arrive in the right
sequence. If all you do is look for solid ones or solid zeros you don’t get a
lot of data. Counting the ones and counting zeros is another
Jim,
Check the archives, I am pretty sure I reported on one of them, I think it was
on the FTS-250.. Or FTS-125.
My recollection: Not that bad for the price, but phase noise and spurs on my
sample unit were significantly worse than what they show in their plots no
matter what I tried, and
Jim,
If I get you right, you want to compare the 10MHz outputs (not the
1PPS). As Jim and Bob told us so far, the thing is to provide, that
input A _always_ starts before input B (or the other way around).
Connect the signals to an oscilloscope, and check, how much the phase
differs - if the
On Sat, Feb 22, 2014 at 11:56 AM, J. Forster j...@quikus.com wrote:
You are about 1/4 the distance away. Inverse square law.
If we were in free space I might concur on the inverse square law. We
aren't and propagation certainly has an effect on path loss. I posted
signal levels coming from my
svn64 alive and well
Using sirfdemo pc software coupled with sirf iv gps receiver I picked up the
first signal from svn64 (now assigned prn30).
The sat was launched from cape canavral (airforce station) florida last
thursday evening 2-20-14 about 17:55pdt.
The gps control people seem to be
On 2/22/14 10:01 AM, Said Jackson wrote:
Jim,
Check the archives, I am pretty sure I reported on one of them, I think it was
on the FTS-250.. Or FTS-125.
Found it.. thanks.. the key was to put your name in the search
My recollection: Not that bad for the price, but phase noise and spurs
Hi Jimmy,
Someone touched on the idea of using a scope. Go to the Agilent site and
download a copy of the 10811 manual, 10811-90002.pdf. Section 3 describes how
to adjust the 10811 and gives info on how to time the phase drift to calculate
the frequency error. You can pull the time base out
Thanks Bob,
Found several papers that describe the process after getting your info.
Bob Darby
On 2/22/2014 1:00 PM, Bob Camp wrote:
Hi
When you do any of these delay line based gizmos, you get some very strange
outputs. Flip flops go metastable, edges don’t quite arrive in the right
I picked up prn30 signal for the second time around 11:30pdt but did not get
any data till 12:11pdt
All though my sirf receiver is advertised to track some rediculous amount of
sat's at once (something 32 or is it 48
sats) the sirfdemo software only allows 12 sat's to be tracked at once..
Hi Jim,
On 22/02/14 14:17, Jimmy Burrell wrote:
I need some help with a 'noob' question regarding some practical examples in
some of the NIST literature. When attempting to compare two clocks, I'm a bit
confused on the subject of exactly how to use my counter to compare a delayed
clock
Hmmm... Magnus thank you for your comments. The 5 ns figure is certainly
helpful. My 1980 manual from HP just says Time Interval A - B = 0 ns to 10E7
seconds. Not very helpful.
May I ask where you found your 1992 reference? Perhaps you have a link?
Many thanks,
Jim...
N5SPE
On Feb 22, 2014,
Fractal antennas are nice artworks, but as long as their geometry does
not contain elements , which are comparable with the wavelength of the
incoming signal they are more or less not much assets,
73
KJ6UHN
Alex
On 2/22/2014 8:50 AM, Alan Melia wrote:
Claims on antenna efficiency at these
Hi Jim,
On 23/02/14 01:10, Jimmy D. Burrell wrote:
Hmmm... Magnus thank you for your comments. The 5 ns figure is certainly helpful. My 1980
manual from HP just says Time Interval A - B = 0 ns to 10E7 seconds. Not
very helpful.
May I ask where you found your 1992 reference? Perhaps you have
Jim,
when I did the test on the 53132A, I did the test with the two signals on
top of each other with a very small cable offset of 400ps, then I added a
10ns delay line to the B signal just to see if the counter would behave
differently. Here are the results, pretty much looks identical
On 2/22/14 6:06 PM, saidj...@aol.com wrote:
Jim,
not sure if I had sent these before, or if you found them in the archives,
here are my ADEV, phase noise, and frequency stability measurements results
of the FTS-250.
All I did was remove the GPS antenna for about 10 seconds during the test
to
Thank you Paul, there is some detailed info there which is sure to be
helpful. The number of variations on this thing is mind boggling.
FYI my two identical units havePPS out, no RF out and don't require 5V
in. I will probably wire the RF out to pin 4 of the D-Sub.
I will let you know if I
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