If you ned the 10KHz, Jupiter is one that has been used. I think a
10KHz GPS will make your GPSDO converge quickly but for long term use
a 1Hz GPS works as well and will be easier t replace years from now.
Also a 1HZ GPS with about equivalent performance is MUCH less
expensive (see ebay 2711528542
Dave wrote:
You didn't say, but I get the feeling maybe I should be getting
smaller ppt numbers? When you say noisy, is high ppt generally a
result of excess noise (front end NF)?
Hard to say about the ppt numbers -- my TBolts give somewhat lower
numbers than you are getting, but they use
Hi,
Does anyone know the suitability of this module for GPSDO ?
I am new to the group.
Thanks,
Bill R
http://www.ebay.com/itm/Navman-jupiter-T-Tu60-GPS-Kit-1pps-10khz-GPS-Module-/260790984470?pt=US_Ham_Radio_Amplifiers&hash=item3cb85a9f16
___
time
Hi
Some numbers:
Your Rb should hold <10 ppt per month. It's 1 second ADEV should be about 10
ppt as well. (makes it interesting to measure).
Your Rb should hold < 1 ppt per degree C on average. It will have a nasty
glitch (around 1 ppt as it steps over a temperature boundary). Best to keep i
HI,
Sorry to come in with a Out-of-Topic question, but I am stuck. I am trying to
bring an HP 5350A frequency counter back to life. I am looking for the two
EPROM loads. If you can help, please contact me direct.
Thanks,
Bert, VE2ZAZ
___
time-nuts ma
Hi
There are lots of case solutions. A busted piece of HP gear is a nice way to
come up with a case. Heatsink material is available from several web sites cut
to order quite cheap. A simple computer fan is way more air than you will ever
need. The obvious missing link is the controller. I'd run
Bob, I've been mulling over the question of a case, and I was thinking of
getting a 2M brick amp and putting it inside, bolted upside down to the heat
sink. Good idea? Anybody got a busted one?
Bob
>
> From: Bob Camp
>To: Discussion of precise time and fre
Hi
When I want to tune an Rb, I just hook up to it with a terminal program and
hack away at it. There's not a lot to the protocol.
Bob
On Sep 18, 2013, at 6:49 PM, Bob Stewart wrote:
> Hi Bob,
>
> As always, thanks for your informed help. I had been reaching the same
> conclusion, but nee
Hi
The purpose here is to estimate the stability of a GPSDO. For that, you don't
need "perfect". You simply need to get the Rb close enough that it's error is
manageable.
Bob
On Sep 18, 2013, at 8:18 PM, Azelio Boriani wrote:
> The GPS's PPS wanders but it can be used to have an idea whether
Hi
The Rb's have a couple of issues:
1) Its been years since they were set on frequency and they do have a yearly
drift rate
2) They have a temperature coefficient of drift that may be fairly large (0.1
ppb over -30 to +70)
3) They self heat quite a bit, so they do move temperature / need a hea
The GPS's PPS wanders but it can be used to have an idea whether your
Rb is fast or slow. How much the wander will be, depends on the type
of GPS receiver, the antenna position and the survey, the GPS clock
granularity (the sawtooth). Given a suitable amount of time (5
minutes, for example) you can
Hi John and Azelio,
The problem with the GPS 1PPS is the +/- 52ns sawtooth. Without some magic
hardware, you're left with using a stable 1PPS and then calibrating that to the
correct frequency. If my software does what my math says it does, then my OCXO
is very close to correct. Testing is t
Azelio and Fellow Time Nuts,
Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I
imagine this is in the specs of the specific receiver -
but I was wondering if some of you have actually measured what that is -
and could report the numbers that you have found.
Thanks!
John
Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you
will find out that the Rb is slow... you can also check the Rb's PPS
against the GPS's PPS.
On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart wrote:
> I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz
> GPSDO to C
Hi Bob,
As always, thanks for your informed help. I had been reaching the same
conclusion, but needed unbiased confirmation. I think the RUBY4 software does
what I want? I'll look into it.
Bob
>
> From: Bob Camp
>To: Discussion of precise time and freque
Oh - sorry - did not mean it that way.
I wants to let you know you can talk to them and they will work with you
(and sometimes get a better deal if you write a check and can wait ).
Glad to see what you have done - I am just starting back in the precise
time work, but I used to work in USAF with
Hi
One cycle of 10 MHz would be 100 ns. 100 ns per second would be 100 ppb. 100ns
per 20 seconds would indeed be 5 ppb.
Since the Rb is *stable* but not *accurate*, the real question is - how much
does the 5 ppb change by? The Rb can't tell you if the GPSDO is correct. The
best it can do is te
Hi
1) Have you done a 3 day long survey at any of the locations? You need to do
that to get the errors down.
2) Fiddling with the gain and filter settings on a NTBW50 isn't useful. The
unit does *not* work the same way as a TBolt. Just leave them alone.
3) Because of the way the uint works ther
I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz
GPSDO to Channel A, .05us trace, and turned the lights out so I could
see it. The 10MHz is marching right to left about 1 cycle every 20
seconds. So, can I say that the Rb considers my GPSDO to be too fast by about
5ppb?
B
Gerald,
I wasn't trying to make any derogatory remarks about RGR. I did email him
about the Nortel unit I got and he responded quickly with an appropriate
answer, so my dealings with them have been fine. I actually bought some other
stuff from him after the GPS unit. I'm happy with what I've g
Hi Dave,
Hopefully not too far off topic, just wanted to chime in here.
I have known the people at RDR Electronics (I live in NY and am not
affiliated with them) for over 15 years. I used to live in the Denver area
and got to know the original owners. They used to buy industrial aerospace
surplus
Thanks Charles,
I have tried the &a command and that is where LH put the numbers, TC from 100
to 500, Damp from 1.2 (that's how it came) to 1.0, and it changed the gain from
1.2 to 1.403. I could certainly try playing with the DAC voltage. I haven't
written anything to the prom yet, I think, w
I still get generally about a 400 ppt swing with
the OSC, about 20 ns swing with the PPS and the
other things are just what they are. Different
filters and surveys don't seem to change anything that I've seen.
* * *
Is this acceptable?
You seem to have a reasonably decent view of t
Moved antenna to fence line on a 10' emt. Nothing much seems to change no
matter what I do, so I guess this is what I'm locked into unless I start
getting carried away. I still get generally about a 400 ppt swing with the
OSC, about 20 ns swing with the PPS and the other things are just what t
Hi
If you re-tune the Rb, the already divided down output on the pps will be at a
really odd rate. You can use it, but unwrapping the phase is going to be
"interesting" (= it will wrap a lot).
There are other ways to do things. One is to synthesize a highly accurate 100Hz
off of the Rb output.
I remember a story told to me many years ago, about a discussion between an
American Astronaut and a Russian Cosmonaut.
It goes along something like this...
Astronaut to Cosmonaut: " I wouldn't be happy sitting on the top of that
low technology rocket"
Cosmonaut to Astronaut: "I would rather t
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