Hello all
I am looking for information on the different
Motorola Oncore GPS's. Would like to know what the
difference is between the UT+ and VP, and the
differences between the different model numbers.
Advantages of one over the other? Stuff like that.
The links from TAPRs page to Motorola is
On 12/10/06, David Forbes <[EMAIL PROTECTED]> wrote:
> Tom Van Baak has compared the stability of some of these devices...
> see the chart at the bottom of the page.
> http://www.leapsecond.com/museum/lpro/
When computing a 1,000s tau Allan Dev., do the measurements need to be
taken back-to-back,
Hi Jamie,
The VP is the top of the line model. I bought one of the VP models from
midnight_seller on eBay, it is running the latest firmware (10), has an
onboard battery, right angle MCX, and has all the features enabled (IBC),
position hold, 1PPS and all that jazz. I asked Randy @ Synergy what th
Wow, thanks! You answered all my questions, and very
quickly. -- Jamie
--- Jason Rabel <[EMAIL PROTECTED]> wrote:
> Hi Jamie,
>
> The VP is the top of the line model. I bought one of
> the VP models from
> midnight_seller on eBay, it is running the latest
> firmware (10), has an
> onboard bat
> Now, about the Rockwell Jupiter 8 boards...
>
> The TU30D140 is 5V powered (Antenna can be passive, 5V or 12V)
> The TU30D160 is 3.3V powered (Antenna can be passive, 5V or 12V)
>
> Both boards have 10 KHz output. That's about it...
Maybe I should clarify that one statement. I didn't mean they
Can someone explain the accuracy numbers that are represented in specs for GPS
receivers?
I find that Trimble says the Resolution T
(http://www.trimble.com/resolutiont.shtml) has 15 ns (1 Sigma) like the M12+.
So I guess the real question is; are you comparing apples to apples when the
stan
One problem is that older GPS receiver spec sheets give numbers with SA on,
even though SA has been off for quite some time, so their numbers will be
inherently higher.
Probably the most accurate GPS receiver today would be the Motorola M12M
Timing. I would go into more detail but I'm about to hea
Hi I am looking for info on using the Brooks Shera GPS-VCXO Controller
with an EFRATOM LPRO-101?
I currently have it locking an old and unknown single oven Xtal
oscillator this is working as well but I hope to replace this with the
LPRO-101
Has anyone any suggestions as to how best to choose the
Jack,
Jason is right. I think the M12M is currently at the top of the heap.
Rick Hambly and Tom Clark have developed some circuitry that knocks the
jitter down quite a lot.
Basically, for a "normal" timing receiver (please don't flame me guys, I
know there is other stuff out there) the jitter is
Hello,
Can anyone give me somenumbers?
Allan Bart
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If by "GPS based standard," you mean an GPS discplined Rb oscillator,
I think you should be able to do it for under $500. If just quartz is
good enough, then you could do it for under $100. I've put together
some of my figures and notes at:
http://net127.com/notes/index.php?title=Cheapest_True_Atom
Mit freundlichen Grüssen
Paul Klöckler
Coral links Gmbh
Postfach 6955
CH-3001 Bern
Schweiz
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Randy Warner
Sent: Mittwoch, 13. Dezember 2006 19:27
To: Discussion of precise time and frequency measurement
S
Paul,
Sie sind willkommen
Randy Warner
Senior Applications Engineer
Synergy Systems, LLC
[EMAIL PROTECTED]
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]
Sent: Wednesday, December 13, 2006 12:23 PM
To: 'Discussion of precise time and f
The Brooks Shera is a good DIY project too.
The bare board costs $21.45 shipped.
I got a programmed PIC chip and DAC from Brooks for $43 shipped.
The rest of the board components (minus the display and project box) I spent
maybe $20?
Now for the oscillator, that you can spend whatever your heart
Hi Brendan,
I would contact Brooks Shera directly before you go any further as the span
of his controller is set at 4.5e-8 and the maximum span on an LPRO is about
5e-9. He can reprogram the controller by changing the filter gain and loop
time so it is about 8X more sensitive so it will work with a
Bruce Lane wrote:
>
> Actually, I've gotten quite lucky antenna and receiver-wise. I had the
> unit open today, and
> discovered that the receiver is a fairly late-model Magellan OEM type,
> specifically an "OEM 5000."
> I've already dropped a note to Thales (who bought Magellan) to se
Hi guys,
slightly off-topic, but has anyone done stability tests with the m12+ or
M12M when the antenna goes bad in TRAIM-enabled mode (e.g. less than 4 good
sats
being received by i.e. disconnecting the antenna)?
I see that the 1PPS output goes away only after about 5 or so additional
p
If I'm totally missing something here please correct and enlighten me.
On the subject of Brooks Shera's design, the one thing that troubles me is the
use of a 24 MHz oscillator to count the width of the 1PPS signal.
This yields a precision of 4.16e-8, but does it really?
This oscillator is unco
You have to be careful with the 10 kHz output. The output is only
updated once per second (the 10,000 pulses in the 1 second period are
equally spaced), so you still need the same filter as if you were using
the 1 PPS output. I am not sure what the 10kHz output was intended to,
but it's not tha
> the one thing that troubles me is the use of a 24 MHz oscillator to
> count the width of the 1PPS signal. This yields a precision of
> 4.16e-8
> Question: Why not multiply the VCXO or OCXO output by 5 or 10 and run
> that into 24 or 32 bit counter? OR just sample the counter on every
> 10th PP
Said,
The software does allow several seconds of free running pulses to be
sent out while it verifies the alarm. My guess is that the time error of
the "free running" pulses would not be significant (unless you are a ns
hunter ;-) ). Many users do "flywheel" from these pulses just to keep
some so
Hi Randy,
as always, great info!
yes, please do send out the old VP TRAIM doc :)
thanks,
Said
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Jack Hudler wrote:
> If I'm totally missing something here please correct and enlighten me.
>
> On the subject of Brooks Shera's design, the one thing that troubles me is the
> use of a 24 MHz oscillator to count the width of the 1PPS signal.
> This yields a precision of 4.16e-8, but does it real
Ah I too wondered about the 10kHz output and wince it came.
One phase lock circuit being sold on eBay uses this by dividing it down to 1
PPS.
Perhaps he wanted to save one 74HC390.
Still I wonder what the precision cost is?
Jack
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL
I haven't looked at the one on eBay, but I did find the following example (I
think I posted a link earlier today).
http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm
I have the parts sitting on my desk, I just haven't had the time to assemble
it yet. I'll report back with some numbers on
That's essentially the same circuit.
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
Of Jason Rabel
Sent: Wednesday, December 13, 2006 9:07 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] motorola oncore descriptions
I
Many thanks for the long post!
You validated many of my concerns about the current state of amateur GPSDO's.
Thanks again,
Jack
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Bruce,
Can you describe further your idea about phase detection using an ADC.
Who produces the sinewave from the filtered counter?
(Thinking out loud) Using a 10MHz oscillator as an example:
Is this dividing the clock down to (say) 1 MHz and using a square->sine
conversion then sampling the pha
> When computing a 1,000s tau Allan Dev., do the measurements need to be
> taken back-to-back, ie a 1,000s Tau is 1,000 readings taken in one
> 1,000s window?
Yes, back-to-back. To compute ADEV for tau 1000
seconds you need several or many measurements
1000 seconds apart. The minimum is usually 4,
I tried Googling but kept hitting dead ends, so I'm hoping maybe someone
here has a good link or maybe some old source code.
Basically I would like to have a PC driven IRIG-B generator (doesn't have to
be super accurate), probably via a sound card (I've seen a few Windows
programs - none for free
I'm sure Brooks Shera can describe the nuances of his GPS locking circuit
far better than I can; but that said, the 24MHz oscillator is not used to
directly count the 1PPS signals. It is used over a 30 second measurement
interval, yielding a precision of about 1.4nS per count. Also the digital
Good day,
*** REPLY SEPARATOR ***
On 13-Dec-06 at 23:16 Jason Rabel wrote:
>I tried Googling but kept hitting dead ends, so I'm hoping maybe someone
>here has a good link or maybe some old source code.
>
>Basically I would like to have a PC driven IRIG-B generator (doesn't have
> On the subject of Brooks Shera's design, the one thing that troubles me is
the
> use of a 24 MHz oscillator to count the width of the 1PPS signal.
> This yields a precision of 4.16e-8, but does it really?
No, with averaging it's much better than that.
> This oscillator is uncontrolled and any d
> I haven't looked at the one on eBay, but I did find the following example
(I
> think I posted a link earlier today).
>
> http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm
>
> I have the parts sitting on my desk, I just haven't had the time to
assemble
> it yet. I'll report back with som
I would like to share my experience using the Brooks Shera controller
with a rubidium oscillator. 3 Years ago, I decided to discipline a
Efratom FRS-C rubidium. For a 1PPS timing reference, I am using a
Motorola M12+ GPS receiver.
Starting with the rubidium, which was new old stock on EBay
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