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 battery,
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 only
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
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
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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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
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
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 see if I
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
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
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 PPS?
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 sort
Hi Randy,
as always, great info!
yes, please do send out the old VP TRAIM doc :)
thanks,
Said
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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
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
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
to
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
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
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