Substitute GPS in a Z3801A
Has anyone ever put another GPS in a Z3801A? Will the software accommodate
another GPS that tracks say, 12 channels?
Bob
On 06/24/2010 04:48 AM, Robert Benward wrote:
Has anyone ever put another GPS in a Z3801A? Will the software accommodate
another GPS that tracks say, 12 channels?
I very much doubt that the software would handle more than 6 channels
properly. Also, wasn't there a shift in commands when jumping from 6 to
8 channels in the Motorola receivers?
Cheers,
Magnus
At 10:48 PM 6/23/2010, Robert Benward wrote...
Has anyone ever put another GPS in a Z3801A? Will the software
accommodate
another GPS that tracks say, 12 channels?
Possibly 8 channels. You must use a Motorola Oncore VP. A 6 channel one
was what HP used. There are mixed reports on using an 8 channel VP -
some say it works fine, others say you must configure it in 6 channel
mode (but you do pick up improved reception). Whether the different
reports are due to changes in configuration or firmware of the z3801a,
the Oncore, or both - I have no idea.
The commands/responses used by the z3801a prevent it from working
directly with newer GPS modules, like the GTs, UTs or M12s (even if you
adapted them physically).
If you want to try and get better performance with a newer GPS
receiver, you should be able to leave the existing board in place, and
bypass the 1PPS input with the signal from the newer receiver. You'd
only get in trouble in exceptional conditions (new receiver loses sync,
but existing one is reporting good satellite lock, etc.). Of course,
the z3801a satellite reporting wouldn't be worth much.
Mike,
Thanks for the info!. Does anyone know for sure if the timimg improves
with more satellites tracked? I don't know how they derive the 1PPS, is it
a blend or one satellite at a time? Maybe I will leave well enough alone.
Bob
----- Original Message -----
From: "Mike S" mikes@flatsurface.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Thursday, June 24, 2010 9:01 AM
Subject: Re: [time-nuts] Substitute GPS in a Z3801A
At 10:48 PM 6/23/2010, Robert Benward wrote...
Has anyone ever put another GPS in a Z3801A? Will the software
accommodate
another GPS that tracks say, 12 channels?
Possibly 8 channels. You must use a Motorola Oncore VP. A 6 channel one
was what HP used. There are mixed reports on using an 8 channel VP -
some say it works fine, others say you must configure it in 6 channel
mode (but you do pick up improved reception). Whether the different
reports are due to changes in configuration or firmware of the z3801a,
the Oncore, or both - I have no idea.
The commands/responses used by the z3801a prevent it from working
directly with newer GPS modules, like the GTs, UTs or M12s (even if you
adapted them physically).
If you want to try and get better performance with a newer GPS
receiver, you should be able to leave the existing board in place, and
bypass the 1PPS input with the signal from the newer receiver. You'd
only get in trouble in exceptional conditions (new receiver loses sync,
but existing one is reporting good satellite lock, etc.). Of course,
the z3801a satellite reporting wouldn't be worth much.
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07:11:00
Hi Mike,
At 10:48 PM 6/23/2010, Robert Benward wrote...
Has anyone ever put another GPS in a Z3801A? Will the software
accommodate
another GPS that tracks say, 12 channels?
Possibly 8 channels. You must use a Motorola Oncore VP. A 6 channel one
was what HP used. There are mixed reports on using an 8 channel VP -
some say it works fine, others say you must configure it in 6 channel
mode (but you do pick up improved reception). Whether the different
reports are due to changes in configuration or firmware of the z3801a,
the Oncore, or both - I have no idea.
The commands/responses used by the z3801a prevent it from working
directly with newer GPS modules, like the GTs, UTs or M12s (even if you
adapted them physically).
If you want to try and get better performance with a newer GPS
receiver, you should be able to leave the existing board in place, and
bypass the 1PPS input with the signal from the newer receiver. You'd
only get in trouble in exceptional conditions (new receiver loses sync,
but existing one is reporting good satellite lock, etc.). Of course,
the z3801a satellite reporting wouldn't be worth much.
Is it established that the Z3801 does not use sawtooth corrections for the
1PPS pulses it receives from the oncore VP?
IF it use these corrections even a substitute "perfect" 1PPS will be worse
than the orginal setup.
--
Björn
Sorry to butt in on this thread but, although you need a number of
birds to get an accurate position, you really only need one to get
timing. If you have a six sat tracking receiver there should be enough
to give accurate time. You can always set the elevation to limit what
sats you can see so to screen out multipath reflections and it can
still track six birds. OK, my Z3805A is currently tracking 9 birds but
3 of those are quite low horizon, although I really don't have
anything to cause multipath from where I'm situated. The minimum
number of sats I track is 4 and the max is 12 on a day, night cycle
and the average is about 6.
Steve
On 25 June 2010 02:01, Robert Benward rbenward@verizon.net wrote:
Mike,
Thanks for the info!. Does anyone know for sure if the timimg improves
with more satellites tracked? I don't know how they derive the 1PPS, is it
a blend or one satellite at a time? Maybe I will leave well enough alone.
Bob
----- Original Message ----- From: "Mike S" mikes@flatsurface.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Thursday, June 24, 2010 9:01 AM
Subject: Re: [time-nuts] Substitute GPS in a Z3801A
At 10:48 PM 6/23/2010, Robert Benward wrote...
Has anyone ever put another GPS in a Z3801A? Will the software
accommodate
another GPS that tracks say, 12 channels?
Possibly 8 channels. You must use a Motorola Oncore VP. A 6 channel one
was what HP used. There are mixed reports on using an 8 channel VP -
some say it works fine, others say you must configure it in 6 channel
mode (but you do pick up improved reception). Whether the different
reports are due to changes in configuration or firmware of the z3801a,
the Oncore, or both - I have no idea.
The commands/responses used by the z3801a prevent it from working
directly with newer GPS modules, like the GTs, UTs or M12s (even if you
adapted them physically).
If you want to try and get better performance with a newer GPS
receiver, you should be able to leave the existing board in place, and
bypass the 1PPS input with the signal from the newer receiver. You'd
only get in trouble in exceptional conditions (new receiver loses sync,
but existing one is reporting good satellite lock, etc.). Of course,
the z3801a satellite reporting wouldn't be worth much.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.
No virus found in this incoming message.
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07:11:00
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--
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
So there is no point in substituting another GPS RX? What is the sawtooth
compensation is see mentioned? What about the antenna cable length
compensation? How much does that affect the AVAR?
Bob
----- Original Message -----
From: "Steve Rooke" sar10538@gmail.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Thursday, June 24, 2010 11:11 AM
Subject: Re: [time-nuts] Substitute GPS in a Z3801A
Sorry to butt in on this thread but, although you need a number of
birds to get an accurate position, you really only need one to get
timing. If you have a six sat tracking receiver there should be enough
to give accurate time. You can always set the elevation to limit what
sats you can see so to screen out multipath reflections and it can
still track six birds. OK, my Z3805A is currently tracking 9 birds but
3 of those are quite low horizon, although I really don't have
anything to cause multipath from where I'm situated. The minimum
number of sats I track is 4 and the max is 12 on a day, night cycle
and the average is about 6.
Steve
On 25 June 2010 02:01, Robert Benward rbenward@verizon.net wrote:
Mike,
Thanks for the info!. Does anyone know for sure if the timimg improves
with more satellites tracked? I don't know how they derive the 1PPS, is it
a blend or one satellite at a time? Maybe I will leave well enough alone.
Bob
----- Original Message ----- From: "Mike S" mikes@flatsurface.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Thursday, June 24, 2010 9:01 AM
Subject: Re: [time-nuts] Substitute GPS in a Z3801A
At 10:48 PM 6/23/2010, Robert Benward wrote...
Has anyone ever put another GPS in a Z3801A? Will the software
accommodate
another GPS that tracks say, 12 channels?
Possibly 8 channels. You must use a Motorola Oncore VP. A 6 channel one
was what HP used. There are mixed reports on using an 8 channel VP -
some say it works fine, others say you must configure it in 6 channel
mode (but you do pick up improved reception). Whether the different
reports are due to changes in configuration or firmware of the z3801a,
the Oncore, or both - I have no idea.
The commands/responses used by the z3801a prevent it from working
directly with newer GPS modules, like the GTs, UTs or M12s (even if you
adapted them physically).
If you want to try and get better performance with a newer GPS
receiver, you should be able to leave the existing board in place, and
bypass the 1PPS input with the signal from the newer receiver. You'd
only get in trouble in exceptional conditions (new receiver loses sync,
but existing one is reporting good satellite lock, etc.). Of course,
the z3801a satellite reporting wouldn't be worth much.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.829 / Virus Database: 271.1.1/2958 - Release Date: 06/23/10
07:11:00
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.
--
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.829 / Virus Database: 271.1.1/2960 - Release Date: 06/24/10
02:35:00
I now have two Z3801A units which misbehave in the following way
(which this thread reminded me of):
The GPS status says it acquires quite a few (5-6) satellites with high
signal strength... then after a minute or two, for no apparent reason,
it loses all of them simultaneously but immediately goes back into
"acquiring" for the ones it was seeing, and a few seconds later, they're
all back. During this time, survey (if in progress) is halted and then
restarts and runs for a bit before halting again when it loses
everything briefly again. Then, within days, the unit ends up out of
lock... if I go check it, I see it doing the same thing, and when the
satellites are being received it is in "fine frequency adjust" mode, but
so far off the 1pps phase that it really has no hope of re-locking
before the next time it drops and then reacquires all the satellites.
This is independent of antenna, location, and 48v power source... one
unit apparently has been this way since I got it, the other worked fine
for months and then developed this problem.
Without knowing more, I'm thinking it might simply be a bad GPS receiver
board, thus the idea of trying to find a replacement, perhaps one that
is better at staying acquired, has crossed my mind.
Matthew Kaufman
Hi Bob,
Old GPS receivers had bad resolution with regard to when they could flipp
the 1PPS signal. Think along these lines... you have a digital system,
clock running at say 10MHz. You can only invoke the 1PPS at a clock edge,
this gives you 100ns resolution. The receiver then needs to calculate
GPS/UTC time and use the clock edge closest to its solution. With the
current non SA GPS system the accuracy of the calculation is in the
10-30ns-ish region. This means the receiver internally have much better
clock information than it have means to export via the 1PPS signal. It can
however send its estimate on how wrong the 1PPS signal is via the serial
port.
Newer receivers have hardware with better 1PPS resolution - and better
tracking/position etc.
Tom probably has a much better explaination...
http://www.leapsecond.com/pages/vp/sawtooth.htm
http://www.leapsecond.com/pages/vp/heater.htm
http://www.leapsecond.com/pages/m12/sawtooth.htm
--
Björn
So there is no point in substituting another GPS RX? What is the
sawtooth
compensation is see mentioned? What about the antenna cable length
compensation? How much does that affect the AVAR?
Bob
----- Original Message -----
From: "Steve Rooke" sar10538@gmail.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Thursday, June 24, 2010 11:11 AM
Subject: Re: [time-nuts] Substitute GPS in a Z3801A
Sorry to butt in on this thread but, although you need a number of
birds to get an accurate position, you really only need one to get
timing. If you have a six sat tracking receiver there should be enough
to give accurate time. You can always set the elevation to limit what
sats you can see so to screen out multipath reflections and it can
still track six birds. OK, my Z3805A is currently tracking 9 birds but
3 of those are quite low horizon, although I really don't have
anything to cause multipath from where I'm situated. The minimum
number of sats I track is 4 and the max is 12 on a day, night cycle
and the average is about 6.
Steve
On 25 June 2010 02:01, Robert Benward rbenward@verizon.net wrote:
Mike,
Thanks for the info!. Does anyone know for sure if the timimg improves
with more satellites tracked? I don't know how they derive the 1PPS, is
it
a blend or one satellite at a time? Maybe I will leave well enough
alone.
Bob
----- Original Message ----- From: "Mike S" mikes@flatsurface.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Thursday, June 24, 2010 9:01 AM
Subject: Re: [time-nuts] Substitute GPS in a Z3801A
At 10:48 PM 6/23/2010, Robert Benward wrote...
Has anyone ever put another GPS in a Z3801A? Will the software
accommodate
another GPS that tracks say, 12 channels?
Possibly 8 channels. You must use a Motorola Oncore VP. A 6 channel one
was what HP used. There are mixed reports on using an 8 channel VP -
some say it works fine, others say you must configure it in 6 channel
mode (but you do pick up improved reception). Whether the different
reports are due to changes in configuration or firmware of the z3801a,
the Oncore, or both - I have no idea.
The commands/responses used by the z3801a prevent it from working
directly with newer GPS modules, like the GTs, UTs or M12s (even if you
adapted them physically).
If you want to try and get better performance with a newer GPS
receiver, you should be able to leave the existing board in place, and
bypass the 1PPS input with the signal from the newer receiver. You'd
only get in trouble in exceptional conditions (new receiver loses sync,
but existing one is reporting good satellite lock, etc.). Of course,
the z3801a satellite reporting wouldn't be worth much.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.829 / Virus Database: 271.1.1/2958 - Release Date: 06/23/10
07:11:00
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.
--
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.
No virus found in this incoming message.
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Version: 9.0.829 / Virus Database: 271.1.1/2960 - Release Date: 06/24/10
02:35:00
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When you say you changed location, are we speaking of moving the antenna to
the other side of the roof, or across town? Sounds suspciously like
interference.
Bob
----- Original Message -----
From: "Matthew Kaufman" matthew@matthew.at
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Thursday, June 24, 2010 11:41 AM
Subject: Re: [time-nuts] Substitute GPS in a Z3801A
I now have two Z3801A units which misbehave in the following way
(which this thread reminded me of):
The GPS status says it acquires quite a few (5-6) satellites with high
signal strength... then after a minute or two, for no apparent reason,
it loses all of them simultaneously but immediately goes back into
"acquiring" for the ones it was seeing, and a few seconds later, they're
all back. During this time, survey (if in progress) is halted and then
restarts and runs for a bit before halting again when it loses
everything briefly again. Then, within days, the unit ends up out of
lock... if I go check it, I see it doing the same thing, and when the
satellites are being received it is in "fine frequency adjust" mode, but
so far off the 1pps phase that it really has no hope of re-locking
before the next time it drops and then reacquires all the satellites.
This is independent of antenna, location, and 48v power source... one
unit apparently has been this way since I got it, the other worked fine
for months and then developed this problem.
Without knowing more, I'm thinking it might simply be a bad GPS receiver
board, thus the idea of trying to find a replacement, perhaps one that
is better at staying acquired, has crossed my mind.
Matthew Kaufman
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.829 / Virus Database: 271.1.1/2960 - Release Date: 06/24/10
02:35:00