Today I went out and collected some data to compare antenna mountings, the subject of another thread.?ÿ
I had two Trimble 4000sse receivers about 8 feet apart.?ÿ One of them picked up SV19 for most of the time I was out and with a good SNR, and the other receiver never did, but did get at least 5 other sats.?ÿ
Both receivers had run long enough to have a current ephemeris.?ÿ All satellites were enabled in the receiver, SV19 was listed as healthy (SV23 was not), and they both agreed that 19 was high in the sky at the same position, where there was no obstruction.?ÿ Channel 7 that was assigned to SV19, and not receiving it, received another satellite after a reboot but SV19 never came through this receiver. The receivers can process 9 channels of L1/L2 and I never had more than 7 sats.
Any ideas what was going on?
Sometimes one unit will block the signal for the other on an outlier in that direction.
Some men change wives. For this very reason!?ÿ
4000s are older receivers that go through the constellation looking for satellites at a very slow pace. That is the main reason I stopped using my Z-12s, and they work on up to 12 channels. I would assume that it was locking on to PRN 19 (SV numbers are totally different) but never resolving the ambiguities in the time allocated thus not recording data. If you must use the 4000s then it behooves you to do planning and block all satellites that are not in the sky during your session. and maximize your chances of finding what is.
Paul in PA
4000s are older receivers that go through the constellation looking for satellites at a very slow pace. That is the main reason I stopped using my Z-12s, and they work on up to 12 channels. I would assume that it was locking on to PRN 19 (SV numbers are totally different) but never resolving the ambiguities in the time allocated thus not recording data. If you must use the 4000s then it behooves you to do planning and block all satellites that are not in the sky during your session. and maximize your chances of finding what is.
So Trimble labeled them wrong??ÿ It lists them as SV numbers-very confusing.
Ambiguities make some sense, but doesn't it keep trying to lock on to a satellite after a channel has been assigned to it??ÿ If it gets a fix from the other satellites, then it should eventually be able to resolve this one, too??ÿ It was high in the sky, no obstacles, and had a good SNR on the other receiver.
I also pulled the antenna connection and reconnected, with no change, and even power cycled, only to get the same result. I would have thought that it would do better the second time, knowing close to where it was when power went down, as the other sats came up really fast.
Bill, check to verity you have the exact same firmware in both receivers.
Plus PRN 19 is SVN 59, which has been buggy from launch. As I recall in SVN 59 they hooked up an L5 signal broadcast to secure space rights to the L5 signal. That was spliced into the broadcast from the L2 antennas and was never properly filtered. With the L5 turned off there is still somewhat of a short circuit. Also, I see they list SV 59 as a IIR satellite when it was originally a IIR-M, so they must have also stopped the 2C signal to deal with the short circuit.
But then, I have not followed the GPS status as closely as in the past, I pretty much just turn it on and use what I get.
Paul in PA
FWIW,
On the issue of SVN/PRN designations see: https://www.navcen.uscg.gov/?Do=constellationStatus
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From the US Space Command site this table of SV capabilities/characteristics:
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Space Command site URL: https://www.gps.gov/systems/gps/space/#orbits
I went out in the driveway this afternoon, at about the time I was out the previous day, and that receiver got 6 sats, including PRN 19 at good SNR.
So it will remain a mystery.
@bill93 do both units have the same firmware version?
I have nothing but love for Z-XII.
I see red light/green light receivers, compared to the 15 screens on ZXII. There’s so much information. And they work as well today as they did in 1998 when they got their last upgrade.
ZXII seems to lock on 10-12 SVs much faster than Zsurveyor. And ZSurveyor will rarely record more than 9-10.
ZXII may be primitive in respects, but still fantastic RF section.
@bill93 do both units have the same firmware version?
The NAV and SIG versions are the same. There is s slight difference in the BOOT version, which I wouldn't think would affect performance.
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My ZXII picked up 19.
however, it makes a real-time screen plot and they??re not in the right place. And I think some SVs are labeled wrong.
Fortunately the data is unaffected. Except for week-rollover date, of course.
still rock solid, mm phase differential baselines