Discussion:
Holdover: Z3801A vs KS-24361
(too old to reply)
Hal Murray
2018-04-12 05:30:44 UTC
Permalink
On that Status page, A Z3801A says:
Predict 2.5 us/initial 24 hrs

A KS-24361 says:
Predict 394.1 us/initial 24 hrs

Both have been running for weeks.

Is anybody seeing similar?


Also, the Satellite Status area has a header of SS on the Z3801A and C/N on
the KS. Does anybody know the units and/or what that is actually measuring?
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Bob kb8tq
2018-04-12 12:58:47 UTC
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Hi
Post by Hal Murray
Predict 2.5 us/initial 24 hrs
That sounds about right for a 3801. The prediction is something better than
a wild guess and not what one would call a solid number.
Post by Hal Murray
Predict 394.1 us/initial 24 hrs
That would suggest the unit is unlocked. It should be below 10 us. Just as with
the 3801, the estimate is a bit fuzzy. You should be able to see issues in the data
on the Z3809/Z3810.

A prediction of < 1 can pop up on occasion, on either unit. More typical estimates
are in the “couple of us” range. If you yank the antenna, it still does a respectable
~5 us / 24 hrs or so either way.
Post by Hal Murray
Both have been running for weeks.
Is anybody seeing similar?
no
Post by Hal Murray
Also, the Satellite Status area has a header of SS on the Z3801A and C/N on
the KS. Does anybody know the units and/or what that is actually measuring?
There are tables that translate the Motorola (and some of the other brands) status
numbers into rough dbc/ Hz. I would not count on the numbers on a 20+ year old
design lining up directly with the latest and greatest modern module. Apparently
the SNR calculations are a bit weird.

Bob
Post by Hal Murray
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Mark Sims
2018-04-12 16:44:40 UTC
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SS is signal strength. CN is carrier to noise ratio. They basically indicate the same thing, but their scale may be different. You can't compare the absolute magnitude of the values from different types of receivers, only do relative comparisons. Other receivers can report dBc, etc. And Trimble devices can report AMU (amplitude measurement units). Some Trimble devices don't support dBc readings. By switching a Tbolt between AMU and dBc, I worked out a table that Lady Heather uses to convert AMU to dBc to that those devices can display the more common dBc values. On the Trimble devices you set the signal level mask in AMUs.

-------------------
the Satellite Status area has a header of SS on the Z3801A and C/N on the KS
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