Re: $GPGGA / increased number of satellites

[Hans Mayer]

Yo Gary !

Uh, no.  I much prefer: gpspipe -R -x 30 > raw.log

Attached you can find such a file as .gz compressed.

The sat data is not just in GPGGA, and you might be getting some
binary messages as well.

Do you want to have the log of May 4th ?

If what you see it not repeatable, then your issue is moot.  So log
of any day is fine.

Now I realized that the logs before the upgrade had 86400 lines +/-
1. This is one line per second. Now the files have about 10800 lines.
Each night I do a logrotate.

One line a seconds???  No way that is enough!

Big sorry, my mistake. Before the update there are 86400 lines per day, but after the update I see now 108000 lines per day ( I missed a zero previously ) So there are now more entries, about 21600 lines more. Why this ?

I assume your answer: because it's counting the signals too, isn't it ?

What you did not notice is that the number of satellites did not
increase, but the number of satellite/signal pairs increased because
u-blox had failed to document that until recently.  

I didn't update ZED-F9P

By signal, I mean: L1, L2, L5, B2, etc.

You can see this using cgps, or xgps.
 

Hmm ? Not sure what you mean. When I start xgps I don't see the bands.

Yes, you do, but not obvious.  Hover your mouse over a sat icon in 
the skyview.

Yes, when I move the mouse over a sat I see a lot of additional information. But what is the interesting value ?

Do you mean the SIGID. Some of the satellites have one SIGID, same have 2 values.

What I see is a flickering screen which changes about twice per
second.

And that fkilering screen is chock full of data.

I tried to attach a 3 second video. But this is too big for a mailing list with a limit of 400 KB.

On the bottom right corner in one screen there is sat seen: 50 and
used 31, the other one say seen: 78 and used 71

And both can be true.

Why ? Independent "what is a satellite" it should not change twice within a second.

When I run gpspipe ( as described above ) I get currently about 70 
satellites in the GPGGA record.

It goes uch faster when I can see what you see.  By that, I mean send
me your raw capture.

But when I use gpscsv to filter out the unique satellites I get about
49 ( in the moment )

Which comes back to what is a "satellite"?  Is a "satellite" a orbitting
object at that elevation, azimuth and pseudorange?  Or is it several
satellite/ginal pairs.  Like PRN 20/L1, PRN20/L2 and PRN 20/L5?

NMEA uses both definitions.  Very confusing.

But colloquially I would say a satelite is that what I can see on the sky.

This is the way I have done it:

mayer# gpscsv -n 10 -c SAT --header 0 | awk -F, '
BEGIN {
   GNSSID=99999 ;
   SVID=99999 ;
   PRN=99999 ;
}

You are ignoring the sigid.  So you will count PRN 20/L1 and PRN 20/Las
as one "satellite", not two.

Fine for me. I want to know the number of satellites and not signals.

And how do I get the SIGID ? Obviously not with gpscsv.

If I am correct the OID for the number of satellites is .1.3.6.1.2.1.25.1.32

This is also jumping between 2 values:

mayer# while true  ; do  gpssnmp -g .1.3.6.1.2.1.25.1.32 ; sleep 0.173 ; done
.1.3.6.1.2.1.25.1.32
INTEGER
75
.1.3.6.1.2.1.25.1.32
INTEGER
29
.1.3.6.1.2.1.25.1.32
INTEGER
74
.1.3.6.1.2.1.25.1.32
INTEGER
29
.1.3.6.1.2.1.25.1.32
INTEGER
74
.1.3.6.1.2.1.25.1.32
INTEGER
29
.1.3.6.1.2.1.25.1.32
INTEGER
74
.1.3.6.1.2.1.25.1.32
INTEGER
29
.1.3.6.1.2.1.25.1.32
INTEGER
74
.1.3.6.1.2.1.25.1.32
INTEGER
29
.1.3.6.1.2.1.25.1.32
INTEGER
74
^C

Kind regards

Hans

--

raw.log.gz
Description: GNU Zip compressed data