[teqc] Some Glonass sats L1 only ?

Lou Estey lou at unavco.org
Thu Jul 5 07:23:34 MDT 2018


Whatever is the issue, it has been going on for a while, at least half a year
for R12.  Of the ~2250 permanent stations for which we archive data daily, about
750+ track GLONASS, so remarks below are from that set.

Going back to 2018-001, only a few sites that use Javad receivers (of various
types) show G2 (aka "L2") data for R12, i.e. not necessarily all sites using Javad
show G2 data, but those having G2 data have Javad receivers.  Other sites show massive
loss-of-lock (probably on G2) or massive G2 slip counts on R12.  R6 was generally
ok on 2018-001 -- just minor problems specific to a few sites.

By 2018-090, no sites that we have were showing G2 data for R12.  R6 was still good.

But on 2018-100 R6 was just as bad as R12 for G2 data.

There's also been more intermittent G2 problems with R24 and R5 in the last few months.
(Perhaps other SVs?) But on 2018-185, G2 on R24 and R5 were aok.

These unusual G2 goings-on were brought to my attention in mid-April by a teqc user
at Geoscience Australia.

--lou

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Louis H. Estey, Ph.D.              office:  [+001] 303-381-7456
UNAVCO, 6350 Nautilus Drive           FAX:  [+001] 303-381-7451
Boulder, CO  80301-5554            e-mail:  lou  unavco.org

"If the universe is the answer, what is the question?"
                                                -- Leon Lederman
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

On 05-Jul-18 02:46 AM, Mathieu Peyréga wrote:
> Hello,
> 
> this is not really a teqc question, i'm rather hopping to take advantage of the large GNSS specialist audience here to try get an answer.
> 
> It seems that recentrly some receivers have had issues tracking L2 on some glonass sats (e.g. R12, R6)
> 
> e.g. :
> 
> 
> http://rgp.ign.fr/STATIONS/#SMNE
> http://rgp.ign.fr/STATIONS/#AXPV
> 
> 
> use Trimble receivers and have some sats in L1 only
> 
> http://rgp.ign.fr/STATIONS/#TLSG
> http://rgp.ign.fr/STATIONS/#BRST
> 
> use Septentrio and also got some sats in L1 only
> 
> http://rgp.ign.fr/STATIONS/#MLVL
> http://rgp.ign.fr/STATIONS/#EGLT
> 
> use Leica and have the "issue"
> 
> Other stations use Laice :
> 
> http://rgp.ign.fr/STATIONS/#PANA
> 
> or Trimble :
> 
> http://rgp.ign.fr/STATIONS/#CLFE
> 
> and do not suffer this apparently.
> 
> I've hooked an AsterX4 card on the splitter of my station (main board is Trimble) and both are reporting no L2 for R12 and R6
> 
> The spectrum view from AsterX4 shows no special spikes around L2 glonass freq
> 
> Glonass constellation status page does not report special stuff for R12 and R6.
> 
> Does someone have an idea what is going on ?
> 
> Best regards,
> 
> Mathieu Peyréga
> 
> 
> -- 
> tel : +33 (0)6 87 30 83 59



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