[time-nuts] Galileo service currently degraded

[Bob kb8tq]

Hi

There are an enormous number of combinations and permutations to the whole 
GNSS timing question.

1) Does your multi band receiver only track GPS L2C? ( = is it like a F9T or F9P) 
If so, the number of GPS stats will be smaller and performance will not be as good
as it might be. 

2) Are you afraid of a specific system being “bonked”? Right now the poor people
at Galileo are in a mess. A while back it was the GPS guys. Glonass has had more
than it’s share of issues. I’m not sure anybody is really watching the Chinese system
very closely ….

3) Is this a multi band setup? Without multi band, you are heavily dependent on 
corrections. Different systems handle them different ways. If you are looking for 
augmentation (SBAS), can you get it for this system in your region? 

4) Multipath is a very real thing. More sats helps. Constellations repeat on a regular
basis. Thus some errors on a “single system” will have a very periodic nature to them. 
Having multiple systems spreads this out a bit. 

yes the list goes on and on from there ….

Bob

> On Jul 13, 2019, at 6:34 AM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> 
> I wonder if a case could be made for multi-GNSS reception in the case of a
> poorly-
> located GPS antenna at the reception site.  That is, could the benefits of
> having a lot
> more sats in the sky outweigh poorer performance of some of the systems with
> respect to other systems?
> 
> Dana
> 
> 
> On Sat, Jul 13, 2019 at 1:02 AM Kevin Croissant <kevin at kevincroissant.com>
> wrote:
> 
>> Hi Luciano,
>> 
>> Yes this is typically the case. GPS is the most reliably good system
>> currently. When the Galileo system is working nominally and the geometry
>> over our antenna is good (remember, the constellation is not yet complete),
>> the single frequency performance easily rivals GPS. BeiDou will likely be
>> similar once the constellation is finished, assuming they don't
>> intentionally degrade the civilian signals over non-Chinese regions.
>> GLONASS, well that's another case altogether.
>> 
>> Keep in mind the limitations of the website's data collection - single
>> frequency "professional grade" receivers which do not perform carrier-phase
>> or any kind of satellite based corrections/augmentations (SBAS, etc). If
>> the receivers were more sophisticated and in another region, the story may
>> be different. If anyone wants to set up a similar monitoring system in
>> another part of the world, let me know, I would be very interested in that.
>> 
>> Kevin
>> 
>> On Sat, Jul 13, 2019 at 1:05 AM timeok at timeok.it <timeok at timeok.it> wrote:
>> 
>>> 
>>>   Looking at the data it seems that GPS is the best system among the
>>> four, correct?
>>> 
>>>   Luciano
>>> 
>>> 
>>>   Da "time-nuts" time-nuts-bounces at lists.febo.com
>>>   A "Discussion of precise time and frequency measurement"
>>> time-nuts at lists.febo.com
>>>   Cc
>>>   Data Fri, 12 Jul 2019 18:29:10 -0400
>>>   Oggetto Re: [time-nuts] Galileo service currently degraded
>>>   I built this website as my senior design project last year,
>>> unfortunately
>>>   there's no timing data (except for tdop) being logged but you can see
>>> the
>>>   impact. Data is collected with four ublox m8n receivers, one per
>>>   constellation.
>>> 
>>>   Galileo data from last 1 week:
>>>   https://gnssperformancemonitor.com/viewdata.php?constellation=2×pan=1
>>> 
>>>   Kevin
>>> 
>>>   On Fri, Jul 12, 2019, 4:06 PM Hal Murray <hmurray at megapathdsl.net>
>>> wrote:
>>> 
>>>> 
>>>> 
>>>>> Galileo service is currently degraded, see:
>>> https://www.gsc-europa.eu/
>>>>> notice-advisory-to-galileo-users-nagu-2019025
>>>> 
>>>> Thanks.
>>>> 
>>>> Is anybody monitoring a Galileo-only setup to see how far off the
>>> timing
>>>> drifts?
>>>> 
>>>> 
>>>> --
>>>> These are my opinions. I hate spam.
>>>> 
>>>> 
>>>> 
>>>> 
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>> 
>> 
>> --
>> Kevin Croissant
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