Beidou vs Galileo

This is what I typically see on Maui.

Hi hpalmer,

There are many GNSS availability viewers online which allow you to check any location worldwide.?ÿ I find these two useful.

http://www.taroz.net/GNSS-Radar.html#

https://app.qzss.go.jp/GNSSView/gnssview.html?t=1589319271847

Here is what we are currently tracking at our manufacturing facility in San Jose, California.?ÿ?ÿ

?ÿ

Michael Glutting
JAVAD GNSS, Inc. | Sales
M 408.375.9135 | E [email protected]

@antcrook  Do you use all 3 signals in Beidou in solutions?  and if so, what instrument

@michael-glutting  Thanks Michael.  You track many more BDS on the West coast than East coast USA.  Are you using all 3 BDS signals in solution and if so which instrument?

Beidou is designed for use in China and there is a good number of their satellites in polarized orbits that concentrate over China. Plus there geostationary satellites are only visible in the China side of the globe. I imagine that on our West coast the majority of visible satellites are to the West. One needs a balance of satellites East and West to get good mathematical position solutions. Galileo are in a global spread such as GPS but are bit more favorable than GPS due to their higher orbit elevations. If you need to limit your available channels I suggest Galileo over Beidou in the Continental US.

Paul in PA

I don't understand why you'd have to chose one constellation over the other.?ÿ Can't the newer receivers use any combination of whatever's available?

@allen-wrench

Depends on whose receiver and how much extra you want to pay. Why pay for something that may in fact dilute your precision?

Paul in PA

@paul-in-pa

I don't really understand the way the calculations are done as well as I should, and I've probably made some bad assumptions.  I'm assuming that a) satellites from GPS/GLONASS/Beidou/Galileo are (generally) of equal quality and reliability, and that b) you can mix and match satellites from any combination of the four to get a corrected position.  For example, use signals from 3 of each constellation if that's what's visible for a total of 12 to triangulate (trilateral-ate?) a point from.

I've asked this question (probably a silly one, but anyway) before, in RTK are all the calculations done at the receiver - e.g. selection of satellites, determining a "fix", etc - or is that done by the DC software (in our case SurvCE) using the raw stats from the receiver?

@richard-imrie

It's done by the DC software, I guess the DC for a Javid can be in the receiver box. But the computer is doing the calculations.

@mightymoe

So, the "quality" of the DC software could be a factor, where we have traditionally debated the performance particular receivers?

@richard-imrie

I would say yes, both the receiver and DC are important to the process.

@richard-imrie

I am only familiar with Trimble, the calculations are done in the receiver, NOT the data collector. I imagine others are the same. 

@paul-in-pa

Once again you have spoken "authoritatively" about something you don't know very much about.

?ÿ

I get plenty of Beidou SV's all day in western PA. And they are in all four quadrants. Tracks are similar to other constellations. The initial "test" constellation was indeed mainly over China and the western Pacific, now their more recent SV's are in orbits similar to GPS/Galileo/Glonass

@john-hamilton

So in that case, for RTK, it is the receiver tells the DC that the receiver has a fix, then all the DC does is determines whether the stats are within the tolerances preset in the DC and whether the point can be stored, or the tolerances overridden.

In the case of SurvCE there are things like elevation mask, but from memory that is a DC command to the base during its startup. Or maybe I'm wrong on that, because presumably the DC running the rover has the same elevation mask, or maybe the mask is only applied to the rover. 

@hpalmer You are most welcome hpalmer. The screenshot I shared was a moment in time when there were more BDS than GAL visible in San Jose, California. Using GNSS-Radar, you can see that this trend of more BDS than GAL continues each day on the West and East coast of the U.S.  For example, here are screenshots from GNSS-Radar's website availability calculator for the next 12 hours:

Galileo, San Jose

BeiDou, San Jose

In Philadelphia, PA, over the same time span, here is the availability:

Galileo, Philadelphia

BeiDou, Philadelphia

Yes, the JAVAD GNSS TRIUMPH-LS Plus RTK rover and TRIUMPH-3 RTK base track BDS B1, B2 and B3 and the TRIUMPH-LS Plus uses signals from all three of these BDS frequency bands to compute an RTK solution.  Specifically, the signals used are B1C, B1, B2B, B2A, Bboc (BeiDou AltBOC) and B3.  

You can find additional information on these instruments on our Surveying Solutions page, http://www.javad.com/jgnss/survey/, and I'd be happy to send you more details by email, just send me an email.

@richard-imrie

The computer inside the rover is called the "rtk engine", it does the comps and send info to the DC like position, stats, how many SV's, what SV#'s, etc. It is of course a 2 way communications, the dc has to tell the receiver what mark to use, what sv's, etc. Sometimes when connecting to VRS over cell, the DC receives the RTCM or CMRx, etc corrections over the network and sends them to the receiver, but my R10's can be configured to connect directly from the receiver to the NTrip caster, so they would receive the corrections directly, no data collector involved. In the case of radio link RTK the corrections go directly from base to rover.

On my way to a job right now, and logged in to my base to check that it is running since I shut it down last night to do the S6/SX10 testing. It is tracking more Beidou than anything else.

Use https://www.gnssplanning.com/ and find satellite availability for yourself. It works great on a phone and it ideal for knowing which times of the day you should avoid GNSS use if you are needing to use it that day.