The main reason for using such GPS is basically the size, because it has to fit into a small box without anoter cable and dongle.
GLONASS USB GPS Module Compatible with U-blox Pixhawk Stratex IPEX
I would be ready to change for a GPS with a better performance, and possibly a better GPS module.
Actually the receiver you are using cab be found here
I don’t think it will fit in the box and would add another antenna. Why not trying after all.
Edit: I have found this GPS that looks like studied for stratux box
Interesting!
They mould over the standard interface with a USB socket.
And this one is a smaller version of the MIKRO-E module I am using, which is nice, but 2x the cost
It also has a 5V input, while the MIKRO-E has a 3.3V input. I bet their “UART” is only 3.3V though…
I would not mind buying one to test. I emailed them re postage to the UK; a lot of places don’t want to ship to the UK right now.
They seems to ship to France, so i may be testing the one I showed because “they advertise stratux compatible”, but didn’t decide yet.
What surprise me is that either my samsung galaxy S9+ and my Ipad mini 2 has better gps performance without waas. Anyway gps accuracy is not a key performance here, we are using it for EFB and not to fly LPV approaches.
Peter,
If i interpreted the two documents correctly that I referenced for SPS PANS performance and WAAS PANS performance, here are the differences between SPS and WAAS:
Specifications:
SPS Accuracy H < 9 Meters; V < 15 Meters
WAAS LPV Accuracy H < 1.5 Meters; V < 2 Meters
Measured Accuracy 95% values during the evaluation periods
SPS Accuracy H < 1.66 Meters; V < 3.6 Meters
WAAS LPV Accuracy H < 0.6 Meters; V < 1.1 Meters
So both SPS and WAAS perform much better than their specification limits, but WAAS improves the accuracy by a factor of 2.77 in the horizontal and 3.27 in the vertical and these don’t take into account ionospheric variations which will have a much greater effect on the uncorrected SPS vs WAAS.
@NCYankee wrote:
SPS
What does “SPS” mean?
WAAS
Do you mean SBAS or do you specifically mean the USA implementation of SBAS?
Sorry, SPS (Standard Positioning Service) used to describe GPS service without augmentation. I mean WAAS, the US system. The performance reports and standards are for the US systems. WAAS is the US SBAS system. GPS became operational in 1993 (28 years ago) and WAAS in 2003 (18 years ago). GNSS is the generic term for Global Navigation Satellite System.
I understand that the Garmin GNS/GTN/GX000 systems will work with SBAS systems other than WAAS such as EGNOS, will they also work with the Galileo GNSS systems?
Nothing certified in GA works with anything other than US GPS (Navstar) for lateral positioning. No idea if there is any move to support Galileo but clearly nobody “needs” it.
For SBAS, the certified boxes support WAAS and EGNOS and possibly some of the other augumentation services.
I am still working on my GPS project.
SBAS is interesting. It is pretty obvious that some products out there are reporting “SBAS active” but they are not actually using it to improve the fix. That may well explain some of the results I saw, where an EGNOS-reporting GPS was no better than the KLN94.
The SBAS satellite IDs (allocated worldwide) are 120 thru 158 and a reception of any of these can be used to indicate SBAS is active, when it actually isn’t. One has to search the NMEA sentences to see if a satellite in that numeric range is being used.
@Peter, it may have to do with the existence of two signal strength thresholds in most receivers: the threshold to acquire a new satellite is intentionally set higher than the one to keep tracking a satellite already acquired.
Interesting.
However, any given receiver should be tracking no more than one SBAS satellite, no?
I am currently writing the code to search the relevant NMEA sentence for all possible SBAS satellites but my plan was to report just the first one found that is being used in the fix.
Putting it another way, if one is trying to establish the general integrity of the GPS fix by means of SBAS / no SBAS (as well as HDOP VDOP etc) then any SBAS satellite being used will do, even if the GPS is actually using 2 or 3, or is about to switch to a better one.
Looking at this with 50N and 0 long, there should be 3 in view
but I am seeing none.
