GNSS 2 Poor performance


(George Papadimitropoulos) #1

I have a 2.0 hardware board running 3.2 fw, however after testing I only get 12 - 13 satellites most, and average HDOP of 0.8 - 0.9.
This is fairly poor performance even compared to other hobby grade receivers. For example the MN8M gets 15-19 sats with much lower HDOP.

This is my configuration :
uavcan.bit_rate = 0 [0, 1000000] (0)
uavcan.node_id = 50 [0, 125] (0)
uavcan.pubp-time = 0 [0, 1000000] (0)
uavcan.prio-time = 1 [0, 31] (1)
uavcan.pubp-stat = 200000 [2000, 1000000] (200000)
uavcan.prio-stat = 20 [0, 31] (20)
uavcan.pubp-fix = 100000 [66666, 2000000] (100000)
uavcan.pubp-aux = 1000000 [100000, 1000000] (1000000)
uavcan.prio-fix = 16 [0, 31] (16)
uavcan.prio-aux = 20 [0, 31] (20)
gnss.warn_dimens = 0 [0, 3] (0)
gnss.warn_sats = 0 [0, 20] (0)
uavcan.pubp-pres = 20000 [0, 1000000] (0)
uavcan.prio-pres = 16 [0, 31] (16)
pres.variance = 100.000000000[1.000000000, 4000.000000000] (100.000000000)
temp.variance = 4.000000000 [1.000000000, 100.000000000] (4.000000000)
nmea.uart_on = 0 [0, 1] (0)
mag.scaling_coef = 1.000000000 [0.100000001, 2.000000000] (1.000000000)
mag.variance = 0.004999999 [0.000000999, 1.000000000] (0.004999999)
uavcan.pubp-mag = 10000 [10000, 100000] (10000)
uavcan.prio-mag = 16 [0, 31] (16)

Let me know if I am missing something.
Thanks


(Pavel Kirienko) #2

Hi George, how are you assessing the performance of Zubax GNSS 2? Are you using u-blox? The information reported via QGC/MissionPlanner (if you’re using PX4 or ArduPilot) may be inaccurate. If you could compare the performance of your receivers using u-center (see https://kb.zubax.com/display/MAINKB/Evaluating+GNSS+performance+with+u-blox+u-center), that would be helpful.

Also, where did you source your Zubax GNSS 2 from — TitanElite or Zubax?

Thanks.


(George Papadimitropoulos) #3

Hello Pavel, thanks for your reply. The module was bought directly from you in 2015 and was shipped from Russia.
My main question is what’s an acceptable number of satellites for this module ? Is 13-14 what I should be getting ?

Thanks!


(Pavel Kirienko) #4

The number of satellites is highly dependent on your conditions. I am not sure I understand what hardware are you using to compare Zubax GNSS 2 against, could you please clarify? Also, as I indicated above, a side-by-side comparison using u-center would help.


(George Papadimitropoulos) #5

Hello again, unfortunately I’m unable to test through u-center outdoors at the moment due to bad weather.
The module I did the comparison with (through arducopter) is this : http://www.rctimer.com/?product-1287.html
The comparison was nothing scientific I just saw the number of satellites , HDOP, overall drift and time it took for a cold start 3D FIX.
The module linked above seemed to outperform the zubax.
However I do need to perform the test through u-center like you suggested.