Slower effective update rate than expected on ZED-F9R

Q&A forumCategory: QuestionsSlower effective update rate than expected on ZED-F9R
francescorav.es483 asked 1 month ago
Dear all,
I am writing as I own a ZED-F9R ArduSimple kit, with NTRIP RTK corrections via 4G.
I would need to use it with an update rate of ideally 20 Hz. However, I am currently struggling to get such a high update rate.
I tried setting an update rate of up to 40 Hz with u-center, and a baud rate of 921600, but that did not help.
Indeed, I tried recording a localization trace with gpspipe, and post-processed it to get a .wkt file, reporting for each GNSS receiver update a timestamp and the position, together with other information.
I also developed a Python program which reports an estimate of the actual update rate, by parsing the .wkt file and analyzing the timestamps for each update from the GNSS receiver.
Even if I set 40 Hz and increase the baud rate, I always get as a result an effective rate of 10 Hz or less (more than 4 times less than expected).
Do you know why we are observing this behaviour? Is there some setting we can tweak to try to improve the performance of the receiver?
Thank you very much in advance.

1 Answers
clive1 answered 1 month ago

>Do you know why we are observing this behaviour?

Probably because you are configuring it incorrectly, you don’t describe exactly what you set.
As I understand it, you need to decouple the rates, such that (CFG-RATE-MEAS × CFG-RATE-NAV) >= 500 milliseconds (<= 2 Hz). This is the rate at which it will solve for an RTK position.
​CFG-RATE-NAV_PRIO is the synthetic high rate you want position reporting, a subset of messages will report at this rate.

clive1
replied 1 month ago

20 Hz position reporting

CFG-RATE-MEAS = 500
CFG-RATE-NAV = 1
CFG-RATE-NAV_PRIO = 20

30 Hz is the maximum rated speed, and you should probably be using TIMEPULSE, and perhaps TIMEMARK, to get a systemic understanding of time, of when/where that’s reflected in the solution.

https://portal.u-blox.com/s/question/0D52p0000CweE5xCQE/c102f9r-zedf9r-fails-20-hz-output-rate-in-high-priority-mode-after-sensor-calibration

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