Increasing F9P Update Rate

Has anyone tried increasing the update rate on the F9P to 15 or 20 Hertz? The spec sheet for the F9P shows it is capable of those rates by using fewer constellations. The spec sheet further shows that RTK horizontal and vertical accuracy are unaffected with fewer constellations. The only performance issue the spec sheet shows is increased convergence time when using only GPS. Convergence time increases from 10 to 30 seconds.


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Ive set a trimble bd970 to 20hz with AOG. If your board is using i2C to read the Bno085 it will make performance worse.

With bno in RVC mode there still will not be a performance increase or decrease because the program is built for 10hz. But at least imu timing will not mess up.

F9P at 10Hz is plenty accurate.

The horizontal and vertical accuracy are significantly affected in farming when you lose visibility to a number of satellites. Why would we have multi constellation receivers if GPS alone would suffice.

The AOG code shows the BNO085 is already being read every 20 millis or 50Hz. It looks like the code is triggering the building of the NMEA sentence based on the availability of the GGA data from the GPS for non-dual operation. For dual operation it looks like it is looking for GGA and RelPos. If those were available more often it would seem the NMEA sentences would be updated more often.

Perhaps I am mis-reading the code.

With the Trimble set to 20 Hz was the display of the tractor position more smooth / less laggy on AOG?

The spec sheet does show accuracy is affected for non-RTK fixes when reducing the number of constellations. However, in my original question I was asking about RTK fixes. The spec sheet shows no degradation in accuracy for RTK fixes.

For the i2c its pre fetching the bno data before the next gga because it has to make a request for it first. This process is very slow. But the timing is based off of gga arriving at 10hz.

In RVC mode the BNO is always dumping out the data at 100hz regardless, no request needed. So you just read the data available at the point in time that aligns with the gga arriving.

Not absolute accurate that either but the point is that you lose RTK fix if you lose too many satellites (trees, buildings etc.). It is a real problem with small fields surrounded by forests etc.

If you always work on open fields, perhaps less constellations and higher rate would work better for you.

I guess the other reality check is F9P at 10hz, with 3 constellations holds a line extremely well. +-1cm. Even on curves around headlands AOG holds 2-3cm very well with the same position data.

If your steering accuracy is still less than the gps accuracy, and your not above 50km/h there is nothing to gain by using a higher rate than 10hz.

Good point. The practical application versus the theoretical possibility. Thanks for the feedback.

F9P is a great performer for the price, and excellent for agriculture.

But it is fun trying other receivers. BD970 at 10hz was very impressive in open areas, even has a setting for ag equipment. It was worse though in the trees than an F9P. Also the BD970 is a trimble so of course a few constellations still need “unlocking” :-1:

Soon to try a Septentrio Mosaic M5, will be neat to see its performance vs ublox and Trimble.


I agree with you that AOG holds a line very well, but that’s also what many people said before panda was implemented, and now I wouldn’t want to go back to the pre-panda days. Maybe 20Hz would improve the capabilities around corners! :grinning: