Question about ZED-F9P GPS implementation

GPS/GNSS Development Boards
1

Hi,

I am currently working on a team that needs to have GPS on a weather balloon payload. We were thinking of using the ZED-F9P Board (https://www.sparkfun.com/products/15136) that you are currently selling, since it seems to record a lot of the data we need to take. We know, however, that federal export control regulations require GPS boards to stop working when they are going faster than 1000 knots AND are above 60,000 ft. Unfortunately, I have been told that most GPS boards stop working when they are going faster than 1000 knots OR are above 60,000 ft. This can be a problem if GPS data needs to be taken at high altitudes.

Obviously, being on a weather balloon, our GPS board will not be going faster than 1000 knots, but does the implementation of the ZED-F9P board cause the GPS to stop working when it goes above 60,000 ft, anyway? I haven’t been able to find such information on the sparkfun website or in any of the datasheets, so I just wanted to confirm before I made a purchase.

2

I would assume so - it sound like manufacturers were only required to implement a STOP-case when BOTH conditions are occurring (>1k knots, >60k ft)…but the easiest way for a hardware manufacturer to accomplish this would be to program it to stop if EITHER are satisfied, so they don’t risk running afoul of regulations

https://www.nightcrewlabs.com/high-alti … 0off%20GPS. this page has some good info, where they mention having to work with Broadcom about the project - perhaps reach out to U-blox directly?

3

If it’s not too much trouble please report back here @Spydercrawler when you find an answer.

4

The u-blox datasheets are quite clear on what the operational limits are for each module. E.g. from the MAX-M8 datasheet:

Operational limits:

Dynamics: ≤ 4 g

Altitude: 50,000 m

Velocity: 500 m/s

I can personally vouch for the MAX-M8Q working very well on weather balloon flights at altitudes well over 30km:

http://arxiv.org/abs/1904.04321 (see section 2.3.4)

The trick is to set the dynamic model to (e.g.) “Airborne <1g”

https://github.com/sparkfun/SparkFun_u- … cModel.ino

Best wishes,

Paul

5

I’ve just noticed that I’ve been silly and having used !!! in some of the error messages in the dynamic model example. !!! can cause avrdude (the standard AVR upload tool used by the Arduino IDE) to crash. I will fix that in the next version of the library. But for now please delete the !!!'s!

Best wishes,

Paul