- Brian Nadeau November 16, 2021 at 2:57 am
What are the hardware/protocol requirements for the external GPS? I have not been able to connect my ublox based GPS, Spike connects to the serial port but indicates communications error. I’ve tried various baud rates and protocols. The gps unit itself is working and connects fine with other software. Any hints welcome. thanks.Andrew November 16, 2021 at 8:08 am
I’m assuming you are on Windows? The software is looking for the RMC NMEA sentence. Have you used something like tera term to verify the serial output of the GPS? What is the model number for your unit?
AndrewBrian Nadeau November 16, 2021 at 9:08 am
Software is Windows 10
Device is Reyax RY636AI (https://reyax.com/wp-content/uploads/2017/09/RY636AI.pdf)
The string looks like this — $GPRMC,123456.80,V,,,,,,,123456,,*16
I changed my actual data with the 123456. The string does look a bit abbreviated, perhaps that is the issue?Andrew November 16, 2021 at 9:54 am
The ‘V’ in the second field indicates “void” or that the data is invalid. You can see this too, as the fields after the ‘V’ should contain the lat/lon but they are empty.
Are you getting the “Comm Err” message? If yes, then it’s not even getting that far to see the ‘V’. The Comm Err indicates the software is not even seeing the “RMC” substring, which does indicate potentially the baud rates not matching or some other issue with the data. It looks like you can control the baud rate in the document you linked, you might try configuring different rates on the unit itself. Presumably you can also see the device listed under the COM ports in the device manager?
If you were able resolve the comm error, then the device would still report “Unlocked” with your current message shown and the lat/lon wouldn’t be available to the mapping measurements.
We used this USB GPS antenna (linked below) with success in our testing. It did involve some setup we can try to help you with if you go this route.
Justin CrooksModeratorJustin Crooks November 16, 2021 at 11:04 am
One thing to watch out for is noise from the USB cable ends can mass with weak GPS signals, so it is best to have some distance between the GPS antenna and any USB 3.0 cable. A couple of meters is usually sufficient.Brian Nadeau November 16, 2021 at 2:15 pm
I managed to connect, I get a lat/lon/locked/other info in the GPS control panel but I also get an almost immediate “Comm Error”.
Does Spike stop using the GPS after the “Comm Error”, or will it continue to parse the serial stream? Seems like it stops.
I suspect the GPS is sending sentences Spike can not parse, it would be nice if it would ignore those and keep looking for updated lat/lon/other data.Andrew November 16, 2021 at 3:27 pm
Looking at the logic now. It does not appear to stop reading after a comm err. It continues to read the input and if it found the RMC sentence in a subsequent message it would update the dialog with the nav info found.
The Spike software does expect the RMC string to be sent in each update, and it does expect roughly a 1 second update rate. My COM reads have a 50ms readintervalTimeout, and a 2second total timeout. I read 2k bytes at a time in a loop. If you are using a low baud, like 9600, you might simply be trying to transmit too much data in this interval. Consider increasing your baud rate or decreasing your message size if you can.
If RMC messages were still coming in periodically, I would expect you to see it flip between valid and Comm Error.
Looking at the code here, it also looks like it will still save the last lat/lon it found. So even if it was flipping between valid data and comm err, the mapping mode should still be able to query the last valid value seen.
Brian Nadeau November 16, 2021 at 3:44 pm
- This reply was modified 2 years, 3 months ago by Brian Nadeau.
When I do a disconnect and reconnect I have a maybe 1 in 20 chance of getting an update (vs. last value seen). I have never seen an automatic update after the comm error.
I also sometimes see a log pause when connecting, like something is getting reset. After this reset I often see a locked GPS and lat/lon/etc.
If there is value to you in this I’m happy to provide data/debug. I’m also happy to get the GPS unit you recommended as a solution.
On the specific GPS unit I am using, this is something I have had for a long time and use it with various software and have a high degree of confidence in it, it also works great with the u-center software provided by ublox. It would also be interesting to know what GPS you have tested with and if any use ublox chips.
on the baud rate I am set at 115200. 2k is a fair bit of data, I may not be compliant with your timeouts.
thanks for the help.Andrew November 17, 2021 at 8:07 am
I’m not sure if we’ve used an external GPS with a ublox. Our SM200 uses this chipset, but we don’t interface it over serial as Spike does.
It is probably better in the short term to consider using a different GPS if possible. If you would like to email me at aj at signalhound dot com, I can keep your email and let you know if we are able to acquire the GPS you are using and get it working in Spike. Also, it might be interesting for us to add some debugging utilities to the GPS interface in a future release of Spike, and I can reach out if we ever add something like that.
I apologize for the inconvenience. Thanks for your patience and providing the information.
GSilesParticipantGSiles May 1, 2023 at 3:18 pm
Andrew, I have the external GPS unit BU-353S4 (5 Hz) you mentioned, but I am getting the CommError message. Using Windows 10 and tried different baud rates. Can you please give me some support about the setup I have to use?
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