PmodGPS RTCM enable and example/tutorial

[jacklu333333]

Hi, 
I am currently working on PmodGPS. I get to read the data from the serial port without any problem. And I would like to improve my accuracy further. I read on the datasheet there is something called RCTM using Differential GPS to enhance accuracy. However, according to the datasheet, it is inactive by default, I need to contact globaltop for detailed information. Yet, it seems the company no longer exists. Therefore, I was unable to contact them.  Also, I am new to Differential GPS, so I am not sure exactly what kind of information I need to send to the IC.

 

So my question is 

 

1. How to enable the RTCM?

2. Is there any example or tutorial available?

 

Thanks in advance. 

Sincerely, 

Jack Lu 

[artvvb]

Hi Jack,

Unfortunately, we don't have any more information about how to enable the RTCM feature of the GPS module.

For examples targeting various different host devices and more info on what the Pmod sends and receives, take a look at the resource center and the Interfacing with the Pmod section of the manual. The GPS module repeatedly sends data back to the host over UART, which the host then needs to receive and decode into whatever information is necessary. There are some additional datasheets linked in the Pmod's reference manual which detail all of the different information which is sent back:

Quote

Here are links to websites listing various commands or things that the Pmod GPS will receive and then send to the system board– here and here.

Thanks,

Arthur

[jacklu333333]

Hi Arthur, 

Sorry for late reply. Thank you for providing the link. The PMTK documentation helps a lot. The GPS performance improve a lot after reconfiguration.

Best Regard,

Jack Lu

 

For those who have similar problem, the PMTK can help improve the PmodGPS sensor, by enabled different mode. Also, you can use this to write the EPO file, to improve the oribt prediction. It would be a little  better than build-in EASY mode. It is important to remember to write the initial time and location. As far as the RTCM, I think it would be difficult to acquire any info to enable this function. According to my trace, the company, Gtop GPS division, has been sold to Sierra. But Sierra cannot provide any info for how to enable it. 

If you have the need to improve the accuracy, I would suggest to take a look at other GNSS module. Remember paying attention to the mode supported by the GNSS you selected. Some of them only support two system at same time. However, according to my experiment, smartphone build-in GNSS block mostly support 4 system simultaneously. Also, if your application is ASIC like me, I would suggest to use serial communication between the FPGA and GNSS modules. According to my experience, most GNSS modules at least support this interface.

Hope this will helps others.

 

Edited April 28, 2023 by jacklu333333