UBX-RXM-RTCM

GPS/GNSS Development Boards
1

Is there a way to check the UBX-RXM-RTCM message?

You can check the CRC24Q prior to pushing it to the GPS module but that does not mean the GPS modules receives it correctly.

If the UBX-RXM-RTCM RTCM input status flags then the check sum of all the RTCM messages can be confirmed at the same time.

Any easy way to do this?

I saw these functions.

  // Functions to turn on/off message types for a given port ID (see COM_PORT_I2C, etc above)
  bool configureMessage(uint8_t msgClass, uint8_t msgID, uint8_t portID, uint8_t sendRate, uint16_t maxWait = defaultMaxWait);
  bool enableMessage(uint8_t msgClass, uint8_t msgID, uint8_t portID, uint8_t sendRate = 1, uint16_t maxWait = defaultMaxWait);
  bool disableMessage(uint8_t msgClass, uint8_t msgID, uint8_t portID, uint16_t maxWait = defaultMaxWait);

What is the difference between configure allow you to set the rate while enable defaults to the “navigation rate”?

Then we need to parse the message when it comes in?

Thanks

Bruce

2

I often use u-center: connect to your ZED (or other) and then view the UBX / MON / COMMS message. This will show you if the device is receiving packets on the various data interfaces (UART1, I2C, etc). If the ZED correctly receives a RTCM3 packet, it will show an increase. If the packet is corrupt, it will show up under ‘skipped’.

I was working on a radio link and thought everything was good but never got RTK lock. Checking COMMS, the ZED was skipping everything. It was obvious my radio link was destroying the packets. Once fixed, COMMS correctly showed a regularly increasing RTCM3 message.

3

UCENTER is great for development but I want to monitor this in situ so if the user is having unexpected issue they can know why.

Thanks

4

Hi Bruce,

The library does not support UBX-RXM-RTCM directly, but it does support UBX-RXM-COR. The advantage is that COR provides feedback on all corrections: RTCM, SPARTN and PMP (from the NEO-D9S). Example19 shows how to use the callback.

https://github.com/sparkfun/SparkFun_u- … EO-D9S.ino

You can extract the RTCM reference station Id from ubxDataStruct->statusInfo.bits.correctionId .

I haven’t looked at ubxDataStruct->msgType but I’m guessing that contains the RTCM3 message type (1004 etc.)?

Best wishes,

Paul