Tiny RTK Base to telemetry connection


I would like to know the configuration for sending the RTCM 3 correction messages from the base’s telemetry. I am using HM-TRLR-S LoRa data link from Drotek. I was able to set the base, the survey-in was successful. The ‘Fix Mode’ changed from 3D to TIME. I had also set up the port for RTCM. However the telemetry link does not transmit the data to the rovers.

The results of setting up the base:

Overview of the implementation:

Telemetry configuration:

I have tried using the TX in the rover port too, but didn’t work.

The HM-TRLR module works well in general (was tested in another application; used without jumper).

So, I would like to know if I have set up things right and hence would like to solve the problem of the telemetry’s transmission. (Note: In the telemetry the TX is RX and RX is TX… The names are interchanged…)

Thanks !

Hi Hari,
have you already tried to use your radio in other “Mod” than LoRa?

I think the problem is as follows: this radio in LoRa mode working like a “packet” radio (information sent in small packets). As you can see in the setup your current packet (payload Data Length) is 32 bytes.
If the information (telemetry data) size is bigger then 32 bytes then the problem probably there…

I had the same problem with sending RTCM messagfes via radio. RTCM always received with CRC error because RTCM message sizes are bigger than the packet size of LoRa (even if I set it to max, 127 bytes)

After I changed “Mod” to FSK everything started to work well.
I suggest to try that.

Hi Rugo,

I too have figured out that the problem is with the HM-TRLR (had plugged in the TinyRTK’s UART to RPi3, used miniport and saw that the messages were actually there). In the LoRa mode the wireless rate was much lower hence I guess it didn’t click. I’m currently trying to figure out the settings with the FSK. Any ideas? I was able to transmit through the PC config software to two other HM-TRLRs, but it is not working with the TinyRTK directly. (57,600 baud; FSK; without NodeID;No Parity; LNA disabled; Power 20dbm).

Any ideas as why it doesn’t work?

I would conect the two radios into PC via USB1 and USB2
Then run serial terminal program (eg. Terra terminal) or somathing same on both virtual serial port.
This way what you write on one terminal you should receive/see on the other
Also you can try to copy paste bigger data to see if the whole arrives well to the other terminal.

If on this way the radio is working then you can connect one of them to Tiny’s UART then set it to TIME mode.
On the other side of radio (on the terminal windo) you should see “garbage” receiving since RTCM is a binary code.
If this also works then connect your real device to receiver side and see if it is working…

Thanks for the reply. I had used the HM-TRLR-PCconfig software and tried the same that you have recommended. It actually worked with this software. I had also tried sending and receiving through UART of RPi3 with the HM-TRLR chipset and it worked fine.

However the same thing does not happen with the TinyRTK when connected to the chipset. Even FSK does not seem to work.

Have ypu tried the other connector (uart) on tiny?

Yes Rugo. I did try the TX on the other UART, no luck.