RS232 Configuration for RTK on RS2+?

There are several posts in the past regarding external transmitter/receivers but they did not help. I have 2 of the eByte E90-DTU transmitter/receiver units. I am receiving two rs232>usb cables today so that I can configure the units. The lowest baud rate on the RS2 is 9600 (in Emlid Flow) so I need to set that in the E90. I think it ships with a default setting of 4800 for the rs232 data rate and 9600 for the air rate.

Has anyone configured the E90’s to work with the Emlid RS2(+) units? Any help will be appreciated.

That baud rate seems fairly low transmitting RTCM data with all constellations

Hi Christian, I got it working. I will just have to test and see what the required baud rate is. Unless someone else can chime and and let me know. Today I received a rs232 >USB cable and then connected to set the internal rate to 19200. I matched that in the Emlid Flow app and they are communicating just fine. Again, no idea if the baud rate needs to go up. The lowest rate needed will allow the maximum distance.

I also plan on getting something printed so it will mount between the pole and RS2 like the guy in cambodia did. That will be a clean nice setup.

1 Like

(post deleted by author)

What is the absolute minimum baud rate needed to support the default settings for RTCM3 messages? I believe the RS2 defaults to 9.11 kb/s for the data rate. So I am trying to determine what is the minimum required.

It takes a little bit of calculation: Difference between Bit Rate and Baud Rate - GeeksforGeeks

1 Like

Christian, that is beyond my knowledge :joy:. Maybe you or one of the folks from emlid would male a spreadsheet that would calculate what is needed based on the settings selected.

That would be very nice to have. Thanks for the link. I did get educated on baud rate vs bit rate.

Hi Tim,

If you send the corrections over RS-232, then the minimum baud rate which you can select is 4800. But I’m not sure what you mean by the support of default settings for RTCM3. Could you please elaborate a bit more on this?

You can select the data rate for LoRa radio only. So if you’re working with RS-232, then this setting can’t be selected.

Hi Liudmila,
I will show more details so you can help me. For the External Radio (ebyte E90-DTU) I can set the following parameters (see below). With the parameters below I can have corrections through the RS232 port. I can achieve about 1.3 km with some trees and houses between the rover and the base. Christian sent a link yesterday explaining the difference between bit rate and baud rate. I did not know the difference and I would need to study it more to fully understand it.

The one thing I know is that the LoRa range is longer with lower data rates. So I am simply trying to understand what is the minimal settings required in the External E90 radio to transmit the and receive all the corrections without loss of data. There should be a mathematical solution to that number for someone who fully understands it. I do not.

Baud Rate options in external radio

Air Rate options for external radio

For the external radio to work, the Baud rate setting in Emlid Flow must match the baud rate setting in the E90-DTU transmitter/receiver

Below are my RTCM settings. I was thinking these are default values but they may not be. So forgive me if I mispoke on that.

My Base is set to Static at 1hz
My Rover is set to Kinematic at 5hz.

Please let me know if you need more details. Thank you for your help.

Hi Tim,

Thanks for the details on this.

You’re right, the baud rates should match with the radio settings for both the base in Base output and the rover in Corrections input.

That’s correct, these settings for RTCM3 are the default ones.

I can hardly give particular recommendations for calculating the necessary air rate, but with such update rates for RTCM3, we suggest choosing 9.11 kb/s for LoRa. The higher the air data rate the larger number of RTCM3 messages you can send. I believe you can start from this and change the setting according to this rule to find the ones that work best.

1 Like

This topic was automatically closed 100 days after the last reply. New replies are no longer allowed.