Repeater Mode can be easily set up from the front screen of any SATEL radio (Main Setup>Additional>Repeater>select ON>Save changes). Many SATEL users stop there, however additional steps can be taken in order to prevent potential issues with your system. Some rather common issues we hear about when a repeater is in place are:
“I get a signal when near the base, but not when near the rover”
“I’m getting a signal, but not getting a fix”
“The rover sometimes hears both the base and repeater and it looks to be creating issues with my GPS”
The first scenario is likely an antenna issue; you will want to check your antennas and cables. The second scenario is likely due to parameters; you will want to go back through your settings and make sure parameters match. The last issue of an “echo” or double signal is a common problem you’ll experience with a repeater, especially in Precision Ag applications, or other scenarios in which the rover is moving. Some GPS are immune to the echo, while we’ve seen others get confused by the double signal. Here are some tips for fixing this common issue, depending on your licensing:
If You Have More Than 1 Frequency:
If in your licensing you have more than one frequency available for use, we recommend using separate TX/RX frequencies. For example, let’s say you have 469 MHz and 462 MHz available. You would set up the base to transmit at 469 MHz. You would set up the repeater to receive at 469 MHz (Main Menu>Radio Frequency>RX Frequency (change setting)) and to transmit at 462 MHz (Main Menu>Radio Frequency>TX Frequency (change setting)). Then you will set the rover to receive at 462 Mhz. This will ensure that even if the rover hears the base at times, it will not receive and interfere with the communication.
If You Do Not Have More Than 1 Frequency:
The alternative option, if you do not have more than one frequency available to use in your application, is to set up addressing. This is easily done through the programming software on your PC, using either Configuration Manager or SaTerm. The set up would look like this:
Base = Address 0001 0001
Repeater = Receive Address 0001 0001, Transmit Address 0002 0002
Rover = Address 0002 0002
As above, this also ensures that the base will not interfere with the rover, even if a double signal can be heard at different points.
Other Common Issues:
Another common issue in repeater set ups relates to modulation settings. Using a slower protocol, such as GMSK, is not recommended on a repeater set up because of the length of the data stream. The data string nowadays are so long that it can create a back up of data; the repeater may still be transmitting to the rover as the base is trying to send the next string. This can be resolved by using a faster protocol.
Set up should also be considered; we have seen numerous situations in which the repeater is placed too close to the base, instead of near the rover. You want to make sure the repeater and rover are as close as possible in order to ensure the best signal.
Double repeater set ups are much more complicated, especially when the rover is moving. Addressing, as described above, is recommended in this scenario.