VM130T transmitter specs

Hi

We are working on a project that was using a remote transmitter similar to the VM130 rf transmitter to control a switch on a piece of agricultural equipment. When using it with the the gps of the tractor engaged it would override the gps signal and cause the tractor to lose the gps tracking, but when we used the VM130 it would have no effect on the gps at all. We believe it is not the frequency that is causing the problem, but rather the type of RF modulation. Would to be possible get info on what type of modulation the VM130 uses?

thanks in advance

gilbert