I don't think this is an issue but just to be sure: About to go on a Litchi mission & I want my son to be able to communicate with me when he sees my (3-Adv.) overhead. His position will be out of site/shouting range so we want to use the 2 ways to stay in touch. 2 ways are- Motorola DTR -550's. They work at 950mhz. Any concerns about interference?