Lscott Posted July 1, 2022 Report Share Posted July 1, 2022 19 minutes ago, tweiss3 said: I think any implementation would have to come from Motorola directly, or whichever FHSS radio manufacture you are using. That being said, lets talk about a theory that might work as a repeater. My understanding is the radios utilize at least 50 frequencies, and hop about 50 times a second. The privacy is caused by changing up the hop set (order and number of frequencies), which means any repeater would have to be programed identically to the radios, but that's not a problem, that's typical of repeaters. Two problems exist, which we have to overcome: 1) At any given time (snapshot), the radios are using a single frequency for both receive and transmit. This could potentially be overcome by having a small delay in the re-transmission, say 2 hops behind the transmitting radio. Any radio in range of the transmitting station would continue to sync and receive from that station, stations outside that range would instead be synchronized and receive from the "repeater" station. Problem solved? 2) Second problem is, a traditional repeater usually has a fixed frequency set, and uses a duplexer to separate receive from transmit to eliminate desense in the receiver. The alternative is two antennas. Since 902MHz is such a high frequency, vertical separation can be relatively small and provide good isolation. 1 foot vertical provides 27dB isolation, and 2 feet increases that to 39dB, more than enough decent selectivity can overcome. Make sense? I think the theory would work, practice might be a bit harder to accomplish. There there is getting 15C certification for the "repeater". That might work for a large site. However if one wanted to install a private repeater for family use it doesn't look practical. Also as far as I know there is no open standard for FHSS radios so any implementation would be proprietary and the manufacture likely wouldn't be all that interested in opening it up or licensing the technology. So further along that line if another manufacture sold FHSS radios they probability they would work with another manufacture is nearly zero. That's why an open public standard or one that is open to licensing is much preferred. Quote Link to comment Share on other sites More sharing options...
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.