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Here in the San Francisco Bay and Sacramento regions we have started hearing a "baby monitor" type devices using GMRS 462 and 467 MHz primary repeater frequencies, in nursing home settings (given the message content). We are aware of about twenty incidents of this over the past three months, but the rate of occurrence is rising. The most recent was strong enough to interfere with a CERT/Fire Council repeater out here. These typically operate during daylight periods, and appear to be continuously keyed for up to 12-16 hours at a time, although background noise, such as televisions, could be keeping them transmitting if set for VOX. They do not have time-out timers enabled. These change channels occasionally, but usually end up on 462.625, 462.725, 467.625 and 467.725 MHz. They use a D754 or a D734 DCS code. This kind of device was explicitly mentioned in past FCC GMRS rulings as it was feared that manufacturer's might use these channels for such things. Given most repeaters here in California are on 1500-4000 ft. mountains, continuous destructive interference will occur to our repeater inputs. I tried to DF the source of one of these last week, but it was found to be in San Francisco and we ran out of time. SF is a particularly difficult place to do this due to the density, hills and other sources. Thankfully these are constantly keyed. The device I was looking for was horizontally polarized, making it about 10-20 dB weaker when received on a vertical vehicle antenna. A Yagi in horizontal worked best. My goal was not to go after the user (they don't know better), but instead get a picture of the device, determine its manufacturer and model number, and establish who is selling it. As these may be used in nursing care facilities, they will likely have to bring the device out to us to be safe. Please let us know here if you hear these as we are trying to keep a list of the channels and codes in use so we can identify the specific radio model. This is clearly in violation of §95.1733(a)(10) and §95.1763© for GMRS, and §95.587(3) for FRS. It also appears to violate §95.533.