3

Could very well be someone who is bored and opens the repeater without actually transmitting anything useful. Happens on a lot of repeaters. You only need one person to do this to bother all users of the relay...


2

The answer can be fond in The ARRL Handbook 2019, Vol 3, although it's spreaded across different chapters. In short, SNR is typically calculated for the noise floor of 2500 Hz SSB signal. Particularly this is how WSJT-X calculates negative SNRs for FT8 and other modes. Now the trick is that by deviding the bandwidth in half you decrease the noise floor by 3 ...


1

Without looking at the specific device, I'll give a generic answer. If you have the manual for the device, rarely it will tell you how it is modulated or what frequency it uses. The next place to check would be the FCC. If the device is type accepted, it should have a FCC registration number, and you can look up technical documentation on FCC's website ...


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