[RFI] Something is jamming 900mhz weather station

[Jon Suehiro]

900MHz ISM band is wild-west.As 900MHz Analog Cordless Telephone devices, typically902-905MHz and 925-928MHz are paired for full duplex channels.As initial 900MHz products, they were typically narrow FMand assigned into 30 channels.Later, for the cost down, the IF filter is eliminated orspec down, the IF bandwidth is extremely wide and out of intended channelrejection performance is reduced significantly.  So if you have any 900MHzcommercial repeaters (or old paging transmitter) nearby, the wideband analogsystem can easily be interfered.The same channel plan is used by baby monitors.It is not very known, but 5.8GHz analog cordless uses 900MHzside for a part of full duplex.Typically the analog signal goes to 2-3 house long.  Soif you are in the city, the source of the interference can be easily on thenext street.Then 900MHz spread spectrum technology is developed. The power output is equivalent of 100mW or more, and will reach over 1 miledistance in the open field.RF bar code reader was on 900MHz but mostly moved up to2.4GHz now.If you are close to warehouse or store environment, typicalRFID bar code system is running strong at 915MHz.Good long distance wireless microphone is also on the 900MHzISM band.In your weather station, is there any option of channelchange ?  If so, try change the channel from the default to see if thereis any improvement.Anyway 902-928MHz is totally RF uncontrolled environment. If there is any interference, you need to change the channel or comecloser. GL de NN5T Jon