On HDSdr and other programs you an tune down to DC but not really. My SDR Play goes really low but the TV tuner SDRs don't but you still hear things, even signals, where there shouldn't be. So first why are there mirror signals down below DC is this just software or is there actually something to this? What are you hearing below 50mhzon the TV tuners; artifacts inside the radio itself? I thought at first that the hardware really went this low but the specs say no. Another thing I couldn't figure out was on the SDRPlay I would hear the BBC down in shortwave. At first I thought it was a station but there are none and it would disappear but other long distance stations should disappear too but they didn't . Also it wasn't a ghost image like AM or FM broadcast because we don't have any in this area. I thought maybe it was the IF of another radio but that was a higher frequency and almost all radios are the same. Since we are on impossible questions what do the numbers stations say?
(the smiley is for the readers with Asperger's who will think that's a real question) I'm also 99% convinced radio Havana plays number stations on the same mast/antenna as their civilian one from the exact same sound/strength of the two signals. Isn't the tower owned by the government making this easy to do covertly? I would think a spy with a SW radio would be more obvious then one getting instructions over the internet or phone. Any chance of ever seeing the one time pad found in the bar of soap of that British spy?