I can remember Tempest protetion first time round; and the prof at the Dutch PTT conducted in 1985; (he also demonstrated it on Tomorrows World with the BBC). indeed I tried some myself and found I could pick up the stray signals from various home computers using a 1970s “portable” Japanese TV/radio/cassette recorder (that weighed about 15 kilos) my dad had given me as this had the VHF TV bands that were no longer used in the the UK for TV but still were (or are) elsewhere in Europe. I didn’t however have the uni paper or the correct test equipment to keep the pictures synchronised and the screen on this TV was tiny anyway.
At least some good may come of it if it nudges laptop manufacturers into ensuring their computers do not chuck out RF at all sorts of frequencies as badly as 30 years ago; currrently it is a nightmare trying to record anything from an HF (shortwave) radio or even a VHF/UHF scanner to a laptop by directly connecting the audio input as the RF swamps the signal you want to receive.
I have been reduced to using a 1980 vintage radio cassette recorder and will have to solder a DIN plug (which is fiddly and I nearly always burn my fingers as I forget the thing retains heat for a good few seconds after the job is done).
Desktops are less vulnerable to this as their cases and the power unit are usually solid metal; it is the law worldwide this must be connected to protective earth (“earth ground”) which also prevents as much radiation escaping.
I do live at the top of a hill (and work in various buildings at the top of others, with full access to roofspaces etc); and part of my job involves ensuring equipment that is intended to transmit and receive radio signals works; and any other stuff introduced into the buildings does not upset this equipment.
A few days ago I was listening to France Info on Band II (FM) due to atmospherics; by using the same roof antenna which is only optimised for Band II I could still monitor two alarm type devices in the neighbourhood around 863-865 MHz and plot about 20 aircraft some as far as NL and DE (the Japanese freeware is about best for this). I could not however decode any pagers as the signal was too strong!
Its certainly true the right antenna helps and modern receivers are very portable (in comparison to a 40 kilo rack mounted Racal or Rhode & Schwarz RX); but its also a matter of keeping all the other noise and interference and there is loads these days.
Those who are particularly paranoid could maybe operate their laptop inside an earthed shipping container or if space doesn’t permit the housing of a builders portable WC lined with conductive material connected to earth; but it will need to be connected via a wired connection. Otherwise the Japanese still make typewriters and the Germans good fountain pens 😉
