Hi, Please ask me to stop in whatever words you like, with a reference to this request, if I talk about anything other than this.
I'd like to make a cheap device for taking ongoing measurements of the effectiveness of a shielded enclosure. Would you be willing to briefly review my first prototype theory, and _concisely_ offer any _concise_ problems or _concise_ better ideas you can think of? > Noise source emits EM signal noise function, which at the receiver is present > as Rn(t). This signal oscillates in what is roughly a square wave, for > example > with a relay. > > During inactive time, receiver receives only Rb(t) the background signal. > > During active time, receiver receives Rb(t) + Rn(t) = Rr(t). > > When the signal is weak, heuristics can't differentiate between active and > inactive time periods. So, we separate the problem of keeping the receiver in > sync with the emitter from that of measuring the signal, and compare the > probability distributions of the active and inactive timeperiods to discern > the > strength of Rn(t). Now, summation over time can be used to increase > sensitivity > if the signal is very weak. > > First, estimate the probability distribution of Rn(t) from our observations of > the probability distributions of Rr(t) and Rb(t), possibly using e.g. the > convolution theorem for the sum of two independent random variables, which is > not complex. > > Then, discern mean electromagnetic properties such as relative power by > solving > from the distribution of Rn(t). I've started pursuing this algorithm and goal a couple times over the years, and I'd like to try again. Step 1 is to identify in software the precise oscillation period of such a waveform, similar to implementing a van eck phreaking attack. I imagine while exploring step 1, plotting the accumulated shape of a single cycle visually, as if an oscilloscope had a trigger set for it. Each time point in the plot would be a fully colored column, like in a spectrogram, but of the frequency of occurrences of different signal powers, rather than spectral decomposition. I think such a plot would be worthwhile because it would help move towards both this goal, and other goals in electromagnetic security, of quickly reviewing the details of a repeating signal. Such signals are common in clocked digital electronic systems.
