If you have a bit of time for radio history... the intelligence, creativity and resources that went into the first WW2 integrated radar system are quite incredible considering the limitations of the time.
"To ensure that the stations did not broadcast at the same time, power from the National Grid was used to provide a convenient phase-locked 50 Hz signal that was available across the entire nation. Each station was equipped with a phase-shifting transformer that allowed it to trigger at a specific point on the Grid waveform, selecting a different point for each station to avoid overlap. The output of the transformer was fed to a Dippy oscillator that produced sharp pulses at 25 Hz, phase-locked to the output from the transformer. The locking was "soft", so short-term variations in the phase or frequency of the grid were filtered out. The system of spacing the transmissions out in time was known as "running rabbits". "Raid assessment was largely an acquired skill and continued to improve with operator experience. In measured tests, experimenters found that acquired skill was so great that experienced operators could often pick out targets with returns less than the current signal-to-noise ratio. How this was accomplished was a great mystery at the time - the operators were spotting blips in static that was larger than the signal. It is currently believed this is a form of stochastic resonance. https://en.wikipedia.org/wiki/Chain_Home
