Machinbird,
Real electronic black magic
PLL is just a "building block" that can be "hardware based". And are powerful.
DSP systems are IMPRESSIVE. You use the "computing power" to "remove" the noise (that is ramdom) to detect the signal (that is coherent) using Redundancy.
The results i observed are simply unbelievable. So i designed a "Propagation Tester" using it that can be understood in my
PY2CW mobile Ham Station website.
Using the synergy between HF and Internet in "near real time".
I am curious to known what kind of Receiving Technique they used in the failed ULB location.