The days when software-defined radios were exotic are long gone and we don’t miss them. Example in this regard: [Laakso Mikko’s] a research group has built a multi-channel receiver using 21 inexpensive RTL-SDR switches to create a phase coherent grid. This is useful for everything – from orientation and passive radar or beam formation. The code is also available on GitHub.
Phase coherence requires the key tuner to turn off distraction. This means that the code only works with keys that use the R820T / 2. The project modifies the keys to use a common clock and a switching reference noise generator.
A single clutch can hold seven keys for about $ 180. The team used up to 5 of them to create arrays of 35 receivers. The processing is a bit mathematically intensive and part of the code is in Matlab.
In addition, some of the reports deal with increasing the performance of diluted receiver arrays to bring it closer to the performance of a fully populated array. Obviously, even at this low price, fewer receivers will be desired for cost, space and power.
Of course, not everyone needs dozens of channels for phase-coordinated reception, but if you do, it’s good to know a cheap way to get there.