What even is this?

• It is a small board that will help measure the phase offset between a reference signal and 1/4 inputs.
• A quick and dirty way of knowing if the two measured signals are in/out of phase was needed. The resistor combiner allows a device to measure either a null or max output power depending on the inputs' destructive/constructive interference.

What does this mean?

• Absolute phase offsets are not easily obtainable using this method
• The phase of each input can be tuned until the output reaches a minimum/maximum output, this indicates 180/0 phase difference respectively
• Due to issues with dynamic range, the null points (180 degree destructive intfer.) are easier to measure

Why did I make it?

• This board is to prove out a relatively novel way of phase matching a large number of HackRF SDRs, for use in phased antenna arrays
• The board will hopefully prove the technique's ability to work with 4 units and from there it can be scaled up ~40/50 element arrays (each element powered by a separate radio)