Following along the lines of work done around 1980 at Plessey Avionics in the UK by Chris Richardson (G3NAE), a VHF/FM "Simplex Repeater" capable of simultaneous Tx and Rx on the same channel is being developed for amateur use.
The system looks like this:
The transmitted signal, yM returns with a little delay, τ, along with some return signal, y60 with inadvertent phase modulation from active devices connected to mains power. The SR must suppress these unwanted components so that the incoming signal, y, can be extracted either for local use or re-modulation. By taking advantage of the properties of angle modulation, such a system is feasible.
Here is a picture of the SR, as of February, 2018:
See a short video of the SR in action:
I was a block away talking on an HT, through the SR (upstairs), to the HT-220 in the video (downstairs).
A page about my restoration of a RCA T60.
A page about my restoration of a GE 93.
A great place for parts: