A Cheap Simplex Repeater A type of system known as a simplex repeater uses a single transceiver and a short-duration voice recorder, which records whatever the receiver picks up for a set length of time (usually 30 seconds or less), then plays back the recording over the transmitter on the same frequency. A common name for them is a "parrot" repeater.
I'm building a system to replace atx2000 with Raspberry Pi.
UPDATE 26 Oct 2016
QParrot (old version)
First test on Raspberry-Pi
System Configuration Diagram
Line level signal to microphone input adapter schema
Follows the video of the hardware to be replaced.