OpenSky is M/A-COM's implementation of AMBE digital modulation over a TDMA channel format.
AMBE is another vocoder developed by DVSI Inc. Operation is very similar to Nextel TDMA digital voice systems.
OpenSky systems do not use a control channel.
Like ProVoice Open Sky cannot be monitored by any scanner, past or future.
OpenSky technology is owned by M/A-COM, Inc. a unit of Harris.
Here is the MA Com link for this product. Signal Harbor has a list of pending and implemented OpenSky systems.
Opensky is based on CDPD, the data format used by cellular modems on the now obsolete AMPS network. The signal format has a raw bit rate of 19,200 bps in a 25 kHz wide channel. Channel access is 4 slot TDMA. Slots may carry voice or data.
Harris has since introduced Opensky 2. This version supports 2 slot TDMA at a raw bit rate of 9600 bps in a 12.5 kHz channel. Harris sells Opensky equipment for 770 MHz, 851 MHz and 935 MHz.