Theory of Operation:

Transmit Audio: From the Catalyst Remote Client, your audio is digitized, compressed (usually) and packetized and sent over an IP Network to a Catalyst Gateway that is also connected to the network. In Phase I, the Catalyst Gateway recodes the audio into PCM, maintaining its digital format, and send this audio to the Daniels Electronics MT-4 with a Universal Interface Card. The Daniels Electronics Universal Interface Card connects the MT-4 to the network through an Ethernet port on the UIC. The Daniels MT-4 recodes the audio from PCM to the P25 IMBE digital codec for RF transmission compatible with P25 portable radios. The P25 portable radio decodes the IMBE digital voice to audio.

In later development phases, the audio at the Catalyst Remote Client will digitize, compress, and packetize the audio in the IMBE codec format. This will allow the system to remain in P25 digital audio mode through both the wireline (IP Network) and wireless (RF) networks.

Note also that the Catalyst Gateway and Daniels MT-4 do not have to be co-located. Each needs to be connected to the network, but from there, communicate via IP.

Transmit Control: From the Catalyst Remote Client, control messages (PTT, change channel, and new P25 enabling capabilities) are sent to the Catalyst Gateway over the IP Network. The Catalyst Gateway reformats this information into a data stream that is designed to be compliant with the emerging TIA P25 standard for the Fixed Station Interface.

Receive Audio: Audio from the P25 portable radio is digitized using the P25 IMBE codec and sent over the air to the Daniels MT-4. The Daniels MT-4 recodes the digital audio into PCM and sends it to the Catalyst Gateway. The Gateway sends this audio (which may have been compressed) to the Catalyst Remote Clients, which convert it back to audio for the dispatcher.

Receive Control: As with transmit control, P25 provides a wealth of new information that can be presented to the dispatcher, including the identification of the channel, individual user, emergency indication, and other information that can significantly improve radio operations.  The initial release of IP|25D™ begins the use of this information.  Contact Catalyst for a list of currently available features.