Product manual

Communication Interface
15
Conventional Radio Interface
Besides the 2-wire or 4-wire transmit and receive connection, the Model 26 provides an
open drain Push-to-Talk (PTT) output signal for transmitter keying and a Carrier
Operated Relay (COR) input for detecting channel availability.
Figure 4 shows a typical
interface. If the radio does not provide a COR output signal the Model 26 has an internal,
adjustable threshold VOX circuit for detecting channel activity. Along with these special
hardware circuits, there are a number of user configurable software parameters for
configuring and optimizing this interface.
Figure 4: Typical Model 26 Interface to a Conventional Radio
Conventional
Radio
J14 J13
Model 26
9 - AUD+ 10 - AUD-
2-W RX/T
X
3 - AUD+ 4 - AUD- 5 - RX COR+
4-W R
X
TX
RX
NOTE: If a COR output is not available from the radio,
then the Model 26 can use its internal VOX circuit.
COR
1 - PTT 2 - GND
PTT
GND
Trunked Radio Interface
Besides the 2-wire or 4-wire transmit and receive connection, the Model 26 provides an
open drain Channel Request signal (the PTT connection) and a Channel Grant input (the
COR connection). Along with these special hardware circuits, there are a number of user
configurable software parameters for optimizing this interface. The connections would be
similar to the ones shown in
Figure 4, except for the signals called out on the radio end.