PTT
PTT
Interface via Serial Port
CTS, DSR
This program supports the use of serial ports for switching between receive and transmit, in other words PTT interfacing. The text below is from Mike, N1JEZ.
SDR Console accepts an external input via serial port for PTT (push-to-talk). It uses positive and negative logic level voltages on either the RS232 CTS or DSR pins
to toggle between TX and RX. These voltage must be sustained, not simply momentarily supplied.
There are various ways of interfacing which are determined by the serial interface used. Not all serial ports are created equal and provide the necessary voltages. You will need +V and -V serial logic levels.
Below are two examples of interfacing I used. The first is a 'real' DB-9 serial port on a laptop. The switch used for testing was a SPDT toggle switch. This serial port had the necessary voltages.
This uses the CTS pin for input:
- N/C - pin 3 (TX -V)
- Common - pin 8 (CTS)
- N/O - pin 7 (RTS +V)
To use DSR, substitute pin 6 for Common.
For use with a DB-25:
- N/C - pin 2 (TX -V)
- Common - pin 5 (CTS)
- N/O - pin 4 (RTS +V)
To use DSR, substitute pin 6 for Common.
I also tested using a Belkin USB to Serial adapter. This was a "PDA Interface" unit. As such, it did not supply all the voltages needed. In this case, an extermal supply was provided. I used a +5 volt bench supply for +V.
Most footwitches which would most likely be used for PTT are SPST N/O, so they will need to have a relay interfaced to maintain voltages to the CTS or DSR input pins. There are obviously other ways to interface as well. I leave that up to your imagination.
When checking your serial port for proper voltages, be aware that you need to specify the right Comport and input pin in SDR Console and have the software running as it initialises the port on startup. If you make a change to the input pin, make sure to restart. You set up the PTT interface under Transmit | Options | PTT (Serial Port).
Serial Port
You can also user the serial port CAT interface, more information is here.
