The above circuit is recommended for use in SSTV applications with use of the sound card with a computer. This is the JVComm style of interface. This circuit may also be used for RTTY and PSK31 applications. Many users modify the above circuit to include 1:1 isolation transformers within the Speaker out and Line-in or microphone in lines. These isolation transformers are used to preclude ground loops within a system from introducing hum and interference on the transmitted signals.
The following circuit is used in applications of WinRtty for receiving RTTY signals using the sound card. This circuit is also applicable to SSTV and PSK31 modes and works well in all three applications. This circuit may be implemented into the JVComm interface shown above as discussed in the JVComm interface text. Note that the sound board and receiver are transposed in the two circuits.
The following circuit is used in applications of WinRtty for transmitting RTTY signals using the sound card. Notice this circuit does not have a PTT component and relies on VOX for transmit control. This circuit is also applicable to SSTV and PSK31 modes and works well in all three applications. This circuit may be implemented into the JVComm interface shown above as discussed in the JVComm interface text. Note that the sound board and transmitter are transposed in the two circuits.
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