On 2/23/2025 12:58 PM, George Privett
via groups.io wrote:
Thanks again.
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Is C media a distinct piece of hardware or a protocol. E.g.
is a the RA sound card used in VARA FM PTT and discussed in the
pdf document C media compliant?
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George
_._,_._,_
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The C-Media CM-108 and CM-119 sound chips, ? used in many USB
sound "dongles" sound card, and used in several ham digimode
interfaces (DigiRig, Masters DRA, etc), ?? have a single-bit I/O
pin in addition to the analog audio inputs and outputs.??
Some sound card applications including VARA, DireWolf, the UZ7HO
Soundmodem and FLdigi can set this pin high or low for PTT keying
purposes. -- as an alternative to traditional serial port RTS/DTR
PTT keying, or the complexities of CAT control, or VOX.?? This
option variously shows up in application dialogs as "RA-PTT" or
"C-Media PTT".
Because this is part of the sound system driver, (not a logical
com port), there is no problem with several apps contending for
control of this pin at the same time.
Data sheet on the CM-108 Sound Chip Attached
Stephen H. Smith??? wa8lmf (at) aol.com
Skype:??????? WA8LMF
EchoLink:? Node #? 14400? [Think bottom of the 2-meter band]
Home Page:?????????
30 Meter?? APRS-over VARA? Frequency?? Details Here:
????
- APRS over VARA? --
??
"Studio B" Ham Shack on Wheels
??
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