[App_rpt-users] usb radio config file

[David Powell-Williams]

This probably explains why I never experienced this. I never use the mic
input with a URI as I like to send the pre-emphasized and limited audio
directly to the modulator. This works quite well as long as you have a a
transmitter using direct FM and not phase modulation.

Steve
WA6ZFT
********************************************************************

I find the term 'rxdemod=flat' a little confusing, since discriminator audio
will contain pre-emphasized audio, generated by a user's transmitter.

I assume that apt_rpt converts receive audio to 'flat' by de-emphasizing
discriminator audio but not 'speaker' audio, (as selected) prior to
presenting it to other nodes or to the transmitter software routines? 

I'm also guessing that the apt_rpt internal flat audio, generated as above
or from other nodes/Iaxrpt, feeds the radio transmit software module, where
it is treated as per the 'txprelim' switch before going to the analog
interface.

I hope I'm not the only one that wondered about the precise functioning of
the usbradio.conf audio selections and how they operate. If I am, it's worth
a beer.

Snippet from usbradio.conf.sample:
rxdemod=flat ; Rx Audio Source Type from Radio
                 ; Options = no, flat, speaker
                 ; no - RX audio input not used
                 ; flat - source is un-filtered discriminator signal
                 ; speaker - source is filtered, de-emphasized audio

txprelim=yes ; Tx Audio PreEmphasis and Limiting in software
                 ; no - Audio is not pre-emphasized and limited.
                 ; for application to radio microphone input
                 ; yes - Audio is pre-emphasized, limited and filtered
                 ; for direct connection to an FM modulator

I second Ken's motion to clarify the wording a little, next time you're
revising the file.

73,

Dave
VE7MQ.