Re: Masters Communications VOX
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My understanding is NOT backward at all. Remember the original post is about VOX, not HARDWARE PTT control.? With VOX, the actual radio PTT line CANNOT be asserted until there is audio for the VOX to act on.? The computer application has no way of knowing when the radio's PTT is actually activated, only when it is requesting it to be activated.
So, what you are stating differs from my understanding ONLY in that you state that during TXDELAY there are actually tones being sent (to sync modems).? That would mean that the VOX control would assert the PTT as soon as these audio tones start and allow the TX of actual packet tones to start later and be decoded properly.?
In the past, I have had issues with using VOX on packet, and it must have been due to my TXDELAY being too short for the PTT and sync to be completed properly in the TXDELAY time.
So for John Kristian's post, the reply is that the VOX should work fine, but you may have to increase TXDELAY to allow the VOX circuit to activate with the sync tones and enough time to sync.
Thank you for clarifying!
On Monday, March 15, 2021, 10:05:36 AM EDT, Scott Currie <scott.d.currie@...> wrote:
Robert, Your understanding of TXD is backwards. TXD starts when PTT is set. During the TXD time flag characters are sent which gets the receive modem in sync. When TXD ends the data frame is sent. We do not start PTT before packet tones are sent, that's not how it works. This is what the timing looks like:  When we start a frame, PTT is set and TXD starts, and flag characters are sent. With VOX, the flag characters will trip the VOX and activate PTT. When TXD ends the data frame is sent. So, if the data frame is being cut off in VOX mode, you just need to increase TXD. CAT7200 will work as well to activate PTT on C-Media based sound card interfaces that use GPIO 3 for PTT, I requested that addition from John, G8BPQ. However, it would be better if Direwolf had this functionality added in the Windows version. Other applications have added C-Media GPIO support under Windows (Soundmodem, Vara). -Scott, NS7C
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