Hi Bob, VOX can be done to generate the RX COS signal, but, it isn't ideal at all--I've tried it. The list of reasons is long, below is a quick from my experience. The circuit in QST is designed to provide PTT from a computer-generated digital signal, and it should work well for that. Remember that when the radio should be transmitting, MODEM audio from the computer is continuous and roughly constant in peak level. Once the computer MODEM transmission is complete, the output level drops to virtually zero, with very little audio noise of any kind from the computer. This scenario is ideal for VOX--a single, predictable keying threshold set-point and a very short no-signal cut off delay. Audio from an FM receiver is different. It has many complications for trying to use VOX to generate COS. First, you'll need a more complex circuit that implements both an adjustable unkey delay (remember: human voice isn't constant) and input level set-point, which may be complicated to adjust due to various noises coming from the RX. So, at best, you'll likely end up with a customized solution that works only with a signal FM radio without tweaking all the settings again and again. Then, another issue is that you may loose the first syllable of audio at key-up, while the VOX activates. As I said, VOX can be done for casual use. But, with the effort involved to get VOX to work, just put that same effort into making a real COS circuit! 73, David KB4FXC On Sat, 28 May 2016 k5mvz@verizon.net wrote:
What about VOX control for PTT? See page 67 in June 2016 QST. But it still uses an ext. USB sound adapter.
de- Bob K5MVZ
-----Original Message----- From: Skyler F <electricity440@gmail.com> To: app_rpt-users <app_rpt-users@ohnosec.org> Sent: Fri, May 27, 2016 8:07 pm Subject: Re: [App_rpt-users] usbfobs
It seems easy to use GPIO as an output to toggle the Transmitter, but I can't figure out how I would use the GPIO on the pi as an input for COR if I am using speaker audio
On Fri, May 27, 2016 at 7:00 PM, Steve Wright <info@meshnetworks.co.nz> wrote:
yeah
On 28/05/16 12:47, Skyler F wrote:
even better GPIO on the pi
On Fri, May 27, 2016 at 6:46 PM, Steve Wright <info@meshnetworks.co.nz> wrote:
I think we're on the wrong track with our fixation on cmedia hackable chipsets. It's too hard.
Why can't we use one of the other DSP modules and some serial USB _TX signalling?
On 28/05/16 04:00, Sam Skolfield <kj6qfs@gmail.com> wrote:
Please share any findings with the group, many of us are looking for them too...
On Thu, May 26, 2016 at 9:17 PM, Steve Wright <info@meshnetworks.co.nz> wrote:
Does anyone have a reliable source of modifiable USB audio devices?
It's really really difficult to find hackable ones without buying one here and there...
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Skyler Fennell amsatnet.info
KDÃWHB
electricity440@gmail.com