[App_rpt-users] tone sent in usbradio setting

[Pierre Martel]

I know uswd it to adjust the deviation of my dmr repeater that run on a
mmdvm and raspberry py. The thing with the 1000 hz you need to make lots of
calculation to achieve the desired settings. But with a 1247 hz signal the
bessel null happen at exactly 3 khz deviation. And this is what we are
looking for with the radio txvoice command. Of course we could work our way
with setting a 1000 hz xmitter at the sessel null modulation level and use
it to feed the receiver of the repeater and then do the same for the
xmitter and adjust the same bessel null. The input would be balanced to the
output. But would it be balanced to the rest of the network.. not so sure.

Le 22 juin 2017 2:19 AM, "David McGough" <kb4fxc at inttek.net> a écrit :

>
> Hi Pierre,
>
> The Bessel-null method for setting deviation certainly works and can be
> accurately performed with a $15 rtl-sdr style receiver.
>
> Note that the tone frequency generated from app_rpt is 1000 hertz. And,
> this frequency will work fine for testing, as explained in this video:
>
> https://www.youtube.com/watch?v=lWcFqsh7ZvQ
>
>
> 73, David KB4FXC
>
>
> On Wed, 21 Jun 2017, Pierre Martel wrote:
>
> > Hi I am trying to find what is the frequency of the tone sent when we use
> > the command radio tune txvoice??
> >
> > I am asking cause if it would be 1247 hz we could use the bessel null
> > methode to adjust our tx to 3hz with just a simple rtl-sdr and sdr#
> >
> > the theory behind this is a bit complcated but at a certain frequency and
> > level the carrier is completly or almost completly off.
> >
> > this can easily be seen on a spectrum analyzer. but our sdr# are like
> > spectrum analyzer.
> >
> > so if we would want a 3khz deviation we need to send a 1247 hz signal and
> > adjust the levels till the main carrier disapear on the spectrum
> analyzer.
> >
> > the maths are this 3000/2.405=1247
> >
> > you can see the theory at use here:
> >
> > https://www.youtube.com/watch?v=8IBOYoIV5m8
> >
> > So if there is a way to decide the tone we want we could use that methode
> > to adjust or repeater deviation ( for the voice part at least)
> >
> > now if we wanted to adjust the deviation for the ctcss, this is another
> > story. but could it be calculated by the voice level setting if sent on
> the
> > same output?
> >
> > thanks for listening to my crazy idea ;-)
> >
> > By the way you can set a radio with a sound card attached to it a known
> > level and use that as the signal to adjust the rxvoice level also. since
> we
> > can set that with simple audio generating software available free online
> >
>
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