<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">Brian,<br>
<br>
Signal Strength is determined by the noise level of the inputted
audio from the receiver. Normally, with audio from a good
discriminator source, calibrated by the radio tune rxnoise
command, you'll have a signal strength of around 500 to 600 with
NO signal. This is shown by inputting the command "radio tune
rxsquelch". This number goes up as the noise level is reduced
(from an increasing signal level making the FM receiver quiet). <br>
<br>
A level of 999 with the adapter unplugged from the receiver is the
expected result. The adapter/application doesn't know if the
receiver has reached full quieting or if the audio has simply
disappeared from the adapter. The result is the same no matter
which happened. <br>
<br>
In the case, no signal input results in an audio signal that's
full of broadband noise. It's a loud white noise. When the
receiver quiets, the amount of white noise is reduced, to a point
of "full quieting" where the receiver is not outputting much or
any noise. This is why a strong signal into the receiver shows as
999 and no signal results in something between 0 and 500 or so. <br>
<br>
Again, this all points to muted audio from the receiver, and that
by definition is NOT discriminator audio. Real discriminator
audio is not muted, or filtered in any way. Please have a look at
the discriminator audio from your receiver and make sure noise is
there when the receiver is not hearing a valid signal.<br>
<br>
Kevin<br>
<br>
<br>
<br>
<br>
On 12/23/2018 9:58 PM, Brian G wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAHhhW2_AO5rqrYEr5vn0WhGQ-w3C8UAt3H+6BPrhKEHY8K5CEA@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">
<div dir="ltr">Hi Kevin, thanks very much... I understand 999 is
supposed to represent a strong fully quiet signal. That's the
issue, there isn't one...but app_rpt thinks there's a signal
present and is sending it 100% of the time, unless I use CTCSS
decode (or plain vox), which I don't want to do for this node.
<div><br>
</div>
<div>I'm using the discriminator output from a Motorola Radius
M120, but the same issue occurs on other rigs, and the
"signal level" is still at 999 regardless of if there's a
radio connected to the dongle or not :( If there's no input,
signal level should be at (or close to) zero, shouldn't it?</div>
<div><br>
</div>
<br>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr">On Sun, Dec 23, 2018 at 9:29 PM Kevin Custer
<<a href="mailto:kuggie@kuggie.com"
moz-do-not-send="true">kuggie@kuggie.com</a>> wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF">
<div class="gmail-m_6715075134168745870moz-cite-prefix">Brian,<br>
<br>
If the application reports 999, my guess is you aren't
inputting raw discriminator audio into the interface.
If the audio you are inputting into your radio interface
has been Low Pass Filtered or is squelch gated, you
cannot use DSP for noise squelch detection. The
application will tell you if there is sufficient squelch
noise to utilize DSP noise squelch detection after you
do the "radio tune rxnoise" command. If it fails, the
audio type, amount, or quality isn't sufficient for DSP
noise detection. <br>
<br>
When fed with good discriminator audio, the noise
squelch detection in app_rpt is nearly as good as a
Motorola M6709 (analog) squelch chip, commonly thought
to be the high water mark in noise squelch detection.
999 is the total absence of noise, and is the result one
would expect with a full quieting signal, or an
inappropriately muted RX audio line. <br>
<br>
Kevin W3KKC <br>
<br>
<br>
<br>
On 12/23/2018 7:28 PM, Brian G wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr"><span>Hi all, Merry Christmas</span><br>
<br>
<span>My local club is working on setting up a few ASL
nodes, and I've been busy modifying some CM119 based
USB sound cards to control the radios. I'm using
this card/dongle: </span><a
href="https://www.amazon.ca/Syba-SD-CM-UAUD-Adapter-C-Media-Chipset/dp/B001MSS6CS"
rel="nofollow" target="_blank"
moz-do-not-send="true">https://www.amazon.ca/Syba-SD-CM-UAUD-Adapter-C-Media-Chipset/dp/B001MSS6CS<br
style="box-sizing:border-box">
</a><br>
<span>I've done several so far and have a few nodes
working great with CTCSS carrier detect. One issue
I'm consistently running into, is when setting the
"RX Squelch Level" in the radio-tune-menu, it
detects the current RX signal strength as 999. This
results in the inability to use anything other than
CTCSS for carrier detect. I can make plain old VOX
work too, but it results in considerable (2 sec+)
hang time.</span><br>
<br>
<span>Using DSP carrier detect won't work because it's
impossible to set the squelch high enough (max value
999). It always thinks there's a signal present when
there isn't. This happens regardless of whether
there's a radio connected to the dongle or not. As a
matter of fact it happens even when plugging in an
unmodified dongle right out of the package. I need
it to work with no CTCSS. VOX would be fine if it
wasn't for the hang time, but would rather use the
DSP option in usbradio.conf. </span><br>
<br>
<span>I assume it's just the nature of the beast, and
if I want it done properly I need an adapter and
radio capable of COS. But maybe someone knows if
there's something that can be done or not? Anyone
have any insight on how to either eliminate the VOX
hang time, or eliminate that "invisible" signal? </span><span>I
might be overlooking something. Thanks for reading!</span>
<div>
<div>
<div dir="ltr"
class="gmail-m_6715075134168745870gmail_signature">--<br>
Brian - VA3DXV<br>
</div>
</div>
</div>
</div>
</blockquote>
<br>
</div>
</blockquote>
</div>
</div>
</blockquote>
<br>
</body>
</html>