[App_rpt-users] DMK URI questions

Sat Nov 2 14:41:20 UTC 2013

OK Perhaps I am not using the right Allstar terminology here.  My understanding is that simple USB works similar to IRLP in that you use pre/dempahsized audio and COS and there is no further processing. CTSS tones, squelch, etc. are not decoded by the SW but rather by the incoming DC level of COS.

On the other hand in what I call DSP the CTSS, etc. are decoded by the software. As a for instance the GM300 example on the DMK site uses no COS just audio in, out, and PTT. When using this mode you use flat audio from the RX or audio that has not been demphasized. 

DSP is digital signal processing.  That is what the SW does to look at the incoming signal to decode things like CTSS, DTMF, squelch noise etc.  I am assuming that simple USB just uses the COS signal to detect carrier. My question was why would one prefer one method over the other or does one work better than the other. 
73 Doug
WA3DSP
http://www.crompton.com/hamradio

From: kj6ko at innercite.com
To: doug at crompton.com
Subject: Re: [App_rpt-users] DMK URI questions
Date: Sat, 2 Nov 2013 00:13:15 -0700

Doesn't matter.  It's a preference 
thing.  By the time audio gets to the internet, it is all digitized and 
de-emphasized.  What comes out the other end depends on what you 
want.  If you are going to feed a modulator directly, you need 
pre-emphasized audio, and I don't think the URI will do that.  It will 
de-emphasize DISC audio on RX.  You should just use MIC audio into the 
radio and de-emphasized audio into the URI to keep it simple.  I would 
ALWAYS use "CTCSS Valid" signal out of the radio (if avail) and feed the 
signal to the COS port of the URI.

COS and CTCSS are meant to be used together, like 
in a repeater, but it doesn't have to be

MIC DC and MIC AC??  you will have to read the 
radio manual on that one.

PS:  DSP does NOT mean FLAT Audio.  It 
means "Digital Signal Processing" and really has nothing to do with audio 
shape.

I guess I'm not sure what you mean by "DSP vs 
Simple USB"??  Is there a device called a "DSP?"  

I'm guessing you should keep it simple and use the 
"Simple USB" because that is what it is...simple!  Not much involved, Audio 
in, audio out, PTT Out and COR/CTCSS in.(Either or).  For a CTCSS detect, 
you need to find something that will give a GND or +5VDC when an active PL Tone 
is received.  I think the DMK device can do this for you if you don't 
have one on your radio, in which case you will HAVE to use discriminator audio 
for RX.  The DMK will de-emphasize it before it goes out over the 
network.  

  ----- Original Message ----- 
  From: 
  Doug Crompton 

  To: app_rpt-users at ohnosec.org 
  Sent: Friday, November 01, 2013 10:53 
  PM
  Subject: [App_rpt-users] DMK URI 
  questions

  About a week ago I asked about DMK URI 
  connections to an Alinco radio and I got several responses. I do have a few 
  more questions regarding that. 

The Alinco has both flat and 
  pre/de-emphasized audio available on its data connector as 1200 baud and 9600 
  baud connections.

I assume I would use the 1200 baud connections along 
  with COS and PTT for a simple USB interface and the 9600 baud connections 
  along with just the PTT for a DSP interface?

Do I use the  (Alinco 
  9600 baud) audio to the TX also? Does the DSP pre-emphasize audio or is the 
  processing just on the receive side?

Why would I want to use one over 
  the other (DSP vs simple USB)? Which is preferred and/or works better? I am 
  thinking there might be some differing opinions here!

The DMK URI has 
  both mic_DC and mic_AC inputs. Does this refer to frequency response or just 
  that one has DC blocking?

If you are using flat response (DSP) would 
  the audio in (from the receiver) connections at the URI end matter?

The 
  DMK URI has both COS and CTSS inputs. Why would you use one over the other? 
  When using DSP I assume neither is needed?

All 
  of the questions above assume I am using the Acid release on a faster 
  processor.

73 
  Doug
WA3DSP
http://www.crompton.com/hamradio

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