[App_rpt-users] GM300 Cable pinout question

[pete M]

you did a way better job them me at explaining this ;-)))



-----Message d'origine----- 
From: Ramesh Dhami (VA3UV)
Sent: Wednesday, April 10, 2013 5:16 PM
To: app_rpt-users at ohnosec.org
Subject: Re: [App_rpt-users] GM300 Cable pinout question

On 10/04/2013 5:05 PM, Mike wrote:
> I have decided to build an allstar node.  Got the radio, got the account,
> got the URI, got the Linux box, got the software, now I have to build the
> cable and put it all together.
>
> But in looking at the cable description on the DMKeng site, I don't see
> any COS signal used.
>
> http://www.dmkeng.com/images/9080-GM300.pdf
>
> Isn't the COS from the radio needed to suppress transmitting dead autio
> over the network?  I thought a COS signal was required.  It's talked about
> as necessary  but the signal isn't shown in the gm300 cable description.
>
> Anyone care to explain why this is not needed or when it is needed?  And
> if it is needed, which pin on the 25 connector would it go to?
>

<-- Hi Mike; Welcome to Allstar! - the diagram that you reference above
shows the use of "flat audio" from the GM300.  I often get questions
about the RX audio and my response is usually, "raw discriminator audio,
with a flat frequency response from a few Hz up to around 5kHz"

The Allstar (app_rpt) software can be setup to use DSP - i.e., it can
decode the raw audio to detect PL.... this method is much faster than
using a COS line, which can sometimes be very sluggish.

So for this reason, COS is not mandatory - assuming that the radio of
choice can provide the raw discim audio with a flat frequency response;
and the GM300 can.

Hope this helps.... I am on a train and approaching my stop.

Cheers!

Ramesh.
Admin for many things!

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