[App_rpt-users] GM300 Cable pinout question

[Mike]

> 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!

So, let me see if I understand this.

1) The DSP chip inside the URI can decode the COS and know when it's
present.  Therefore, having a separate COS isn't required.

2) Since the diagram shows wiring for this case, can I assume that pin 11,
on the GM300 connector, is the correct RX to use, use for receive audio,
to the URI?

3) Is there anything else required (changes inside the radio) for this wor
work correctly?

4) Since the tone is decoded in the DSP, where do I specify what that tone
is, so the app_rpt software knows what tone to look for?

Mike