[App_rpt-users] Audio too much highs and not balanced when connecting to RTCM

Tim Sawyer tisawyer at gmail.com
Sun Apr 2 20:07:12 EDT 2017

Here's a note I wrote on this subject a while back:

The RTCM is totally flexible regarding emphasis. Although the way it is set
is completely obscure. It tries to automatically do the right thing for
you, which is great most of the time. But when it’s not it's hard to know
what is going on.

On the TX side the RTCM expects the repeater to accept mic audio. In other
words, the repeater is providing the pre-empahais, not the RTCM. This can
overridden by setting CTCSS on in voter.conf in which case the RTCM will
provide pre-emphasis. If you don’t want TX CTCSS but do need pre-emphasis
set the level to 1 which is low enough that it won’t be there.

On the RX side the COR Type setting determine the emphasis. 0=Normal means
the RTCM squelch circuit is in use and expects discriminator audio,
therefore will provide de-emphasis. 1=IGNORE COR uses the CTCSS input for
COR (+CTSCC) and expects line audio, therefore will not provide

On Sun, Apr 2, 2017 at 1:19 PM, Kevin Custer <kuggie at kuggie.com> wrote:

> The notes in this document may help you:
> http://www.masterscommunications.com/products/radio-adapter/txt/tkr.txt
> Kevin
> On 4/2/2017 2:26 PM, Bradlington wrote:
>> Hi
>> I am a custodian for our local clubs repeater and have just installed
>> the Allstar unit .
>> Can you please confirm if emphasis settings can be done on the RTCM
>> module for both RX and TX audio chains from and to the Repeater.
>> TKR-750 External accessory as duplex unit .
>> Audio appears to sharp and not enough lows - I am suspecting it is being
>> double emphasised somewhere in the RTCM.
>> There is one setting on the RTCM unit known as "nodeemp"--anyone got more
>> technical details on how these units are designed and what type of audio
>> the unit is expecting
>> ?
>>  Regards
>> Bradley Glen
>> ZS5BG
>> South Africa
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