Ron Wright wrote:
Nate,
I've been designing 8870s and 8880s in things for over 15 years. Good chip
and it has lasted.
Pin 3 is simply the output of the internal op-amp and using a feed back
resistor to 2 and driving with another one can set the AC gain over a wide
range. The gain is
:37:15 CDT
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] False DTMF Muting On CAT-1000 Controller
Ron Wright wrote:
Nate,
I've been designing 8870s and 8880s in things for over 15 years. Good chip
and it has lasted.
Pin 3 is simply the output
:14 AM
Subject: Re: Re: [Repeater-Builder] False DTMF Muting On CAT-1000
Controller
Nate,
Chill out...take a pill, hi.
The 3 V p-p is for the 8870/8880 internal op-amp level. Is it in stone?
No, but found to be good level. This is not an input level to the circuit
or IC
-Builder] False DTMF Muting On CAT-1000 Controller
I once had the same problem with users' voices falsing the DTMF decoder and
causing the cover tone to be activated during voice conversations, just like
the original poster's problem. I contacted the controller manufacturer,
Peter at NHRC I think. He
At 3/28/2008 12:07, you wrote:
If we were muting DTMF, we'd have had no idea why he was complaining.
If DTMF mute is on tones are being muted, they must not be too bad.
One system I maintain has ADMs set to a bit longer than the DTMF detect
time, the DTMF mute delay is set to the same time,
@yahoogroups.com
Subject: Re: [Repeater-Builder] False DTMF Muting On CAT-1000 Controller
Ron Wright wrote:
The voltage levels on most DTMF decoders are set by the IC designer. On
decoders like the 8880 and 8870 pin 3 is what the internal op-amp of the IC
is producing
Same problem with the CAT200 controllers as well. The
recommended procedure for adjusting the DTMF input
level seems to call for a specific amount of audio on
a test point. If the radio you use to adjust the CAT
is on the low side (deviation), then it will be a bit
over-sensitive and will mute
From: Jim Brown [EMAIL PROTECTED]
Date: 2008/03/27 Thu PM 11:30:46 CDT
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] False DTMF Muting On CAT-1000 Controller
My experience is with the CAT-300 controllers, but I have found that if the
level to the DTMF
Tony,
The reason why it falses on one of 3 controllers is probably not the
controller, but what is feeding the controller and maybe slight differences in
the adjustment.
With varying audio characteristics from one repeater to another is probably the
difference.
73, ron, n9ee/r
From: Tony
Ron Wright wrote:
This problem has bothered IC type dtmf decoders for years. One would not see
it as much if controllers did not mute rx-to-tx audio for security reasons.
Some controllers allow this muting to be turned on/off. Other needs for
passing the dtmf, such as for echolink, can
to allow it to achieve what
is needed.
73, ron, n9ee/r
From: Nate Duehr [EMAIL PROTECTED]
Date: 2008/03/28 Fri PM 02:07:43 CDT
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] False DTMF Muting On CAT-1000 Controller
Ron Wright wrote:
This problem has
Ron Wright wrote:
The voltage levels on most DTMF decoders are set by the IC designer. On
decoders like the 8880 and 8870 pin 3 is what the internal op-amp of the IC
is producing and this parameter is determined by the IC designer. As with
any IC one needs to supply the proper levels to
Tony,
Yes, but it requires throat surgery. Seriously, though, one repeater user
in my area has a tendency to make a high-pitched eee sound when others
might say um, and this will sometimes cause the controller to mute his
voice just as it would a DTMF tone. Slightly reducing the DTMF decoder
My experience is with the CAT-300 controllers, but I have found that if the
level to the DTMF decoder is set too high, it is a lot more prone to falsing
and covering a transmission with the cover tone. I have found that female
voices gave the most problem. Reducing the level to the DTMF
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