Re: DTMF tones not recognized

David Cameron - IRLP

Based on a schematic found here:

On page 2, section C1 you will see the 47K variable VR1 that takes a portion of the audio to ground. The more you turn that VR1 to ground, the less audio will appear on the 6-pin connector CON6. SO the level RX-A on the schematic will raise or lower with changes to VR1. This looks identical to the Alinco DR-135T, and I know I have been down this road before.

It appears that the variable resistor VR1 controls the level of the audio to CON6, which is where the audio is being pulled from that you are using in your node. That being said, no idea what revision of board you have, if the 220 and 440 models are different in the audio section, etc. Your system may vary.

Based on the levels of gain you need to adjust the audio (in alsamixer), I am going to wager a guess that the level FROM the radio is very low, and the decoder chip is having an issue with not enough audio.

David Cameron

On 2020-05-14 11:42 a.m., Albert Febraro wrote:
 The auto gain has an "OO" in it. Second Mic setting or Capture is set to 44 at the moment. You make an interesting point about the TYT level at the connector. I guess I can put a scope on it at some point and try to measure it if that is possible.
Again, thanks for all the troubleshooting help.
*From:* <> on behalf of David Cameron - IRLP <>
*Sent:* Thursday, May 14, 2020 11:32 AM
*To:* <>
*Subject:* Re: [IRLP] DTMF tones not recognized
The software mixer controls do not affect the level seen by the DTMF
decoder. It sees the raw audio from the receiver.
I think the audio point on the TYT connector is de-emphasized, but I
wonder how much level is there.
If you are using a Syba sound card, you are likely using a Pi setup. On
the program alsamixer, press TAB twice and:
Does the Auto Gain Control have an "MM" or an "OO" in it?
What is the second Mic setting with CAPTURE set to?
That will give me an idea if the level is too low or too high out of the
On 2020-05-14 11:08 a.m., Albert Febraro wrote:
    I am using the TYT-9000D UHF radio for my node.
The audio source comes directly from the radio main board (RX Audio) to the mic input to a SYBA USB sound adaptor to the Pi.
The alsamixer MIC input  is set to 33.
When I run the audio test , it passes the test using voice through my Alinco Ht. It fails if I send a DTMF tone for 8 seconds (reports 0 clipping, ) audio).
*From:* <> on behalf of David Cameron - IRLP <>
*Sent:* Thursday, May 14, 2020 10:30 AM
*To:* <>
*Subject:* Re: [IRLP] DTMF tones not recognized
This is not a common problem, but it creeps up from time to time.
What radio are you using for the node radio? What audio source are you
using in the radio? If the source is not a squelched, de-emphasized
source, then the DTMF decoder is not able to decode due to the variance
in levels in the tones.
What audio output are you using from the node radio? If it is a
discriminator source, that is the problem.
Also, if the level of the audio from the node radio to the node is
either very high or very low, it can affect the ability for the decoder
to work. What is the input audio settings like on the alsamixer screen?
David Cameron
On 2020-05-14 9:13 a.m., Albert Febraro wrote:
This may be a common issue but being new to IRLP I'm still fine tuning my node and learning. The issue is that when I send DTMF tones from different radios the node does not recognize the tones. I have one radio (Kenwood TH-F6) that when I transmit tones the node doesn't decode them at all, however another radio (Alinco DJ-MD5) works perfectly. What is interesting is that when I'm using my mobile radio (ICOM ID-5100) I can bring up the echo node 9993, but cannot disconnect. I send a "73" but I only hear the 7 when the node returns the echoed audio. My audio levels are adjusted correctly as far as I can tell. I then have to disconnect with a different radio. When I use the Alinco HT, I get good reports audio and received audio is fine.
node 3913

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