Topics

Weird DTMF Decode Behaviour


Brian
 

Our node, stn 2920, is experiencing a DTMF decode problem.  Certain DTMF codes do not decode at all, some decode properly, and others decode with the wrong digit. 

For the following cases, all codes were sent from two different radios to ensure that the radios were not the issue.  Here is a sample of the output from readInput when I was sending various DTMF codes.  Do not assume that a DTMF decode number in the example was the result of me pressing the commensurate keypad number (see case 4).  This sample is to show that readInput was seeing data and flags flowing from the IRLP board through the parallel port:
 
COS ACTIVE <-- I pushed the PTT on the HT
DTMF 3
DTMF 3
DTMF 1
DTMF 2
COS INACTIVE  <-- I released the PTT on the HT 

Case 1:
- Sent DTMF Code "1" from an HT, readInput shows no decode

Case 2:
- Sent DTMF Code "2", readInput shows "2"

Case 3:
- Sent DTMF Code "1" again directly following case 2 while PTT was still pressed, readInput shows "1"
- Sent DTMF Code "1" one more time, readInput shows nothing

Case 4:
- Running through all DTMF digits in a row from 1-0 on the HT's keypad yielded while PTT was pressed:
  • "1" --> Nothing, unless it directly follows any decode except itself (see case 3)
  • "2" --> decodes "2"
  • "3" --> decodes "3"
  • "4" --> Nothing
  • "5" --> Nothing
  • "6" --> decodes "2"
  • "7" --> decodes "3"
  • "8" --> Nothing
  • "9" --> decodes "1"
  • "0" --> decodes "2"

I have re-seated all cables and verified that the DTMF LED on the IRLP board is lit when a DTMF code is received from the link radio (Motorola).  

Note:
  • IRLP Board is v3.00
  • OS is Debian 8.11
  • Computer is an x86 Thin Client, running the node s/w via a USB Stick
  • If there is an IRLP node number that can be constructed with 3's and 2's (and there is, e.g., Hawaii :-) ), the IRLP node works fine.  Of course, I can't disconnect from it because I cannot send a 73
  • All troubleshoot-irlp tests pass
  • This node is an Echo-IRLP node.  Echolink is working fine.
I have reached my limit of being able to debug and figure out what is going on.  Has anyone else seen this problem or have some other things I can try to help me know if this is a hardware or software problem? 

Aside: I am not sure where readInput inserts itself into the flow of data from the IRLP card to the DTMF Daemon.  But, I do believe that the DTMF daemon is still receiving the codes because" /home/irlp/log/messages" contains log statements from my tests that have long DTMF codes (and of course this is an error).  Anyway, I mention this only to ask anyone where readInput is in the data flow.

regards, 
Brian
VE3IBW


David Cameron - IRLP
 

How / where is the irlp board mounted? Sounds like the dtmf logic is not triggering reliability, and it could be a bad ground. 

The other suggestion would be that there is an issue with the parallel port. 

David Cameron 

-------- Original message --------
From: Brian <brian.waterworth@...>
Date: 1/2/20 8:12 AM (GMT-05:00)
To: IRLP@irlp.groups.io
Subject: [IRLP] Weird DTMF Decode Behaviour

Our node, stn 2920, is experiencing a DTMF decode problem.  Certain DTMF codes do not decode at all, some decode properly, and others decode with the wrong digit. 

For the following cases, all codes were sent from two different radios to ensure that the radios were not the issue.  Here is a sample of the output from readInput when I was sending various DTMF codes.  Do not assume that a DTMF decode number in the example was the result of me pressing the commensurate keypad number (see case 4).  This sample is to show that readInput was seeing data and flags flowing from the IRLP board through the parallel port:
 
COS ACTIVE <-- I pushed the PTT on the HT
DTMF 3
DTMF 3
DTMF 1
DTMF 2
COS INACTIVE  <-- I released the PTT on the HT 

Case 1:
- Sent DTMF Code "1" from an HT, readInput shows no decode

Case 2:
- Sent DTMF Code "2", readInput shows "2"

Case 3:
- Sent DTMF Code "1" again directly following case 2 while PTT was still pressed, readInput shows "1"
- Sent DTMF Code "1" one more time, readInput shows nothing

Case 4:
- Running through all DTMF digits in a row from 1-0 on the HT's keypad yielded while PTT was pressed:
  • "1" --> Nothing, unless it directly follows any decode except itself (see case 3)
  • "2" --> decodes "2"
  • "3" --> decodes "3"
  • "4" --> Nothing
  • "5" --> Nothing
  • "6" --> decodes "2"
  • "7" --> decodes "3"
  • "8" --> Nothing
  • "9" --> decodes "1"
  • "0" --> decodes "2"

I have re-seated all cables and verified that the DTMF LED on the IRLP board is lit when a DTMF code is received from the link radio (Motorola).  

Note:
  • IRLP Board is v3.00
  • OS is Debian 8.11
  • Computer is an x86 Thin Client, running the node s/w via a USB Stick
  • If there is an IRLP node number that can be constructed with 3's and 2's (and there is, e.g., Hawaii :-) ), the IRLP node works fine.  Of course, I can't disconnect from it because I cannot send a 73
  • All troubleshoot-irlp tests pass
  • This node is an Echo-IRLP node.  Echolink is working fine.
I have reached my limit of being able to debug and figure out what is going on.  Has anyone else seen this problem or have some other things I can try to help me know if this is a hardware or software problem? 

Aside: I am not sure where readInput inserts itself into the flow of data from the IRLP card to the DTMF Daemon.  But, I do believe that the DTMF daemon is still receiving the codes because" /home/irlp/log/messages" contains log statements from my tests that have long DTMF codes (and of course this is an error).  Anyway, I mention this only to ask anyone where readInput is in the data flow.

regards, 
Brian
VE3IBW


Brian
 

Happy New Year Dave !!  Thanks for the quick response.  I have attached a jpg of the node to show how the IRLP board is attached in the Thin Client computer to answer your question.

regards, 
Brian
VE3IBW


k9dc
 

Also it might be helpful to know what radio you are using on the node, and how you are picking up the audio from it. Do you know that the audio is de-emphasized?

-k9dc

On Jan 2, 2020, at 09:55, Brian <@VE3IBW> wrote:

Happy New Year Dave !! Thanks for the quick response. I have attached a jpg of the node to show how the IRLP board is attached in the Thin Client computer to answer your question.

regards,
Brian
VE3IBW


Brian
 

I have taken pics of the link radio’s front and back.  The RJ-45 cable from the front is used for audio in/out and ptt.  The wire on the back is the COS detect line.  The RJ-45 jack i/o provides constant audio levels not affected by the volume setting on the radio.   

I don’t know if the radio was programmed with de-emphasis.  However, this IRLP setup has been in use for many years and worked fine until recently.  The only thing about the setup is that we needed to refresh the irlp mode software as the previous USB stick went bad.  Also, the link radio and thin client computer have been moved to my QTH instead of at the repeater site.

regards
Brian
VE3IBW


Teton Amateur Radio Repeater Association (TARRA)
 

I don't know why you aren't using the full 16 pin connector on the back of the radio. Chances are the audio on the RJ45 is going to be flat since it is for the microphone and speaker (when used with a handset). You also don't mention having a ground. Do you have pins 3 & 4 tied together for the "on hook" that you need? You should also get rid of the RF adapter on the back of the radio. That can cause problems. De-emphasis is not a programming option on this radio, it is taken care of with an internal jumper, but then again that would be for Pin 11 on the 16 pin connector and not the RJ45. Looks like you have some clean up to do with your wiring.

Running the computer from a USB stick isn't the best thing to do either. Are you trying to run this as a simplex node now or as a user on the repeater? Certainly far better if you can run the node connected to the repeater controller at the repeater site. Not sure how you had it hooked up there. If you can move it back to the repeater site,  it would be much better.

Mick - W7CAT
Node 3464

----- Original Message -----
From: Brian
To: IRLP@irlp.groups.io
Sent: Thursday, January 02, 2020 12:07:24 PM
Subject: Re: [IRLP] Weird DTMF Decode Behaviour

> I have taken pics of the link radio’s front and back.  The RJ-45 cable from the front is used for audio in/out and ptt.  The wire on the back is the COS detect line.  The RJ-45 jack i/o provides constant audio levels not affected by the volume setting on the radio.
>
> I don’t know if the radio was programmed with de-emphasis.  However, this IRLP setup has been in use for many years and worked fine until recently.  The only thing about the setup is that we needed to refresh the irlp mode software as the previous USB stick went bad.  Also, the link radio and thin client computer have been moved to my QTH instead of at the repeater site.
>
> regards
> Brian
> VE3IBW
>
>
>
>
--


David Cameron - IRLP
 

What do you have for resistance between the radio output and the usb input? It could be simple overload or underload of the audio level.

Is the audio from the radio squelched and deemphasized? There are jumpers in the radio that set these. 

Also, the USB sound cards put a 5v bias on the mic line, and that can affect the audio. This is why it is important where you place the resistor. 

Dave Cameron 

-------- Original message --------
From: Brian <brian.waterworth@...>
Date: 1/2/20 2:07 PM (GMT-05:00)
To: IRLP@irlp.groups.io
Subject: Re: [IRLP] Weird DTMF Decode Behaviour

I have taken pics of the link radio’s front and back.  The RJ-45 cable from the front is used for audio in/out and ptt.  The wire on the back is the COS detect line.  The RJ-45 jack i/o provides constant audio levels not affected by the volume setting on the radio.   

I don’t know if the radio was programmed with de-emphasis.  However, this IRLP setup has been in use for many years and worked fine until recently.  The only thing about the setup is that we needed to refresh the irlp mode software as the previous USB stick went bad.  Also, the link radio and thin client computer have been moved to my QTH instead of at the repeater site.

regards
Brian
VE3IBW


John VK4JJW
 

On 3/01/2020 8:11 am, David Cameron - IRLP wrote:
What do you have for resistance between the radio output and the usb input? It could be simple overload or underload of the audio level.

I had almost the same prob recently after years of mostly reliable operation.
Turned out to be low audio out from the radio due to deteriorating components simply because the unit is so old .... 30+!!

HTH

JW
--

EchoIRLP
IRLP Node 6527
EchoLink Node 96527

DMR 5054314


http://www.vk4jjw.info


Brian
 

Thank you John for your reply and experience.  The IRLP node has been around with this setup for as long as I have been a member of my local HAM radio club (10+ years).  I am not sure how old the Motorola Radio is that I posted a picture in a previous post.  I will ask some of the club members who might know.  We might have to refresh all the node hardware.  We are certainly thinking about changing up the Thin Client computer at minimum.

cheers, 
Brian
VE3IBW


Brian
 

Hi Mick, 

Lots of questions...here are my responses:

  1. Choice of audio connector from the radio to the Thin Client computer?
    • Since I didn't build this setup, I cannot comment on decisions made in the past.  This setup has been working for many years with this radio and thin client computer.  Recently, DTMF decoding has become unreliable. 
    • The IRLP board's DTMF LED for each push of a DTMF code from an HT always lights.  That tells me that the IRLP board has registered the DTMF signal in the audio feed. Some component after the detection of a DTMF code fails to decode the DTMF tones properly.  This is what I am trying to zero in on at this time.  
  2. Ground?
    • I think that is something I can confirm.  Thanks for the info.  I haven't been successful in finding a diagram that shows the wiring for the D25 and D9 connectors to/from the IRLP board.  If you have a link, I would appreciate knowing where to look.
  3. RF Adaptor on the back of the Radio
    • Perhaps, but this would be low priority as this setup has been working for many years until recently.  I have removed and re-seated this adaptor.
  4. USB Disk Drive Stick vs Internal HDD
    • Yes, I agree with you.  In fact, one of our club members has his own IRLP node (exactly the same setup (radio and thin client computer) and he has been encouraging me to do the same thing.  However, low priority until I get the DTMF problem solved.
  5. Simplex node?
    • Yes, we use a simplex approach to the link.  This setup has not been directly connected to the repeater controller and never has been to my knowledge, even when it was at the repeater site.  All comms between the repeater and the IRLP node (computer and link radio) have been RF.
    • Our repeaters are moving sites of late and of course the need for an internet connection poses a challenge.  Our club is zeroing in on a repeater home that will have reasonable internet (cost-wise).  Until that time, the IRLP node must be located at my QTH (a club member) so we can have IRLP and Echolink functionality in our region.
regards
Brian
VE3IBW


Brian
 

Hi Dave, 

What do you have for resistance between the radio output and the usb input?
  • Not sure how to answer your question as there is no USB input used for the audio path.  
  • Since I didn't make the cable, I will have to ask the person who did to know if there is any inline resistance added.  If I can't get an answer, then I will have to open up the cable to be able to answer your question.
  • Your comment and that of another responder in this thread may have a point I can look at with regards to the audio level making its way directly to the IRLP board.
  • However, if the IRLP DTMF LED lights with each DTMF tone sent by an external radio to the node, does the lit LED indicate that the IRLP board has enough audio drive to be able to process the DTMF tones?
Is the audio from the radio squelched and deemphasized?
  • Yes, squelched.
  • Not sure about de-emphasis.  I will inquire.
  • However, as I mentioned above, the IRLP DTMF LED lights up for each DTMF code sent to the link radio and passed to the IRLP board.  How should I interpret the lit LED for each code sent?
FYI...Our setup, as per the pictures I sent, do not use a USB audio adaptor.  Line-in (mic) and line-out (speaker) on the back of the Thin Client computer are used.  The USB stick you see in the pictures is the IRLP node's disk drive.

regards, 
Brian
VE3IBW


Teton Amateur Radio Repeater Association (TARRA)
 

Hello Brian,

What is the node number you are working on, in case I missed it?

We can't blame you for much since you didn't build it : ) 

I think your audio - de-emphasis & pre-emphasis is all over the place. Something you need to straighten out and take care of.

Just because you get a DTMF light, doesn't mean it is seeing the correct DTMF. It could just be a level problem. Have you gone through and checked your audio levels to make sure they are still set up correctly?

There may very well be a ground and then again there very well may not be. Something you should check. I wouldn't check it with an ohmmeter because you could just be seeing a DC ground path. I would do a visual inspection of the wiring to see if it is there.

Some of this won't apply, but take a look at this link:

http://www.irlp.net/pi/manual.pdf

Look at page 4, the first paragraph is wrong, but read the rest of it and also look at page 5. The following is from September this past year:

> If you position the board to look at the 10 pin header on the top right,
> the pins are numbered from the bottom left, to the right along the
> bottom row (1-5), then from the top left to the right along the top row
> (6-10).
>
> Pin 1 unused
> Pin 2 PTT
> Pin 3 AUX 1
> Pin 4 AUX 2
> Pin 5 AUX 3
> Pin 6 GND
> Pin 7 COS
> Pin 8 RX audio
> Pin 9 unused
> Pin 10 (impossible and unused)
>
>
> -------------------------------------
> ! 6 7 8 9 10 !
> ! 1 2 3 4  5 !
> ! !
> ! !
>
> TOP RIGHT OF BOARD

I'm not sure if there is much out there on the DB25 but that is mostly control signals and nothing to do with the audio/DTMF.

Just a good idea to remove any RF adapters. They usually don't work very well, especially a lot of the mini-UHF adapters.

You could have an issue going on with your flash drive that is causing you problems. I believe you said that it went bad. (sure helps if your reply to the email to keep the chain going rather than to cut it off which makes it hard to follow).

Note sure how things were set up at the repeater site. Is this radio being used as a "link" or a "repeater user"? If the node was at the repeater site, such a shame not to have it directly connected to the repeater controller. No radio involved. Not a good set up and rather clunky.

I would work toward cleaning up the wiring for the audio path and being careful of the "emphasis" as you do that. Also make sure your levels are correct. Another detail is the volume control on the radio is going to affect the audio level when you are using audio from the RJ45. And you could also be having an audio level issue from your computer. Have you run the audio level tests to make sure levels are correct? Do you have any test equipment (and the know how) to use?

Mick - W7CAT
Node 3464

----- Original Message -----
From: Brian
To: IRLP@irlp.groups.io
Sent: Friday, January 03, 2020 05:23:10 AM
Subject: Re: [IRLP] Weird DTMF Decode Behaviour

> Hi Mick,
>
> Lots of questions...here are my responses:
>
> * *Choice of audio connector from the radio to the Thin Client computer?*
>
> * Since I didn't build this setup, I cannot comment on decisions made in the past.  This setup has been working for many years with this radio and thin client computer.  Recently, DTMF decoding has become unreliable.
> * The IRLP board's DTMF LED for each push of a DTMF code from an HT always lights.  That tells me that the IRLP board has registered the DTMF signal in the audio feed. Some component after the detection of a DTMF code fails to decode the DTMF tones properly.  This is what I am trying to zero in on at this time.
>
> * *Ground?*
>
> * I think that is something I can confirm.  Thanks for the info.  I haven't been successful in finding a diagram that shows the wiring for the D25 and D9 connectors to/from the IRLP board.  If you have a link, I would appreciate knowing where to look.
>
> * *RF Adaptor on the back of the Radio*
>
> * Perhaps, but this would be low priority as this setup has been working for many years until recently.  I have removed and re-seated this adaptor.
>
> * *USB Disk Drive Stick vs Internal HDD*
>
> * Yes, I agree with you.  In fact, one of our club members has his own IRLP node (exactly the same setup (radio and thin client computer) and he has been encouraging me to do the same thing.  However, low priority until I get the DTMF problem solved.
>
> * *Simplex node?*
>
> * Yes, we use a simplex approach to the link.  This setup has not been directly connected to the repeater controller and never has been to my knowledge, even when it was at the repeater site.  All comms between the repeater and the IRLP node (computer and link radio) have been RF.
> * Our repeaters are moving sites of late and of course the need for an internet connection poses a challenge.  Our club is zeroing in on a repeater home that will have reasonable internet (cost-wise).  Until that time, the IRLP node must be located at my QTH (a club member) so we can have IRLP and Echolink functionality in our region.
>
> regards
> Brian
> VE3IBW
>
>
>
>
--


Teton Amateur Radio Repeater Association (TARRA)
 

> *Is the audio from the radio squelched and deemphasized?*
>
> * Yes, squelched.
> * Not sure about de-emphasis.  I will inquire.

You only have two choices here with this radio. Either "squelched and de-emphasis" or "unsquelched and flat".

Unless the radio itself has a problem (and doesn't seem that is does) it is a very good radio for this. Again, I would clean up the wiring and make sure the levels are setup correctly.

Mick - W7CAT
Node 3464

----- Original Message -----
From: Brian
To: IRLP@irlp.groups.io
Sent: Friday, January 03, 2020 05:49:18 AM
Subject: Re: [IRLP] Weird DTMF Decode Behaviour

> Hi Dave,
>
> *What do you have for resistance between the radio output and the usb input?*
>
> * Not sure how to answer your question as there is no USB input used for the audio path.
> * Since I didn't make the cable, I will have to ask the person who did to know if there is any inline resistance added.  If I can't get an answer, then I will have to open up the cable to be able to answer your question.
> * Your comment and that of another responder in this thread may have a point I can look at with regards to the audio level making its way directly to the IRLP board.
> * However, if the IRLP DTMF LED lights with each DTMF tone sent by an external radio to the node, does the lit LED indicate that the IRLP board has enough audio drive to be able to process the DTMF tones?
>
> *Is the audio from the radio squelched and deemphasized?*
>
> * Yes, squelched.
> * Not sure about de-emphasis.  I will inquire.
> * However, as I mentioned above, the IRLP DTMF LED lights up for each DTMF code sent to the link radio and passed to the IRLP board.  How should I interpret the lit LED for each code sent?
>
> FYI...Our setup, as per the pictures I sent, do not use a USB audio adaptor.  Line-in (mic) and line-out (speaker) on the back of the Thin Client computer are used.  The USB stick you see in the pictures is the IRLP node's disk drive.
>
> regards,
> Brian
> VE3IBW
>
>
>
>
--


Darin Lehnert
 

Hey Brian,
This a link to the interface cable I use for all my  IRLP Motorola's link radios
All you need to do is solder on the female db-9


If you need the pinouts email me and I will send them to you.

Darin kc7tig
Node 8350


On Fri, Jan 3, 2020 at 9:34 AM Teton Amateur Radio Repeater Association (TARRA) <tarra@...> wrote:

> *Is the audio from the radio squelched and deemphasized?*
>
> * Yes, squelched.
> * Not sure about de-emphasis.  I will inquire.

You only have two choices here with this radio. Either "squelched and de-emphasis" or "unsquelched and flat".

Unless the radio itself has a problem (and doesn't seem that is does) it is a very good radio for this. Again, I would clean up the wiring and make sure the levels are setup correctly.

Mick - W7CAT
Node 3464

----- Original Message -----
From: Brian
To: IRLP@irlp.groups.io
Sent: Friday, January 03, 2020 05:49:18 AM
Subject: Re: [IRLP] Weird DTMF Decode Behaviour

> Hi Dave,
>
> *What do you have for resistance between the radio output and the usb input?*
>
> * Not sure how to answer your question as there is no USB input used for the audio path.
> * Since I didn't make the cable, I will have to ask the person who did to know if there is any inline resistance added.  If I can't get an answer, then I will have to open up the cable to be able to answer your question.
> * Your comment and that of another responder in this thread may have a point I can look at with regards to the audio level making its way directly to the IRLP board.
> * However, if the IRLP DTMF LED lights with each DTMF tone sent by an external radio to the node, does the lit LED indicate that the IRLP board has enough audio drive to be able to process the DTMF tones?
>
> *Is the audio from the radio squelched and deemphasized?*
>
> * Yes, squelched.
> * Not sure about de-emphasis.  I will inquire.
> * However, as I mentioned above, the IRLP DTMF LED lights up for each DTMF code sent to the link radio and passed to the IRLP board.  How should I interpret the lit LED for each code sent?
>
> FYI...Our setup, as per the pictures I sent, do not use a USB audio adaptor.  Line-in (mic) and line-out (speaker) on the back of the Thin Client computer are used.  The USB stick you see in the pictures is the IRLP node's disk drive.
>
> regards,
> Brian
> VE3IBW
>
>
>
>
--


bruce clements
 

Update.
Had node delivered to me to look at.
Found irlp board defective. Replaced with a spare. All good.

Bruce
Ve3bv
Node 2226