I replied to Cory privately but wanted to share a thought and some successes I have with the group.

Jim graciously added MDC1200 support to Asterisk/Allstar last summer. I have been using MDC1200 as my primary method of control since. It does not mute like DTMF does and therefore could be used for control purposes.

Some reasons:
1) MDC is a fixed-length data packet transmitted within 175mS, has built-in error correction and will ignore the packet if the correct number of bits are not received (checksum). DTMF is subject to partial command interpretation during signal drops.

2) MDC is equally as insecure as DTMF. It is a little harder to recreate by a jammer and can mask the real command digits.

3) While mobile, I have my radio programmed with different MDC systems (ID's). Changing modes or channels and keying up is enough to send the command over to the repeater. Contrast this to holding a mic and pushing numbers while driving, which is very prone to error and takes your eyes off the road.

Allstar can both encode and decode MDC, so a suggestion instead of the propagate_dtmf and its current design would be to craft a series of ID codes to be sent between nodes over the air, and have the target side map these to DTMF commands and/or macros. I do just this on my systems. Some radios have a limitation of 8 unique MDC ID's, but Allstar node-to-node should be fine.

Example:
Radio Mode 1 - MDC ID = 1234. Allstar decodes and maps to DTMF command *32000 (link to node 2000).
Radio Mode 2 - MDC ID = 1235. Allstar decodes and maps to DTMF command *12000 (disconnect node 2000).
Radio Mode 3 - MDC ID = 1236. Allstar decodes and maps to DTMF command *987 (disconnect ALL nodes).

[mdcmacro]
I1234 = *32000
I1235 = *12000
I1236 = *987

I would be glad to help out with how this could work, or do some testing if asked. You'll need to copy the mdc1200.h and .c files from the extras directory and uncomment the #include files within app_rpt.c to get it to compile in.

Tony



On 01/24/2011 11:56 AM, Corey Dean N3FE wrote:

I am actually wanting things just a little different.  Until I can get internet to each site so I can get asterisk there I would like to use a command that I could enter and anything following it would generate the DTMF.

 

Here is my current scenario…  I use one of my UHF machines as the hub (for now) and I have different machines that listen to the hub.  At times other repeaters will connect in as well.  DTMF muting is enabled on the local repeater but DTMF is NOT muted on the link side that goes to the hub.  This way I can control the repeaters through the links if I need to until I can get some type of ip network setup.

 

Say a cop command is created for this and I make 932 my dtmf for that cop command and I was to issue  1234 to turn on something at a remote site, I would like to enter  *9321234 and have the controller either pass or regenerate the 1234.

 

I hope this makes sense.  I know a couple of groups that would like to do this as well and that is the only reason they haven’t moved over to app_rpt.  They have seen how powerful it is!  One of the systems has 15 repeaters in it and the only way they would be able to do something would be a piece at a time.  That is why this would be so handy!!!!

 

Corey  N3FE

 

From: app_rpt-users-bounces@ohnosec.org [mailto:app_rpt-users-bounces@ohnosec.org] On Behalf Of VE3GIH Gordon Hewit
Sent: Monday, January 24, 2011 12:34 PM
To: app_rpt-users@ohnosec.org
Subject: [App_rpt-users] DTMF passthru

 

KE2N Ken suggested using the propagate_dtmf command in the rpt.conf file, as a way to propagate DTMF signals to other nodes.  I need this capacity to allow our members access to the local phone patch.  However with all nodes set to duplex=2 (full duplex) and  propagate_dtmf=yes,  I'm still not getting DTMF on the other local repeaters.  The asterisk console sees the DTMF, but Asterisk isn't passing the digits onwards.

 

Does anyone have a suggestion about what else I can try?

 

VE3GIH Gord

______________________________________________

Date: Sat, 22 Jan 2011 09:42:49 -0500 (EST)
From: Ken <ke2n@cs.com>
To: n3fe@repeater.net, telesistant@hotmail.com,
app_rpt-users@ohnosec.org
Subject: Re: [App_rpt-users] DTMF Allow

Cory

I think there is a setting for this

propagate_dtmf=     see MailScanner warning: numerical links are often malicious: http://209.159.155.200/drupal/node/134
<snipped>
GL
Ken
KE2N



Gordon Hewit
289-800-1473  (home)


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