pl tone

[tango82]

Can anyone tell me what a 411 dpl tone is for gmrs use. Thanks Brian B.

[Radioguy7268]

411 is a Digital Private Line code. It is transmitted along with your voice on the frequency you operate on. Normal operation is that the radio would transmit and receive with the same DPL code. This acts as a "mask" or Filter - helping to reduce or eliminate unwanted noise on your channel. It is useful when other user groups are operating on the same frequency, and you don't want to hear their traffic. With a properly set up DPL code, your radios will only hear (and talk) to each other.

 

If  your radio operates without a DPL or Private Line code (Carrier Squelch mode) - then you will hear all traffic on the received frequency. However, if you transmit without the correct DPL code, then there's a pretty good chance that the other users in your fleet (which are all programmed to only open their audio circuits when code 411 is received) will not hear your transmission.

 

That's the simple level explanation, there's more to it, but that's enough for now.

[Jones]

Wiki has a couple of great fact-filled articles on Squelch systems, CTCSS, and DCS.  It a good semi-technical read, if you are interested.

 

https://en.wikipedia.org/wiki/Continuous_Tone-Coded_Squelch_System

 

https://en.wikipedia.org/wiki/Squelch

[Jones]

More info on DCS, including the valid code chart:

 

https://wiki.radioreference.com/index.php/DCS

 

Even more tech:

http://onfreq.com/syntorx/dcs.html

http://www.repeater-builder.com/tech-info/ctcss/ctcss-overview.html

http://mmi-comm.tripod.com/dcs.html

 

Some of this is heavy reading, but I sure found it interesting and educational, so I'm sure many of you will also.