[chirp_users] Thoughts after looking at the most recent build

Robert Terzi rct at r-t.org
Tue Aug 9 08:19:52 PDT 2011

On 8/9/2011 9:45 AM, Dan Smith wrote:
> On 8/9/2011 12:49 AM, Ron McKenzie wrote:
>> [...]
>> Some questions to help increase my knowledge of current practices:
>> [...]
>> 2. Is a repeater operator precluded from selecting different CTSS or
>> DTCCS codes for Rx and Tx?
> Yes, at the moment.

Err, perhaps repeater operator is a bit ambiguous here?

The repeater owner/administrator, who configures the repeater can
can set up a repeater with different tone or digital squelcn
settings for transmit / receive.  The occurrences of this are
pretty rare, and a number of popular radios do not support the
setting of different squelch encoding / decoding on the same
memory channel.  However, I've seen a couple of popular linked
repeater systems in the NYC area move to this configuration
to avoid interference.

Also, I'm going to take the risk of being a bit pedantic here
since I've seen a lot of misunderstanding on different mailing lists.

CTCSS, Aka Tone Squelch, or PL (Private Line) is a method for
including an analog tone in a transmitted signal in order to
allow the receiver to operated in a mode where it will only
open the squelch if the tone is present.  This prevents noise or
even other undesired signals from being heard.

DCS, Digital Coded Squelch, uses a digital code embedded in
the transmitted signal that provides for more possible squelch
codes and greater reduction in an unwanted signal opening the
receiver's squelch.

The typical repeater setup (especially in the US) is that the
repeater's receiver has a tone squelch setup to prevent the repeater
from keying up on unwanted noise or signals.  This means that in order
to use the repeater, your radio must *encode* the squelch tone in your

The repeater when retransmitting a signal may encode a squelch
tone or digital code.  This is a feature for the convenience of
the people who listen to repeater to provided added protection
against hearing unwanted noise or signals.  None of the receive
squelch settings on your end are required to use the repeater
and if set incorrectly can prevent you from hearing the repeater.
Given that it is often best to make sure you've got the settings
for the repeater working correctly before you enable any receive
squelch settings for that memory.  If you don't live in a noisy
area you could skip that step entirely.

About half of the repeaters that I've come across do transmit
tone squelch which makes monitoring and scanning that much
more pleasant.  I've only come across three repeaters in my area
so far that use DCS.

The most of the non-typical setups I've seen are from linked
repeater systems in areas that are densely packed with radios.

Hope This Helps,

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