[chirp_users] Tone Settings TX, RX (TSQL & DCL) discussion

Bill Kasper williamkasper at frontiernet.net
Tue Jul 22 10:29:58 PDT 2014

Hi Forrest et al,

The TX tone (CTCSS DCL and other names) may be required
for the ham repeaters that use it. Modern radios' menus
may set the tone independently for each channel or
for the entire rig. This tells the repeater that
"I really want to talk thru you" and I'm not some
skip-signal coming from a different part of the country.

Historically (a hundred years ago?) commercial repeaters
had several to many business users on them, as they were
expensive and each business that used, ie. paid for the
repeater service, had a different tone to open only that
businesses own radios: a taxi had one tone, the road-repair
company another tone, and the delivery company another tone
and so on. They had to share the resource (the repeater) and not 
interfere with each other any more than necessary. CTCSS is the
modern technical name of that tone process that used to be
called PL - Private Line (Motorola), CG - Channel Guard,
General Electric, and privacy codes for various FRS radios,
plus other names.

It is the tone ENGAGED on the RECEIVER end that can be
problematic: the exact tone MUST be present on the
transmitted signal for the receiver squelch (TSQL)
to open so you can hear the other station on that
frequency; which may or may not be what you want.

As an example, I setup a simplex ham voice channel
for myself and XYL to use as a 'Private Line'
(Motorola trademark) only for us: car-house, car-car
etc. This is fine for us, and I have TSQL set on both
radios for this channel. On this 'unused' simplex
channel she can only hear me and I can only hear her.
If someone else hears us, which they could, and then
tries to answer me, I would not hear them unless they
figured out and then transmitted our 'PL' tone.

As an aside, this feature, as implemented on the FRS
private channel radios, means that you can only hear
people transmitting your private code on your channel;
people with no (RX) tone set can hear you too, so not
really very private, but helps reduce chatter from
other users when listening on a shared resource/channel.
The implication is that, if you use your FRS channel 1,
by convention, as an emergency receiver, make sure the
privacy codes are turned off, so you will be able to
hear everyone on channel 1, even if they have a privacy
tone enabled.

other comments?

73 de Bill WB2SXY


On 7/22/2014 12:26 PM, Forrest wrote:
> Curious why you say that using tone squelch on both TX and RX is not recommended???
> THX.
> Forrest
> On Jul 21, 2014, at 6:51 PM, John LaMartina<JohnLa at usa.net>  wrote:
>> Yes, TSQL sets the CTCSS or DCS tone on both TX and RX. (Not Recommended).
>> Tone sets CTCSS or DCS on TX only.
>> This explains in a bit more detail. http://www.miklor.com/COM/UV_CTCSS.php
>> I hope this helps...
>> John K3NXU
>> http://www.miklor.com
>> -----Original Message-----
>> From: chirp_users-bounces at intrepid.danplanet.com [mailto:chirp_users-bounces at intrepid.danplanet.com] On Behalf Of Dave Nathanson
>> Sent: Monday, July 21, 2014 7:22 PM
>> To: Discussion of CHIRP
>> Subject: Re: [chirp_users] Settings
>> Someone else will hopefully correct me if I'm wrong, (and I didn't look this up) but I believe that in this usage, "Tone" applies
>> when transmitting only.
>> TSQL, or Tone Squelch applies to both transmitting&  receiving.
>> "Tone" is more common.
>> If you use TSQL when you should have used Tone, others will be able to hear you, but you will only be able to hear them if they also
>> use the same tone.
>> To complicate things slightly, many repeaters require a tone to activate them, but many repeaters strip out the tone as the
>> re-transmit.
>> It is often a good idea to start with "tone" and only use TSQL if needed.
>> Best,
>> Dave Nathanson

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