Bryan: Created page with "category:onfreq.com The below is an archive of "http://onfreq.com/syntorx/ctcss.html" which is no longer available. The links below have not been updated, so they don't..."

2023-10-23T17:13:34Z

Created page with "category:onfreq.com The below is an archive of "http://onfreq.com/syntorx/ctcss.html" which is no longer available. The links below have not been updated, so they don't..."

New page

[[category:onfreq.com]]

The below is an archive of "http://onfreq.com/syntorx/ctcss.html" which is no longer available. The links below have not been updated, so they don't work.

<html>
<a name="top_dcs"></a>
<table border="0" cellpadding="0" cellspacing="0" width="630">
<tbody>
<tr>
<td bgcolor="#00ffff" width="3%"> </td>
<td colspan="3" valign="bottom"> - PL
/ CTCSS Information</td>
</tr>
<tr>
<td bgcolor="#00ffff" width="3%"> </td>
<td width="3%"> </td>
<td colspan="2"> - <a href="#ctcssintro">PL / CTCSS
Introduction</a></td>
</tr>
<tr>
<td bgcolor="#00ffff" width="3%"> </td>
<td width="3%"> </td>
<td colspan="2"> - <a href="#usage">PL / CTCSS Usage</a></td>
</tr>
<tr>
<td bgcolor="#00ffff" width="3%"> </td>
<td width="3%"> </td>
<td colspan="2"> - <a href="#revburst">PL / CTCSS
Reverse Burst</a></td>
</tr>
<tr>
<td bgcolor="#00ffff" width="3%"> </td>
<td width="3%"> </td>
<td colspan="2"> - <a href="#stdtones">Standard PL /
CTCSS Tones</a></td>
</tr>
<tr>
<td bgcolor="#00ffff" width="3%"> </td>
<td width="3%"> </td>
<td width="5%"> </td>
<td width="89%"> </td>
</tr>
</tbody> <tbody>
<tr>
<td bgcolor="#00ff00" width="3%"> </td>
<td colspan="3"> - <a href="index.html">HOME</a></td>
</tr>
</tbody>
</table>

 
 

<center>[<a href="syntor/index.html">SYNTOR</a>]
[<a href="syntorx/indexx.html">SYNTOR X</a>] [<a href="syntorx9k/index.html">SYNTOR
X 9000 and X 9000E</a>] [<a href="syntorx/trunking.html">TRUNKING
SYNTOR X and SYNTOR X 9000</a>] [<a href="spectra/index.html">SPECTRA</a>]</center>


<center>
<center>[PL] [<a href="dcs.html">DPL</a>] [<a href="pac.html">PAC-PL
and PAC-RT VEHICLE REPEATERS</a>][<a href="hhch.html">HHCH</a>] [<a href="prom.html#top_prom">PROM
PROGRAMMERS</a>] [<a href="wiring.html">POWER
WIRING</a>]</center>
</center>


<center>[<a href="gloss.html">GLOSSARY</a>]
[<a href="links.html">WEB LINKS</a>] [<a href="surplus.html">SURPLUS
PARTS GUIDE</a>] [<a href="forsale.html">ITEMS FOR
SALE</a>] [<a href="w_rev.html">WEB SITE REVISIONS</a>]
[<a href="contact.html">CONTACT</a>]</center>

 
<a name="ctcssintro"></a>PL /
CTCSS Introduction:
This section has background information that applies to two
similar
analog coded
squelch systems. One squelch system is used by Motorola and the other
squelch system is used by almost every major radio
manufacturer. The name PL is a Motorola trade
mark and Continuous Tone-Coded Squelch System (CTCSS) is a generic
name. The difference between PL and CTCSS is in how the optional
reverse burst is implemented. See the <a href="dcs.html">DPL / DCS</a>
page for information on a digital coded squelch system (unlike the
analog PL/CTCSS squech systems, the 23 bit DCS/DPL squelch system is
the same for all manufacturers).
The Syntor X has specific information on it's <a href="syntorx/pldplx.html">PL/DPL</a>. 

PL / CTCSS is an analog squelch scheme in which an audio tone
is sent by a transmitter
to control the squelch opening of a receiver. PL / CTCSS is designed
to work in the "so called" sub-audible portion of the
communications audio band below 300 Hz. The individual
PL or CTCSS tone operates below 300 Hz while the voice
modulation operates
from 300 Hz to 3000 Hz. These tones are not really sub-audible,
except that the radio receiver filters out anything below 300
Hz. Encoded tones are sent by the transmitter and decoded tones
are used by the receiver. When used, the receiver must receive
the programmed tone or it will mute the audio output (i.e. the
operator will not hear anything from the radio unless the programmed
tone is present). There are 42 standard Electronic Industries
Association CTCSS tones from 67 Hz to 254.1 Hz. Execpt for the original
Syntor, these radios can
be programmed for all standard tones and non standard tones. However,
there are cutoff filters that make it difficult
to go much above 254.1 Hz and frequencies around or below 60 Hz
are not very practical. For example,
some MARS operators may need a tone of 150 Hz which is not an EIA
standard tone.
Carrier Squelch (CSQ) is used when PL / CTCSS coded receive is not
used.
Even if any PL / CTCSS tone is present in the received signal, the
receiver just ignores it and the squelch opens strictly when any
received signal is strong enough to overcome the squelch level setting. 

Because a receiver that uses PL / CTCSS will not open its squelch
without a matching tone and in commercial use many different users
share the same frequencies in the exact same geographic area, there is
a secondary way to turn off the PL/CTCSS tone decoding. It is called
the hang-up box that the microphone rests on. The original versions
were actually small boxes, sometimes with a slide switch which is where
the name hang-up box comes from. Modern radios might use a simple
grounded clip, where the radio detects if the button on the back of the
microphone is grounded or not. Some microphones also include a switch
built into the back of the microphone itself. While the microphone is
in the hang-up condition the receive squelch only opens when the
programmed PL / CTCSS tone is present. However, when the microphone is
removed from the hang-up state the receive PL / CTCSS decoding is
disabled and the radio operates in CSQ. When sharing a frequency the PL
/ CTCSS decoding keeps you from having to listen to radio transmissions
that are not of any interest to you, however when you want to transmit
this same PL / CTCSS decoding prevents you from hearing if the
frequency is already in use or not in use and clear to transmit on. The
hang-up function solves this problem. When you pick up the microphone
to trasmit, the PL / CTCSS decoding is disabled and you can hear anyone
on the frequency which allows you to avoid interfeering with anyone
else already transmitting. In the Spectra the hang-up function can
optionally be programmed to stop the scan. 

<a name="usage"></a>PL / CTCSS
usage:
The basic premise behind PL / CTCSS is: stations that
share the
same frequency, but use different PL / CTCSS tones do not have
to listen to each other. HAM radio operators do not have much
use for this application of PL / CTCSS. PL / CTCSS tones are
also used to protect
repeater input frequencies among other things (HAMs do have a use for
this application). Basically, the
transmitting
station must transmit a PL / CTCSS tone and the receiving
station
must use the same Rx PL / CTCSS tone. If the PL /
CTCSS tones do not match,
the receiver remains muted and the operator does not hear the
transmitting station. Some multiple repeater systems use PL /
CTCSS
to select which repeaters are used. If the receiver uses carrier
squelch (i.e. no PL / CTCSS) then all stations on the
frequency are
heard regardless of any transmitted PL / CTCSS. The "Private
Line" part of the PL name is not to be taken literally because
there is really nothing private about it when it comes to monitoring.
The designed feature of not hearing stations that do not
transmit
the matching PL / CTCSS tone can cause a problem. When someone
does not
hear any activity on a frequency they assume it is not in use
and they can transmit. With receive PL / CTCSS the frequency
can actually
be in use, but the receiver does not hear it. This creates the
potential problem of two or more stations unknowingly transmitting
simultaneously and interfering with each other. The solution is
the accessory called the hang-up box or clip. When the microphone
is removed from the hang-up box or clip, the PL / CTCSS
receiver squelch is
disabled allowing the operator to hear everyone on the frequency.
It's a natural, pick up the microphone and find out if it's really
clear to transmit. Put the microphone back and the unwanted signals
without matching PL / CTCSS disappear.
<a name="revburst"></a>PL / CTCSS
reverse burst:
Reverse burst only applies to radios using coded
receiver squelch. Reverse burst actually changes the way the
transmitter
operates for the benefit of the receiving station. Radios using
carrier squelch do not need or benefit from reverse burst.
To understand reverse burst, first you have to understand how
PL or CTCSS coded receiver squelch operates. The normal setup
for
receiver encoded squelch is STD/STD which mutes the receiver
audio and runs the squelch setting wide open (maximum noise would
be heard on a frequency without any activity, except the audio
is muted). This helps ensure maximum receiver sensitivity. When
the radio receives a signal with a matching PL / CTCSS signal it will
unmute the receiver audio so you can hear the signal. Since there
is now a received signal present, the noise previously mentioned
is absent. However, when the received signal disappears at the
end of the transmission, there is a brief period of time before
the receiver can detect the loss of PL / CTCSS and mute the
audio
again. This brief period of time causes a short burst of noise
in the receiving radio speaker commonly called a squelch tail.
Reverse burst causes the transmitting station to go through
a special process every time the transmission ends. When the
transmitting
station releases the PTT the transmitter will still transmit for
about 180 milliseconds. During this 180 ms time, a transmitted
PL signal phase will be delayed by 120 degrees (other
radio manufactures use an incompatible 180 degree phase shift during a
150 ms Tx time).
This phase shift gives
the receiver time to decode and recognize the loss of a valid
PL or CTCSS and mute the receiver audio before the
transmitted
signal disappears, which is while the receiver is still quiet.
This eliminates the squelch tail noise burst in the receiver speaker.
The reason for using a phase shift for the PL reverse burst
probably came about because in the old days mechanical resonate
reeds (called Vibrasponders) were used to detect PL tones. The
sudden PL signal phase shift of the resonate frequency PL signal
would more quickly reduce the vibrations of the reed, rather than
letting the vibrations wind down on their own as in if the resonate
frequency PL signal was simply changed to a non-resonate frequency
or removed. Without the reverse burst phase shift, the old Vibrasponder
PL squelch would probably not close very quickly.
The different PL reverse burst phase shift used by Motorola
as compared to other manufactures is why Motorola PL reverse
burst usually does not work with other brands and why their
CTCSS reverse burst usually does not work with
Motorola
radios. Keep in mind that PL and CTCSS do work together, the reverse
burst is the only thing that can be incompatible.
The effect of loosing the squelch tail is very pleasant to
the ears of the human receiver.
On radios equipped with Securenet encryption, the PL/CTCSS tone and
its reverse
burst is automatically disabled
when transmitting encrypted audio.
<a name="stdtones"></a>Standard PL
/ CTCSS tones:

<table style="width: 605px; height: 546px;" border="1" cellpadding="0" cellspacing="2">
<tbody>
<tr>
<td colspan="4" align="center" bgcolor="#00ffff">Standard PL / CTCSS Tones (42 total) 
 
Tone Frequency - Motorola
Code</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
67.0 - XZ
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
97.4 - ZB
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
141.3 - 4A
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
206.5 - 8Z
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
69.3 - WZ
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
100.0 - 1Z
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
146.2 - 4B
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
210.7 - M2
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
71.9 - XA
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
103.5 - 1A
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
151.4 - 5Z
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
218.1 - M3
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
74.4 - WA
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
107.2 - 1B
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
156.7 - 5A
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
225.7 - M4
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
77.0 - XB
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
110.9 - 2Z
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
162.2 - 5B
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
229.1 - 9Z
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
79.7 - WB
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
114.8 - 2A
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
167.9 - 6Z
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
233.6 - M5
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
82.5 - YZ
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
118.8 - 2B
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
173.8 - 6A
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
241.8 - M6
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
85.4 - YA
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
123.0 - 3Z
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
179.9 - 6B
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
250.3 - M7
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
88.5 - YB
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
127.3 - 3A
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
186.2 - 7Z
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
254.1 - 0Z
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
91.5 - ZZ
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
131.8 - 3B
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
192.8 - 7A
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
 
</td>
</tr>
<tr style="">
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
94.8 - ZA
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
136.5 - 4Z
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
203.5 - M1
</td>
<td style="padding: 6.75pt; width: 25%; text-align: center;" valign="top" width="25%">
 
</td>
</tr>
</tbody>
</table>
 
 

 

<center>[<a href="syntor/index.html">SYNTOR</a>]
[<a href="syntorx/indexx.html">SYNTOR X</a>] [<a href="syntorx9k/index.html">SYNTOR
X 9000 and X 9000E</a>] [<a href="syntorx/trunking.html">TRUNKING
SYNTOR X and SYNTOR X 9000</a>] [<a href="spectra/index.html">SPECTRA</a>]</center>


<center>
<center>[PL] [<a href="dcs.html">DPL</a>] [<a href="pac.html">PAC-PL
and PAC-RT VEHICLE REPEATERS</a>][<a href="hhch.html">HHCH</a>] [<a href="prom.html#top_prom">PROM
PROGRAMMERS</a>] [<a href="wiring.html">POWER
WIRING</a>]</center>
</center>


<center>[<a href="gloss.html">GLOSSARY</a>]
[<a href="links.html">WEB LINKS</a>] [<a href="surplus.html">SURPLUS
PARTS GUIDE</a>] [<a href="forsale.html">ITEMS FOR
SALE</a>] [<a href="w_rev.html">WEB SITE REVISIONS</a>]
[<a href="contact.html">CONTACT</a>]</center>


<center>[<a href="#top_dcs">TOP</a>]
[<a href="index.html#top_home">HOME</a>]</center>

 
--
PL, Private Line, DPL,
Digital Private Line,
Vibrasponder, MPL, Talkaround, MDC-600, MDC-1200, MVS-20, Securenet,
Smartnet, Privacy Plus, Trunked X2, Trunked X3, Touch Code, Quick
Call II, Channel Scan, Talkback Scan, System 90, System 90*s,
Systems 9000, PAC, PAC-PL, PAC-RT, PAC-TR, PAC-TL, MX-310, HT220,
Mitrek, Micor, Spectra, MataTrac, Syntor, Syntor X, Syntor X 9000
and Syntor X 9000E are trademarks of Motorola Inc.

</html>

PL/CTCSS Information - Revision history

Bryan: Created page with "category:onfreq.com The below is an archive of "http://onfreq.com/syntorx/ctcss.html" which is no longer available. The links below have not been updated, so they don't..."