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Author Topic: CTCSS use in split frequency operation  (Read 11236 times)
2E0WBL
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« on: March 09, 2014, 08:00:11 AM »

I have a Kenwood TS2000, and would like to be able to use the split frequency facility with some of our local repeaters.  However, the repeaters require a CTCSS code for access, but they don't transmit using a code.  My problem is that I can't figure a way of limiting the CTCSS code to transmit only.  On the main VFO's (A & B), if I switch on the CTCSS, it's applied to both TX and RX.  Anyone know a way round this?  I've read through the manual, but it doesn't give any obvious way of doing it that I can find.  I can use our local 2m and 70cm repeaters using the CTCSS on the sub VFO for TX, and RX on the main VFO's, but the sub doesn't operate on any other bands, and I'd really like to be able to use the local 6m repeaters.  Any suggestions gratefully received!

73's
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KG4RUL
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« Reply #1 on: March 09, 2014, 05:26:51 PM »

I just went to my TS2000 and programmed it split for a local 2M repeater along with the tone.  It accessed the repeater without any problems.  As we have no 6M repeaters in the area, I was not able to check on that band.
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2E0WBL
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« Reply #2 on: March 10, 2014, 01:00:54 PM »

Thanks for the reply.  Does the repeater you used transmit with a tone too?  If not, how do you get to hear the output from the repeater?  On my radio the CTCSS is applied to both the TX and RX. Maybe the US version of the radio is set up differently?
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KB2VUQ
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« Reply #3 on: March 10, 2014, 07:37:20 PM »

Mr. Riley (M6MEQ),

You are over thinking this whole thing.

CTCSS is Tone encode AND decode. This is found on page
35 of the manual and is menu item 6. This will only work
if the repeater or other station is transmitting the same tone
you are set to decode. Your radio will display CT when set to
encode AND decode


What you want is TONE encode only. Page 33 of the manual,
menu item 4. Your radio will display T when set to encode only
and carrier squelch receive.

I do not own either a TS-2000, nor a manual for a TS-2000, but
did download the manual from Kenwood to look into your problem.

You cannot have T and CT at the same time. Turn off the CT (#6) and
turn on T (#4). Select the tone you need to transmit and away you go.

Most VHF/UHF radios in the states use the same T / CT convention.

Best Regards,
Dennis
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NZ4ZN
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« Reply #4 on: March 11, 2014, 07:19:45 AM »

Mr. Riley (M6MEQ),

You are over thinking this whole thing.

CTCSS is Tone encode AND decode. This is found on page
35 of the manual and is menu item 6. This will only work
if the repeater or other station is transmitting the same tone
you are set to decode. Your radio will display CT when set to
encode AND decode


What you want is TONE encode only. Page 33 of the manual,
menu item 4. Your radio will display T when set to encode only
and carrier squelch receive.

I do not own either a TS-2000, nor a manual for a TS-2000, but
did download the manual from Kenwood to look into your problem.

You cannot have T and CT at the same time. Turn off the CT (#6) and
turn on T (#4). Select the tone you need to transmit and away you go.

Most VHF/UHF radios in the states use the same T / CT convention.

Best Regards,
Dennis
Agreed. Just use "Tone", not "CTCSS".

My TS-590 sets up the same way from the front panel. If I click on the [AGC/T] button once, it goes to Tone and displays a "T". If I click it again and again, it steps through several modes, including CTCSS. When in "Tone" mode, I press and hold the [AGC/T] button and it allows me to select the tone frequency.

My Yeasu radios call it "Tone" for just a transmit tone to open the repeater and the function "Tone Squelch" means the repeater has to transmit a tone to open my radio as well. Most repeaters I use are simply tone coded on their input and do not transmit an outgoing tone.
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KG4RUL
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« Reply #5 on: March 11, 2014, 10:23:30 AM »

Continuous Tone-Coded Squelch System or CTCSS is a circuit that is used to reduce the annoyance of listening to other users on a shared two-way radio communications channel. It is sometimes called tone squelch. Where more than one user group is on the same channel (called co-channel users), CTCSS mutes the other users if they are using a different CTCSS tone or no CTCSS.

Receivers equipped with a CTCSS circuit usually have a switch that selects normal mode or CTCSS mode. When enabled, the CTCSS radio circuit, instead of unmuting the receive audio for any signal, causes the two-way radio receiver's audio to open only in the presence of the normal RF signal AND the correct sub-audible audio tone (sub-audible meaning that the receiver circuitry can detect it, but is not apparent to the users in the audio output). A carrier squelch or noise squelch receiver not configured with CTCSS will receive any signal. A receiver with CTCSS circuitry (and with it enabled) locks out all signals except ones encoded with the correct tone. CTCSS can be regarded as a form of in-band signaling.

============

I misread the initial post.  There is a distinction between a "Tone" for accessing a repeater and CTCSS for selective reception.  What the poster needs to do is select "Tone" operation (page 33 of the user manual) vs CTCSS (page 35 of the user manual).
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KB2VUQ
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« Reply #6 on: March 12, 2014, 11:13:14 PM »

I noticed when this thread started, Andy was M6MEQ, but has since
changed to 2E0WBL...congratulations on the upgrade!
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2E0WBL
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« Reply #7 on: March 13, 2014, 11:49:01 AM »

Dennis, thanks for the congratulations on my licence upgrade they're much appreciated, and thanks to everyone who's responded to my query.

I'm aware of the purpose of the CTCSS system, and how it's intended to be used.  Now, I don't know about the repeaters over the pond, but here in the UK it's common for them to require a CTCSS code (as opposed to a tone code) for access, but they don't then re-transmit using a code.  Due to the congested airways in the UK the CTCSS access code has been adopted to stop the repeaters blocking each other up.  

I've asked a couple of other TS2000 users in my club (wadarc.com) if they had any ideas about this problem, but neither of them had even tried to use the 6m repeaters!  One did suggest that a CD ROM control programme might include a way round the problem?

73's
Andy
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AA4PB
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« Reply #8 on: March 13, 2014, 02:31:39 PM »

I'm not familiar with the TS2000, but I've seen HTs over hear that mistakenly use the term "tone" to mean a ctcss tone rather than tone burst. Perhaps that is confusing the issue?
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AA4PB
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« Reply #9 on: March 13, 2014, 02:51:45 PM »

I just took a quick look at the TS2000 manual. Page 33 explains the tone use.
Tone referrers to the sub-audible transmit tone (what the repeater wants to hear in order to open its squelch). You turn "TONE" on, you select "continuous", and you select a tone frequency (88.5Hz for example) that the repeater requires. The tone will then be transmitted continuously along with the microphone audio any time PTT is depressed.

CTCSS refers to the tone squelch system in the receiver. If you turn CTCSS on then your receiver will not open the squelch unless the transmitting station includes a matching tone frequency. You want to turn CTCSS off since you want your squelch to open any time there is any signal on the frequency (whether it has a tone or not). If you turn on CTCSS then the transmit "tone" setting will be disabled and the transmitter will transmit whatever tone you have selected for your receive CTCSS.

Note: Turning on burst tone mode causes the selected tone to be transmitted only momentarily when the PTT is first depressed. Some repeaters used to use an audible momentary tone burst to activate the repeater.
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2E0WBL
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« Reply #10 on: March 15, 2014, 12:23:34 PM »

AA4PB - Thanks for your reply.  " If you turn on CTCSS then the transmit "tone" setting will be disabled and the transmitter will transmit whatever tone you have selected for your receive CTCSS".
My problem is, as I said in my first post, that I need to be able to disable the CTCSS on RX, but still have it operate on TX, so I will be able to transmit and access the repeaters which require a CTCSS tone, but which don't then transmit with a tone.  If the CTCSS is applied to the RX as well as the TX, I can't hear the repeater.  If you can figure a way of doing this, I'd really appreciate it.

73's
Andy
2E0WBL
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AA4PB
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« Reply #11 on: March 15, 2014, 12:49:57 PM »

You are being confused by the manufacturer's terminology. Using their terminology (which is not technically correct), you want to turn on "TONE" and turn off "CTCSS". The "TONE", when set to "CONTINUOUS" mode, amounts to transmit only CTCSS on the TS2000. Give it a try and see if that doesn't fix your problem.

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KB2VUQ
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« Reply #12 on: March 15, 2014, 08:59:20 PM »

Lets try to simplify this....

Turn on the "T" and turn off the "CT"...
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2E0WBL
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« Reply #13 on: March 16, 2014, 05:26:06 AM »

Everyone,  thanks for your assistance.  Having had a hunt around on the web, I discovered the article below which explains things in the UK pretty clearly.  The repeaters here do transmit with a CTCSS code, which is not as I had thought, but only when in talk through. That was what I had missed out on....my mistake. So, now I know.


CTCSS on the Repeaters.

 

CTCSS- Continuous Tone Controlled Squelch System- is now used on most UK repeaters.

The system is used in addition to the conventional 1750Hz toneburst access system, not as a substitute, its use is at the discretion of each Repeater Group, except on 6 metres, where it is compulsory.

The official RMG specification for CTCSS is:-

There is no need for any groups to fit CTCSS to their repeaters, but if they wish to do so they must adhere to the RMC plan which is based on geographic areas (see below)
CTCSS when available is in addition to the standard 1750Hz toneburst access NOT a substitute.
The current standard remains unchanged. It expects a normal receiver sensitivity of 0.3µV
In practice, this means that a signal of about 0.6µV is required to open the squelch which usually has a 6dB hysteresis. However when the repeater's receiver detects its own CTCSS sub-tone, the squelch can open at a lower level, providing a better service for those equipped to take advantage of it, while not affecting the service to others.
The repeater has to radiate the same sub-tone but only when it is in talkthrough. Thus stations which monitor the repeater with receivers using CTCSS need not hear the regular morse identification.
Where a repeater is fitted with CTCSS it must identify the sub-tone used by appending a word gap (7 dot spaces) and then the sub-tone identification letter to its morse identification so that all users are made aware of the sub-tone required.
The recommended deviation for the CTCSS tone where used shall be 500Hz ± 200Hz

 

Nine different sub-tone frequencies are allocated for UK repeater use:-

 

Tone A = 67.0Hz
 Tone B = 71.9Hz  Tone C = 77.0Hz 
Tone D = 82.5Hz  Tone E = 88.5Hz  Tone F = 94.8Hz 
Tone G = 103.5Hz  Tone H = 110.9Hz  Tone J = 118.8Hz
 

I hope this has proved of some interest. I now know how to access the 6m repeaters, which was the reason for my question.
73's Andy.  2E0WBL
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