VHF repeater access

Hi Ivan,

I corrected the points you mentioned and also changed the code a bit so that it is more accurate (ish) and goes up to up to about 16kHz.

I have added it to the three servers, along with loads of file corrections (destroyed by Teleport).

Also tidied up the links pages a lot.

Very best regards and thank you for your help. 
from Harry - SM0VPO

Hi all,
the free ISM 433 MHz band is inside the 70 cm ham band. This may be troublesome in some cases. Some type of interference protection may be necessary.

My pocket size Icom IC-7E, which I use for repeater access, can be progammed to any CTCSS frequency on any channel. The 1750 Hz burst can be used as well. Thanks to that I had never a problem opening any analog repeater so far, provided that I entered its parameters in advance.

VBR from Ivan

Hello Glenn,
Thank you very much for the information. It was very interesting reading.

The first option is almost exactly that which I have built, except that I did not use a crystal oscillator because the 12F509 has an internal clock. My PIC will also cover all the 50 tone frequencies quoted, but it can be programmed for any frequency between 0.5Hz to about 300Hz, within +/-0.5Hz (+/-0.1Hz below 100Hz). It will go even higher than that but the frequency increments become larger with increasing frequency.

The ATTINYX5 also has the same voltage requirements, but I noticed that it uses DDS to generate a sinusoidal waveform. That could be very useful. Mine is a simple square-wave with a bit of filtering, which is all I really needed to get it working. I really love tinkering with this sort of thing. The more simple it is so the better it feels.

In the 70s and 80s I worked for PYE telecom, and CTCSS was one of the features we used to setup for customers. From about 1985 I did a lot of work with the Zetron Community Repeater panel for another company (Tait). I left the UK around 1980, but I returned around 1990 for just one year after losing the job in Saudi.

1990 I also worked with "Selcall"; CCIR, EEA, EIA, ZVEI, DZVEI, etc. That was also mega-interesting. I once designed a system for mobile (vehicle) telephones installed on oil tankers and oil rigs in the North sea. A tanker would dial up the oil rig's ident and establish a connection. Modems then allowed the computer on the tanker to communicate with the rig to monitor the oil flow. If the pipe became disconnected then it had to be shut off instantly. There is a big trench in the North Sea so it is not possible to lay a pipeline to Norway.

I am glad they did not consider Selcall or DTMF for general amateur repeaters in Europe  

But CTCSS used for ham-radio is really interesting. The old 1750Hz "Tone-Burst" is illegal in the UK, or so I have been told. I would like to know why the change was made to use CTCSS in amateur repeaters. Before I left the UK there were several problems with UHF repeater outputs being within the same band as the remote locks for cars, and other services that could trigger a carrier-operated repeater. So I suppose the move to CTCSS was inevitable. I understand from colleagues in the UK that it is not so popular, especially on the 2m VHF band.

Thank you very much for the links, there was a mine of information, especially for the ATTINYX5 basic chip. I have never looked into that as I became somewhat blinkered by the Microchip Baseline and Midrange devices. I have a coupe of Raspberry-PI computers and and several Arduino micro-controllers. They are interesting, but I still keep going back to the Microchip family and the assembly-language.

Very best regards from Harry - SM0VPO

Hi Harry

Found another CTCSS (Motorola branded: "PL"/"Private Line" tone. Bendix King branded: "Channel Guard"...) module - two versions (a more "clever" module could use one pushbutton/rotary encoder for selection (next CTCSS) - and another pushbutton to morse the frequency (or a unique number) in the speaker or to a CTCSS-LED - or both - or let the microcontroller tell you the selected frequency):

Two Miniature Crystal-locked CTCSS Tone Encoders.
Do you have an elderly FM transceiver that needs CTCSS? Here is a very low cost versatile, accurate and super-stable CTCSS tone encoder module which should be ideal for your requirements. Two versions are described here, both using the same tiny single-sided PCB - The first is a BASIC encoder allowing link selection of one of four programmed tones, and yhr second is a MULTITONE encoder with Reverse Tone Burst allowing pushbutton selection of one of fifty CTCSS tones.
https://www.zl2pd.com/CTCSS_encoder.html
backup:
https://web.archive.org/web/20200719065929/https://www.zl2pd.com/CTCSS_encoder.html
Quote: "...
CTCSS tones generally still comply with the earliest EIA standard RS-220 first released back in April 1959.
...
Tones must be within +/-0.5%, with harmonics less than 10%
...
An 8MHz crystal was used here. These are inexpensive and widely available, and the desired tone resolution of 0.05Hz was readily achieved by the software. Temperature performance is consequently well within RS-220 limits.
...
this design generated a pulse-width modulated (PWM) output tone via a single output pin on the microcontroller. The 64 kHz PWM ‘carrier’ containing the modulating CTCSS tone can be easily filtered using a single resistor-capacitor low pass filter (R1, C2).
...
The resulting sinewave is very clean, with less than 1% distortion, and the 64kHz carrier is more than 40dB below the wanted CTCSS signal. No evidence of the PWM carrier could be detected on the transmitted FM signal with a spectrum analyzer.
...
Downloads
Software: The HEX files are available here for direct programming of your ATtiny85:
...
PCB Layout:
..."

attiny85 is still being sold:
https://www.mouser.dk/c/semiconductors/embedded-processors-controllers/microcontrollers-mcu/8-bit-microcontrollers-mcu/?q=attiny85

.

Let the microcontroller tell you the selected frequency:

Talkie: Speech library for Arduino.
https://github.com/going-digital/Talkie
Quote: "...
Talkie comes with over 1000 words of speech data that can be included in your projects. Most words only take a fraction of a KB, so you can add plenty.
...
Talkie sets up a special very high speed PWM, so audio can be taken directly from pin 3 with no other filtering.
..."

17 Sep 2013, Adding words or converting .wav file #4:
https://github.com/going-digital/Talkie/issues/4
Quote: "...
It looks like LPC-10 uses a very similar algorithm, with different coefficient encoding and bit mapping. That is publicly available, with source - but the official distribution is machine translated from FORTRAN and it shows.
...
bperrybap commented on 23 Jan 2014
As a point of information, there is also this speech code for the AVR:
http://www.societyofrobots.com/member_tutorials/node/211 [ https://web.archive.org/web/20170106211906/http://www.societyofrobots.com/member_tutorials/node/211 ]
It has amazingly compact text to speech using phoneme codes.
The actual speech output is not all that great, very scratchy and robotic.
...
ptwz commented on 8 Oct 2017
Hi there, just a shameless plug: To create bitstreams you can either use BlueWizard ( https://github.com/patrick99e99/BlueWizard ) or my command line port Python Wizard ( https://github.com/ptwz/python_wizard ).
They both import wave files and give you Talkie compatible bitstreams.
..."

Arduino speech synthesizer using the Talkie library:
https://rimstar.org/science_electronics_projects/ardunio_speech_synthesizer_using_talkie_library.htm
Quote: "...
Shown below is the circuit diagram for the last demonstration in the above video. To use the Talkie library yourself with your own circuit, the only thing you need is the speaker and optional amplifier on the right which is connected to pin 3 and to ground.
..."

Synthesized Speech using a small Microcontroller:
https://www.slideshare.net/iosrjce/synthesized-speech-using-a-small-microcontroller

-

More types of repeater in-band signalling mentioned:

Get the Right Signal Tone
https://hamradioschool.com/get-right-signal-tone/
https://web.archive.org/web/20210315045344/https://hamradioschool.com/get-right-signal-tone/

A Historical and Technical Overview of Tone Squelch Systems
A primer on tone systems, with a little on digital systems.
By Mike Morris WA6ILQ.
Lots of hams and scanner listeners use tone squelch today without really understanding it.
http://www.repeater-builder.com/tech-info/ctcss/ctcss-overview.html
https://web.archive.org/web/20200408191637/http://www.repeater-builder.com/tech-info/ctcss/ctcss-overview.html

Danish:
https://da.wikipedia.org/wiki/Continuous_Tone-Coded_Squelch_System
English:
https://en.wikipedia.org/wiki/Continuous_Tone-Coded_Squelch_System

Thank you very much, Ivan. I really do appreciate this, as always.

Abbreviations - I quoted Continuous Wave, instead of Carrier Wave.
I also thought I would try to make them either funny, or thought provoking. If you have any suggestions then all will be welcome.

Today I found one reason for the "correction factor". After the first count (variable) I repeated "Scale" (dc2) number of times. Repeat "Count" (dc1) was always re-seeded with 255. The very first instruction to test is decrement (and set flags), so the true starting value becomes 254, not 255. Count is now seeded with 000, which when decremented becomes 255. 

The article you have will not change, just a bit of code and numbers.

But you have a nice weekend.

Very best regards from Harry

Hi Harry,
I do not mind of course. I will write to you ASA I study your article.

VBR from Ivan

Hello all, just  little update:

Over the Christmas holiday I was not able to do anything in the garden with antennas as Maj-Lis really wanted me beside her for a cosy Christmas. This was the first Christmas we have had together for about 7 years. I have always worked over Christmas so that the other engineers with children could have the time off. This year Maj-Lis really wanted it together and the line manager gave me priority.

I was able to do some experiments with the PIC processor and I found that a simple tone generator is not so easy to program. The traditional "nested loop" timer can change the frequency in big, chunky steps with an 8-bit processor, so I really needed a 16-bit register. I learned a bit more about programming 8 bit PICs to get 16 bit count resolution. You will soon be able to read about that in the article.

As a spin-off, the 8+8-bit technique speeded up the generator enormously, so much so that it can be used for frequencies of several kHz, such as AFSK for RTTY, and even the traditional 300-baud or 1200-Baud modem encoder.

The article has been written and now it is hopefully being reviewed. I still have to sprinkle in a few photographs and drawings, to break up the monotony of pages of text. The final project works good, even though it is built as a "mid-air-rats-nest". At least I have now got a CTCSS encoder on my FT-290 (but at the moment it is taped to the back of the microphone with duct tape) and it didn't cost me a dime. Just one chip I had laying around, two caps, three resistors and a Zener diode.

I once read an interesting fact that men over 65 years use 3X more glue than adult men under the age of 65 years. Perhaps this means that older people are more inclined to "fix and find" than "throw and buy"? Whatever ... the project is completed for publication. I have some 3D printing to do before I can mount it inside the microphone. I don't want to drill and butcher my pristine FT-290 original microphone.

@ Ivan - Perhaps I should have asked first, but I sent you a copy of the document by e-mail (files not included). I hope that you do not mind?
The links to Feng5 and this forum should work ok. If you want to have a look at the files then please let me know.
I have already spotted three leading capitals errors, and the code can be further simplified by doing just one bit-test (If it is not a "0" then it must be a "1", so no need to test twice!). This will save 0.5μs and make the two timer loops more equal.

According to my calculations, I may be able to get 150kHz out of this generator, but the steps will be rather large. I will do a few tests for this as it could open up some more possibilities. Maybe I can't play with antennas or soldering irons in my lunch breaks, but I can still write programs, design 3D and even do a bit of "chassis-bashing" in the sheet metal workshop.

Ok, that was the update. Hope you all have fun. Very best regards and "good continuance" (a Swedish thing), from Harry - SM0VPO

Hi Andrew,
Yes, I will be documenting the mod. At the moment I am calculating the timing for all 50 CTCSS tones and I will add those to the source file, so anyone with a PIC programmer can burn a new chip for different tone frequencies.

I solved the timing problem by using two different delays for each tone; one timer and one range. That way the timing loop always has a value of between 150 and 255, which give nice increments.
The internal clock is only 4MHz so low timer values will give larger frequency steps. But it looks as though I can get 67.0Hz to 180Hz with better than +/-0.5Hz steps. The lower the tone frequency so the more accurate the tones are.

The CTCSS tone frequency tone frequencies are also rather interesting. There are tones at exactly 100.0Hz and 150.0Hz, which I thought would be asking for mains-hum pickup problems at the repeater, assuming it is powered from 50Hz AC. Maybe not a problem in the USA and ME. But in EU it would make the TX encoder very simple

As regards the circuit, using 8-pin DIL processor circuit, it is very simple: 5V to pins  1 and 8. Tone comes out of port-1. Nothing complicated. Only need to add an RC filter.

BR Harry - SM0VPO

Hi Harry, happy to have been of some help, are you going to document the "mod" on your site ?

Hello again Andrew,
I already have a module, and it is dead-cheap. It is a PIC12F509 and it has been programmed with the internal oscillator (no external components) to generate 77Hz and 123Hz, which covers all the Repeaters in the Stockholm area.

It outputs the tone from one pin, one pin for 77/123 selection (switch on the microphone). Just three resistors and two caps filter the output and stuff the tone into the microphone.
PIC powered from 2 button cells (and a diode) that is trickled-charged from the PTT line.

When you hit the PTT switch it grounds the PTT line, but the battery keeps the PIC alive during transmission.
I am just working on the assembler to add the calibration values for all the CTCSS tones from 67.0Hz to 254.1Hz. I have a problem with frequency tolerance at the higher frequencies because an 8-bit register can only store a max value of 255 (at 65Hz), which means the frequency steps are a bit off at the higher tones where the count is smaller. Not too worried as I only need a maximum of 123Hz.

It can be done if I also include the second time-delay routine delay factor (multiplier), and change it to a smaller value. I might have to do that.

Later on I may use some of the other unused pins and either:
1 - Have a resistive 4-bit D-A converter to improve the sine filtering 16x
2 - Use a rotary DIP switch to allow selection of 16 tones.

But at the moment it has got me on the air again and I can access about 6 different repeaters, from the South of Stockholm to Uppsala.

I have seen several modules and your links were starting points for me to Google it. Thank you very much. I really appreciated the information. That is what started this quest, although I do think that HB is always better :-)

Very best regards from Harry - SM0VPO

Admin wrote:

Andrew wrote:
https://pe1grl.khds.nl/ctcss/ctcss.htm

https://www.tuckley.org/ctcss/

https://billingtonrepairs.wordpress.com/modifications/ctcss-for-the-yaesu-ft290r-mk1/

I will look at the links you gave and see what others have done.

Harry, the first link carries a circuit for a full CTSS module to be inserted into the FT290 and the page also carries a link showing how to connect the module inside the 290

This may be useful SM repeater list

VBR from Ivan

Admin wrote:...But modifying my FT-290 to add CTCSS could be really interesting. I only need to add a tone to the TX, so perhaps this can easily be injected at the microphone...

Hi Harry,
a high-pass filter with cutoff frequency of 300 Hz may be necessary on the RX output, so that the CTCSS does not disturb on receive.

VBR from Ivan

Andrew wrote:Harry, just some pointers

https://pe1grl.khds.nl/ctcss/ctcss.htm

https://www.tuckley.org/ctcss/

https://billingtonrepairs.wordpress.com/modifications/ctcss-for-the-yaesu-ft290r-mk1/

HTH

Hi Andrew,
Thank you very much for the links. I appreciate that.

I was working with CTCSS professionally back in the 80´s, even SELCALL (ZVEI, D-ZVEI etc).But modifying my FT-290 to add CTCSS could be really interesting. I only need to add a tone to the TX, so perhaps this can easily be injected at the microphone.

I think I still have a CTCSS module installed in my old GDO. I used it in Saudi to generate a CTCSS tone and another oscillator for 1kHz, that injected into the 21.4MHz Intermediate Frequency. I could open the receivers and generate a tone for testing the system. Saved having a huge Marconi 995 generator and tone generator in the car

I will look at the links you gave and see what others have done. To be honest, VHF / UHF repeaters have never really interested me since I got my A-Class license, so I may do something in the future. It would be nice to monitor a local station and listen to the locals.

I used to find VHF repeaters were a "stage for fools", although that was in the UK in the 80's. Loads of "squeekies" who misused the system:
"'Ello der, dis is Idi Amin ..."
"'Ello der, diss is der queen mudder. No praps I won't get away wiv dat one!".

Here in Sweden, in the 90's and early 2000's, the VHF repeaters were taken a lot more seriously, although activity was much less. They also had a series of interconnected repeaters across the country to form a huge network, which gave a lot more activity and regular, serious use. If it is still there (and non-digital) I would like to monitor that one.

Thank you very much for sharing your knowledge and links. I will read them all later today.

Very best regards from Harry - SM0VPO

Ivan wrote:Hi Harry,
you probably encountered a DMR (Digital Mobile Radio) repeater, originally a profi standard, accepted also by hams. It requires a digital or hybrid TRX, registered into the system to get a unique numeric identifier. CC is a color code. If regions of two or more repeaters on the same frequency channel overlap, they are distinguished by their CC. The default value is CC=1. TDMA is used for increased speech capacity and privacy.

Try to find a classic analog repeater if there is any...  

VBR from Ivan

Hi Ivan,
Thank you very much for the info. It is very rare that I ever use VHF or UHF. So things have changed in just a few years
I will have to have a good scan and see what I can find. They usually have a periodic broadcast of callsign, so it is just to listen and log.

I am not sufficiently interested in getting any new equipment, so it is either analogue or nothing, for me, unless I want to put up my own retro-repeater. I believe that is possible under Swedish rules and regs.

Very best regards - Harry - SM0VPO

Harry, just some pointers

https://pe1grl.khds.nl/ctcss/ctcss.htm

https://www.tuckley.org/ctcss/

https://billingtonrepairs.wordpress.com/modifications/ctcss-for-the-yaesu-ft290r-mk1/

HTH

Hi Harry,
you probably encountered a DMR (Digital Mobile Radio) repeater, originally a profi standard, accepted also by hams. It requires a digital or hybrid TRX, registered into the system to get a unique numeric identifier. CC is a color code. If regions of two or more repeaters on the same frequency channel overlap, they are distinguished by their CC. The default value is CC=1. TDMA is used for increased speech capacity and privacy.

Try to find a classic analog repeater if there is any...  

VBR from Ivan

I have a question for you guys,
I resurrected an old FT-290 last night. I tried to access the local repeater, but there is no VHF repeater I can access.

Now when I check the Swedish Radio Society for repeater access info I find loads of WeIrDe information.
Tone-lock - sub-audio tone I can understand, but not my FT-290 - no tones
CC1? - What the dickens is CC1?
I also see "digital" modes.

Does anyone have any clue as to what has happened to the old-fashioned analogue repeater?
Can anyone explain what CC1 is? (CC2?)

Best regards Harry - SM0VPO