Re: [bascom] OT : CTCSS (subaudible tones) encoder / decoder

["Paul Boldt" <boldt@online.de>]

Hi Luke,

(I'll also will contact you off list for details)

 

shure, I have been thinking about the MX-comm chips, but as usual, it's hard to get stuff here in Europe if you need it for hobby purpose.

If you want to buy 10K you are a customer of interest, if you only need some few devices they charge you with a $25 handling fee,  a $10 cod fee and they price it double or more the 100pcs price.

If I then have to order it in the US , our customs charge some more 20% customs fee plus the usable VAT (16% in Germany) .

That's why I didn't succeed in ordering my MAX5102 (ZN429 replacement), all these fees brought my price up from $3 to more than $6 ea in 100pcs qty.

 

What I was looking for was some easier to get CTCSS IC, but there seem not to be much manufacturers .

 

Now, your idea of generating and decoding it by software seems to be a good alternative solution. No, I dont want to support all tones,but several, let's say some 10 to 16 ones , but if I`m on my way I even could implement all 38.

If it was only one or two I would have been thinking about NE567 decoder such as I'll do for 1750Hz .

But now, your suggestions bring me to a different idea, I could use a 89C1051 or 2051 (depends on which one is cheaper hi) to make my own (standalone) CTCSS tonedecoder unit.

 

My general idea is to keep the repeater in "open architecture" so that I can add as many features as I want, even now it is not  allowed to implement other than speech relaying , opening relay with 1750 Hz or DTMF tone, and that's it.

As an experiment one is allowed to add other features, but not permanently.

Only if one doesn`t start to implement other features like tiny pager, wx info, etc it will never be allowed.

 

So, If anyone has some good ideas just let me know, and Luke, I`ll contact you in direct mail.

 

Vy 73 de Paul, DB8ET

 

----- Original Message -----

From: Luke Rainville

To: bascom@grote.net

Sent: Wednesday, July 04, 2001 1:00 AM

Subject: Re: [bascom] OT : CTCSS (subaudible tones) encoder / decoder

Hi Paul,

 

From experience, I can tell you that very accurate ( .1 Hz) CTCSS generation lends itself better (really it's just easier to code) to an 8052 device using timer2.  That said, real world CTCSS decoder systems are supposed to accept a +/- 1.5 Hz error, and many are looser than that.  Email me off list, and I'll be happy to help you with the details.

 

The best I have been able to achieve (when trying to sythesize all CTCSS tones) using one of the timer0 interupts is about 1 Hz.  Decoding is simply counting pulses, and is just the reverse process. 

 

Have you thought about using an MX-Comm CTCSS encode/Decode chip, and just using the 4051 to control it?  Using the chip might even lower component count, since you won't need an op-amp circuit to feed your controller a square wave for decoding or the other half of an op-amp or filter chip for filtering the controller square wave.  My thought on CTCSS is the same as DTMF - using a support chip makes things better, and cheaper.

 

Do you plan to make your controller capable of selecting all 38 analog CTCSS tones or just one?  

 

Regards - Luke - K6LO

 

 

----- Original Message -----

From: Paul Boldt

To: bascom@grote.net

Sent: Tuesday, July 03, 2001 2:50 PM

Subject: [bascom] OT : CTCSS (subaudible tones) encoder / decoder

Hi,

I have the intention to make my own HAM repeater-controller to control a 2m amateur-radio repeater. It will be based on a AT 89C4051 and I am planning to integrate all possible stuff like for instance DTMF, CTCSS (subaudible tones) and even a sort of pager-function.

DTMF is no problem, I have some M8870 ic's and BASCOM even supports DTMF output.

My problem is CTCSS , I searched the www but not really fond a simple cirquitry to do the encoding nor the decoding.

 

Any suggestions are welcome, BTW , has somebody done a lookalike project before?

 

best regards Paul