My IC-02AT is usually over 1hz off of all the base CTCSS tones, sometimes more, but most repeaters allow it through...
A watch crystal should be good enough to make the timing right... with some of the newer MSP430's you get a DCO that can hold it's frequency to a multiple of the low frequency crystal if you need to lock to a little higher a frequency... Matthew Peters On Sun, 7 Dec 2003, J.C. Wren wrote: > CTCSS is the correct name, in the context of repeater usage. They're > considered sub-audible because they're outside the normal audio passband of > the radio. Internally, most radios roll off everything below ~300Hz and > above 2700 to 3000Hz. > > Most CTCSS detectors require a fairly pure, clean tone. I'm not sure > what > the tolerance of the decoders are, but several of the CTCSS chips spec 0.3% > accuracy. That's 0.41Hz at 123Hz. > > http://www.xs4all.nl/~hanvu/ctcss.html is a complete list of tones. > > --jc > > > On Sunday 07 December 2003 16:48 pm, Chris Howard wrote: > > On Sun, Dec 07, 2003 at 10:00:07PM +0100, Chris Liechti wrote: > > > Chris Howard wrote: > > > > What I want to build is a little card that will > > > > output three different sub-audible tones, 100hz, > > > > 123hz, and another similar one. I would like three > > > > > > if "sub-audible" means that the human ear cant hear it then i have to > > > say that those frequenciey are clearly _not_ sub-audible. but it may be > > > that your kenwood transeiver has a band pass built in, so that it does > > > not transmit those low frequecies, or the receiver does filter them. > > > > I think the official name for them is CTCSS tones. Many repeater > > systems require them. > > > > > yes, timer a or b in PWM mode is well suited to generate tones. > > > that way you can program the frequency in CCR0 and set CCR1 = CCR0/2 for > > > a symmetric square output signal. you can also add a RC lowpass at the > > > output to filer out the harmonics. > > > > Thanks! > > > > ------------------------------------------------------- > This SF.net email is sponsored by: IBM Linux Tutorials. > Become an expert in LINUX or just sharpen your skills. Sign up for IBM's > Free Linux Tutorials. Learn everything from the bash shell to sys admin. > Click now! http://ads.osdn.com/?ad_id=1278&alloc_id=3371&op=click > _______________________________________________ > Mspgcc-users mailing list > Mspgcc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/mspgcc-users > >
