My measurements were made on an Alinco DR-605T radio which, given the known deficiencies of the brand, may be unrepresentative of the state of the art. The TIA Standard 603 is dated December 2004, so it is likely designed to have rather liberal limits on decoder responses. I agree that modern DSP chips are capable of very fast tone recognition, but often those capabilities are poorly implemented in some transceiver brands.
The TIA standard also gives 250 ms as the maximum time for audio cutoff upon removal of the CTCSS tone without reverse burst STE, and 50 ms with reverse burst STE. The world would be a better place if repeater controller manufacturers included reverse burst capability... 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Ken Arck Sent: Saturday, December 29, 2007 5:50 PM To: [email protected] Subject: Re: [Repeater-Builder] CTCSS Decoder Response Times I'm curious if you're talking mechanical or something else? Except for a funky MSF5000 I've been beating on (which takes a good 900 ms to decode 1Z), I've never seen performance as bad as you point out in an electronic type decoder. Mechanical, sure. For example, I have a reedless Mitrek decoder and that puppy is very fast, even at 67 Hz. Ken At 05:04 PM 12/29/2007, you wrote: Ken, TIA/EIA-603-C, the international standard for Land Mobile Radio performance, states that CTCSS decoder response times may vary between 224 milliseconds at 67.0 Hz to no more than 150 milliseconds at 100.0 Hz and above. I have measured response times of 80 milliseconds in some radios to tones of 250.3 Hz, when the response at 67.0 Hz was close to 200 milliseconds. So, you are correct that the difference in response times between low and high tones can be measured in microseconds- in my experience the difference can be 120,000 microseconds and still meet the spec. 73, Eric Lemmon WB6FLY -----Original Message----- Ken Arck wrote: > > At 02:29 PM 12/29/2007, you wrote: > <----Nope. A delay board won't do a thing for the decode pickup time > and probably not for the release time either. > > And a using a higher tone probably won't help either. You're talking > microseconds in difference between a tone at the low range and one at > the top end. > > Ken ---------------------------------------------------------------------------- -- President and CTO - Arcom Communications Makers of repeater controllers and accessories. http://www.arcomcontrollers.com/ <http://www.arcomcontrollers.com/> Authorized Dealers for Kenwood and Telewave and we offer complete repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net <http://www.irlp.net/> "We don't just make 'em. We use 'em!"
