At 9/19/2008 21:48, you wrote: >What signal are you using as the COS from the receiver? If you use RUS >you will have a combination of the squelch and the CTCSS detect. The two >are anded together so that both have to be present for RUS to be active. > >If you are using only the detected CTCSS you will have the hangover you >mention as it takes a short time for the detected tone to clear out of the >filter and turn the detect output off. > >Typical operation using RUS and a CTCSS decoder is that the RUS signal >will delay slightly going active as the tone decoder is locking on. Even >though the CAS has gone instantly to active, this slight delay will be >present due to the AND gate action. At the end of a transmission, the RUS >will go inactive instantly, as soon as the CAS signal goes away, even >though a CTCSS signal detect is still present. So RUS gives you the best >of both signals, delayed keying (only a few tens of milliseconds) and a >fast unkey (the squelch mod comes into play).
Only problem is the RUS signal is already ANDed in the radio. Most repeater controllers made today will perform this function for you, & in addition some of the newer ones like the SCom 7330 have different access modes for voice & DTMF paths. This is significant in that you can set your DTMF access to be pure CTCSS so that brief chops in your signal that would normally cause a brief closing of the noise squelch won't cause the controller to interpret that as the end of your transmission & try to execute a partial command. IOW, you can achieve slightly improved commanding performance by using CTCSS only mode instead of CTCSS AND COS. If you have EOT command execution disabled it doesn't matter, since the carrier squelch chopping will have no effect. BTW, I found the RUS line in Mastr IIs & MVPs to have a slight delay on opening even in COS mode, causing the chopping on weak signals to be much more noticeable. I use CAS instead, which has a faster attack time. Bob NO6B
