> "Jeff DePolo WN3A" <[EMAIL PROTECTED]> wrote: > > Worked very well as long as the microwave > > hops to the site didn't have too much > > group delay. > > Those Allen Avionics analog delay lines have horrible group delay,
Not uncommon. The real setup is to have equalization along with the delay lines. You'd need it anyway if you're dealing with often neglected microwave hops. > distortion/ringing, and frequency response abberations. > I've put them on my HP 8903 audio analyzer and decided > they weren't going to be worthwhile for my simulcast > repeater project. The original application was a tone and voice paging system. You'd have to know what this delay line was orignally spec for. > You can tweak their performance them to some > degree by tailoring both the source and load > Z depending on the delay setting but I never > found a combination that I was thrilled with. Loading other than the design impedance changes the operational preformance pretty fast. The unit described is probably an early or mid 80's vintage at best. Things are much better these days, and a lot cheaper. > I've got several GE Delta-S radios on the > air as exciters that I modified for use > with an external GPS reference oscillator. Nice, but one must start with the initial system preformance and align it right. Most people don't know how to properly align simulcast systems. > Right now they're on the air as a > "sloppycast" system with no audio > delay correction. Probably sounds rough in areas with overlap. > Someday when I have more time (yeah, > right) I want to work on a digital delay > solution. For now, lacking audio delay, S-Comm makes a killer digital delay board that's really cheap (cost wise) with excellent preformance. If you have an older controller with an audio delay board, you can diddle it, but it won't stay on long term. You'd have to reset it every x-months/weeks. You need one less number of delays than transmitters you have on the air. > the repeaters that are being sloppycasted > are far enough apart that the distortion > in areas where there is a little overlap is > noticible but not unbearable. It's been done before, even in some commercial dual mountain repeater systems. > How well did the voice simulcast system work > with the AA delay lines? Every system required a proof of preformance, which means it had to work well. I don't remember the exact model of delay lines we used, but additional hardware is/was always required to make them play well. > How bad was the audio in the areas with > common coverage? You could not tell it was a simulcast system, other than it was loud in all places and sounded great. > I've heard voice paging on Micor PURC > simulcast systems and always though it sounded > horrible... --- Jeff Then something was not done right. Every one of them should sound good, else its back to the drawing board. cheers Jeff regards skipp025 at yahoo.com Yahoo! Groups Links To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
