There's a click generated every time a light switch opens or closes
anywhere in the neighborhood, also aquarium heaters, furnace
thermostats, furnace fan switches, motor start switches, TV sets, and
computers, e.g. ANYTHING that's turned on or off. The sound is different
in the Tentec because its filters don't ring as much as Collins or rice
boxes which tend to ring for a significant time and turn a click into a
crash. Collins filters ring long enough that the clicks from line noise
arcs that should be limited to twice per cycle (per phase) get run
together. The same thing often applies to lightning static. In the
Tentec, they are clicks, in the other filters they are turned to long
crashes. Then the FAST acting AVC in the Tentec deflects the S-meter and
holds for a while.
It would be hard to not have such AGC response and still have the AGC
work well on audio signals. Probably what it needs is a dedicated DSP
for the AGC that could discriminate between a pop and a fast rising
voice syllable or CW dit and could limit the amplitude of the pop
without reading it on the s-meter but do the AGC for the preferred
signals properly. Probably even with a DSP handling the AGC, it would
also need to handle the audio so it could delay the audio while it
determined the appropriate treatment.
73, Jerry, K0CQ
--
FAQ on WWW: http://www.contesting.com/tentecfaq.htm
Submissions: tentec@contesting.com
Administrative requests: tentec-REQUEST@contesting.com
Problems: owner-tentec@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|