I believe there is more that just amplitude involved Dan. The vocoder coding algorithm handles sound patterns to (hopefully) improve intelligibility. I remember part of the selection of the IMBE vocoder dealt with voice inflection and the receiving station being able to discern subtleties in voice - fear - panic, or so I have heard. Of course I very well may be wrong. I do remember the old Secode consoles having compression and alc on the TX - not sure about receive - made the mechanical clock sound like a teletype machine next to the mic. Lets see, in 1995 were you referring to Motorola DES voice encryption as the digital communications system ?
73, Steve NU5D Dan Hancock wrote: > I never cease to be amazed at how the simple answer to problems like > this get overlooked. > Give the FD /noise cancelling microphones. /The less background the > mic picks up the less distortion problem there is. > I've been on an 800 digital sytem for about 13 years now. Our earlier > purchased radios came with noise cancelling mics, that later ones > didn't. OMG what a difference. Some radios are so low in TX audio that > even with the console volume at full you have trouble hearing the > troopers. Then you get someone who's used to the noise cancelling mics > using the non cancellers and they blow you out of the console. I guess > the Motherola engineers never heard of ALC or the concept of using it > on the console to keep audio levels even. > > Dan Hancock N8DJP >
