Low volume

Hi;
I have noticed that a lot of the CSX radios produce very low audio on the VX-150 that I am using as a scanner. NJT trains usually come in much louder, and some CSX trains do, but I am curious as to how the RR employees hear the transmissions if the modulation level is so low. Of course, if I wear my headphones, as I believe engineers / conductors do while operating their locomotives, it is easier to hear the aduio, but it is still much lower on CSX than on NJT.

Any ideas?

FW

CSX uses low volumes system wide I have a Pro 95 portable and I nerver clearly hear the engineer speek, but the dispatch always comes in clear.

CPSK wrote:Hi;
I have noticed that a lot of the CSX radios produce very low audio on the VX-150 that I am using as a scanner. NJT trains usually come in much louder, and some CSX trains do, but I am curious as to how the RR employees hear the transmissions if the modulation level is so low. Of course, if I wear my headphones, as I believe engineers / conductors do while operating their locomotives, it is easier to hear the aduio, but it is still much lower on CSX than on NJT.

Any ideas?

FW

Conjecture, but I suspect that CSX has been installing the newer narrow band deviation FM transceivers that will become mandatory by FCC regulation in a few years. When a narrow band transmitter 'talks' to a matching narrow band receiver, there is no loss in audio volume since the receiver bandwidth is designed to match the lower deviation modulation transmission. So crews would hear fine at normal audio levels, no different than conventional bandwidth. However, receivers such as most (if not all) scanners on railroad frequencies are set to receive +- 5kHz deviation and will produce low volume from a +-2.5kHz deviation transmission. Same is true for older railroad transceivers, where the audio from narrow band will be lower.