"Jose" wrote in message
. net...
Can you explain me please how this(meaning increase of channels by
reducing their width) will increase the number of available
frequencies
for the increasing number of VOR stations.

It means you can put channels in between existing channels. If done
right, there is no interference. It requires that existing
transmitters be modified (if they are not already "narrow" enough) so
that there in fact is no interference.

Actually the biggest limiting factor is the receivers. I'm not sure
what was done during the VOR changeover, but I can say that when the FAA
went from 50Khz to 25Khz spacing for voice channels, the only change to
the ground equipment was to change the bandpass of the receivers. Older
receivers were less sensative and had to have a wider bandpass. As
receiver technology progressed, the bandpass could be made more narrow.