--- In [email protected], Ron Wright <[EMAIL PROTECTED]> wrote: > For D* there is the one issue of less bandwidth. D* occupies about > 6 kHz, about 1/3rd that of analog allowing for putting 2 D* in same > space as 1 analog. This little tidbit of "information", courtesy of ICOM's badly misleading charts, needs to be laid to rest once and for all.
Although the bandwidth occupied by D-Star and other digital modes is 1/2 (or less) than that of wide band FM operation it DOES NOT mean that one can "automagically" get 2 for 1 by going digital. However, allocating a full FM channel to a D-Star or other narrow band repeater is a complete waste of bandwidth. Something needs to be done. . . First: It's not necessarily simple to change repeater frequencies. We are channelized in our repeater operation. In some places 2M channels are allocated in 15 kHz and 20 kHz (I hope there are no 25 kHz) channels. D-Star repeaters can operate on ONLY either 5 or 6.25 kHz channels. Do the math: If you can't divide the "new" channel by 6.25 or 5 it can't be used for D-Star. The same for many other synthesized radios. Second: We have and live by band plans. As a coordinator I would never consider putting both an digital and analog repeater on the same channel with overlapping 19 dBu contours. Tis best to not mix the lions and lambs. I'm not even sure about sharing a channel between D-Star and P25 digital. Any volunteers? Third: What do we really want to do? If bandwidth reuse and maximizing channels is the ONLY intent, Narrow Band FM works just fine too. In this case, 12.5 kHz channels make the most sense for everybody. If it's just a case of finding a way to weasel "new" channels for new D-Star toys, get thee to the back of the line; we have a waiting list. Fourth: The taxi is already occupied. There are many, many existing systems and users on the current channels. How does one convince them that it is their best interest to move off "THEIR" channel to make room? In MANY cases, existing repeaters are crystal controlled and not easily moved even "only a couple of kHz". In summary: No matter how we do it, gaining / splitting channels is by no means simple - especially when the human element is added to the mix. But, we have to do "something" sooner or later. JMNSHO, Bill - WB1GOT
