Bill Powell wrote: > 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.
Definitely do the math. Can you describe any normal splinter frequencies you can't get to using those two offsets combined. (It's a trick question... there's really no issue there... most commercial rigs only do 5 and 6.25 internally too. I had to have a 1/2 hour phone conversation with someone a lot quicker at math than I am to figure it out, but then the light bulb went on.) > 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? Well we will eventually have them on adjacent pairs at 12.5 KHz spacing here... will let you know if it causes problems. Even 15 KHz spacing on analog VHF is a pain in the butt, since user radio's front-ends are wide, and the real required bandwidth of a 5 KHz deviation system is 16 KHz, as we've all learned over the years... > 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. The problem there is the end-users... forgetting to switch on their FM Narrow mode, and/or users who "hear the repeater fine" but can't figure out why they can't "get into" the repeater they hear with their 5 KHz deviation FM rig. That problem would be so ugly that it'd take years of user education to avoid it. "You're too quiet!"... I can hear it now. > 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. Or work with bored, boring analog system owners... many people would be amazed how many backyard pairs could be "had" for the price of a single new rig so the operator could try out the new system himself/herself. (Disclaimer: If the area has a REAL 'waiting list', conversion of a system from analog to digital might be workable, but you'd be "jumping the line" and probably piss off some folks. But if the local area has no official waiting list, and you've already been told "no pairs", getting creative is the only way to go.) > 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". A very good sales pitch, and perhaps budgeting for buying them their first user rig. Or maybe you start with a repeater that's dual-mode like a P25 Quantar or MASTR III, so they can still use their analog gear... to start with. > 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. It's already happening... it just has to be "shaped" into something good in each coordination area. Great comments Bill. Nate WY0X
