That was why someone suggested that 220 be looked at rather than 440. Both 2m and 440 have heavy usage with analog repeaters plus SSB/CW (and satellite). Thus 220, or 900 Mhz, would be far better for a third generation digital (trunked) network. After all it is going to mean a new radio anyway.
As for "tactical", that is a term used by the ARES group in my county for five simplex frequencies on 2m and five on 440 that are backup for when the repeaters go down. They are also used during exercises and during disasters for local communications at the scene. The national trunking networks on 800 have five frequencies that are for simplex and "tactical" operations. If we have a ham version of a trunked, digital network, that is a feature that needs to be included. Just some thoughts but you did bring up good points. --- In [email protected], "af6it" <af...@...> wrote: > > A perhaps narrow outsider's opinion: There is potential here for both good > and for wreaking havoc with fellow users of VHF/UHF amateur bands given a > paradigm shift into a G3 digital era. Improving upon packet's abilities could > be a very good thing- particularly for those involved in EmComm. But running > analog FM users away just because commercial & gov't users have had the > change to digital crammed down their throat would be a very bad idea. If it > can peacefully co-exist with current users- then no problem! As a potential > user I confess that I'm not terribly interested in digital modes up here. > Adding more specialized equipment has no appeal nor any advantage to my > operating style. HF digital is much more exciting & useful to me. (YMMV) My > greatest fear is that someone in an urban upper 5% utilization zone might > find a listening ear in the FCC who would recklessly force a draconian change > to make us all go 100% digital VHF & above- even for the 95% who have no > trouble finding available analog freq's. This is ham radio after all- not > hard core government EmComm! (Which is I suppose STILL waiting to see how > beneficial the move will prove to be for them) > > One other comment: "Tactical" ham frequencies??!!! What in the world??? For > ham SWAT teams? <LOL> Didn't Indianapolis PD get into trouble for less than > that? :-) > > 73 de Stu AF6IT > > --- In [email protected], "Greg" <n9nwo@> wrote: > > > > If the first generation of digital was PACKET-IRLQ-Echolink-APRS > > (generation Zero was CW and RTTY), then the second generation was D-Star. > > D-Star brought everything together along with digital voice. While D-Star > > is great, its technology is already dated. > > > > So what will the third generation of digital radio look like? I am > > thinking that it will be more like the Trunked Radio (digital) or either > > P25 phase II or TETRA. TETRA is 25 Khz wide channel with four TDMA slots > > with a very low cost handheld (under $400) and is used in Europe within the > > 400 Mhz band. P25 digital currently is 800 Mhz, FDMA (25 Khz channel). > > Phase II will move to a single 12.5 Khz channel with two TDMA slots. > > Additional capacity can be added with additional repeaters (12.5 Khz) > > working under a common controller. > > > > So, could we do something like that within amateur radio? We have to be > > above 220 Mhz in order to get 9600 baud rates. If we look at bands, 900 > > Mhz may be to high and 440 may be too crowded. It was suggested that we go > > 220 as it gives a mix of characteristics of both 2m and 440 and is fairly > > open. If we go to P25 (phase II) we do have to overcome the cost of the > > VOCORDER. That could be done with open P25 in software in an software > > defined radio (SDR). Most of the military radios these days are SDR. > > > > A trunked system would allow us at least state wide communications that > > would include voice, data and position reporting (APRS). Also that one > > could link into the system via VoIP (like D-Star or Echolink). A small > > community might only need a single repeater with two FDMA slots. In big > > cities it might be that there are multiple repeater sites with two or three > > repeaters (4 to 6 slots). Also five simplex frequencies for tactical > > operations or remote areas (like using 146.52 and 144.39 now). > > > > Using 9600 baud rates would allow for greater amounts of information. And > > an SDR would be flexible enough to handle such data rates. > > > > Any comments or ideas? Let the flame wars begin..... > > >
