Re: [digitalradio] 3rd Generation Digital radio
--- On Tue, 20/4/10, "John Becker, WØJAB" wrote: > I can't think back this far. What > came first - > Packer or Amtor (ARQ mode to boot) . Good question Amtor was developed by G3PLX circa 1979/1980. The first issue of the TAPR Packet Status Report newsletter was July 1982, see http://www.ka9q.net/psr-1.pdf So I guess a form of packet must have been in use slightly earlier than that 73 Trevor M5AKA
RE: [digitalradio] 3rd Generation Digital radio
Don't forget Hellschreiber in all this ! Simon Brown, HB9DRV http://sdr-radio.com > -Original Message- > From: digitalradio@yahoogroups.com > [mailto:digitalra...@yahoogroups.com] On Behalf Of "John Becker, WØJAB" > > I can't think back this far. What came first - > Packer or Amtor (ARQ mode to boot) . >
Re: [digitalradio] 3rd Generation Digital radio
I can't think back this far. What came first - Packer or Amtor (ARQ mode to boot) . At 12:03 PM 4/19/2010, you 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.
Re: [digitalradio] 3rd Generation Digital radio
I'd say the 3rd generation has been available for several years now. Both Kenwood and ICOM manufacture VHF and UHF mobiles, handhelds and repeaters for the new standard. The key advantage is its spectrum efficiency. It supports both voice and data but uses 6.25 kHz channel spacing. D-STAR typically needs 10 kHz channel spacing. 2010 - NXDN™ Forum and dPMR MoU collaboration http://www.southgatearc.org/news/march2010/nxdn_dpmr_collaboration.htm 2009 - Guide to Digital PMR http://www.southgatearc.org/news/august2009/guide_to_digital_pmr.htm 2008 - Icom IC-F4029SDR Transceiver for Digital PMR 446 http://www.southgatearc.org/news/march2008/digital_pmr_446.htm 2008 - The Gadget Show tests digital and analog walkie talkies http://www.southgatearc.org/news/november2008/gadget_show_radio_tests.htm 2007 - Ofcom statement on Digital PMR-446 http://www.southgatearc.org/news/september2007/digital_pmr446.htm 73 Trevor M5AKA
[digitalradio] 3rd Generation Digital radio
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.