Re: [digitalradio] VHF / UHF Digital Beyond line-of-sight
Hi Tony, Thanks for making the recording of aircraft reflections. Yes, we also see and hear aircraft reflections mixed with atmospheric disturbances all the time. The aircraft reflections sound similar to what you hear on the beacon, and you can identify those because they vary in frequency and intensity as the airplane approaches or recedes, just like you hear. However, what we experience on UHF over longer paths is a constant chopping up of the SSB phone signal, or narrow digital signals, and that seems to correlate with the Hepburn propagation maps, especially when the path crosses two or more levels of ducting, when signals can be strong, but SSB is still not very understandable. When both stations are within the same ducting level, the only audible Doppler effect is usually reflections from airplanes, and sounds much like your recording. When there is no propagation enhancement showing on the Hepburn maps, there is usually a fast, constant, chopping up of the SSB phone signal, and when we switch to a relatively wide digital mode, like Olivia or Contestia, which continues to print for a couple of seconds after transmission has ceased (due to the interleaving and FEC, I guess) print is perfect. The frequency of the audible chop is generally around two to three times per second, which is less than the latency of the digital mode. Those modes which display very little or no latency seem to be the ones that fail to print. Over the next few weeks, we are now going to compare Contestia variations with different bandwidths and latency to see how print compares to the observed period of chop on SSB phone. 73 - Skip KH6TY
Re: [digitalradio] Multipsk
Hello John, You must normally start the Instal.exe to instal Multipsk (which will create and fill the Maps sub-directory). You can also copy the Multipsk Maps sub-directory from another Multipsk implantation. 73 Patrick - Original Message - From: jgmags2000 jgmags2...@yahoo.com To: digitalradio@yahoogroups.com Sent: Tuesday, April 20, 2010 12:54 AM Subject: [digitalradio] Multipsk Hello Group, Upon starting MultiPsk, I get an error message No sub-directory Maps!? Any way to fix error? 73, John KJ1J http://www.obriensweb.com/digispotter.html Chat, Skeds, and spots all in one (resize to suit)Yahoo! Groups Links
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] Re: 3rd Generation Digital radio
I think you missed a generation or two. First generation - CW (binary states plus time) Second generation - RTTY and FAX Third generation - AX.25 packet Fourth generation - what the OP called the first generation etc... 73 de Dave, NF2G
Re: [digitalradio] VHF / UHF Digital Beyond line-of-sight
On Tue, Apr 20, 2010 at 03:32:18AM -0400, KH6TY wrote: Hi Tony, Thanks for making the recording of aircraft reflections. Yes, we also see and hear aircraft reflections mixed with atmospheric disturbances all the time. The aircraft reflections sound similar to what you hear on the beacon, and you can identify those because they vary in frequency and intensity as the airplane approaches or recedes, just like you hear. However, what we experience on UHF over longer paths is a constant chopping up of the SSB phone signal, or narrow digital signals, and that seems to correlate with the Hepburn propagation maps, especially when the path crosses two or more levels of ducting, when signals can be strong, but SSB is still not very understandable. When both stations are within the same ducting level, the only audible Doppler effect is usually reflections from airplanes, and sounds much like your recording. When there is no propagation enhancement showing on the Hepburn maps, there is usually a fast, constant, chopping up of the SSB phone signal, and when we switch to a relatively wide digital mode, like Olivia or Contestia, which continues to print for a couple of seconds after transmission has ceased (due to the interleaving and FEC, I guess) print is perfect. The frequency of the audible chop is generally around two to three times per second, which is less than the latency of the digital mode. Those modes which display very little or no latency seem to be the ones that fail to print. Over the next few weeks, we are now going to compare Contestia variations with different bandwidths and latency to see how print compares to the observed period of chop on SSB phone. I find the above very interesting indeed. Jim, WB5UDE, and I have just begin a series of experiments on VHF (2m) digital mode communications. We live about 20 miles apart as the crow flies, I in Norman, OK, and Jim in west OKC, OK. We've both been using Yaesu FT-897D with 2m J-poles. Jim has been using FLDigi, and I have been using HRD with DM780 and MixW. Since I live down in the South Canadian River valley, there isn't much chance I'll get LOS contacts with anyone outside my immediate area, until I get antennas up on a 400' tower. I wish. So far we have found that the FH-style modes (OLIVIA, Contestia, THOR, etc.) don't work at all well for us. We tried some changes to bandwidth and bitrate for OLIVIA and Contestia, than tried very slow THOR-4 just to see if _any_ FH mode would work; no go, which was very most surprising. I'll see the signal level go well up past the squelch marker, but can't get a good decode. In contrast, the PSK-style modes (BPSK-31 and -63, so far) work very well, with solid copy once we get the decode passband overlaid on the received signal. This has been difficult for some reason: we have found we have to do it manually. The audible received signal isn't at all choppy, and I haven't heard fading, choppiness, or aircraft reflections, though there may be some, as Jim lives 2 miles S of Wiley Post airport and I live 1 mile S of Max Westheimer Airport in Norman, with the approach/takeoff paths for Will Rogers Airport directly between us. Jim and I are planning to have lunch together today, and I expect to work out a formal test program with him, setting out the mode/BW/rate list. Readers in the Metro OKC/Norman area are invited to join us. -- Mike Andrews, W5EGO mi...@mikea.ath.cx Tired old sysadmin
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.
[digitalradio] Re: 3rd Generation Digital radio
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 digitalradio@yahoogroups.com, Greg n9...@... 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.
Re: [digitalradio] 3rd Generation Digital radio
--- On Tue, 20/4/10, John Becker, WØJAB w0...@big-river.net 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
[digitalradio] LOTW/SKCC and other Sked Page use. March Report
A reminder that the K3UK Sked Page supports interactive dialog facilitating skeds and other general fun. The pages can be found at http://www.obriensweb.com/sked/ Specific pages for the Straight Key Century Club and the LOTW Triple Play are very popular. There are also pages for digital mode QSO experiments, WARC bands skeds, and more. We have also had a few nice mentions in QST of late.FYI here is our March 2010 data, over 2000 hams in the user database. Monthly Statistics for March 2010 Total Hits 1633080 Total Files 1468824 Total Pages 23692 Total Visits13717 Total KBytes23719322 Total Unique Sites 6999 Total Unique Referrers 485 Total Unique User Agents854 . Avg Max Hits per Hour 34028802 Hits per Day81654 112904 Files per Day 73441 104418 Pages per Day 11841816 Visits per Day 685 1028 KBytes per Day 1185966 1916741 Andy K3UK
[digitalradio] Re: 3rd Generation Digital radio
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 digitalradio@yahoogroups.com, 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 digitalradio@yahoogroups.com, 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.
[digitalradio] 4M200AJ [2 Attachments]
QSO,, con la 4M2OOAJ en MFSK 16 modalidad ROS ,banda de 40 Metros ,Frecuencia 7.050.00 Khz 30 wts tx. antenna Windom Short ,en commemoracion del Bicentenario de la Independencia de Venezuela ,Special Call 73 Francesco YV4GJN
