Re: [digitalradio] Some thoughts on antenna polarization for emergency use
Ted, I agree that in a single array configuration it does not have the gain realizable by a directive antenna, no omni-directional antenna will. But in those cases where a rotatable antenna is not feasible nor permitted (as on some public structures housing EOCs) This illustrates the core of the problem of not having enough total path gain to communicate with the EOC if the repeaters are down. Either the portable station in the disaster area, or the EOC 100 miles away, will have to have at least a 10-element beam in order for the portable station to be heard at all. I have a 13 element beam with 14 dBi of gain and several times, I have worked WO4DX on 2m mobile on SSB phone to his stacked loops and 100 watts. He periodically travels on business from the coastal town where I live (near Charleston, SC), to his home QTH in Dawsonville, GA, and I can consistently work him for 100 miles, going NW up I-26, until he turns and starts heading to Augusta, GA on I-20 and then I start losing him. I also periodically work rover NK4Q, also with 100 watts and stacked loops on his truck, up to 120 miles away, along I-20 as he heads east to the Outer Banks for the VHF contest, but to copy these stations, I must use my 13-element beam. If I switch to my skeleton-slot antenna, which I use for the local PSK63 net (6 dB down from the beam), I cannot copy either of them. If NK4Q switches from stacked square loops to the skeleton-slot antenna I made for him, picking up 6 dB more gain, I can again copy him until he gets over 120 miles away. When he arrives at the Outer Banks, I again cannot copy him unless I switch to the 13-element beam, and copy is still marginal on phone. However, if we switch to PSK63, print is over 50%. If NK4Q then switches to a 10-element beam, picking up another 3 dB, print improves to 100%. This is a distance of 300 miles, with both stations at sea level. So, if the EOC is not able to either have extra height, or to use a higher-gain antenna, or if I cannot set up a beam outside the hurricane shelter, I will simply be unable to reach the state EOC in Columbia from a hurricane shelter in Charleston, 100 miles away, if the repeaters are down locally, and we will have no commumications except hopefully on 80m or 40m using NVIS antennas, which takes more real estate to set up, and is more susceptible to QRN. I do realize it is going to take time for a substantial number of stations to discover 2m VHF SSB phone and digital for both emcomm and casual operating, but in the end, 2m VHF SSB digital, with sufficient antenna gain, is the most practical and reliable emcomm alternative to using repeaters, which may not be operational when we need them. If anybody reading this is within 200 miles of Charleston, SC, and would like to try 2m PSK63, you are invited to beam toward Charleston and check in to our informal ragchew net on 144.144 MHz, USB, around1500 Hz tone frequency, at 8 PM on Wednesday nights and 9 PM on Sunday nights. 73, Skip KH6TY
Re: [digitalradio] Some thoughts on antenna polarization for emergency use
Lots of interesting things. I completely accept that VHF SSB (which can also mean digital) communication is really the only practical longer distance VHF mode that works without infrastructure. But will we have a turn around in the number of operators who actually use these modes? There is no question that an increasing number of hams have the equipment now. But very few are using them for 6 and 2 meter SSB. Fewer hams are operating weak signal SSB, which has caused a significant drop in interest considering that there are several times as many hams today than when this was much more popular. A local weak signal ham (50 miles north) said to me recently that years ago (decade or more) there used to be many midwest U.S. stations on 2 meter SSB, both fixed and mobile. But that is no longer true. And there does not seem to be any improvement as of late. Maybe other areas are seeing some increase? But the unaswered question is, how much different would the path gain be between horizontal and vertical polarization? And that might depend on the distance since it seems that the farther out you go, perhaps the horizontal polarization gives a slight edge. But really how much of an edge? Isn't it really the gain of the antenna over the polarization of the antenna? Just because weak signal operators use horizontal does not mean that emergency and local SSB operators need to do this. We have many stations (most stations) that have gain on vertical and nothing available on horizontal and never will have anything on horizontal. Even hams who buy a multimode/multiband rig and now might want to try SSB or digital are rarely buying a new beam just for 2 meter SSB. Partly because of cost, partly because they can not due to local restrictions, and partly because they often have upgraded and also want to put energy into HF. The other factor that seems to be in play, is that there does not seem to be much correlation between hams who do weak signal and also do public service, compared with the ham who is primarily involved in public service and might add an new dimension to their operation if asked to provide this needed service providing that they could use their existing antenna or at least not have to have two separate antennas. Consider the number of FM hams who have beams on vertical polarization including fairly high gain antennas such as the double 13 element Cushcrafts. Using vertical polarization, they can often use FM to access repeaters from one side of our state to the other but unlike SSB they can drop below the threshold at times as there can be QSB on these kinds of signals. SSB would give them at least 6 dB or more margin and digital should give quite a bit more. Your comment about PSK63 only working 50% of the time when you have marginal phone communication makes me wonder if the digital modes are able to work as deeply into the noise as claimed. Shouldn't there be solid copy in PSK modes, even PSK250 or at least PSK125 at a few dB below zero dB S/N? Phone communication, even SSB would need a bit over zero dB wouldn't it? 73, Rick, KV9U kh6ty wrote: This illustrates the core of the problem of not having enough total path gain to communicate with the EOC if the repeaters are down. Either the portable station in the disaster area, or the EOC 100 miles away, will have to have at least a 10-element beam in order for the portable station to be heard at all. I have a 13 element beam with 14 dBi of gain and several times, I have worked WO4DX on 2m mobile on SSB phone to his stacked loops and 100 watts. He periodically travels on business from the coastal town where I live (near Charleston, SC), to his home QTH in Dawsonville, GA, and I can consistently work him for 100 miles, going NW up I-26, until he turns and starts heading to Augusta, GA on I-20 and then I start losing him. I also periodically work rover NK4Q, also with 100 watts and stacked loops on his truck, up to 120 miles away, along I-20 as he heads east to the Outer Banks for the VHF contest, but to copy these stations, I must use my 13-element beam. If I switch to my skeleton-slot antenna, which I use for the local PSK63 net (6 dB down from the beam), I cannot copy either of them. If NK4Q switches from stacked square loops to the skeleton-slot antenna I made for him, picking up 6 dB more gain, I can again copy him until he gets over 120 miles away. When he arrives at the Outer Banks, I again cannot copy him unless I switch to the 13-element beam, and copy is still marginal on phone. However, if we switch to PSK63, print is over 50%. If NK4Q then switches to a 10-element beam, picking up another 3 dB, print improves to 100%. This is a distance of 300 miles, with both stations at sea level. So, if the EOC is not able to either have extra height, or to use a higher-gain antenna, or if I cannot set up a beam outside the hurricane shelter, I will simply
[digitalradio] Reminder: Digital Voice Net today.
WinDRM / DRMDV / FDMDV Digital Voice Net at 3:00PM EDT, 2000 UTC , 14236 USB.
[digitalradio] CQ Rhode Island
I was checking my LOTW data and discovered I just need Rhode Island for WAS (any mode). I long ago got WAS via paper QSL cards (all on 10M as a Novice) but never got around to packaging up the cards and taking them to a field check. LOTW is much easier. So anyone here in Rhode Island that I can 'sked with? Andy K3UK
Re: [digitalradio] Some thoughts on antenna polarization for emergency use
Rick, I completely accept that VHF SSB (which can also mean digital) communication is really the only practical longer distance VHF mode that works without infrastructure. But will we have a turn around in the number of operators who actually use these modes? There is no question that an increasing number of hams have the equipment now. But very few are using them for 6 and 2 meter SSB. Fewer hams are operating weak signal SSB, which has caused a significant drop in interest considering that there are several times as many hams today than when this was much more popular. There are probably thousands of IC-706MKIIG's, IC-746's, FT-857's,FT-890's, or Kenwood TS-2000's in circulation that all have 2m SSB capability. Of course, it is sure that there are many more HT's and FM-only transceivers than those SSB transceivers. It is my understanding that weak signal operating is on the increase, mostly due to the introduction of WSJT, which is good, since the same digital interface can be used for 2m digital SSB. A local weak signal ham (50 miles north) said to me recently that years ago (decade or more) there used to be many midwest U.S. stations on 2 meter SSB, both fixed and mobile. But that is no longer true. And there does not seem to be any improvement as of late. Maybe other areas are seeing some increase? Don't know... Of course NBEMS on HF with NVIS antennas is still a viable alternative, but setting up point-to-point communications with EOC's on 2m is more reliable, and a 2m antenna, even a 10 foot long beam, is more portable than a long HF antenna for 80m or 40m. The advantage of medium range 2m (i.e. up to 100 miles) is that propagation is quite constant, whereas on 80m and 40m, it varies according to the time of day, and QRN can be distrupting to the ARQ transfer, slowing it down. There is little QRN (i.e. from static crashes) on 2m. But the unaswered question is, how much different would the path gain be between horizontal and vertical polarization? And that might depend on the distance since it seems that the farther out you go, perhaps the horizontal polarization gives a slight edge. But really how much of an edge? I guess only RCA knows, since they made the tests in the early days of TV. I wonder the same thing, and hope to find time to test, but just rotating an existing vertically polarized beam 90 degrees does the trick at no cost. Isn't it really the gain of the antenna over the polarization of the antenna? Just because weak signal operators use horizontal does not mean that emergency and local SSB operators need to do this. A local ham on our 2m net here designed and constructed a cycloid to see if random polarization was significant, and it turned out not to be. His work can be seen at KR1ST.com. Emergency and local SSB operators do not need to go horizontal, but if they do, then the existing weak signal operators can assist emcomm by being forwarding stations, and will have superior antenna gain to do that over longer distances. The antenna change from vertical to horizontal is much easier, and less expensive, than the change from FM-only to SSB. Perhaps a bigger problem is that many vertically-polarized beams are fixed in the direction of a desired repeater and do not have rotators. Once a rotator is added, it is easy to just rotate the beam 90 degrees at the same time. The catch-22 is that many of those 5-element beams are rear-mounted (to keep the metal mast out of the antenna field), and that puts an undesirable strain on a rotator, since it presents an unbalanced load, but it will probably not be a problem for a medium-duty rotator. Anyway, a non-metallic mast extension (like fiberglass) can be used to solve that problem and allow the beam to be center-mounted. We have many stations (most stations) that have gain on vertical and nothing available on horizontal and never will have anything on horizontal. Even hams who buy a multimode/multiband rig and now might want to try SSB or digital are rarely buying a new beam just for 2 meter SSB. Partly because of cost, partly because they can not due to local restrictions, and partly because they often have upgraded and also want to put energy into HF. They can just rotate the beam 90 degrees if they have a beam, but most probably do not, so they can just build the inexpensive design that will appear soon in QST, or use the latest three dipole Big Wheel in the March QST issue. The decision will depend upon how successful the ham is trying to use NBEMS or other messaging systems on HF with NVIS antennas compared to 2m. All my 2m antennas are in my attic (including my 13-element beam), due to restrictions barring outside antennas. The signals pass through the wood and shingles on 2m just fine, but there is some absorption on 70 cm. A 10-element 2m beam is around $100 and is the minimum amount of gain that should be considered. If one already has a multimode 2m
[digitalradio] ALE400 frequencies
Expeditionradio said: This narrow auto sub-band is time-shared with many different automatic/semi-automatic nets and stations, including various packet and pactor modes. The segment is only 4kHz wide, so if one is using a standard 3kHz SSB filter, it almost covers the whole segment. It is important, as ALE400 operators, for us to co-operate with the other nets and modes we share this narrow segment of the band with. We will never achieve a worldwide clear frequency specific to ALE400 in this narrow sub-band, so we must accept some non-ALE400 interference, as the reality of operating in this part of 20 meters. If the frequency is already in use, this means that we sometimes may need to wait a few minutes to make an ALE400 call. The HF link folks are NOT an official body, rather a small group of ALE enthusiasts who actively support PCALE software. They do not support multipsk. In my opinion PCALE is inferior to MultiPSK and is unable to do many of the things that MPSK is capable of , including working down into the noise, and the ease of an ARQ QSO , or passing files. The HFlink folks would relegate ALE400 to frequencies which would be undesirable, with birdies, and packet interference. Why? It is up to ALE400 users to pick a frequency, more particularly, it is up to US users to pick frequencies which conform to the US band plan , which the rest of us don't understand. There is no reason why ALE400 could not share 14109.5 with regular ALE stations, of which there appears to be relatively few active. Maybe an adjacent frequency such as 14108.5 would be satisfactory. The point is as ALE400 users, we don't have to take Bonnie and the HFlink's suggestions as gospel. We can, and should find our own way with a frequency that is relatively clear and useable. John VE5MU
Re: [digitalradio] Some thoughts on antenna polarization for emergency use
Please correct FT-890 to read FT-897. Thanks, Skip KH6TY
[digitalradio] D-STAR at the 2007 Medtronic Twin Cities Marathon
http://www.arrl.org/news/features/2008/03/01/2/?nc=1 D-STAR at the 2007 Medtronic Twin Cities Marathon By Erik Westgard, NY9D [EMAIL PROTECTED] March 1, 2008 Minnesota hams put the D-STAR system to work. The Hennepin County Communications Van joins other Amateur Radio vehicles and trailers in D-STAR integration testing. Ryan Westgard standing by to scan the bib numbers into the Amateur Radio tracking database of incoming injured runners at the Medical Tent at the 2007 MTCM. The 1st generation ICOM RP-1 repeater. The finish line area at the 2007 Medtronic Twin Cities Marathon. The 40x80 foot Medical Tent and attached Amateur Radio managed Interagency Dispatch Center at the MTCM 2007. Peter Corbett, KD8GBL, monitors the database server and D-STAR and packet uplink transmitters in the data trailer at the 2007 MTCM event. The MTCM 2007 Family Medical Information Tent — amateurs in yellow shirts and community medical volunteers use 802.11b networked laptops to query the Amateur Radio database of runners who have left the course. Kelly Black, KB0GBJ, (L) and Max Klingert, KB0RSQ, led the software development team for the Linux appliance back end to the D-STAR repeaters and our database uplink system for the 2007 MTCM. At first glance, the Minneapolis/St Paul Metropolitan Area has a good Amateur Radio infrastructure for public service events. We have more than 40 FM voice repeaters, (about half are on good sites) and two 1200 bit/s packet radio networks, three counting APRS. An increased focus on data applications by served agencies has strained our data capabilities. While it is certainly possible to use the operating range of commercial Internet services, our stated goal of providing backup communications makes this an imprudent choice. Many of our agencies use the Internet for primary data communications, and using the Internet to back up the Internet may be fine under normal conditions but is a poor design for truly catastrophic emergencies. The recent collapse of the I-35 bridge in Minneapolis was marked by a well publicized overload of the commercial cellular telephone networks in the area of the incident, and in some cases, cellular data and voice services share limited bandwidth to the cell sites. A Big Marathon with Big Communication Needs The Medtronic Twin Cities Marathon is one of the larger marathons in the United States in terms of starting runners, with more than 6100 in 2007. There is also a 5000 runner 10 mile race on a similar course at the same time, and hundreds of thousands of spectators and family members also participate in the weekend of events. The race organization has long relied on Amateur Radio for backup medical communications, utilizing more than 130 amateur operators spread across the racecourse and finish line area. We run five voice nets and also provide net controls for the medical channels on the rented UHF business band radios used by the medical teams. On the data side, we track the location only (for HIPAA reasons) of runners who seek medical attention or leave the course for other reasons. This data is input based on voice reports to the on-course net controls and from information input at runner bus stops and at the medical aid stations throughout the course. For inputting information out on the course, packet and a character interface have worked reasonably well, but we do not have enough data bandwidth for much in the way of database queries. Families and medical teams are always inquiring about the location of runners. This requirement is acute at the finish line, when runners do not appear in the Family Meeting Area on schedule. We set up six laptop computers in the Family Medical Information tent, where queries can be made. We also have computers in the main medical tent for runner check-in and check-out and in the communications center where finish line EMT and physician “(Cardiac) Arrest Teams” are dispatched. This much data moving around at the finish line is well beyond the capability of packet radio. We also needed an easy-to-use Web interface to our database so untrained and non-amateur volunteers could be utilized. For this reason we have implemented commercial 802.11b access points from our data trailer. Our database, called Trivnetdb, has a packet AX.25 interface and TCP/IP support for Web and telnet users. Enter D-STAR The recent release of the ICOM D-STAR L-band repeaters and radios (such as the ID-1) presented a possible solution to our problems across the course. If several wide area repeaters were installed, we could access our database of runner status across the entire course using a familiar Web interface. We could perform as many queries as we wanted, and be able to handle high data volumes if we had hot or other unfavorable weather. Doug Reed, N0NAS, bought our first RP-1D repeater under the ICOM “buy five ID-1s and get a free repeater” program. After a few
[digitalradio] Re: Final goodbye for early web icon
My first ISP was AOL (July 1995), even before AOL connected to the World Wide Web. After AOL connected to the WWW it was difficult to get on as the telephone lines were always busy. Quit AOL and went with a local newspaper portal and they used ATT's World Wide Web. Netscape was the browser used. Have been a user of Netscape since and now use Mozilla Firefox and Mozilla Thunderbird. Jerry - K0HZI --- In digitalradio@yahoogroups.com, Andrew O'Brien [EMAIL PROTECTED] wrote: Not a ham radio related topic but I thought I would share this, I am sure some hams used this. Final goodbye for early web icon By Jonathan Fildes Science and technology reporter, BBC News Netscape's demise clip -- Andy K3UK www.obriensweb.com (QSL via N2RJ)
Re: [digitalradio] Some thoughts on antenna polarization for emergency use
Moving on to mode/throughput, let me put on my Incident Commander cap... As an incident commander, I would rather have a printed/written message than one delivered verbally. If I know that you have a digital print system, I would want that and especially if you tell me its error free. The thing important to me is getting every word correct...no errors and sending/ receiving a message in a timely manner. Thus a PSK63/125/250 message that is error free is what you want to make me happy. If you use FlARQ with FlDigi or with DBdigi and at PSK125 or 250 then I shouldn't ask for anything more. how you accomplish the message exchange really becomes unimportant. When it comes to setting up a comm. unit, I ask the operators to tell me where they want to set up if the area I have recommended doesn't meet their needs. The IC should give you room for you HF antennas as well as assistance in setting them up. Putting on my communicator cap, I can set up a 40M Inverted V with counterpoise and fed with 50 ohm coax with the apex at 20 ft and cover most stations from 25-600 miles in the day and raising the antenna to 30 ft for 80/75M I can cover the same area at night. Two individuals can set up then 40M Inverted V in 15-20 minutes. Of course if you can set up a 10-12 element 2M beam at 30 feet in 30 minutes and have connectivity at the other end, then go for either one. What ever you do, just make sure that you contact on the other end of the string is on the same frequency/mode etc. :-) Good comments all around. 73, Walt/K5YFW
[digitalradio] 160 Meter Digital Voice
Just wondering if anyone in the Northeast would like to meet on 160M while the band is still in good shape and qso in digital voice. I live in Maine and often cannot get good copy on the 14.236 net. I'm sure it would work really well on this band at this time of the year.. Let me know a good date, time and mode (windrm,drmdv or fdmdv48k).I'll be there.
[digitalradio] Keeping NBEMS in mind
I was trolling 20M today and found a familiar callsign sending CQ. The station was looking to test file sending with NBEMS (VBdigi and FLARQ). It has been almost 2 months since I used NBEMS but I fired it up and was able to talk my contact through the process of sending his first PSK ARQ file. I think I should remind people here how useful this software is, very easy to use and good file transfers. N4UM:72 Testing NBEMS de N4UM ARQ:FILE::hi.txt ARQ:ENCODING::ASCII ARQ:FILE::Test File.txt ARQ:ENCODING::ASCII ARQ:SIZE::1008 ARQ::STX This is a test file designed to be 1 kB in length (snip) Received 1008 in 269.0 sec's I was surprised and how long N4UM sent before an ACK was requested and thought that something might be wrong, but at about the 60% received mark...an ACK was requested and then the remainder was sent. We used PSK on 20M. Andy K3UK
