Re: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
Skip, Realistically, the 5/8 wave will be maybe around the gain of a dipole. I would use 2 dBi, maybe 3 dBi at the most. I don't think there are any 5/8 wave verticals that can do much better than that and some antenna gurus point out that they can perform worse than half wave antennas. I have both quarter and 5/8 wave so I will try and do at least a local test. We must not loose sight of the fact that almost no hams have horizontal polarization and almost all have do have vertical polarization. And weak signal hams do not tend to focus on public service activities so you may not have any stations that you can work. I don't know of anyone who has any interest in my area. I would suggest that hams ask their weak signal operators whether or not they would be willing to participate in this. It takes a LOT of practice to make this work. You may not get it to work at the time you most need it. Since voice communication is not going to be used (too weak a signal) for many of these digital transfers, you would need to set up a specific frequency and offset. I have been monitoring and sending on 144.144 as suggested by others, but have never heard anything. But that is mostly on vertical polarization for now. The period transmission is very clever, something like Patrick, F6CTE's Multipsk programs sending of repeated characters. You could just have a macro set with the repeating character, and you probably do this. 73, Rick, KV9U kh6ty wrote: If the signals are in the marginal range, how do you do the coordinating between the stations? To date, we have been able to use a cell phone. How do you calculate the error rate (such as the 6% mentioned)? We send 50eroids.(..). Anything that is not a period is easily recognized as an error. Three on-perionds equates to a 6% error rate. If I understand this correctly, the test was between a 5/8 vertical to quad for vertical polarization vs. quad to quad for horizontal, wouldn't it be about right to see 6 dB difference considering that you are increasing the path budget with the inclusion of the quad? The test was a vertically polarized quad to a 5/8 wavelength whip, and a horizontally polarized quad to a horizontally polarized quad. The quad had 7.5 dBi of gain versus perhaps 5 dBi of gain for the vertical whip. That makes up about 2.5 dBi of the 6 dBi, and the rest is an approximation of the S/N as measured by flidit in both cases. As you can imagine, it is extremely difficult to make exact quantitative measurements under such conditions, but even modeling shows the 6 dB that Cebik references. Our experience is that the 6 dB is about correct. Several ways to do this is with quad to quad vertical and quad to quad horizontal polarization, or some other gain antenna that can switch properly between polarizations. I wonder if you would see such a difference? Based on two different modeling programs, and our own simple tests, I think so. The most significant finding is that we lose communicaton over about 30 miles using vertical-to-vertical, but easily over 70 miles using horizontal-to-horizontal, even though the horizontal antenna on the mobile end is 5 feet higher than the whip is. In the end, anectodal evidence from others also suggests a 15 to 20 mile range with vertical whips, and we already know we can exceed 70 miles in flat country using a low, horizontally-polarized quad instead of a vertical, and that is all that is important to our purpose. It would be nice to have more and better controlled tests, but you can just imagine the difficulty in arranging for such tests without doing it on an antenna range. You have to switch polarization on both ends, and one existing antenna may be on a tower, 50 feet in the air. Of course, any such tests are possible, but the difficulty of finding people to participate is difficult, at best. As far as we are concerned, together with the common knowledge that all weak signal communications on 2m use horizontal polarization, TV stations use horizontal polarization because long ago it was found to be better for propagation, and the confirming results from modeling, are sufficient enough reasons to insist on using horizontal polarization for distances longer than a repeater can provide. Add to that the probability that many existing vertical beams are not mounted on rotators, and the change to horizontal polarization appears to be well worth the effort, based on available information. You can also include the possibility that using a horizontally polarized quad provides a lower takeoff angle close to ground that a yagi, and you can see why there are many reasons to insist on using horizontal polarization. Finally, in a serious emcomm situation, NBEMS only needs to reach connectivity with the Internet for email delivery or POTS for phone delivery, so any
Re: [digitalradio] You Have Mail Re: How Can We Push HF Emcomm Messages to the Field?
Bonnie, While your question has been answered quite well by several of us, the main thing to keep in mind is that if you are going to use amateur radio communications, both stations must be operational and within range. These kind of communication must be done with tactical phone for immediacy and confirmation. If you are mobile and use VHF FM, you will have more modest range than VHF SSB, but should be able to contact your EOC or whoever is dispatching you for local support (such as shelters). Even in our difficult terrain, in the Driftless Region of Wisconsin, we can (mostly) work within the county. Some low areas can not even reach the repeater but may get through (weakly) on SSB based on our test results. If you are portable, you can quickly erect a small VHF gain antenna to increase communication distance. Note the article in the December 2008 issue of QST. We have had to do this even with repeater use for public service support of Adventure Racing. We need to keep in mind that HF use is never a practical option for 24/7 operation. And almost no hams have mobile HF (OK, my wife does if she puts on the Texas Bugcatcher, but she is a rare exception). HF SSB phone can not work consistently once you are out of ground wave coverage which can be only a few miles (5 to 15). VHF works consistently better than HF, for shorter distances and can even work well for longer distances too depending upon power levels and antenna gain and height of stations. When NVIS operation requires a lower frequency than you can operate, (160 meters for example), HF totally fails for short and medium range (typically from more than 10 to even over 200 miles), so it really is not a 24/7 option like VHF. This is especially true at night when the FoF2 can easily drop to only 1 Mhz. Even CW can be of limited use. And remember that during high QRN, which can be common during emergency weather situations, HF phone can be of limited value even if NVIS operation is possible between two points. 73, Rick, KV9U expeditionradio wrote: The core question still remains: How can we initiate (push) a message to the mobile or portable operator in the field, when the field operator has no expectation that a message will be sent? Or, even more simply, how can we timely notify the field operator You Have Mail via HF? During the Katrina disaster the traditional HF voice nets failed to adequately provide this type of notification service. It's been 3 years since Katrina. What has we done to improve our ability to notify field ops via HF? How can we work together to forge unified or standard methods to make this happen... in a way that will function across the various ham Emcomm platforms and nets? Bonnie VR2/KQ6XA
[digitalradio] Pushing messages on HF
Happy Thanksgiving to all. I know I will probably get some negative feedback, and be called names, but this is a question more than a suggestion. What about 10m? Tech class licensees have privileges, ground wave is often good out to 40-50 miles station to station. OK I guess I'm ready for the onslaught. Don KA5DON
Re: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
Rick, Skip, Realistically, the 5/8 wave will be maybe around the gain of a dipole. I would use 2 dBi, maybe 3 dBi at the most. I don't think there are any 5/8 wave verticals that can do much better than that and some antenna gurus point out that they can perform worse than half wave antennas. I have both quarter and 5/8 wave so I will try and do at least a local test. Please do! We need as many field tests as possible. This morning I did some modeling studies over real ground with the following results: J-pole at 3m, 5.17 dBi at 6.2 degrees (vertical) J-pole at 3m, 7.7dBi at 9.8 degrees (horizontal) 3 section 5/8 wave collinear at 3m, 6.67 dBi at 9 degrees (vertical) Single vertically stretched quad loop at 3m, 9.65 dBi at 9 degrees (horizontal) Single vertically stretched quad loop at 3m, 6.28 dBi at 7.8 degrees (horizontal) Ground plane at 3m, 4.4 dBi at 46 degrees (vertical) Ground plane gain at 9 degrees, -0.2 dBi. A 3 section, 5/8 wave, collinear is 12 feet tall. A stretched quad loop is only 14 tall in comparison. Turnstiling two of these (like a stretched eggbeater antenna, reduces the gain by 3 dB, resulting in a horizontally-polarized antenna of 6.65 dBi gain, but with a 9 degree takeoff angle, and omnidirectional coverage for mobile use. Compare this to maybe 2.5 dBi for a single 5/8 wave whip (unknown takeoff angle, but somewhere between 46 degrees and 9 degrees). The big problem with any shortened vertical whip is that too much of the energy is radiated at a high angle. The takeoff angle probably accounts for a significant part of the 6 dB disadvantage of low vertical antennas that we have found during actual field tests. The three section 5/8 wave collinear gets its gain by compressing the high angle radiation, but it takes three 5/8 wave sections just to get the takeoff angle down to 9 degrees. The study with the J-pole rotated horizontally was only for comparison and it not a practical solution. The total antenna gain for us to reach 70 miles in flat country was 16 dBi. If an EOC is using a three-section collinear at 30 feet for omnidirectional coverage, and a mobile is using at best a 3 dBi antenna, the total available gain is only 6.7 + 3 dBi = 9.7 dBi, or a huge 6 dB short of the gain that we had but is omnidirectional. The higher gain horizontally-polarized setup is an EOC with four stacked Big Wheels, for about 9 dBi of gain and an eggbeater style, stretched loop, mobile antenna of 6.6 dBi of gain, for a total system antenna gain of 15.6 dBi, and still have a low takeoff angle. This puts the burden on the EOC to have a high, tall antenna, which may not always be practical, so the alternative is to make up the necessary gain on the portable end by using a higher gain quad that can be broken down to fit in the trunk of a car. I have developed three designs - a two element quad that is only 13 thick and does not have to be broken down, and 3 and 4 element quads that can be and reassembled on site. The 4-element quad has 12 dBi of gain if needed to reach an EOC. We must not loose sight of the fact that almost no hams have horizontal polarization and almost all have do have vertical polarization. This again begs the question as to how many have ROTATABLE vertically polarized GAIN antennas. Most I have talked to do not have a rotator. Instead they use multielement vertical collinears. Those that do use yagi's generally have them fixed in direction and pointed at a favorite repeater. None of these installations are going to get much range without a repeater and a way to rotate a yagi. And weak signal hams do not tend to focus on public service activities so you may not have any stations that you can work. I don't know of anyone who has any interest in my area. I would suggest that hams ask their weak signal operators whether or not they would be willing to participate in this. It takes a LOT of practice to make this work. You may not get it to work at the time you most need it. The good thing about the NBEMS concept is that in a pinch ANY ham receiving an emcomm CQ can forward the messages to any EOC with Internet connectivity, phone service or cell phone service. This intermediate station does not have to have emcomm training. He is simply a relay station to the EOC. Takes very little practice as the software is very simple. Since voice communication is not going to be used (too weak a signal) for many of these digital transfers, you would need to set up a specific frequency and offset. I have been monitoring and sending on 144.144 as suggested by others, but have never heard anything. But that is mostly on vertical polarization for now. With vertical polarization, you are 20 dB down from using horizontal polarization, so you will not hear anything. Anyway, currently, there is not much PSK31 activity on 144.144 and probably none in range of your station, even if you have a horizontally-polarized yagi. The
[digitalradio] KN4LF Daily LF/MF/HF/6M Frequency Radiowave Propagation Forecast #2008-34
The KN4LF Daily LF/MF/HF/6M Frequency Radiowave Propagation Forecast #2008-34 has been published on Friday 11/28/2008 at 1500 UTC, valid UTC Saturday 11/29/2008 through 2359 UTC Friday 12/05/2008 at http://www.kn4lf.com/kn4lf6.htm . 73 GUD DX, Thomas F. Giella, KN4LF Lakeland, FL, USA [EMAIL PROTECTED] LF/MF/HF/VHF Frequency Radiowave Propagation Email Reflector: http://montreal.kotalampi.com/mailman/listinfo/kn4lf KN4LF Daily Solar Space Weather Geomagnetic Data Archive: http://www.kn4lf.com/kn4lf5.htm KN4LF Daily LF/MF/HF/6M Frequency Radiowave Propagation Forecast Archive: http://www.kn4lf.com/kn4lf6.htm KN4LF 160 Meter Radio Propagation Theory Notes: http://www.kn4lf.com/kn4lf8.htm
Re: [digitalradio] Pushing messages on HF
Don, I am not sure why you think that anyone would treat your suggestion negatively. In fact, I wrote an article on looking at lower infrastructure amateur radio for the HFDEC yahoogroup that posits the use of 10 meters, 6 meters, and 2 meters for public service emergency use by comparing the pros and cons of each of the bands. We have had modest results when a local ham bought a 50 watt 10 meter SSB rig and used a modified CB antenna as a quarter wave whip on his vehicle. There were times that the ground wave of the 10 meter SSB signal could be heard at my QTH, when he was not able to use the local 2 meter repeater. From his location at the time, I was about the same distance as the repeater, however a couple of hundred feet lower in elevation. His signal would drop way down on 10 meter SSB as it did on 2 meter FM, but we would not lose him completely with the SSB signal. Ten meters is the only common phone band for all classes of licensees, including Novice. Some of us local hams set up a 10 meter SSB phone net several years ago to attract all hams, but there was only interest from the General class and higher hams. Techs and Novices just would not participate and we were quite disappointed. Even at 20 miles, 10 meters can be extremely weak on SSB phone unless you are using higher antennas and they have the same polarization. We often found that by moving to 15 meters, signals were stronger between many of us than on 10 meters. There are some issues for those who use beams on 15 since they will be cross polarized to us vertical operators and not always very strong even though they are using gain antennas up in the clear. And if 15 opens, then local communications is not really appropriate. The size of ten meter antennas and the fact that many hams have beams, make it more difficult to use between base and mobile. Noise levels tend to be worse on 10 than on VHF. The one thing that gives 10 meters some potential over other modes is that most HF rigs have this available at the 100 watt level and for a very favorable price for used equipment. Almost all new HF rigs include 6 meters now, but it does not get much traction in our area for local simplex communication since most hams are on the repeater(s). 73, Rick, KV9U Moderator, HFDEC (Hams for Disaster and Emergency Communications) http://groups.yahoo.com/group/hfdec/ Don Rand wrote: Happy Thanksgiving to all. I know I will probably get some negative feedback, and be called names, but this is a question more than a suggestion. What about 10m? Tech class licensees have privileges, ground wave is often good out to 40-50 miles station to station. OK I guess I'm ready for the onslaught. Don KA5DON
Re: [digitalradio] Odd noise in receiver
Yep - removing the antenna makes it go away, so I know it's coming into the rig and not generated by it. I was hoping someone might recognize the cyclical nature of the pest and give me a clue as to what it might be. Strangely enough, last night it was on, but tonight it has disappeared. Tnx es 73 dave KB3MOW Ed wrote: At 11:46 AM 11/28/2008, you wrote: Wonder if anyone has encountered this type of noise. It's a raspy, pulsating sound. It lasts 10 seconds, is silent for 5, then starts again The pulses are about 5 per second. It's showing up on a lot of bands. Right now I have it at about 21.048, but have heard it on several ham frequencies. We haven't added any new electronics in the house at all. We are in a rural setting, with the nearest neighbor several hundred feet away. We do have cable TV and cable internet, and I wonder if this might be a test birdie I've heard mentioned in the past. It seems to run 24/7, and just started up within the last few days. Does it go away when you remove the antenna? That will pretty much eliminate the likelyhood its a birdie. Lots of cheap consumer stuff emits RF, unfortunately.. Maybe someones' fancy Christmas Lights half a mile away. Ed Dial Broadband has arrived Nationwide! Up to 5 times faster than traditional dialup connections from $13.33/month! See the demo for yourself at www.BigValley.net http://www.BigValley.net
[digitalradio] Fldigi-DXLabs Gateway Update
There is now a new Update available for the Fldigi-DXLabs Gateway. The new version is 1.2.0 and includes the following changes: 1.2.0 (11/28/2008) 1.Connects to DXKeepers TCP Server for logging 2.Allows choice of logging Rig Frequency or Rig + Audio Frequency. 3.Allow choice when logging a RTTY contact to log the Center Frequency or the Mark Frequency. 4.Adds better error checking to make sure Fldigi.exe is in the actual path indicated. 5.Corrects some issues of terminating Fldigi upon closing and causing error messages. 6.Allows Rig Control to be with Fldigi and still allow connecting to DXKeeper and DXView. Both the Full Install and the Update zip file can be downloaded at http://www.n2amg.com/software/fldigi-dxlabs-gateway/ 73's Rick N2AMG http://www.n2amg.com
Re: [digitalradio] Odd noise in receiver
I wonder if it is Pactor 3 ? Sent from my Verizon Wireless BlackBerry -Original Message- From: Dave 'Doc' Corio [EMAIL PROTECTED] Date: Fri, 28 Nov 2008 14:46:45 To: digitalradio@yahoogroups.com Subject: [digitalradio] Odd noise in receiver Wonder if anyone has encountered this type of noise. It's a raspy, pulsating sound. It lasts 10 seconds, is silent for 5, then starts again The pulses are about 5 per second. It's showing up on a lot of bands. Right now I have it at about 21.048, but have heard it on several ham frequencies. We haven't added any new electronics in the house at all. We are in a rural setting, with the nearest neighbor several hundred feet away. We do have cable TV and cable internet, and I wonder if this might be a test birdie I've heard mentioned in the past. It seems to run 24/7, and just started up within the last few days. Any ideas? Thanks in advance 73 Dave KB3MOW
Re: [digitalradio] Odd noise in receiver
Nope - I recognize THAT little nightmare hi hi! Thanks, Andy 73 Dave KB3MOW [EMAIL PROTECTED] wrote: I wonder if it is Pactor 3 ? Sent from my Verizon Wireless BlackBerry *From*: Dave 'Doc' Corio [EMAIL PROTECTED] *Date*: Fri, 28 Nov 2008 14:46:45 -0500 *To*: digitalradio@yahoogroups.com *Subject*: [digitalradio] Odd noise in receiver Wonder if anyone has encountered this type of noise. It's a raspy, pulsating sound. It lasts 10 seconds, is silent for 5, then starts again The pulses are about 5 per second. It's showing up on a lot of bands. Right now I have it at about 21.048, but have heard it on several ham frequencies. We haven't added any new electronics in the house at all. We are in a rural setting, with the nearest neighbor several hundred feet away. We do have cable TV and cable internet, and I wonder if this might be a test birdie I've heard mentioned in the past. It seems to run 24/7, and just started up within the last few days. Any ideas? Thanks in advance 73 Dave KB3MOW
[digitalradio] Re: Odd noise in receiver
This kind of noise has been showing up quite a lot lately. I've chased down a couple TVI complaints with similar characteristics. The problem has consistently been battery chargers, especially the kind to used to charge the batteries for portable tools. They tend to cycle charging power on and off. Now some of the wall wart chargers for small electronic stuff is starting to create the same kind of noise. This may not be your problem but I would recommend against ignoring the possibility that it might be. Gary - N0GW --- In digitalradio@yahoogroups.com, Dave 'Doc' Corio [EMAIL PROTECTED] wrote: Wonder if anyone has encountered this type of noise. It's a raspy, pulsating sound. It lasts 10 seconds, is silent for 5, then starts again The pulses are about 5 per second. It's showing up on a lot of bands. Right now I have it at about 21.048, but have heard it on several ham frequencies. We haven't added any new electronics in the house at all. We are in a rural setting, with the nearest neighbor several hundred feet away. We do have cable TV and cable internet, and I wonder if this might be a test birdie I've heard mentioned in the past. It seems to run 24/7, and just started up within the last few days. Any ideas? Thanks in advance 73 Dave KB3MOW
Re: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
Hi Skip, The numbers for the models seem very optimistic. Normal gain for J-pole (theoretical) can not be more than a dipole, since the antennas is an end fed dipole with the Q section for matching. This means at most 2.14 dBi, but maybe you are experiencing some ground gain which you can get on vertical too from my limited understanding? When the CSVHFS does annual parking lot type tests each year and they seem to come up with higher numbers than the theoretical. That may be why KU4AB's halo antenna exceeds the theoretical maximum by quite a bit. And the take off angle is very important as you note. There are companies that make claims of very high gain numbers but they are not toward the horizon, HI. The nice thing about quads is that they are easier to match than yagis often requiring only a direct connection to the driven element since the other elements reduce the impedance closer to 50 ohms and away from the 100+ ohms of a single loop. Although a bit bulky, with a three dimensional form factor, it is less likely you will poke out your eye. You might remember the portable 2 meter quad that QST published in the early 1980's. The big 3 x 5/8 collinears may be able to reach just over 8 dBi, but it just is not enough for the longer reach. It is of course way better than a half wave J-pole. When you need over 12 dBi or more on one end, (vertical or horizontal), it is pretty hard to do better than a rotatable yagi. An important question to ask: If you need to operate on battery power, will you be able to rotate the base station antenna? Most would at least need AC generator power although an inverter used for short periods, might be possible. Four of the recent Cebik triple dipole arrays look like one of the ways to get the most gain for a stationary antenna. I have asked some antenna companies if they are considering making such an antenna, but no response. In our area, we have some hams with rotating twist type Cushcraft 10 element V and H switchable beams, smaller beams, and some with double 13 element vertically stacked. Interestingly, these are hams who are also more into public service and don't normally get involved in weak signal work. It is a tough call to decide which way to polarize since hardly anyone is going to have H with any mobile setup and you need to have mobile to base communications. NBEMS, which I support wholeheartedly since it is the only cross platform open source digital software program of this type, is not really that easy to use compared with some other systems. You do have to practice this on a regular basis to get hams comfortable with how it works. And the weak signal NBEMS, where there is no phone communication possible, is going to need some very savvy ops who also know where the other station is located on the dial. The only 144.144 signals on 2 meters in my area likely originate from my station. I may be able to get some others to try. One of our local hams unfortunately decided to buy a Yaesu FT-450 instead of an 857D/897D so even though he is on digital with some OJT with the two of us getting together earlier this week, no go on 2 meters. We did OK on 10 meters though. 73 for now, Rick, KV9U kh6ty wrote: Rick, Skip, Realistically, the 5/8 wave will be maybe around the gain of a dipole. I would use 2 dBi, maybe 3 dBi at the most. I don't think there are any 5/8 wave verticals that can do much better than that and some antenna gurus point out that they can perform worse than half wave antennas. I have both quarter and 5/8 wave so I will try and do at least a local test. Please do! We need as many field tests as possible. This morning I did some modeling studies over real ground with the following results: J-pole at 3m, 5.17 dBi at 6.2 degrees (vertical) J-pole at 3m, 7.7dBi at 9.8 degrees (horizontal) 3 section 5/8 wave collinear at 3m, 6.67 dBi at 9 degrees (vertical) Single vertically stretched quad loop at 3m, 9.65 dBi at 9 degrees (horizontal) Single vertically stretched quad loop at 3m, 6.28 dBi at 7.8 degrees (horizontal) Ground plane at 3m, 4.4 dBi at 46 degrees (vertical) Ground plane gain at 9 degrees, -0.2 dBi. A 3 section, 5/8 wave, collinear is 12 feet tall. A stretched quad loop is only 14 tall in comparison. Turnstiling two of these (like a stretched eggbeater antenna, reduces the gain by 3 dB, resulting in a horizontally-polarized antenna of 6.65 dBi gain, but with a 9 degree takeoff angle, and omnidirectional coverage for mobile use. Compare this to maybe 2.5 dBi for a single 5/8 wave whip (unknown takeoff angle, but somewhere between 46 degrees and 9 degrees). The big problem with any shortened vertical whip is that too much of the energy is radiated at a high angle. The takeoff angle probably accounts for a significant part of the 6 dB disadvantage of low vertical antennas that we have found during actual field tests. The three
