[digitalradio] Global emergency Traffic
I echo a lot of Rick's sentiments in traffic handling. There are two types of traffic that we as amateurs would typically handle. One would be the local VHF/UHF tactical messaging as back-up or replacement for local systems and local responders. Secondly we would also handle state/province wide and national messaging in the event of a major disaster. Many of the responding agencies have recognized this need and have built both HF and VHF/UHF capabilities into mobile command units and EOC comms centers. Problem being when the poop hits the fan there is not an organized net that these folks can go to, at least in Canada. We are working to resolve that and also build in the ability to communicate with Homeland Security on cross border incidents. I have been working with several federal and provincial agencies and hopefully solve the net issues into the new year. From an outsider's point of view, it is unfortunate that MARS has decided not to share any software with non-MARS members, particularly MARS-ALE. This limits the ability of MARS to function in an emergency environment since non-members could not assist, and there is also the issue of the learning curve. ALE adherents talk of a national traffic system being in place for over 500 days. This is NOT a message system until stations can pass more than a one-line message between each other, and there seems to be little interest in pursuing message handling beyond a one line message. These folks are only fooling themselves and their served agencies unless they practice moving a larger message . There are good reasons for training at times other than the heat of battle!! So far there are a few digital software products out there which show promise. Some , like RFSM800 can handle higher speed transfers but are not very robust and need a pretty good signal to work well. Olivia and FAE400 are slower but do work well into the noise. From what I have heard so far from beta testers, WINMOR has some promise. We do need a good compromise, with the ability to store and forward digital messages and work reasonably well into the noise. John VE5MU
[digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
Is the volunteer out of VHF range? If the base station has a 100 watt VHF radio like the 746pro - you might be able to still reach the volunteer, but he may not have enough power to get back to you. Or he may be out of VHF range. HF is the way to go - but both ends of the conversation need NVIS antennas. HF antennas tend to be large, and NVIS needs to be horizontal. I'm not sure there exists an NVIS antenna for a car or truck. Maybe something horizontal can be setup in the bed of a pick up truck? In general HF antennas for vehicles do not perform very well - but they are better than nothing. There are portable NVIS HF antennas available that can be setup rather quickly. Perhaps this is something to be done when he arrives at his destination, and then call the base on HF? Also keep in mind that HF radios typically cost over a thousand dollars compared to maybe two hundred for a VHF radio. Howard N3ZH --- In digitalradio@yahoogroups.com, expeditionradio [EMAIL PROTECTED] wrote: The following questions are asked to the amateur radio Emcomm community... how can we work together on this? THE TYPICAL SCENARIO It is a dark and stormy night... You are an amateur radio operator, volunteering with a relief organization, for communication to set up shelters in a hurricane disaster. There has been no power in the area for 24 hours. There is no mobile phone service, and all the VHF/UHF repeaters and digipeaters in the area are out of range or out of service. It is 3AM. You are driving in your vehicle, half-way to your first shelter destination, making your way on back roads. The main highway is flooded. You use your chain saw to pass a downed tree. The road ahead looks worse. THE CALL The relief organization wants to call you now. They have new information since you left on your mission, and they now want to change your destination, to divert you to another shelter location not far from your route. They want you to give the workers at the other shelter a list of supplies that are on the way. They want you to check the shelter's status. They want to know where you are, and if you can possibly divert to the other shelter, so they won't need to send out yet another expedition to the other shelter. THE QUESTIONS How will the relief organization call you? How will they get the actual message to you? How will they know where to route the message to be sure it gets to you? How will they get urgent feedback from you? THE BACKGROUND In the past, Ham radio has generally been very good at a One Way Traffic situation. We can initiate messages. We can pull messages into the field using automatic email systems. It is easy to send messages initiated from the field. But, not as easy to call someone in the field, unless the operator in the field decides to actually initiate some sort of 2-way contact. CAN WE PUSH MESSAGES? What about pushing calls and messages to the field? What are the types of ham radio methods presently in place to call hams in the field when the ham in the field doesn't initiate the contact? What are the existing techniques, and how can these be improved? How is the ham in the field alerted to a call? Can we devise standard method(s) for routing Emcomm push messages to the field? Is ham radio HF viable for pushing messages? Can we make the call day or night, without prior notice? Bonnie VR2/KQ6XA P.S. In case you are wondering, the scenario above was taken from the Katrina Hurricane Disaster. .
RE: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
And further, this thought should be considered as VHF FM, or VHF SSB? In a base/mobile or mobile/mobile environment, SSB on VHF works over much greater distances. With voice communications, VHF SSB benefits from having flutter resulting in the desired signal amplitude going up and down, while the background noise level is held pretty constant, by the AGC in the receiver. FM is opposite in that regard - when the signal gets weak, the background noise level comes up, at least until the squelch closes. In my perception, I seem to be better able to fill in the gaps in syllables when the signal drops out, than when it's filled with noise. VHF SSB also has the benefit of probably not requiring the mobile station to have to take time to set up an antenna. If the mobile station is parked in a null, chances are that moving the vehicle a few inches will change a multipath situation enough to provide good copy. If there's benefit to be had by setting up a portable (v.s. mobile) antenna, putting a VHF omnidirectional stick up 10-20' is a pretty trivial task. While there can be benefit to be had by using horizontal antennas, unless you're into serious weak-signal work, it's not necessary to realize large gains in coverage, even using omni antennas on both ends, using SSB. Digital modes that are designed to work well in weak signal circumstances on HF SSB rigs will similarly work well on weal signal VHF SSB rigs, because the same linear-mode technology is involved. Probably the biggest caveat to that will be frequency accuracy and stability. Radios on a net will need to be well warmed up, or have high stability oscillators, if they are operating unattended, and expected to be able to be received by the sender. I've encouraged those that are working on upgrading our regional hospital network to use the IC-706's that they already have set up for HF pactor, to try VHF pactor using the SSB mode, as a way to gain from the more readily available spectrum, so they don't have to compete for access to the very few frequencies available on HF for digital operations. It'll be interesting to see how they do. 73, Bob, KD7NM -Original Message- From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Howard Z. Sent: Tuesday, November 25, 2008 3:59 PM To: digitalradio@yahoogroups.com Subject: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field? Is the volunteer out of VHF range? If the base station has a 100 watt VHF radio like the 746pro - you might be able to still reach the volunteer, but he may not have enough power to get back to you. Or he may be out of VHF range. HF is the way to go - but both ends of the conversation need NVIS antennas. HF antennas tend to be large, and NVIS needs to be horizontal. I'm not sure there exists an NVIS antenna for a car or truck. Maybe something horizontal can be setup in the bed of a pick up truck? In general HF antennas for vehicles do not perform very well - but they are better than nothing. There are portable NVIS HF antennas available that can be setup rather quickly. Perhaps this is something to be done when he arrives at his destination, and then call the base on HF? Also keep in mind that HF radios typically cost over a thousand dollars compared to maybe two hundred for a VHF radio. Howard N3ZH --- In digitalradio@yahoogroups.com, expeditionradio [EMAIL PROTECTED] wrote: The following questions are asked to the amateur radio Emcomm community... how can we work together on this? THE TYPICAL SCENARIO It is a dark and stormy night... You are an amateur radio operator, volunteering with a relief organization, for communication to set up shelters in a hurricane disaster. There has been no power in the area for 24 hours. There is no mobile phone service, and all the VHF/UHF repeaters and digipeaters in the area are out of range or out of service. It is 3AM. You are driving in your vehicle, half-way to your first shelter destination, making your way on back roads. The main highway is flooded. You use your chain saw to pass a downed tree. The road ahead looks worse. THE CALL The relief organization wants to call you now. They have new information since you left on your mission, and they now want to change your destination, to divert you to another shelter location not far from your route. They want you to give the workers at the other shelter a list of supplies that are on the way. They want you to check the shelter's status. They want to know where you are, and if you can possibly divert to the other shelter, so they won't need to send out yet another expedition to the other shelter. THE QUESTIONS How will the relief organization call you? How will they get the actual message to you? How will they know where to route the message to be sure it gets to you? How will they get urgent feedback from you? THE BACKGROUND In the past, Ham radio has generally been very
Re: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
Howard, We already achieved successful, error-free, VHF communication (with no repeated blocks) using NBEMS software over a 70 mile path in flat country between two 50 watt FM transceivers, one with a 7.5 dBi antenna at 10 feet off the ground and the other with a 7.5 dBi antenna 25 feet off the ground. I have also developed a DOX interface for FM transceivers which have no VOX. A schematic is here: http://home.comcast.net/~hteller/Interface%20schematic.jpg We are now in the process of determining just how much farther we can go using FM. However, using SSB with DominoEX, we have already reached 100 miles consistently between a 9 dBi antenna and a 13 dBi antenna. We think that a 100 mile capability is sufficient to reach outside connectivity for email or phone delivery and confirmation. If so, then VHF can be used most of the time. By using 2m, if the S/N is sufficient, we can also use phone and data interchangably on the same frequency, which is not permitted on HF. When the terrain is too hilly for VHF, NBEMS also supports Hf using NVIS antennas with several modes specifically tailored to work under very high static conditions. However, it obviously easier to put up a small beam than it is to always find supports for a NVIS antenna for portable use. A picture of my 2m portable setup is here: http://home.comcast.net/~hteller/sideview.jpg. By using a two section mast, everything will fit in the trunk or in the back seat. NBEMS does not support push emcomm email, because there is no confirmation of delivery. Instead, there must just be an operator present at each end of the link. This also helps prevent transmitting on an already active frequency. As you correctly note, VHF FM transceivers cost only a couple of hundred dollars instead of a thousand for SSB-capable transceivers, however, it is absolutely necessary to use horizontally-polarized, gain, antennas to go farther than a repeater can go. The portable station antenna is usually going to be near the ground, and at 10 feet off the ground, there is a huge 6 dB penalty to using vertical polarization. We are now changing the emphasis of NBEMS from SSB to FM with DominoEX in order to make it possible for more people to use NBEMS and also take advantage of the low cost FM-only transceivers in the field. There appears to be a 3 dB or greater disadvantage to using FM over SSB, even with horizontally-polarized antennas, but that can be made up with increased antenna gain or power. Phone will not work on VHF over the same long distances as DominoEX or MFSK16 will work, because the noise level is often so high, the voice just cannot be understood or even heard at all. However, DominoEX and MFSK16 can still decode when the S/N is 10 or 12 dB UNDER the noise level, and that is how we get such long distance communication on 2m. 73, Skip KH6TY NBEMS Development Team - Original Message - From: Howard Z. [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Tuesday, November 25, 2008 6:58 PM Subject: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field? Is the volunteer out of VHF range? If the base station has a 100 watt VHF radio like the 746pro - you might be able to still reach the volunteer, but he may not have enough power to get back to you. Or he may be out of VHF range. HF is the way to go - but both ends of the conversation need NVIS antennas. HF antennas tend to be large, and NVIS needs to be horizontal. I'm not sure there exists an NVIS antenna for a car or truck. Maybe something horizontal can be setup in the bed of a pick up truck? In general HF antennas for vehicles do not perform very well - but they are better than nothing. There are portable NVIS HF antennas available that can be setup rather quickly. Perhaps this is something to be done when he arrives at his destination, and then call the base on HF? Also keep in mind that HF radios typically cost over a thousand dollars compared to maybe two hundred for a VHF radio. Howard N3ZH
RE: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
FWIW, in the response to Gustav It was known that Region 4 Resources would be deploying into the area in support of the Southern Baptist Disaster Relief Organization. Days ahead, info was exchanged on formal net operations in that area to allow members from Region 4 to check propagation and effective communications into what was projected to be the effective area; region 6, which is a fairly big target area. Propagation, time of day and available frequencies were reviewed and a net plan was decided on to allow the best chance for reliable communications into the affected area for 24 hour operations to support the deployed members from region 4 as they traveled into the affected area, in-transit to their various support locations and to get them safely back home to region 4. NCS were lined up on 2 hour shifts, and a pool of 12 were scheduled to make sure each day was covered in every 2 hour slot with a minimum of operator fatigue. One member was appointed to gather status reports on the deployed teams and report up the chain of command Weather conditions were constantly given directly to the teams via voice to advise them what they were traveling into, as Gustav was leaving and they were traveling into the edges of the affected area. NVIS can be achieves with two 102 whips, one front and one back, joined in the center over the vehicle, but it is better to have a support team, trained and ready, to understand propagation, MUF, general band conditions and be in emergency net operation with as many members as possible making every attempt possible to shut and listen. The net can periodically be extended by NCS (Net Control Station) calling for only stations with Good Readable to Loud and Clear copy on NCS, and in turn having them make the same call to determine the relay path. An accurate region roster and some idea of geography helps NCS to determine effectives of net and who to use for relay from deployed team members, if NCS does not have directly copy. NCS always chooses an alternate NCS, the furthest distance possible with reliable copy. This allows them to work together and achieve the broadest working net, with just 2 members to start and direct the net. The net is closed at the end of the 2 hours, and a new net is established with each oncoming NCS, which allows maintenance of the most accurate net roster. One member is appointed to track weather conditions in the path of the deployed teams, as radio station coverage is minimal at best from local broadcast stations, Major media resources are monitored to keep abreast of the fuel and power situation along the route. Having plenty of fuel in the ground is no good if the station has no electricity to pump it out of the ground. An open fuel station may clog one lane of a 4 lane divided highway as vehicles line up for miles to exit and refuel. The deployed members need to be in the proper lane, before the traffic snarl happens. They also need to be in touch with federal resources in convoy to keep them abreast, as the federal response may not be as well organized. Cellular coverage is monitored. MCS and ANCS use Skype to coordinate the net via text chat. Deployed members use Echolink where cellular coverage allows use of their air card for wireless access to an ISP. Winlink is used via aircard telnet/internet connectivity to direct messages to a single or group address, giving a little privacy if they are the first to arrive to a delicate situation and wish not to be in the clear with their Sitrep.. SHARES stations are active in the net, or on standby for direct access to federal entities. Phone Patch operators are on hand, ready to provide first access into a developing situation that may involve hazmat, mass casualty, etc. While traveling, something like a TS-2000 in cross band mode could give all members of a amateur caravan access to the HF net, if each member had something useful to report; otherwise, VHF from car to car, and one vehicle contained the team leader from each deployment group to relay the Intel back into the net for distribution. OK, How am I doing so far? Point to ponder: Anyone who deploys without prior notice has a highly technical tactical designator assigned to them - fool David KD4NUE -Original Message- From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Howard Z. Sent: Tuesday, November 25, 2008 6:59 PM To: digitalradio@yahoogroups.com Subject: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field? Is the volunteer out of VHF range? If the base station has a 100 watt VHF radio like the 746pro - you might be able to still reach the volunteer, but he may not have enough power to get back to you. Or he may be out of VHF range. HF is the way to go - but both ends of the conversation need NVIS antennas. HF antennas tend to be large, and NVIS needs to be horizontal. I'm not sure there exists an NVIS antenna for a
RE: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
Conditions just now are at night hostile to even NVIS. We sometimes eke out ground wave between MARS members here with vertical antennas below -- well below -- 3.5 MHz. Some nights I'd like something below 1.8! Nevertheless, my mobile setup, when I have it installed, covers 160-440. MARS frequencies too, of course. I dont rely on the mobile antenna, with a spool of telco CO wire cheap and handy. I have Elk 2/440 LPDA's and painters poles, too. Making a communication system work requires forethought as to HOW it can be done for the requirement of the time. Frequency coordination that doesn't allow for propagation can hobble even a California Kilowatt, assuming anyone had a big enough generator and a 6X6. -- and ravine comms on VHF is really not a good idea. Some prior planning and practice is needed. A club I used to belong to supported bicycle rides over some pretty poor VHF radio paths. It helped when we TESTED those paths. Sometimes a remote cross band mobile repeater was needed. Sometimes an FRS radio link (but the Feds can't legally use those) to the rest stop or aid station from a nearby hill. But we can't rely on such things appearing from thin air. Or helping when large amounts of message traffic must be passed. There has been some discussion involving communication to customer WiFi and Bluetooth.Where it has been tried it has apparently been well received and these are of course well suited for digital traffic. The holes in our planning are not yet all known, either. Cortland KA5S AAR5UT [Original Message] From: Howard Z. [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Date: 11/25/2008 6:59:21 PM Subject: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field? Is the volunteer out of VHF range? If the base station has a 100 watt VHF radio like the 746pro - you might be able to still reach the volunteer, but he may not have enough power to get back to you. Or he may be out of VHF range. HF is the way to go - but both ends of the conversation need NVIS antennas. HF antennas tend to be large, and NVIS needs to be horizontal. I'm not sure there exists an NVIS antenna for a car or truck. Maybe something horizontal can be setup in the bed of a pick up truck? In general HF antennas for vehicles do not perform very well - but they are better than nothing. There are portable NVIS HF antennas available that can be setup
RE: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
The last time I got into something like this I was called (all be it direct reply) a fool. What works for you in the large city may not work for me in the rural area with hills all around. In the floods this spring I at times had the only HF mobile rig in the county.
[digitalradio] Help on Yaesu FT-450 monitor of signal
I spent the afternoon helping a newly licensed General Class ham get on digital modes. He has a Yaesu FT-450 and Tigertronics SignaLink USB. We downloaded the fldigi multimode digital program and were able to get the received audio to show a good display on the waterfall and prints OK. The interface connects via the rear 6 pin mini DIN and the rig is placed into USB DATA mode. When we key the rig via the program, everything seems to be working OK and RF is indicated without any ALC up to about the 25 watt level. The problem is that we can not get the Monitor function to work when in DATA mode. We confirmed it works OK when transmitting SSB phone mode. Is there a way to be able to monitor the signal when in the DATA mode or is this not possible to do? He has no other receiver to listen to his signal so after he gets done with milking this evening, we are going to try working each other. Our farms are only about 14 km apart, so we will try on 10 meters to see if everything is sending cleanly. Appreciate any insight you digital FT-450 owners can give. I see that Yaesu has just made available a flash update to the rig to correct something to do with rig control when using data modes. Does anyone know what they means in practical terms? It sounds like you could not previously use rig PTT via rig control software commands? 73, Rick, KV9U
RE: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
We get quite good results in the 45 to 50 mile range using VHF SSB (2M) and 5 watts with Olivia from fixed location to fixed location and low gain omni vertical antennas. From a mobile to a fixed location, I would estimate as good a signal on SSB as can be expected from the same mobile to a repeater input on FM; unless there is a tremendous height difference to offset the signal to noise gain of the SSB transmission. David KD4NUE -Original Message- From: digitalradio@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Bob Donnell Sent: Tuesday, November 25, 2008 7:47 PM To: digitalradio@yahoogroups.com Subject: RE: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field? And further, this thought should be considered as VHF FM, or VHF SSB? In a base/mobile or mobile/mobile environment, SSB on VHF works over much greater distances. With voice communications, VHF SSB benefits from having flutter resulting in the desired signal amplitude going up and down, while the background noise level is held pretty constant, by the AGC in the receiver. FM is opposite in that regard - when the signal gets weak, the background noise level comes up, at least until the squelch closes. In my perception, I seem to be better able to fill in the gaps in syllables when the signal drops out, than when it's filled with noise. VHF SSB also has the benefit of probably not requiring the mobile station to have to take time to set up an antenna. If the mobile station is parked in a null, chances are that moving the vehicle a few inches will change a multipath situation enough to provide good copy. If there's benefit to be had by setting up a portable (v.s. mobile) antenna, putting a VHF omnidirectional stick up 10-20' is a pretty trivial task. While there can be benefit to be had by using horizontal antennas, unless you're into serious weak-signal work, it's not necessary to realize large gains in coverage, even using omni antennas on both ends, using SSB. Digital modes that are designed to work well in weak signal circumstances on HF SSB rigs will similarly work well on weal signal VHF SSB rigs, because the same linear-mode technology is involved. Probably the biggest caveat to that will be frequency accuracy and stability. Radios on a net will need to be well warmed up, or have high stability oscillators, if they are operating unattended, and expected to be able to be received by the sender. I've encouraged those that are working on upgrading our regional hospital network to use the IC-706's that they already have set up for HF pactor, to try VHF pactor using the SSB mode, as a way to gain from the more readily available spectrum, so they don't have to compete for access to the very few frequencies available on HF for digital operations. It'll be interesting to see how they do. 73, Bob, KD7NM -Original Message- From: digitalradio@ mailto:digitalradio%40yahoogroups.com yahoogroups.com [mailto:digitalradio@ mailto:digitalradio%40yahoogroups.com yahoogroups.com] On Behalf Of Howard Z. Sent: Tuesday, November 25, 2008 3:59 PM To: digitalradio@ mailto:digitalradio%40yahoogroups.com yahoogroups.com Subject: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field? Is the volunteer out of VHF range? If the base station has a 100 watt VHF radio like the 746pro - you might be able to still reach the volunteer, but he may not have enough power to get back to you. Or he may be out of VHF range. HF is the way to go - but both ends of the conversation need NVIS antennas. HF antennas tend to be large, and NVIS needs to be horizontal. I'm not sure there exists an NVIS antenna for a car or truck. Maybe something horizontal can be setup in the bed of a pick up truck? In general HF antennas for vehicles do not perform very well - but they are better than nothing. There are portable NVIS HF antennas available that can be setup rather quickly. Perhaps this is something to be done when he arrives at his destination, and then call the base on HF? Also keep in mind that HF radios typically cost over a thousand dollars compared to maybe two hundred for a VHF radio. Howard N3ZH --- In digitalradio@ mailto:digitalradio%40yahoogroups.com yahoogroups.com, expeditionradio [EMAIL PROTECTED] wrote: The following questions are asked to the amateur radio Emcomm community... how can we work together on this? THE TYPICAL SCENARIO It is a dark and stormy night... You are an amateur radio operator, volunteering with a relief organization, for communication to set up shelters in a hurricane disaster. There has been no power in the area for 24 hours. There is no mobile phone service, and all the VHF/UHF repeaters and digipeaters in the area are out of range or out of service. It is 3AM. You are driving in your vehicle, half-way to your first shelter destination, making your way on back roads. The main highway is flooded. You use your chain saw to pass a downed tree. The road
Re: [digitalradio] Re: How Can We Push HF Emcomm Messages to the Field?
This is something that would likely be more at home at the HFDEC yahoogroup that discusses disaster and emergency communications but lets look at some of the practical aspects. Distance was not specified, but it would be rare to send someone out at night, under dangerous conditions, in unfamiliar territory, to handle communications at a shelter. It would be unusual to be out of range of the EOC unless a very rural area with difficult terrain (OK, maybe not too unlike my region, HI). After recent testing that my wife and I have been doing with 6 meters vs 2 meters with different modes, we have found that 2 meters works the best when there are any possible noise problems (less likely with power lines inoperative though), and using SSB is superior to FM when signals become weak. This can give you a significant coverage area, especially if the base station has some gain. We also use HF mobile since Judy has a Texas Bug Catcher that can be attached to the receiver hitch. While not optimum according to expert mobileers, this is the way we are willing to do HF. Contrary to some claims that bending the antenna over will improve signals, we have not found this to be true and it does not give you NVIS signals. Using an extended wire might be of help but we have yet to test that as it can not be used in motion. There are very large and expensive antennas that are claimed as operating NVIS, but not something that most of us would consider. And I have not seen any tests done to show how efficient or how vertical the radiation really is. When Judy came back from our daughter's home (200 miles) last week, as is our usual custom, we again performed a number of tests at different distances and as long as the FoF2 is above 4 MHz, things are often OK with daytime signals of S5 to S8 (almost no QRN) when she is at the maximum distance. As she gets closer, her signal often drops lower in strength since she is likely transmitting with lower angle radiation than we would like on 75 meters. Her signal got worse and worse and at 100 miles out things became unusable at times. Even when she was only 15 miles out, she was barely able to communicate. And then even at only 7 or 8 miles where she refueled and had to take off the quick release top whip on her last transmission she was extremely difficult copy. The FoF2 had dropped below 2 MHz by then. Some of you may have noticed that lately we have had barely 1 MHz FoF2 in the evening. I just checked and at about ~8 pm CST, almost the entire U.S. is at 2 MHz. This means that you may find HF to be of very limited value in the evening. Since higher frequencies are even worse at close distances, other than ground wave, (which is only a few miles), and since 160 is so difficult to use for mobile, I am convinced that there really needs to be more of a focus on VHF SSB. One other supporting point is that many new mobile transceivers now include VHF and UHF SSB. 73, Rick, KV9U Howard Z. wrote: Is the volunteer out of VHF range? If the base station has a 100 watt VHF radio like the 746pro - you might be able to still reach the volunteer, but he may not have enough power to get back to you. Or he may be out of VHF range. HF is the way to go - but both ends of the conversation need NVIS antennas. HF antennas tend to be large, and NVIS needs to be horizontal. I'm not sure there exists an NVIS antenna for a car or truck. Maybe something horizontal can be setup in the bed of a pick up truck? In general HF antennas for vehicles do not perform very well - but they are better than nothing. There are portable NVIS HF antennas available that can be setup rather quickly. Perhaps this is something to be done when he arrives at his destination, and then call the base on HF? Also keep in mind that HF radios typically cost over a thousand dollars compared to maybe two hundred for a VHF radio. Howard N3ZH --- In digitalradio@yahoogroups.com, expeditionradio [EMAIL PROTECTED] wrote: The following questions are asked to the amateur radio Emcomm community... how can we work together on this? THE TYPICAL SCENARIO It is a dark and stormy night... You are an amateur radio operator, volunteering with a relief organization, for communication to set up shelters in a hurricane disaster. There has been no power in the area for 24 hours. There is no mobile phone service, and all the VHF/UHF repeaters and digipeaters in the area are out of range or out of service. It is 3AM. You are driving in your vehicle, half-way to your first shelter destination, making your way on back roads. The main highway is flooded. You use your chain saw to pass a downed tree. The road ahead looks worse. THE CALL The relief organization wants to call you now. They have new information since you left on your mission, and they now want to change your destination, to divert you to another shelter
