Mobile NVIS Systems (ex- 6m v. 10m)

[KJ4VOV]

Would a Yaesu FT-897D and a Buddipole using 40/80 meters work for this?

An 897 is kind of big for mounting as a mobile, but I know guys who have. The 857 would be a better choice. Same radio, smaller package. And I have no idea how you'd mount a Buddipole on a mobile and still be able to drive.

[Tater Raider]

And I have no idea how you'd mount a Buddipole on a mobile and still be able to drive.

I wouldn't, but I could park and set it up quickly. Not my first choice but definately my best option if I have to have coms for 500-600 mile range. I'm almost thinking I'd have to get a whip antenna and put a load coil on it to get a mobile rig in the 20-40m bands.

However, this might work for a mobile 20m: http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=24041

Ninja Edit: My wallet looked at the Yaesu and began weeping. I mean it covers anything and everything and does base, mobile, and prtable, but that's a lot more radio than I'm looking for. However, I'm bookmarking that page because someday I will be able to get it and licensed to operate it like a boss.

And I am never saying "like a boss" again...

However, there is a mobile for that radio:




You guys got me thinking on this really hard...

[KJ4VOV]

redacted

[CitizenZ]

And I have no idea how you'd mount a Buddipole on a mobile and still be able to drive.

I wouldn't, but I could park and set it up quickly. Not my first choice but definately my best option if I have to have coms for 500-600 mile range. I'm almost thinking I'd have to get a whip antenna and put a load coil on it to get a mobile rig in the 20-40m bands.
...

Still not going to give you the range you need, reliably. IMO, You need an NVIS set up. It will be easier and better for your needs. It was developed as military comms for exactly this use. Basically a simple 40m dipole (or horizontal antenna) that is too close to the ground plane, causes the signal to go straight up and bounce off the atomosphere as a giant reflector dish in the sky. 40m during the day, and 80m at night. That could give you the range you need. It does not work on 20 meters or other bands.


http://www.google.com/url?q=http://en.w ... 9ifrI7fgFg

DIY:

http://www.emcomm.org/projects/nvis.htm

[Tater Raider]

Okay, I think I'm getting this...

NVIS means 3.5Mhz or 7MHz, so 80m or 40m band. 40 works better in daytime and 80 works better at night so an antenna swap is doable with the Hamsticks provided I have a place to store the one not in use, otherwise 2 antennas and then use an antenna switch to swap them out hassle free.

A Hamstick will do me fine for use while driving, but if I want to reach out and touch someone via DX I will need to pull over and deploy a portable dipole antenna horizontally and close to the ground to get good NVIS propagation.

Once I'm able to use groundwave I can use something more along the lines of a 10m or 6m band to free up the DX bands, meaning another antenna.

I can get one radio to rule them all, one radio to find them, one radio to bring them all and in the darkness bind them if I'm willing to pay the big bucks for a new set or shop used with someone local and knowledgable so I don't buy junk. Or I can buy a couple of radios to cover different parts of this to get in on a budget and grow into it then get the One Radio when I'm more ready for it, which sounds like a better plan.

Am I thinking this through correctly now?

[CitizenZ]

Who are you talking to on the ham stick? On what band? No.
It can be as simple as taking a large whip and bending it over the length of the car. That's it. You can have the NVIS on the car all the time. Another at each location.

The car is the ground plane.

[Tater Raider]

Who are you talking to on the ham stick? On what band? No.
It can be as simple as taking a large whip and bending it over the length of the car. That's it. You can have the NVIS on the car all the time. Another at each location.

The car is the ground plane.

K, got it. We've disagreed before on a particular antenna array but on this I know nothing. I should know something, but I don't and am either learning or relearning. You have my sincere thanks and appreciation.

[KJ4VOV]

The only thing I think needs clarification is that the hamsticks are quite capable of working DX. They may not be the best at it,but they do work.

[CitizenZ]

500 miles mobile to base on a hamstick on 6-10 meters? I doubt that. Good luck. If it doesn't, then you might try my suggestion of directional or NVIS antennas.

[gary in ohio]

500 miles mobile to base on a hamstick on 6-10 meters? I doubt that. Good luck. If it doesn't, then you might try my suggestion of directional or NVIS antennas.

Reliable 500mile mobile/base on 6/10m NO.... 500 mile base/mobile communication ii certainly possible but bands need to be open.... A closed/dead band is just that closed/dead. I dont care what kind of power or antenna. If propagation is there it isnt there.

[Tater Raider]

80m at night and 40m during the day with a NVIS setup sounds like what I need to do what I want. How to make it work on a Wrangler with a soft top leaving the soft top functional and still able to rooftop a canoe will be the fun part.

Edit: A tethered whip may be, I did a couple hours of searching, seems to be the best solution - thanks CitizenZ.

I do think a second radio higher up the bands would be better to use once you are within groudwave range, but it's pretty obvious to me now that the 6m v. 10m was a silly question given what I want to do.

Now to get my license and begin saving up some money.

[CitizenZ]

500 miles mobile to base on a hamstick on 6-10 meters? I doubt that. Good luck. If it doesn't, then you might try my suggestion of directional or NVIS antennas.

Reliable 500mile mobile/base on 6/10m NO.... 500 mile base/mobile communication ii certainly possible but bands need to be open.... A closed/dead band is just that closed/dead. I dont care what kind of power or antenna. If propagation is there it isnt there.

Incorrect. My point is to NOT depend on skywave propogation at all. Not random "skip", but controlled directional or NVIS system in a controlled distance under MOST conditions, not the rare skip to achieve the distance. Omni directional antennas cannot do this.

Such things are possible by choosing the right band and antenna system. It's not new either, these methods have been around a long time.

The Global Ionospheric World Map indicates the frequency in MHz at which a signal transmitted more or less straight up (about 70 – 90 degrees) will no longer bounce back to Earth, but rather escape out into space.

In short, this picture shows the Maximum Usable Frequency (MUF) for Near-Vertical Incident Skywave (NVIS) propagation.

NVIS is the mechanism for reliable HF communications within a region (500 mile radius). Without NVIS, there is a skip zone or dead zone where neither groundwave propagation nor skywave propagation are effective. This skip zone is often a band around the transmission site extending from between 20 miles (where groundwave leaves off) and a few hundred miles (where skywave begins to take effect).

http://ah6td.com/359/global-ionospheric-world-map/

[CitizenZ]

Edit: A tethered whip may be, I did a couple hours of searching, seems to be the best solution - thanks CitizenZ.

I do think a second radio higher up the bands would be better to use once you are within groudwave range, but it's pretty obvious to me now that the 6m v. 10m was a silly question given what I want to do.

Now to get my license and begin saving up some money.

It wasn't a silly idea at all. If it was just fixed point to point, 6 - 10 meters could still be good ideas if you had great antennas and recievers. But with a mobile application; giant directional antennas and masts are not practical. NVIS happens to be a more mobile and tactical solution for your needs. As another "feature" it will also limit your practical range to those few hundred miles. You will not get any of the skywave propagation that common antenna systems get. So you won't be making international contacts that others get. This might be a usefull security feature or a limitation you should be aware of. A cool feature of using a tethered whip is that you could simply untether the whip and it would then act as a standard vertical. lose it's NVIS traits, and get the normal long path skip of a vertical whip.

[nacho]

radiograms anyone?

I'm not sure if there are any large RF based intertie networks in Iowa like there are out west, but unless you can successfully communicate regularly over HF I wouldn't count on anything RF working consistently at 500+ miles. Yeah 20 - 40M should do the job, but I would try to have regular comms with your relatives to make sure "lines" of communication are working.

[Tater Raider]

radiograms anyone?

I'm not sure if there are any large RF based intertie networks in Iowa like there are out west, but unless you can successfully communicate regularly over HF I wouldn't count on anything RF working consistently at 500+ miles. Yeah 20 - 40M should do the job, but I would try to have regular comms with your relatives to make sure "lines" of communication are working.

I'm looking to get 1 radio that does it all at this point, followed by radios that do the specific things I use it for well and then reselling the one radio to my brother at below fair market value and 0% interest with a pay-as-you-can-afford-it plan. Lack of space in Dusty dictates I keep the number of radios down and the installation of a ceiling center console to provide a secure theft resistant mounting point up and out of the mud and water I tend to go through, meaning longer antenna cable runs and some power loss in those lines (I know at least 1 band practically demands keeping those lines as short as possible).

TANSTASFL and all that.

[g211]

FWIW: I'm looking for a real-life mostly reliable DX range around 550 miles if possible. I'm trying to set up coms with an out-of-state relative - we use each other as a BOL and reliable coms suddenly make sense to at least address and given a choice mobile seems to me the best place to start.

Going off the convo so far it looks like 10m SSB is the best bet, correct?

Neither band is going to be reliable at that short a distance. 550 miles isn't reliably a single-hop path above 40 meters. First hop on 10 is generally 800 miles or more, 6m is more like 1000 miles. You generally don't hear anything closer unless it's within ground-wave range (20 miles or so).

You'd probably be able to make contact once in a while through multi-hop -- where the signal was coming down some spot about 800 - 1000 miles from both stations on the first hop, and then skipping again to the other station -- but that's a high-loss path; it wouldn't be something you could count on happening reliably.

Why are you limited to just one of those two bands?

Edit: OK, so I went and read the rest of the thread . . . I think a plain old whip would work fine at this range. You don't need near-vertical at 550 miles. A 40m vertical and around 500 watts will radiate enough energy above 45 degrees to make paths down to 400 miles or so very workable.

[Boyscoutdreams]

Tater Raider wrote:FWIW: I'm looking for a real-life mostly reliable DX range around 550 miles if possible. I'm trying to set up coms with an out-of-state relative - we use each other as a BOL and reliable coms suddenly make sense to at least address and given a choice mobile seems to me the best place to start.

Going off the convo so far it looks like 10m SSB is the best bet, correct?

Of the two frequencies you're looking at, yes 10meter SSB would be your best bet.... With that said, as someone else pointed out, for consistent (or close to that) NVIS signals, Lower is better. What I've read, 20 meter and 40 meter, with a low dipole antenna at each BOL, running parallel to each other (there is some slight directionality to the antennas) would give you the best chances of consistent communications. Being NVIS means the signal is being intentionally reflected strait up because the antenna is low to the ground. When it reflects back down it will give you a Cone of influence. Again, if I understand it correctly, adjusting the hight of the antenna will affect the diameter of the cone. All things that need to be worked out before hand. I've played with this idea myself and have one working horizontal loop for it but have not really tried for consistency yet.

Though the antennas can be put up and taken down easily enough, don't know how that would work out in a mobile. Personally I'd try something like a horizontal loop antenna. Use some PVC pipes to make a portable supports for the loop. Here is one link to the loop antennas to give you an idea what I am talking about.
http://www.k5rcd.org/hor%20loop%20instruct.htm
Good luck

[Tater Raider]

Keep in mind these have to be mobile coms. Band is negotiable but installing it in the Jeep isn't.

[44Dave]

If we're talking about NVIS antennas, shouldn't we also be talking about MUF?

The Yaesu 857 looks like it should mount in the ceiling. I've not direct experience with it, but eHam seems to be positive on it.

[TacAir]

Do you need to talk or will passing messages (data) work for your needs?

How wide an area will you be mobile? That is to say - just around town or cross county (Denver to KC for example.)

Meteor burst is an option, but will require some rather specialized accessroy equipment for your mobile rig.

More here

he United States Department of Agriculture (USDA) uses meteor scatter extensively in its SNOTEL system. Over 800 snow water content gauging stations in the Western United States are equipped with radio transmitters that rely upon meteor scatter communications to send measurements to a data center. The snow depth data collected by this system can be viewed on the Internet..

Meteor burst communications faded from interest with the increasing use of satellite communications systems starting in the late 1960s. However, in the late 1970s it became clear that the satellites were not as universally useful as originally thought, notably at high latitudes or where signal security was an issue. For these reasons, the U.S. Air Force installed the Alaska Air Command MBC system in the 1970s, although it is not publicly known whether this system is still operational. (THe USAF MB system was pulled from service in the late 80s - removed in the 90s.

In Alaska, a similar system is used in the Alaskan Meteor Burst Communications System (AMBCS), collecting data for the National Weather Service from automated weather stations, as well as occasional data from other US government agencies.

Most meteor scatter communications is conducted between radio stations that are engaged in a precise schedule of transmission and reception periods. Because the presence of a meteor trail at a suitable location between two stations cannot be predicted, stations attempting meteor scatter communications must transmit the same information repeatedly until an acknowledgement of reception from the other station is received. Established protocols are employed to regulate the progress of information flow between stations. While a single meteor may create an ion trail that supports several steps of the communications protocol, often a complete exchange of information requires several meteors and a long period of time to complete.

Any form of communications mode can be used for meteor scatter communications. Single sideband audio transmission has been popular among amateur radio operators in North America attempting to establish contact with other stations during meteor showers without planning a schedule in advance with the other station. The use of Morse code has been more popular in Europe, where amateur radio operators used modified tape recorders, and later computer programs, to send messages at transmission speeds as high as 800 words per minute. Stations receiving these bursts of information record the signal and play it back at a slower speed to copy the content of the transmission. Since 2000, several digital modes implemented by computer programs have replaced voice and Morse code communications in popularity. The most popular program for amateur radio operations is WSJT, which was written explicitly for meteor scatter communications. Note that data rates are on par with packet radio - that is to say, slow.


Sources for software -
http://physics.princeton.edu/pulsar/K1JT/

http://www.aprs.org/meteors.html (6M MB activity)

http://www.dxzone.com/catalog/Software/Multimode/

For years the USGS tracked choppers in the bush via MB communications, along the lines of APRS, and I worked with the Alaska meteor burst system for a number of years. It does offer a means to communicate over a wide area on 6M or even 10M. Power levels of 45 to 60 watts are the norm.

Hope this is of use.

[CitizenZ]

No. NVIS will not work on other bands. That is a restriction of the NVIS technique. It only works on the 80-40 meter band. SSB with 100 watts (or less) and a long whip bent over the car should provide reliable com with a 500 mile radius. Omni-directional antennas will not provide reliable com at that range. Commercial SW/HF/VHF/UHF broadcasters don't get that range, reliably, with 50,000 watts. Occasional skip and skywave will do that range and more, but don't count on it when you need it.

I don't know of any other way to achieve reliable com at that range for mobile use. NVIS 40-80 meter WILL do it, without a doubt. With digital modes or Morse code it could even be done with 5 watts or less.

[Tater Raider]

Voice only, I live in North Central Iowa and want to talk to Northeast Arkansas, 525 miles direct path. I plan to learn morse so CW is an option, provided my brother learns it as well, which I doubt he will.


EtA: Not sure on snow gauges in AR... no offense.

[CitizenZ]

Voice only, I live in North Central Iowa and want to talk to Northeast Arkansas, 525 miles direct path. I plan to learn morse so CW is an option, provided my brother learns it as well, which I doubt he will.


EtA: Not sure on snow gauges in AR... no offense.

Morse is still a powerful mode. You can cheat and use handheld readers/generators or computers/PDA's to "talk" with CW. With CW, decent NVIS antenna and decent receiver you can do that range with just a few watts, but only on the 40-80 meter band. I'm a philistine and have only used it with a computer doing the work for me. Even then you still have to learn a lot of "cheat" codes and what they mean. Worth the effort.

ETA; also CW only HF radios are much cheaper and can even be home made for a few bucks.

[CitizenZ]

$125 for the kit. Just add whip and morse code generator/reader.


http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3205