Date   

Question the e-mail part of NBEMS

Rick <mrfarm@...>
 

I tried to get Sylpheed set up to work with NBEMS, but I must require at least one "account" in order to make it actively allow you to access the program? The main toolbar appears grayed out.

Since my ham programs are on a different computer (side by side towers with the ham side running XP or can dual boot into Kubuntu Linux and the main computer running Vista), so I don't really want to set up a regular account on Sylpheed or any other e-mail program because I handle e-mail via Thunderbird on my Vista machine.

Any suggestions on setting up Sylpheed? I studied the documents on the program and on the NBEMS site and it did not seem to address this.

Also, I am not clear on what you can and can not do with e-mail and NBEMS. From what it looks like, you are basically using the e-mail program to help you format the e-mail and then saving it as a draft file. Then you have to go in and manually drag and drop it into the NBEMS program.

So you are able to use the e-mail program as a holding site for the drafts and then you can either have files held there for say, another ham who has not connected with you yet, or you can route somehow through the internet?

Is the long term thinking that the integration would be more automatic and you would have a place to store the files for RF only paths, but could also route through the internet if that was available and the sender wanted this?

73,

Rick, KV9U


Re: soundcard question

w1hkj <w1hkj@...>
 

Michael Johnson wrote:
I have a Tigertronics USB with built-in soundcard.  The laptop I am using for EmComm also has an ESS soundcard which is the Windows default.  NBEMS is currently trying to tx through the ESS soundcard.
 
I can disable the ESS soundcard and make the Tigertronics USB Codex the default if necessary.  Is it possible however to configure NBEMS to use the Tigertronics and find the soundcard over the USB connection?  In the NBEMS configuration window I see options for soundcards (Windows default, SC #1, SC #2, SC#3).  Is there a way to specify SC #1 in the configuration as the Tigertronics?
 
Thanks,
Michael (N0VX)
Your setup is very similar to mine Michael.  I test NBEMS on a Dell Dimension 3000 which has an ESS soundcard on the mother board and also the SignaLink USB  for digital use.  Windows will usually (but not always) set the ESS to sound card 0 and the SignaLinkUSB to sound card 1. Which you want as your windows default is configurable from the windows control panel.  I set the ESS to the default so that windows burps and giggles go to the speakers.  That keeps erroneous noises off of the air.

My programming expertise is in Linux, so I am not sure how to ascertain the noun name of the device with the device number in Windows.  I will do some research this evening on the subject.  In the meantime if anyone on the list knows how to do that in VB6 please send me an email with the system call information.

Thanks.

73, Dave, W1HKJ


144 Pol

"Shelby Ennis, W8WN" <w8wn@...>
 

Here are some notes regarding polarization on 2 M:
(First, tho, I have worked all 50 states, 500 grids and 73 countries on 144 MHz, and have also been on 2 M FM for ~35 years. Much of my operation now is digital using Joe's WSJT's suite of pgms).

It's hard to work mobile with horizontal pol. A halo, turnstyle, Big Wheel, or similar will work but give no gain and are big. (Yes, I've worked several who do have small beams they use for MS operation while in motion, but I don't recommend this). But it is not hard to push up a pole with a small horizontal beam when portable, if you're going to be there for awhile. The biggest time-consumer is assembling the beam. With my portable 13-el KLM, this takes a while. A small beam, or a beam carried in two sections on top or inside a van or trailer will go together quickly.

To preserve the pattern of a single vertical beam, the supporting mast and coax should be behind the reflector. For a small beam, up to about 4 elements, it can usually be rear-mounted. For a larger beam, a non-conducting mast should be used (again, with the coax coming off the end). This is awkward in many situations. (The wooden mast on my small vertical beam breaks during high winds approximately every 5 years).

Tests made many years ago (sorry, don't have any references handy) indicated that horizontal polarization had slightly less loss than vertical for weak-signal work. Don't remember any more details.

All weak-signal work is done with horizontal polarization.
There really isn't much in this country compared with Europe. But there is a larger number of fellows who have multi-mode VHF xcvrs and horizontal beams and only chat locally (i.e., 150 miles or less, typically), and seem to have no interest in VHF DX. They typically run 50-100 watts to 5-15 element beams.

All FM, repeater, mobile, etc operation is done with vertical polarization.
The reason for this is because a vertical 19" whip is a lot handier to use than a halo, etc. And this is predicated on the assumption that one of the two stations will nearly always be mobile.
Nearly all vertical operation is done using NFM, a strong-signal mode.

It is not (too) difficult to set up a small beam so that it can be used either H or V. But it generally has to be done manually, on the ground, etc.

Be careful of older beams in the 7-15 element range. Some of them did not work properly (no brands will be mentioned). And just because the old catalog says it's capable of xxx dBi gain, this is worthless unless you know the company well or it has been tested on an antenna range.
Newer beams *should* be pretty good, because anybody can check them with the Yagi modeling programs available now.
Beams of 5 elements or smaller are rather non-critical. Longer ones are more critical. And it isn't the number of elements, but the boom length that determines the maximum gain possible.

Cross polarization (i.e., V to H)? Fine for across town - if it's a small town. For any distance or any type of weak-signal work, forget it!

Does this tell you which to use? Probably not!
What are others in your area using? What else are you going to do?
If only emergency-type work, vertical would be better. (You will be using NFM for voice).
If longer distant operation where CW & SSB will probably be needed, horizontal should be considered. But what are others using, what area of the country are you in, and what would the others be willing to do?
Omni gain, either H or V, is difficult to get. You don't get something for nothing - to increase your signal in one direction, you have to reduce it in other directions. But would your emergency operation likely be point-to-point or spread around the compass?

In general, it's a lot easier to put up a small vertical antenna (but no gain).
If you need 10 dBd or more gain, it's usually easier to put up a horizontal beam.
Either way, if your coax run is more than about 10', be sure it's LOW LOSS coax!
And beyond that, I can't give any real suggestions. Both H & V pol are useful, but in different ways and for different reasons!

73, Shelby, W8WN


Shelby Ennis, W8WN - EM77bq - KY
w8wn@..., w8wn@...
Web: http://www.qsl.net/w8wn/
<><


Re: Update on testing in Independence, Missouri

"kh6ty" <hteller@...>
 

Rick and others,


If I have learned at least one thing in recent time, it is that cross
polarization makes one have to think long and hard about having a
polarization different than what other hams have if they operate VHF. At
least in our area it is about 95%+ vertical, including beams and
collinear verticals.
There appears to be a larger-than-expected pool of hams already using 2m for "weak signal" operations, and all of those are equipped with high gain, horizontally-polarized, beams and SSB-capable transceivers, and probably also brick amplifiers. By simply adding a digital interface and a computer to that setup, all of these "weak signal" operators can serve as forwarding stations for NBEMS. I don't think we want to ignore or diminish this resource.

If a ham wants to assist with emcomm on 2m VHF, he must have, or acquire, a 2m SSB transceiver and rotate a vertically-oriented beam horizontally, or put up a new antenna. If he wants to contine using repeaters, he can probably access the local repeater with a simple 1/4 wavelength vertical whip. If he only has access to a distant repeater or desires to access distant repeaters, he can have one antenna connected to his FM-only transceiver and a horizontally- polarized beam connected to his multi-mode or SSB 2m transceiver.

As I have mentioned previously, there is a whole new and exciting world of 2m SSB phone or digital communication (using horizontally-polarized antennas) to explore for any ham who has only used 2m with a HT or FM-only transceiver and repeaters.

It is probably not going to be possible to do enough testing to positively determine if there is any advantage to horizontal polarization over vertical polarization over long distances, and even if there is only 1 dB of advantage to using horizontal polarization, on VHF, it is important to have as much gain as possible, and that 1 dB is important, as any EME or weak signal operator will tell you.

This will be my last post regarding the issue of horizontal vs vertical polarization. The position of the NBEMS developers is that we *strongly* recommend using the existing convention (i.e. horizontally polarization) on 2m SSB for NBEMS and we will attempt to build interest in supporting NBEMS using horizontally-polarized antennas for 2m.

Any emcomm group that wishes to promote the use of vertical polarization, or other modes, such as FAE400ARQ, is, of course, welcome to do so. We need all the help during emergency situations as possible, and that even includes using the Winlink 2000 network when possible or desired.

For ourselves, we will be concentrating on assisting with the testing and deployment of the modes already supported by NBEMS software, using horizontal polarization on 2m, and MFSK16 with NVIS antennas when the PSK modes do not work as well.

An update to NBEMS will be released very shortly. IT IS IMPERATIVE, BEFORE RUNNING THE UPDATE SETUP.EXE INSTALLATION PROGRAM, TO UNINSTALL NBEMS THROUGH CONTROL PANEL, *AND* ALSO DELETE THE C:/NBEMS FOLDER. The update contains many improvements to the system and all testers are advised to use the latest version. The update will not work with previous installations of NBEMS.

An announcement of the update will be made on this and the digitalradio reflectors, as well as on the NBEMS web page at www.w1hkj.com/NBEMS.

If there are any hams using (or testing) NBEMS with FM rigs it would be
helpful to find out how well that works ... or not. I can see that using
a low cost interface, it would be possible to standardize on something
like NBEMS for local packet like communications. Maybe some kind of BBS
would be possible.
We have made many tests using FM transceivers for PSK63, and find the range is greatly limited in comparison to SSB. ARQ on FM is not needed, because once you achieve limiting, there is little chance for error. In emergency situations, repeaters are often down, and that is the main reason for using point-to-point communications with NBEMS in the first place. You can reach far enough away so that you do not need a repeater network to reach connectivity outside the disaster zone.

We did try vert antenna with very poor results, ~10% copy, even at 35
watts. My vert antenna is a 6 db 2/70 up at 30 feet, not sure what
John has for mobile. Apparently there is better performance using the
Horiz polarized antenna. No doubt vert antenna is the easiest solution
for mobile. We had pre-planned the test using our 'standard' test
frequency 144.144, haven't gotten any protests - yet.
The problem with the vertical antenna was probably the cross-polarization loss of 20 dB. In order to determine if horizontal polarization has any advantage over vertical polarization, the tests need to be done between stations 100 and 200 miles apart, with BOTH stations using the same polarization and then changing from horizontal to vertical.

We strongly encourage the experimentation and development of emcomm systems using modes not supported by NBEMS. We can all learn from such activity. NBEMS is only one tool in the emcomm arsenal. The biggest tool is, of course, phone communication on HF or VHF repeaters, and NBEMS or other systems are available when phone communications are not possible, repeaters are down, HF bands are unusuable, or written documentation of messages is important.

73, Skip KH6TY
NBEMS Development Team


NBEMS testing on 80 meters tonight

"tim.n4um" <N4UM@...>
 

Hello all:

Hope to be on 80 meters this evening to do some file transfer testing
most probably using MFSK 16. Will be on or about 3582 plus 1.5 audio.
Would like to see if I can xfr both text files and e-mail. Hope to show
up about 0100Z.

73, Tim N4UM


Antenna polarization

Rick <mrfarm@...>
 

The physical switching between polarizations would not be very practical at a home or other permanent station, but one thing that would be easily done is setting the polarization at a remote location when operating portable. I plan to have the 4 element Arrow Antenna beam set up so that I can switch fairly quickly. This antenna can be mounted either in the middle or on the end. It has holes drilled in the mount that allows the reflector elements to slide through pre-drilled holes in the mount. Since it is a square tube boom, you can not easily loosen the mount and rotate the beam. Some disassembly required each time you want to switch the polarization. I will likely use my "drive on" wood bracket that will easily allow support of a 10 foot or higher PVC pipe as a mast.

I wonder how many operators will be willing to install horizontal antennas on their vehicles? I expect very rarely since it is so simple and streamlined to use a whip which has very little cross sectional wind resistance. I can see that some of us might opt for a higher gain vertical for mobile use. I have seen that fold down halo that one ham uses for VHF SSB.

http://my.execpc.com/E7/E9/tachyon/ke9se/2MeterSSB.htm

Toward the end of the article, they mention contacting Archie, K9VQR, who lives north of La Crosse, WI and is about 50 miles north of my QTH. We are both on high ridges and work each other on various bands including 75 and then 160 when the FoF2 goes below 4 MHz. When Archie had a much larger array, with 1 KW power, he could work similar stations 24/7/365 out to North and South Dakota from his ridge location in Western Wisconsin, but he now favors HF.

Another ham in Onalaska, WI (about 25 miles N of me) who I have done digital testing with on both HF and VHF, is a well known VHF experimenter with mostly horizontal antennas and he claims that when they have used halos on vehicles, they don't work all that well since they have near isotropic gain (none) compared to a dipole. I would like to try a dipole up at least a quarter wave off the roof of the vehicle (probably needs to be higher) and see how that performs, including the directional issues. Has anyone tried that? Especially when moving around. I have come across claims that it was no worse than the halo since many reflections filled in the null area.

Looking at it from the perspective of favoring horizontal polarization, I was able to find something interesting on L.B. Cebik's site. He discusses the differences between vertical and horizontal antennas at:

http://www.cebik.com/yagi/vhp.html

His modeling of a 3 element horizontal beam at one wavelength will have a substantial gain over a vertical beam. On the order of 5 dB, which is a very large difference. As you elevate the beams, the difference is reduced, but even at 5 wavelengths it is 1.5 dB in favor of the horizontal. That can be a make or break situation in marginal conditions.

And consider that at 2 wavelengths, which might be a typical portable height of around 12 feet on 2 meters, the gain difference would be more pronounced. This effect would be even more pronounced on 6 meters and lower bands where it becomes difficult to even get up as high as one wavelength at the portable location!

This is reduced to about 1.5 dB in favor of the H antenna, when you increase heights to 5 wavelengths. This height would be common for base stations but not as much for portable and never for mobiles. This suggests to me that mobiles using H omni's should have a gain well above a vertical and must be taken into consideration.

Another source of H and V and circular polarization is from:

http://www.fmamplifiers.com/polarization.htm

This information compares various polarizations for commercial FM 88-108 MHz and why they went to vertical. The main reason is that vehicles almost exclusively use whips and they are a major target audience. The use of (CP) Circular Polarization, which has often been employed, also means that the 3 dB hit is 50% of the signal wasted for any given polarization and is likely too much of loss for many of us to use as a compromise antenna.

Their bottom line is to stay with linear polarization, even if it is vertical.

73,

Rick, KV9U



kh6ty wrote:

Rick,

I again want to emphasize that switching from vertical polarization to horizontal polarization only requires that the beam be rotated 90 degrees. Since many vertically polarized bands are end mounted in order to prevent detuning by a metal mast, it is more difficult to switch from a horizontall polarized, center-mounted beam to a vertically-polarized center-mounted beam than it is to switch from a correctly working end mounted vertically-polarized bean to a horizontally-polarized end mounted beam. There is no cost involved in making such a chance other than climbing up a tower.

To make a valid comparison, one must start with a vertically polarized beam and turn it 90 degrees to horizontal polarization and see if reception improves. I know of no other valid way to make the test. I am sure RCA engineers did extensive testing before deciding to use horizontal polarization for TV as it is of such major importance.

All my antenna and receiver evaluations here are done on a 2m beacon located 8 miles distant at 30 feet. This is about as good an antenna range as you can ask for, but will not test vertical polarization versus horizontal polarization of the same antenna because the distance is so small in comparison to 100 or 200 miles.

I again emphasize that the most costly change in going from vertically polarized antennas for repeater operation and FM transceivers is changing the transceiver from an FM-only transceiver to a SSB transceiver capable of running narrow bandwidth modes or wider modes with good S/N performance, NOT just rotating the orientation of the antenna.

FM transceivers and vertically polarized antennas, usually monopoles or 5/8 wavelenght verticals, need repeaters to reach more than a little more than line-of-sight. Thats why we use repeaters. Omnidirectional vertical antennas, such as ground planes, or whips, are better suited to mobile operation than horizontally polarized antennas, which tend to be larger, as is the "Big Wheeel" described in the March QST, but the range is less for a given height. Repeaters are usually situated on a mountain top or high building for very good reasons of coverage, but when the repeaters are down for any reason, it is necessary to span the area to reach connectivity elsewhere and at VHf, as any seasoned VHF operator will tell you, even 1 dB of additional gain can make the difference between copy or no copy, since the noise threshold, unlike at HF, is generally very constant, so that 1 dB can make the difference in copy or no copy. For VHFers, if horizontal polarization has only a 1 dB gain advantate over vertical polarization for some reason, they will elect to use horizontal polarization, and actually have done this for over 50 years.

Good luck with the comparisons, but unless done with precision, and by rotating the same beam in a short enough time frame so that propagation has not changed, they will be unable to tell the true story. However, propagation up to 100 miles usually does not change very much on 2m.

Many thanks to N0EVH for reporting his test results. Using 4-element beams over distances of 100 miles will probably not work very well. It generally takes 10-element beams on both ends (or a stack of 4-element beams) to achieve dependable communications over 100 miles, but that also depends upon the terrain and height of each antenna. In flat country, a 13-element beam with 125 watts can usually achieve dependable communications with a 4- element beam, or the equivalent in gain, over 100 miles. We are looking forward to the next test with great interest! Our VHF tests here over 25 to 35 miles have shown that 4 watts and 4dBi gain antennas on each end produce signals strong enough that PSK250 can be used successfully. We also know that a mobiles with horizontally-polarized antennas of 2.2 dBi gain (same as a dipole, but omnidirectional - a dipole is bidirectional) can be worked as far at 100 miles away in flat country with 13 elements on the fixed station end and 100 watts using SSB phone. Past that, the combined gain of the mobile and the fixed station antennas starts being not enough for Q5 copy.

73, Skip KH6TY



soundcard question

Michael Johnson <michaelkj77@...>
 

I have a Tigertronics USB with built-in soundcard.  The laptop I am using for EmComm also has an ESS soundcard which is the Windows default.  NBEMS is currently trying to tx through the ESS soundcard.
 
I can disable the ESS soundcard and make the Tigertronics USB Codex the default if necessary.  Is it possible however to configure NBEMS to use the Tigertronics and find the soundcard over the USB connection?  In the NBEMS configuration window I see options for soundcards (Windows default, SC #1, SC #2, SC#3).  Is there a way to specify SC #1 in the configuration as the Tigertronics?
 
Thanks,
Michael (N0VX)
 


Never miss a thing. Make Yahoo your homepage.


Re: Update on testing in Independence, Missouri

Rick <mrfarm@...>
 

Hi Larry,

I had a long telecon with John, N0EVH last night and got a lot of information that was very helpful. When you say you tried vert antenna with very poor results, wouldn't have this been cross polarization?

If I have learned at least one thing in recent time, it is that cross polarization makes one have to think long and hard about having a polarization different than what other hams have if they operate VHF. At least in our area it is about 95%+ vertical, including beams and collinear verticals.

On the other hand, if you can get enough hams to move to horizontal, it might be possible to use that polarization for emergency purposes. Can this ever happen for other than say, a group of interested hams? I am thinking of the students that have taken my classes over the years and how many have not even upgraded to General now that it is so easy to do. If they continue their ham activities, they often stay on 2 meters and that means vertical polarization and FM only. I know of one other ham who did set up an elaborate VHF station as a Technician. He has upgraded to General but is not very active on HF, but until recently did not even have internet or a computer.

I think it is mostly when a Technician ham upgrades to General and decide to buy a multimode/multiband rig that they will even have SSB capability. Will they also set up some kind of horizontally polarized antenna for VHF? It does not seem to be happening very often and these rigs have been available for many years. But as more hams test the NBEM System, will we be able to convince them to do this? Also, what about their vehicle for mobile operation? The one place that is easy, is for portable operation, since you could set up a dipole or beam in either polarization.

If there are any hams using (or testing) NBEMS with FM rigs it would be helpful to find out how well that works ... or not. I can see that using a low cost interface, it would be possible to standardize on something like NBEMS for local packet like communications. Maybe some kind of BBS would be possible.

To put this in perspective, after packet became wildly popular back in the 1990's, one of our local hams wrote a simple BBS program for a Radio Shack Model 100 and for some time we used that for message storage and retrieval in our local area. Of course later on we moved to msys, but the basic program on such a low power (and I also mean low power in terms of its need for only a couple batteries for days of operation) worked surprisingly well. I wonder if something like this possible as NBEMS evolves?

73,

Rick, KV9U


larrytkc@... wrote:

Rick,
I was testing with John this afternoon and we were both using H polarized beams. Mine is a Cushcraft 2/70 5 element just over 23 feet up. I believe John was using a 4 element 2M beam at 10 feet from pickup bed, on a hill. Signal to my end was a very solid S9 with virtually 100% copy including PSK 250.
We did try vert antenna with very poor results, ~10% copy, even at 35 watts. My vert antenna is a 6 db 2/70 up at 30 feet, not sure what John has for mobile. Apparently there is better performance using the Horiz polarized antenna. No doubt vert antenna is the easiest solution for mobile. We had pre-planned the test using our 'standard' test frequency 144.144, haven't gotten any protests - yet.
I'm looking forward to seeing how well longer distance works.
73 Larry kb0emb
kc metro


Re: Update on testing in Independence, Missouri

"kh6ty" <hteller@...>
 

I forgot to say that horizontal vs vertical polarization testing will need to be done by BOTH stations changing polarization to be meaningful, of course. There is a 20 dB cross-polarization loss between a horizontally polarized antenna and a vertically polarized antenna. Making a meaningful test is very difficult, but it would be interesting to do it and know the outcome. I have read about the RCA tests, and the outcome, but have not found any detailed measurement results.

73, Skip KH6TY


Re: Update on testing in Independence, Missouri

"kh6ty" <hteller@...>
 

Rick,

I again want to emphasize that switching from vertical polarization to horizontal polarization only requires that the beam be rotated 90 degrees. Since many vertically polarized bands are end mounted in order to prevent detuning by a metal mast, it is more difficult to switch from a horizontall polarized, center-mounted beam to a vertically-polarized center-mounted beam than it is to switch from a correctly working end mounted vertically-polarized bean to a horizontally-polarized end mounted beam. There is no cost involved in making such a chance other than climbing up a tower.

To make a valid comparison, one must start with a vertically polarized beam and turn it 90 degrees to horizontal polarization and see if reception improves. I know of no other valid way to make the test. I am sure RCA engineers did extensive testing before deciding to use horizontal polarization for TV as it is of such major importance.

All my antenna and receiver evaluations here are done on a 2m beacon located 8 miles distant at 30 feet. This is about as good an antenna range as you can ask for, but will not test vertical polarization versus horizontal polarization of the same antenna because the distance is so small in comparison to 100 or 200 miles.

I again emphasize that the most costly change in going from vertically polarized antennas for repeater operation and FM transceivers is changing the transceiver from an FM-only transceiver to a SSB transceiver capable of running narrow bandwidth modes or wider modes with good S/N performance, NOT just rotating the orientation of the antenna.

FM transceivers and vertically polarized antennas, usually monopoles or 5/8 wavelenght verticals, need repeaters to reach more than a little more than line-of-sight. Thats why we use repeaters. Omnidirectional vertical antennas, such as ground planes, or whips, are better suited to mobile operation than horizontally polarized antennas, which tend to be larger, as is the "Big Wheeel" described in the March QST, but the range is less for a given height. Repeaters are usually situated on a mountain top or high building for very good reasons of coverage, but when the repeaters are down for any reason, it is necessary to span the area to reach connectivity elsewhere and at VHf, as any seasoned VHF operator will tell you, even 1 dB of additional gain can make the difference between copy or no copy, since the noise threshold, unlike at HF, is generally very constant, so that 1 dB can make the difference in copy or no copy. For VHFers, if horizontal polarization has only a 1 dB gain advantate over vertical polarization for some reason, they will elect to use horizontal polarization, and actually have done this for over 50 years.

Good luck with the comparisons, but unless done with precision, and by rotating the same beam in a short enough time frame so that propagation has not changed, they will be unable to tell the true story. However, propagation up to 100 miles usually does not change very much on 2m.

Many thanks to N0EVH for reporting his test results. Using 4-element beams over distances of 100 miles will probably not work very well. It generally takes 10-element beams on both ends (or a stack of 4-element beams) to achieve dependable communications over 100 miles, but that also depends upon the terrain and height of each antenna. In flat country, a 13-element beam with 125 watts can usually achieve dependable communications with a 4- element beam, or the equivalent in gain, over 100 miles. We are looking forward to the next test with great interest! Our VHF tests here over 25 to 35 miles have shown that 4 watts and 4dBi gain antennas on each end produce signals strong enough that PSK250 can be used successfully. We also know that a mobiles with horizontally-polarized antennas of 2.2 dBi gain (same as a dipole, but omnidirectional - a dipole is bidirectional) can be worked as far at 100 miles away in flat country with 13 elements on the fixed station end and 100 watts using SSB phone. Past that, the combined gain of the mobile and the fixed station antennas starts being not enough for Q5 copy.

73, Skip KH6TY

----- Original Message -----
From: "Rick" <mrfarm@...>
To: <NBEMSham@yahoogroups.com>
Sent: Saturday, March 08, 2008 9:52 PM
Subject: Re: [NBEMSham] Update on testing in Independence, Missouri


I would like to hear about any experiences with comparing H and V over
various distances. This is primarily to see if there is a real advantage
to using H polarization. When it gets warmer here in Wisconsin, and with
some snow melt, we will be at least doing some comparing from mobile and
portable operation although it is likely to only be SSB since I have not
found anyone nearby who is interested in text data VHF.

Can you tell us more, such as:

1. The height of the beams on each end.

2. Did you use horizontal polarization or did KB0EMB have a vertical
beam and you just went with vertical?

3. Did you coordinate with each other on SSB and then just switch over
to NBEMS on the same frequency?

4. What frequency(ies) did you use for this?


It will be very interesting to hear more about longer distances and how
it all works. Also, the mobile testing.

Realistically, how many of us are going to invest in new antenna systems
for an occasional use of this mode?

Is it more practical to use V polarization in those areas where you
could get some operators to operate NBEMS, but they do not have H
polarized antennas for either fixed homes stations or on their vehicle?

Just about every new ham at least gets on 2 meter FM so they can work
the repeater. Many have computers and some may have laptops that they
could interface with an FM rig. Even though this may not work like SSB
distances, perhaps it will be competitive with packet which also uses
FM? Then they could at least try it out with a simple interface and a
cable to their rig.

If they purchased a new HF rig, particularly if they upgraded to
General, they might be convinced (maybe not that difficult really) to
buy a multiband/multimode rig that would have VHF SSB. Then they could
still use their antenna system for shorter range digital. This would
also allow for the use of V polarized high gain antennas that do not
need a rotor. One less thing to fail in an emergency.

Couldn't this work better than packet between stations that want to
share data, such as at Public Service Events? Even though it is short
range? Is it as convenient as packet, since it can send and receive
"local ham radio" e-mail, so the messages go to an inbox, right? (I have
not tried this yet).

73,

Rick, KV9U



n0evh wrote:
Larry KB0EMB and John N0EVH were able to conduct longer distance
testing today Sat March 8th. The path was from KB0EMB's QTH in NE
Independence to Weston Bend State Park in Platte County, a distance
of 35 miles.

His station was an FT-897 at 20 watts to a 4 el beam and mine an FT-
857 at 20 watts to a 4 el beam. We did not have line of sight to
each other as we had a hill in Liberty that was about 100 feet
higher than our two ends of the path. This test would be much like
an EOC to field station simulation. With somewhat better antennas at
both ends which would be the likely senario, we could probably have
done all the work at 5 watts. Pretty amazing considering we were
moving text files at 400 words per minute.

We had zero packets lost and thus no repeats required by the VBdigi
and Flarq suite of software called NBEMS. We moved emails and text
files back and forth using PSK modes from 31 to 250. Connects were
no problem and band noise very low.

Our testing will now branch into three areas: longer testing over
100 miles from home QTH locations, short range testing 5 to 15 miles
using two meter FM and then QTH to mobile testing 5 to 15 miles
while in motion using a loop antenna on the mobile.

We are very pleased with the reliable connects and performance
today. Thanks to all who have labored on this software.

John


--------------------------------------------------------------------------------


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Checked by AVG.
Version: 7.5.518 / Virus Database: 269.21.7/1319 - Release Date: 3/8/2008 10:14 AM


Re: testing

"kh6ty" <hteller@...>
 

John, I never said NBEMS is VHF only! I said that it is usable on HF NVIS also with similar effectivenes, but more susceptibility to static crashes. I also said we support MFSK16, but it is slower than FA$400 ARQ.

If conditions are terrible, just use MFSK16. The messages will get through error-free, but it will just take more time than using FAE400 ARQ.

FAE400 ARQ is a better choice, of course, being a newer, and more advanced mode, but we do not support it at this time.

Skip

----- Original Message -----
From: "John Bradley" <jbradley@...>
To: <NBEMSham@yahoogroups.com>
Sent: Saturday, March 08, 2008 8:20 PM
Subject: RE: [NBEMSham] Re: testing


As someone who is heavily involved in emergency planning, I'm looking at the
worse case.that being that VHF will not work.



I've used Patrick's software under really poor conditions and it does work
well, especially FAE400 ARQ. There is no way that I could support using
NBEMS on the basis that it is VHF only. It has to work under the worst
conditions that the propagation gods and terrain can give us.



John

VE5MU



From: NBEMSham@yahoogroups.com [mailto:NBEMSham@yahoogroups.com] On Behalf
Of kh6ty
Sent: Saturday, March 08, 2008 1:38 PM
To: NBEMSham@yahoogroups.com
Subject: Re: [NBEMSham] Re: testing



Patrick just posted on digitalradio that ALE 400 in ARQ FAE works down
to -13 minimum S/N, or almost as good as MFSK16. Again, the difference
between the modes is throughput, and if VHF can be used, the throughput is
very fast anyway using the PSK modes.

73, Skip KH6TY




--------------------------------------------------------------------------------


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Checked by AVG.
Version: 7.5.518 / Virus Database: 269.21.7/1319 - Release Date: 3/8/2008 10:14 AM


Re: Update on testing in Independence, Missouri

Rick <mrfarm@...>
 

I would like to hear about any experiences with comparing H and V over various distances. This is primarily to see if there is a real advantage to using H polarization. When it gets warmer here in Wisconsin, and with some snow melt, we will be at least doing some comparing from mobile and portable operation although it is likely to only be SSB since I have not found anyone nearby who is interested in text data VHF.

Can you tell us more, such as:

1. The height of the beams on each end.

2. Did you use horizontal polarization or did KB0EMB have a vertical beam and you just went with vertical?

3. Did you coordinate with each other on SSB and then just switch over to NBEMS on the same frequency?

4. What frequency(ies) did you use for this?


It will be very interesting to hear more about longer distances and how it all works. Also, the mobile testing.

Realistically, how many of us are going to invest in new antenna systems for an occasional use of this mode?

Is it more practical to use V polarization in those areas where you could get some operators to operate NBEMS, but they do not have H polarized antennas for either fixed homes stations or on their vehicle?

Just about every new ham at least gets on 2 meter FM so they can work the repeater. Many have computers and some may have laptops that they could interface with an FM rig. Even though this may not work like SSB distances, perhaps it will be competitive with packet which also uses FM? Then they could at least try it out with a simple interface and a cable to their rig.

If they purchased a new HF rig, particularly if they upgraded to General, they might be convinced (maybe not that difficult really) to buy a multiband/multimode rig that would have VHF SSB. Then they could still use their antenna system for shorter range digital. This would also allow for the use of V polarized high gain antennas that do not need a rotor. One less thing to fail in an emergency.

Couldn't this work better than packet between stations that want to share data, such as at Public Service Events? Even though it is short range? Is it as convenient as packet, since it can send and receive "local ham radio" e-mail, so the messages go to an inbox, right? (I have not tried this yet).

73,

Rick, KV9U



n0evh wrote:

Larry KB0EMB and John N0EVH were able to conduct longer distance testing today Sat March 8th. The path was from KB0EMB's QTH in NE Independence to Weston Bend State Park in Platte County, a distance of 35 miles.

His station was an FT-897 at 20 watts to a 4 el beam and mine an FT-
857 at 20 watts to a 4 el beam. We did not have line of sight to each other as we had a hill in Liberty that was about 100 feet higher than our two ends of the path. This test would be much like an EOC to field station simulation. With somewhat better antennas at both ends which would be the likely senario, we could probably have done all the work at 5 watts. Pretty amazing considering we were moving text files at 400 words per minute.
We had zero packets lost and thus no repeats required by the VBdigi and Flarq suite of software called NBEMS. We moved emails and text files back and forth using PSK modes from 31 to 250. Connects were no problem and band noise very low.

Our testing will now branch into three areas: longer testing over 100 miles from home QTH locations, short range testing 5 to 15 miles using two meter FM and then QTH to mobile testing 5 to 15 miles while in motion using a loop antenna on the mobile.

We are very pleased with the reliable connects and performance today. Thanks to all who have labored on this software.

John


Our focus here in Independence, Missouri

"n0evh" <n0evh@...>
 

All,

I have posted here before and have not taken the time to comment on
the types of emergencies that we have to deal with here in NW
Missouri. Open forum discussions suffer sometimes when we who
appraise commo tools do not reveal to what standard we are measuring
the usefulness of the tools. So here are some things we deal with
here in our state.

Mother nature hands out snow and ice storms here and the occasional
tornado. While twisters get the most press, they do not lay down a
wide path of destruction, max at about 1 mile wide. So, emcom does
not have to cover long paths. However, for ice storms you can get
wide areas of destruction and isolation, reaching 50 to 100 miles
sometimes. Inside that path you can loose all services including in
some cases loss of natural gas pressure, power and internet access.

When the above happens you have to be able to deal with local needs
for dispatch and also longer paths to reach outside of your impacted
area to where the internet is available. This then provides you
contact with those that will send in temporary relief, the state and
federal agencies.

We are on the edge of the earthquake zone that could occur on the
Mississippi river below St. Louis. This would be a wide area
impact, but would most likely not impact much of the normal emcom
infrastructure....if the predictions are accurate.

Finally floods from the Missouri river. These do give warning and
impact a predictable area. We deal with floods more often than
most. They are manageable from the emcom perspective.

Then of course the man-made things such as terrorism. Most would be
localized, unless it was an issue of bio that infected a large
population. These targets tend to be metro areas that are blessed
with good commo capabilities. It is doubtful that commo
infrastructure would be damaged from such an attack.

Now for our terrain and population situation. We are a rolling
hills type of farm country that has scattered cities large and
small. Altitudes range between 700 and 1100 feet ASL, not too
difficult to deal with on VHF, but you do have to pick your field
site locations and perhaps relay. Key to our state coordination is
reaching our state capital which is 125 miles away. If you drop
yourself into an emergency situation anywhere in our state, you will
be easily within 100 miles of a decent size city.

So with that setting of environment and possibilities of emcom our
city which is a well financed one is just at the edge of a large
metro area and we are very interested in NBEMS. It offers good
performance, cost advantages and flexibility to hams.

Yes, we have pactor HF at the EOC and a roving unit that can be
dispatched. But, we would not be good stewards of RF space if we
did an HF hop out and back from our region every time we needed to
email someone 50 to 100 miles away.

We also have several FM telpac stations in the area, but they are
limited by S/N and have their limits on distance. Again there is
the issue of infrastructure failure, Murphy's law. Since we are at
the edge of a metro area our telpacs could be easily clogged with
traffic.

Cost advantages effect how many hams can serve. Some of us have
thousands of dollars worth of gear in our cars and homes (don't
mention this to my wife) to apply to emcom, but most do not.

Then the license grade of the ham who wants to serve, everyone has
permission to use 2 meters. More hams available to serve.

Two years ago a town of several thousand population was leveled by a
twister. It was just at the edge of an FM voice repeater coverage
area. Many of our emcom people traveled there to assist with good
results. NBEMS would have been a great way to hook that area up
with decent email traffic at low cost and a field station that could
be staffed by all hams. We want to be prepared to assist counties
that are adjacent to ours. Again an interest in reaching out 100
miles into the less populated countryside.

Are we placing all our eggs in the NBEMS basket? No. Each week we
test our HF pactor on our MARS station, we have a statewide SSB net
on 80, and we are working with MERS to finish the statewide 6 meter
backbone on the new two meter packet network. Lots of tools give
one flexibility and redundancy. Important advantages when an
emergency decides to hit your area.

Thanks again for the contribution to the ARS community.

John N0EVH


Re: testing

John Bradley <jbradley@...>
 

As someone who is heavily involved in emergency planning, I’m looking at the worse case…that being that VHF will not work.

 

I’ve used Patrick’s software under really poor conditions and it does work well, especially FAE400 ARQ.  There is no way that I could support using NBEMS on the basis that it is VHF only. It has to work under the worst conditions that the propagation gods and terrain can give us.

 

John

VE5MU

 

From: NBEMSham@... [mailto:NBEMSham@...] On Behalf Of kh6ty
Sent: Saturday, March 08, 2008 1:38 PM
To: NBEMSham@...
Subject: Re: [NBEMSham] Re: testing

 

Patrick just posted on digitalradio that ALE 400 in ARQ FAE works down
to -13 minimum S/N, or almost as good as MFSK16. Again, the difference
between the modes is throughput, and if VHF can be used, the throughput is
very fast anyway using the PSK modes.

73, Skip KH6TY


Update on testing in Independence, Missouri

"n0evh" <n0evh@...>
 

Larry KB0EMB and John N0EVH were able to conduct longer distance
testing today Sat March 8th. The path was from KB0EMB's QTH in NE
Independence to Weston Bend State Park in Platte County, a distance
of 35 miles.

His station was an FT-897 at 20 watts to a 4 el beam and mine an FT-
857 at 20 watts to a 4 el beam. We did not have line of sight to
each other as we had a hill in Liberty that was about 100 feet
higher than our two ends of the path. This test would be much like
an EOC to field station simulation. With somewhat better antennas at
both ends which would be the likely senario, we could probably have
done all the work at 5 watts. Pretty amazing considering we were
moving text files at 400 words per minute.

We had zero packets lost and thus no repeats required by the VBdigi
and Flarq suite of software called NBEMS. We moved emails and text
files back and forth using PSK modes from 31 to 250. Connects were
no problem and band noise very low.

Our testing will now branch into three areas: longer testing over
100 miles from home QTH locations, short range testing 5 to 15 miles
using two meter FM and then QTH to mobile testing 5 to 15 miles
while in motion using a loop antenna on the mobile.

We are very pleased with the reliable connects and performance
today. Thanks to all who have labored on this software.

John


Mode comparisons and future directions

Rick <mrfarm@...>
 

Something that I think has escaped my awareness is that MFSK16 and FAE400 are very similar modes. Would it not be correct to say that both are MFSK? FAE400 is 8FSK so it has 8 tones but they are spaced 50 Hz apart and operate at the same speed as the spacing ... 50 Hz.

Here are some of my thoughts on comparing the modes:

Correcting the sensitivity of FAE400 (as noted on your other post) to around -11.5 to as much as -13.5 with many repeats according to Patrick's testing, does make MFSK16 and FAE400 similar in the area of sensitivity.

MFSK16
- 16 tones at 15.626 baud and tone spacing at15.625 Hz
- 62.5 bps raw speed
- Viterbi convolutional coding which reduces net throughput speed to 40 wpm
- a bit over 300 Hz wide
- most difficult mode to tune, requiring good accuracy of around 4 Hz
- thus, may not work as well under emergency conditions (power and temperature fluctuations)
- reduced effect from multipath due to lower baud rate
- increased effect of doppler due to lower baud rate
- slow synch lock on each beginning packet and latency issues without a "pipelined" ARQ

FAE400
- 8 tones at 50 baud and tone spacing of 50 Hz
- 60 to 100 wpm prior to any ARQ
- uses Golay coding and interleaving
- approximately 400 Hz wide
- fairly easy tuning, more forgiving than MFSK16
- first sound card mode to implement memory ARQ, thus higher sensitivity than otherwise would be the case
- less resistance to multipath due to higher baud rate
- increased resistance to doppler due to higher baud rate

Overall, perhaps the FSK modes are more resistant to doppler than are the PSK modes.

If conditions are so difficult on HF that you can no longer get through on NBEMS, Winlink 2000 would not be usable either, assuming you had a Pactor modem. The VHF part of Winlink 2000 can work in highly populated areas that have a co-located Telpac, but this is not possible in many areas. And it would be very risky to base your emergency messaging on having this available and working at the most critical times. VHF packet requires a much stronger signal than what is needed with NBEMS, thus the distance is not very long, often 20 to 40 miles at most.

Compression of data is certainly something that will have to come as it is one of the few practical alternatives to allow for improved performance.

In terms of baud rate, the testing of the older technologies (primarily done with RTTY) showed that baud rates needed to be kept below 50 baud in order to avoid ISI and other vagaries of the ionosphere much (but not all) the time. The initial FSK Pactor had the ability to use 100 or 200 baud, but found that 100 was about the most practical using multi tone PSK modems, thus they only have one speed for P2 and P3 which is 100 baud. (G-Tor tried 100/200/300 and often would be switching back and forth between speeds with changing conditions and this would slow down the throughput.

The MIL-STD/FED-STD/STANAG modems include 39 tone and other multitone modems, but most of the development moved toward highly sophisticated single tone modems. These modems do work moderately well with typical conditions and the NATO robust mode is supposed to work well below the noise with a throughput of 75 bps. The baud rate always is running at 2400 however and it is a very wide mode compared to the modes used with the NBEM System.

Some of us have been testing the RFSM software that simulates a STANAG single tone modem and it has better throughput than most of the slower keyboard modes when +5 or better S/N. The RFSM2400 modem does not support slower bps like the NATO Robust mode so this is something for the future. Since there will be no further development on RFSM2400 and the RFSM8000 has varying costs depending upon use, I don't see any possibility of it succeeding as a serious solution for radio amateurs at this time. Maybe it will have such a compelling capability that this could change (i.e., weak signal capability). Also, as John has pointed out, it is not practical to use in the U.S. ham bands for text data unless the FCC changes the rules and makes it legal to use for that purpose.

For the past hour, I have had success in getting PSKmail to run under Linux OS, but have not been able to connect with any of the five stations that are listed as active. I am continuing to poll them and see if I can connect. By the same token, if I was trying to send traffic to other hams using the NBEMS system, I would not know of anyone who is active.

Perhaps we need to have some kind of database that shows who can operate NBEMS at that moment? Or have specific frequencies that are the place to go. In order to keep this lubricated, we would also want to exercise the system at some level.

73,

Rick, KV9U





kh6ty wrote:


VHF is not the only answer, just more reliable if you don't need the range of NVIS HF. NBEMS works with both, and we do include MFSK16. The only thing is that it is slow in comparison to the speed on VHF or PSK125.

During recent tests of NBEMS, even MFSK16 was not copiable many times, so no mode is going to work if the band is dead.

Here is how the modes stack up as best I can glean from Patrick's numbers:

Lowest S/N:

MFSK16 -13.5 dB
Olivia -12 dB
DominoDF -12 dB
MT63 -8 dB
FAE400 ARQ -6.5 dB [+++ corrected above +++]
Pactor 1 -4 dB

If distances are too great for VHF, then HF or satellites are the only alternatives, and MFSK16 has the best chance of working. It just takes longer to get the message transferred. ARRL used to stand for American Radio RELAY league, and it is still possible for a VHF station, also in the disaster zone, to receive messages, and then relay to another VHF station that has phone and Internet Connectivity. This way, longer distances to reach connectivity can be covered. It just takes organization by emcomm groups. Using ARQ preserves the original message without any relay or translation errors.

I agree that for a portable station to set up a mast and tripod with a 15' boom, 2m beam, in order to reach 200 miles, is not always easy. It is probably a little easier to set up a 12' high NVIS antenna for 80m and 40m (you need both!), and then you can reach 300 miles instead of 200 miles, but sometimes there may not be 120' available for the antenna when there is plenty of room for a 13-element beam on a tripod. It depends upon the situation.

Anyway, either or both can be made available, but if static crashes are so strong, and so frequent, on 80m or 40m that no mode will survive, and VHF will not go far enough, you are simply out of luck unless you shift to a higher HF band and accept the consequences of QSB as propagation varies. NBEMS is just a software suite that is usable on either VHF or HF and already has MFSK16 to use for the toughest conditions. Beyond that, you still have Winlink if necessary and you are willing to spend $1000 for a modem when NBEMS is free. We just recommend to use VHF whenever possible for the fastest thoughput.

Except for using a wider, multi-tone mode for faster throughput, I am afraid that NBEMS is already the best we can do to get error-free messages through using the soundcard. We do not yet use any data compression, such as the F6FBB protocol that Winlink uses, and using that would increase the throughput about 40% I think. We just do not subscribe to the idea that messaging over the air that cannot be monitored by third parties is OK on the ham bands that are supposed to be self-policing, so we do not employ F6FBB compression.

Satellite data phones are an expensive option, but are a workable option, and in a real emergency, extra cost should not be a deterrent to getting help.

100 baud on HF has been shown to be the fastest practical baud rate anyway. Our job as amateurs is to use technology to accomplish the messaging job in as little bandwidth as possible, since others also demand space in which to operate. If that means we must accept slower throughput than we would like, then we should do that, because we do not have unlimited space in which to operate. NBEMS uses hams, not robots, for forwarding, and with sufficient organization by emcomm groups, more forwarding stations can be available than there are robot forwarding stations that are not busy or in range. The savings in time by a faster connection using NBEMS forward stations can easily more than compensate for slower throughput. If it takes 20 minutes to achieve a connection with a robot forwarding station to send a 5 minute message, a ham-manned forwarding station can get the message through in the same time from start of attempted connection to delivery of the message with a mode that is half as fast if the connection time is only 5 minutes instead of 20 minutes because there are more avaialable and reachable forwarding stations than there are robot forwarding stations.

73, Skip KH6TY



Re: Update on testing in Independence, Missouri

larrytkc@...
 

Rick,
 
I was testing with John this afternoon and we were both using H polarized beams. Mine is a Cushcraft 2/70 5 element just over 23 feet up. I believe John was using a 4 element 2M beam at 10 feet from pickup bed, on a hill. Signal to my end was a very solid S9 with virtually 100% copy including PSK 250.
 
We did try vert antenna with very poor results, ~10% copy, even at 35 watts. My vert antenna is a 6 db 2/70 up at 30 feet, not sure what John has for mobile. Apparently there is better performance using the Horiz polarized antenna. No doubt vert antenna is the easiest solution for mobile. We had pre-planned the test using our 'standard' test frequency 144.144, haven't gotten any protests - yet.
 
I'm looking forward to seeing how well longer distance works.
 
73 Larry kb0emb
kc metro
 
In a message dated 3/8/2008 8:53:13 PM Central Standard Time, mrfarm@... writes:
I would like to hear about any experiences with comparing H and V over
various distances. This is primarily to see if there is a real advantage
to using H polarization. When it gets warmer here in Wisconsin, and with
some snow melt, we will be at least doing some comparing from mobile and
portable operation although it is likely to only be SSB since I have not
found anyone nearby who is interested in text data VHF.

Can you tell us more, such as:

1. The height of the beams on each end.

2. Did you use horizontal polarization or did KB0EMB have a vertical
beam and you just went with vertical?

3. Did you coordinate with each other on SSB and then just switch over
to NBEMS on the same frequency?

4. What frequency(ies) did you use for this?


It will be very interesting to hear more about longer distances and how
it all works. Also, the mobile testing.

Realistically, how many of us are going to invest in new antenna systems
for an occasional use of this mode?

Is it more practical to use V polarization in those areas where you
could get some operators to operate NBEMS, but they do not have H
polarized antennas for either fixed homes stations or on their vehicle?

Just about every new ham at least gets on 2 meter FM so they can work
the repeater. Many have computers and some may have laptops that they
could interface with an FM rig. Even though this may not work like SSB
distances, perhaps it will be competitive with packet which also uses
FM? Then they could at least try it out with a simple interface and a
cable to their rig.

If they purchased a new HF rig, particularly if they upgraded to
General, they might be convinced (maybe not that difficult really) to
buy a multiband/multimode rig that would have VHF SSB. Then they could
still use their antenna system for shorter range digital. This would
also allow for the use of V polarized high gain antennas that do not
need a rotor. One less thing to fail in an emergency.

Couldn't this work better than packet between stations that want to
share data, such as at Public Service Events? Even though it is short
range? Is it as convenient as packet, since it can send and receive
"local ham radio" e-mail, so the messages go to an inbox, right? (I have
not tried this yet).

73,

Rick, KV9U
 




Re: testing

"kh6ty" <hteller@...>
 

Patrick just posted on digitalradio that ALE 400 in ARQ FAE works down to -13 minimum S/N, or almost as good as MFSK16. Again, the difference between the modes is throughput, and if VHF can be used, the throughput is very fast anyway using the PSK modes.

73, Skip KH6TY


Re: testing

"kh6ty" <hteller@...>
 

John,

Insisting that VHF is the answer to most emergency communications is a
disservice to many of the hams who like me live in lightly populated areas
of the country. ND,SD,MT,WY,ID and others have the same problem , where we
simply don't have the hams or the stations that can be reached consistently
with an easy VHF hop. I know that is possible to reach out several hundred
miles on VHF SSB, but can you do it every day, AND, can you do it from a
vehicle command post at the site of the emergency?
VHF is not the only answer, just more reliable if you don't need the range of NVIS HF. NBEMS works with both, and we do include MFSK16. The only thing is that it is slow in comparison to the speed on VHF or PSK125.

During recent tests of NBEMS, even MFSK16 was not copiable many times, so no mode is going to work if the band is dead.

Here is how the modes stack up as best I can glean from Patrick's numbers:

Lowest S/N:

MFSK16 -13.5 dB
Olivia -12 dB
DominoDF -12 dB
MT63 -8 dB
FAE400 ARQ -6.5 dB
Pactor 1 -4 dB


So, John, MFSK16, which NBEMS already supports with ARQ, works deeper into the noise than any other digital mode, no matter how wide it is. The tradeoff is sacrificing throughput speed for S/N performance.

The point is that if you cannot copy on MFSK16, you will not be able to copy with any other digital mode. The only difference is that MFSK16 has a lower throughput than wider modes, but with ARQ added, as in NBEMS, the message still gets through without errors.

If distances are too great for VHF, then HF or satellites are the only alternatives, and MFSK16 has the best chance of working. It just takes longer to get the message transferred. ARRL used to stand for American Radio RELAY league, and it is still possible for a VHF station, also in the disaster zone, to receive messages, and then relay to another VHF station that has phone and Internet Connectivity. This way, longer distances to reach connectivity can be covered. It just takes organization by emcomm groups. Using ARQ preserves the original message without any relay or translation errors.

I agree that for a portable station to set up a mast and tripod with a 15' boom, 2m beam, in order to reach 200 miles, is not always easy. It is probably a little easier to set up a 12' high NVIS antenna for 80m and 40m (you need both!), and then you can reach 300 miles instead of 200 miles, but sometimes there may not be 120' available for the antenna when there is plenty of room for a 13-element beam on a tripod. It depends upon the situation.

Anyway, either or both can be made available, but if static crashes are so strong, and so frequent, on 80m or 40m that no mode will survive, and VHF will not go far enough, you are simply out of luck unless you shift to a higher HF band and accept the consequences of QSB as propagation varies. NBEMS is just a software suite that is usable on either VHF or HF and already has MFSK16 to use for the toughest conditions. Beyond that, you still have Winlink if necessary and you are willing to spend $1000 for a modem when NBEMS is free. We just recommend to use VHF whenever possible for the fastest thoughput.

Except for using a wider, multi-tone mode for faster throughput, I am afraid that NBEMS is already the best we can do to get error-free messages through using the soundcard. We do not yet use any data compression, such as the F6FBB protocol that Winlink uses, and using that would increase the throughput about 40% I think. We just do not subscribe to the idea that messaging over the air that cannot be monitored by third parties is OK on the ham bands that are supposed to be self-policing, so we do not employ F6FBB compression.

Satellite data phones are an expensive option, but are a workable option, and in a real emergency, extra cost should not be a deterrent to getting help.

Coincidentally a number of emergency service agencies, both provincial and
federal, are having a fresh look at HF communications links, and these are
data links rather than voice links. Satellite telephones work, but they can
only work at 1200bps for data because of the restricted bandwidth, and
bandwidth is a very expensive commodity. Cellular coverage exists along
major highways, but once off these roads, coverage is spotty, and in an
emergency cellular phones become very congested and almost unusable.



The FCC has to remove the "speed limit" for text communications to encourage
higher speed, narrower width modes for data transfer. It doesn't make any
sense at all why high speed image transfers are allowed but text is limited
to 300 baud or so.
100 baud on HF has been shown to be the fastest practical baud rate anyway. Our job as amateurs is to use technology to accomplish the messaging job in as little bandwidth as possible, since others also demand space in which to operate. If that means we must accept slower throughput than we would like, then we should do that, because we do not have unlimited space in which to operate. NBEMS uses hams, not robots, for forwarding, and with sufficient organization by emcomm groups, more forwarding stations can be available than there are robot forwarding stations that are not busy or in range. The savings in time by a faster connection using NBEMS forward stations can easily more than compensate for slower throughput. If it takes 20 minutes to achieve a connection with a robot forwarding station to send a 5 minute message, a ham-manned forwarding station can get the message through in the same time from start of attempted connection to delivery of the message with a mode that is half as fast if the connection time is only 5 minutes instead of 20 minutes because there are more avaialable and reachable forwarding stations than there are robot forwarding stations.

73, Skip KH6TY


Re: testing

John Bradley <jbradley@...>
 

ask me to move VE5GPM to 3800 or higher for a week or to try out RFSM 8000 on images, if you or others want to try the software

 

John

VE5MU

 

From: NBEMSham@... [mailto:NBEMSham@...] On Behalf Of Jeff Moore
Sent: Friday, March 07, 2008 6:08 PM
To: NBEMSham@...
Subject: Re: [NBEMSham] Re: testing

 

3600 to 3625 is great if you're an Extra,  But I'm a general and can't go above 3600 until the phone band at 3800  --  What am I supposed to do?

 

Jeff Moore  --  KE7ACY

Bend, Oregon

 

----- Original Message -----

From: Rick

Subject: Re: [NBEMSham] Re: testing

 

[snip]

Just mentioning that it was perfectly legal to run image modes on the
phone/image portions of the bands did not set well with him. The IARU
plan probably would suggest using 3600-3625 for "digimodes" as they call
them.

[snip]

73,

Rick, KV9U

Bill McLaughlin wrote:
> Hi Rick,
>
> There are a few, listen around 3.586....the station would be within
> the auto sub-band until running pactor III at the same center freq as
> when using Pactor I/II.
>
> What is heard outside the automatic sub-band on 30 meters is VE2AFQ,
> and callers, running Pactor III....have heard others using the that
> wide mode there but less constant. Legal for Canadians, but still not
> a good practice on a supposedly "narrow" (fill in your definition of
> choice) signal only band. Also approved by Waterman; enough said!
>
> 73,
>
> Bill N9DSJ
> (snip)
>

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