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Started by gil, May 09, 2012, 02:11:40 PM

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Commsguy

Quote from: gil on August 16, 2017, 08:22:04 AM

The most reliable band for NVIS is 80m.
What would be the most reliable time of day to establish an communication on 80m? Early Morning, Noon, afternoon or at night/midnight? And I also reckon seasonal change would have a large impact on this as well, so I'd love to have some more info on that

Don't ditch the 2m band... Using USB on 2m can greatly increase its range. 2m USB can cover the near-regional range and 80m the far-regional range.
2m would be a great band too, but unless you're within omni-directional range(saw your video on it) you'd also need to know someones bearing to use SSB with an Yagi antenna, plus there are a few more factors, like me suspecting I'd need access to two buildings in order to cope with the rather flat terrain.


In any case the most prominent limiting factor for the set-up in mind is the cost of a second, third or fourth rig that can operate the desired band and mode. Since I am the commsguy in my prepping group, I have a nice QRP do-all rig, but now I am looking to create a set-up for the other people in our group with a means to communicate "when SHTF". I've been looking at the recently announced QRP-Labs single band CW transceiver, which looks promising even for people who don't know morse code since it has a built-in decoder and message keyer.
https://www.qrp-labs.com/qcx.html

That way some very basic communication can happen, which would have effect on further SHTF-plan execution and decision-making for both parties communicating, or scheduling a rendez-vous point and time for instance. I'm not aiming for long rag-chews but short, easy & "robust" pre-selected messages that can deliver a situational report to other members

I've gained a lot of "inspiration" for what I'm trying to achieve from Guerrillacomm NVIS experiments, which I'm sort of trying to copy https://www.youtube.com/watch?v=N_F_2BcfqC0

gil

QuoteWhat would be the most reliable time of day to establish an communication on 80m? Early Morning, Noon, afternoon or at night/midnight? And I also reckon seasonal change would have a large impact on this as well, so I'd love to have some more info on that

80m will work better after sunset and in winter.

QuoteI'd need access to two buildings in order to cope with the rather flat terrain.

The trick here is to put your antenna on a mast or hung from a tree branch. 2m indeed will not work well with an antenna close to the ground, unlike NVIS on 80m.

Gil.

Commsguy

#62
Quote from: gil on August 23, 2017, 12:50:25 PM
QuoteWhat would be the most reliable time of day to establish an communication on 80m? Early Morning, Noon, afternoon or at night/midnight? And I also reckon seasonal change would have a large impact on this as well, so I'd love to have some more info on that

80m will work better after sunset and in winter.
So winter is in general better on 80m, and in both winter and summer it would work better after sunset.

Studying VOACAP all-year prediction gives a different result though, link probability gives higher reliability around noon during the winter, and probability drops to zero at sunset in the winter(around 1700h), opening later again at 2300h.
In the summer however VOACAP gives almost a round-the clock consistent link probability, almost not dropping below 90% for the entire day except between 2000h and 0500h

Quote from: gil on August 23, 2017, 12:50:25 PM
QuoteI'd need access to two buildings in order to cope with the rather flat terrain.

The trick here is to put your antenna on a mast or hung from a tree branch. 2m indeed will not work well with an antenna close to the ground, unlike NVIS on 80m.
I don't know what kind of height you were thinking of for 2m but I was planning on an 80m dipole at about 10 meters using a tree as a center support. It's easy to throw a small heavy object over a tree branch and get to that height.

Using a tree for a 2m SSB, it would be pretty hard to get above the general canopy/building roof height around here. A dipole is much easier to deploy the right way the first time.

I think it'd best if this discussion was set forth in a new thread, this thread being a welcome thread and all

scarr

#63
Commsguy - VOACAP is correct - in winter months during lows in the solar cycle (like now) 80M generally becomes a DX band after dark.

During highs in the solar cycle, like last time, on average I found 40M the best NVIS/regional comms band during both day and night - sometimes even 30M was good during the day and 80M would be very good for regional comms in the dead of night and just before dawn.

To explain what I mean by regional comms - I live in Ireland and if I wanted to have somewhat reliable winter night, solar minimum, regional NVIS/regional comms across this island, or into Britain, I'd need to be on 160M.

I strongly advise you to regularly check live foF2 readings in your region - it's the magic critical frequency: http://www.digisonde.com/stationlist.html

If I could give one other piece of advice: in the time I've been licensed, I've learned there is no single magic band that's always reliable - so frequency agility is a must.

Say last weekend for example; I was using the radio for a couple of hours and the conditions were dire on 20/30/40/80 - I decided to go up to 10M (but we're in the solar minimum, it's probably not going to work!) and conditions were brilliant, I was getting all over Europe.

Whether it was sunspots, or Sporadic E's.... being able to switch bands made communications possible.

swxx

#64
I can't find the context of the original quoted question:

"What would be the most reliable time of day to establish an communication on 80m? Early Morning, Noon, afternoon or at night/midnight?" but the answer depends on the location you are in the world, and the location of the other station! Is it 10,000km away or 10km or 100 or 1000? 80m generally speaking offers only local contacts up to a few hundred km during the day, but thousands of km (or more) depending on the antenna, at night. Near the equator there is a lot more static on 80m than at mid latitudes. Signals during the day are absorbed by the D layer, so don't reflect (refract) well hence short distances, again more so in summer than winter. You may look at 80m as being a band that favors darkness over light. BUT for short distances and NVIS at mid to high latitudes it is good. At mid to high latitudes at night though you especially need to make sure you have a horizontal dipole at a low height compared to 80m wavelength, as a vertical is more likely to give you sky wave reflection of F layer, not blocked by D layer, resulting in large dead "skip zone" before landing back to earth far away, for long distance "DX" contacts.

This plot of how a dipole radiates (low angles to the left and right are for long distance, you want the high straight up lobes for close-in contacts) at various heights, this is for 40m. It would be more helpful if I found one that gives height in relation to wavelength, but to make this valid exactly the same for 80m, simply double the heights given, e.g. the 10m high plot on this 40m graph would be 20m high on 80m, etc. Don't worry about the exact frequency, it will be much the same for 3.5 or 3.7 MHz in this case!



Look at the red line: this is what a dipole up 15m on 80m band would look like, so NVIS even at that height, and few can get an 80m dipole up that high! Look at the green line, if you can get it up 60m in the air, you will have BOTH low angle AND high angle but less intermediate angle radiation: good for local NVIS and long distance. But who can get it up 60m? But on 10m band you can get that green pattern at just 7.5m above normal ground. 10m of course is not much use at this part of the sunspot cycle, we have to wait many years, if ever, to get those good conditions again.

red90

Quote from: gil on May 09, 2012, 02:11:40 PM
Information is a vital commodity in a disaster situation. Whomever has any, in the absence of Internet, phone and power services will have a great advantage.

Radio Preppers aims to provide individuals interested in disaster preparedness with an independent tool for the exchange of information about emergency radio communications and preparations. Hopefully it will also help build a community of like-minded individuals who could contact and help each others in times of what is commonly known as 'SHTF' or 'TEOTWAWKI.' Like-minded here means self-sufficient, strong-willed and responsible people. Independent means regardless of nationality, race, gender, political and religious beliefs, as well as unrelated to any organizations. Whether you are a licensed HAM operator, CBer, or simply curious about radio preparedness doesn't matter here.

My motivation for creating this site came from my inability to find an emergency radio club that really wasn't related to some kind of organization, mostly governmental or politically affiliated. Survival is a personal, family or small community affair. I am always suspicious of organizations that plan on telling people what to do for their own good, or else... That said, anti-government rhetoric will not be accepted here. If you don't like your government, vote accordingly. There are plenty of other boads for political ranting. This one is not one of them.

Sign-up, it's free, and stop by once in a while. If you have anything to contribute, please do so! Topics will not necessarily be limited to radio but must be related to disaster preparedness. To avoid spamming, you do need to answer a couple radio related questions; nothing a quick Google search can't answer.

Rules are few: Be courteous. Although some civil political discussions are acceptable, try to avoid them; same goes for religion. Do not suggest anything against the law, or you will be immediately banned.

Please consider supporting this site after joining by subscribing at: Profile > Summary > Actions > Paid Subscriptions. You will get more privileges!

Note that members who do not participate at least once a year will be deleted.

Any suggestions would be appreciated. I hope you enjoy this forum and that it helps make you and your family safer.

Gil.
Finally bought a hand held ham radio going to start studying

Sent from my 5049Z using Tapatalk


gil

Excellent. The Technician license is easy. You might want to check the General book, it might convince you to give it a shot as well...

Gil.

red90

Quote from: gil on November 03, 2017, 04:33:50 AM
Excellent. The Technician license is easy. You might want to check the General book, it might convince you to give it a shot as well...

Gil.
I will definitely be doing that I just have a lot going on right now so it's kind of hard to even make time. Radio is a perfect IV for someone like me though I've always been the person that has to know how things work and then I have to improve the mousetrap lol

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okcrt104

I am just wanting to check in and say thanks for this forum I feel as well it is long over due

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gil


brian44

Hello , Ive been back to ham radio after years of absence , am interested in qrp..like this site and videos Gil has ..dont know much about battery for qrp , thanks , brian

kb1dzc

Quote from: gil on May 09, 2012, 02:11:40 PM
Information is a vital commodity in a disaster situation. Whomever has any, in the absence of Internet, phone and power services will have a great advantage.

Radio Preppers aims to provide individuals interested in disaster preparedness with an independent tool for the exchange of information about emergency radio communications and preparations. Hopefully it will also help build a community of like-minded individuals who could contact and help each others in times of what is commonly known as 'SHTF' or 'TEOTWAWKI.' Like-minded here means self-sufficient, strong-willed and responsible people. Independent means regardless of nationality, race, gender, political and religious beliefs, as well as unrelated to any organizations. Whether you are a licensed HAM operator, CBer, or simply curious about radio preparedness doesn't matter here.

My motivation for creating this site came from my inability to find an emergency radio club that really wasn't related to some kind of organization, mostly governmental or politically affiliated. Survival is a personal, family or small community affair. I am always suspicious of organizations that plan on telling people what to do for their own good, or else... That said, anti-government rhetoric will not be accepted here. If you don't like your government, vote accordingly. There are plenty of other boads for political ranting. This one is not one of them.

Sign-up, it's free, and stop by once in a while. If you have anything to contribute, please do so! Topics will not necessarily be limited to radio but must be related to disaster preparedness. To avoid spamming, you do need to answer a couple radio related questions; nothing a quick Google search can't answer.

Rules are few: Be courteous. Although some civil political discussions are acceptable, try to avoid them; same goes for religion. Do not suggest anything against the law, or you will be immediately banned.

Please consider supporting this site after joining by subscribing at: Profile > Summary > Actions > Paid Subscriptions. You will get more privileges!

Note that members who do not participate at least once a year will be deleted.

Any suggestions would be appreciated. I hope you enjoy this forum and that it helps make you and your family safer.

Gil.
Sorry but I did not know that this is a chat room that you have to pay for. Yes I am a ham radio operator and proud of it. But I am not associated with any club to say, but have knowledge of proper radio edicate and many ideas that might help some people that are new to the game.

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gil

QuoteSorry but I did not know that this is a chat room that you have to pay for.

Hello,

No, you don't have to, but you can if you want to.

Gil.

kb1dzc

Quote from: gil on November 13, 2017, 03:59:04 AM
QuoteSorry but I did not know that this is a chat room that you have to pay for.

Hello,

No, you don't have to, but you can if you want to.

Gil.
Thank you for clearing that up

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CroPrepper

Hi,

I stumbled across Gils videos on Youtube and then over this forum. I am from Croatia, currently preparing for my basic ham license exam.
This topic is very comprehensive and I am eager to learn radio stuff.

Cheerio!