VHF Propagation Map Help !

[GKolo]

VHF Propagation Map

Can anyone explain the color codes and how the map works ?
I think the colors are different frequencies and shading on the map is where those frequencies are active, But i'm not positive what the freqs are and if thats how it actually works.

Thanks
Gary

 

[k9rzz]

That's an awesome resource. It's made from hams using APRS on 2 meters and the data from those contacts are 'logged' on the web. The longer the 'contact' was, the darker the color. That map is a great way to get an idea how the VHF propagation conditions (not "skip"!) might be. What you see on the map is no guarantee, however, so just use it as a guide. Those of us heavy into FMBC DXing or VHF/UHF ham DXing reference this map quite a bit. Once in a while, a contact from HF will sneak in by mistake, so if you see just one streak stretching some 1,500 miles, take it with a grain of salt.

Also, read through the Prop Logger when you turn on your gear. Might also give you a heads up on good, or bad, conditions.

TVFM Skip Log!

 

[Keith_W7KEW]

The map is based on 144 MHz transmissions monitored at digital packet radio nodes. The colors all are the estimated distances the transmissions are monitored from. The distance legend is in the far right lower corner of the map. It can tell you that in a certain area that their might be an opening, but you would have to check with your radio to see.
A opening can last as long as a few minutes to a few hours. HTH. Keith

 

[GKolo]

So its different than the tropo ducting map for skip ?

Tropospheric Ducting Forecast for VHF & UHF Radio & TV

My main intrest is lowband Vhf between 33.0 and about 40.0 mhz
Just trying to determine when the best stuff is rolling in.

Thanks

 

[Keith_W7KEW]

For VHF Low band openings you can use the MUF online map to see if the low bands are opening up around 29-40 MHz.

Near-Real-Time MUF Map

 

[ka3jjz]

At times, though, VHF lo band skip can be enhanced by tropo conditions- I used to notice this many times when I lived somewhere when I had a VHF lo band vertical dipole attached to an old Regency scanner - that was one hot combination...best regards..Mike

 

[k9rzz]

The only true way to know when the good stuff is rolling in is to listen. My buddy across town may have propagation to Timbuktu, and at the exact same time I might have nothing even though I'm only 10 miles away. Set up a scanner or monitor receiver on it's own dedicated antenna and let it run 24/7. That's the best way.

 

[GKolo]

I have a radio that is dedicated to searching 33.0 to 40.0, And i have been looking at plans for building a dipole antenna. as soon as i figure out the real time MUF map i will know when to listen or atleast pay more attention to the radio.

Thanks

 

[k9rzz]

Good. You're on the right track then.

 

[GKolo]

How much better in your opinions will the dipole pick up for searching the lowband stuff ?

 

[k9rzz]

Compared to what? Any kind of skywave is randomly polarized so it really won't matter if you have a horizontal or vertical antenna. Use whatever is easiest to put up _in the clear_.

 

[902]

So its different than the tropo ducting map for skip ?
Thanks

It is different.

The Mountainlake website reflects APRS packet radio traffic through the APRS IS and is happening in realtime on 144.39 MHz (interesting, but not the frequency range you want). These stations ping-pong back and forth and send their locations. When they're heard, it's recorded, processed, and displayed. The more connections along the path that reinforce it, the darker the colors are. Hepburn is a forecast based on Mr. Hepburn's algorithm that analyzes weather patterns and generates probability of tropospheric ducting. So, real vs. forecast. In a perfect world, when the planets line up, one looks like the other during the same time.

Your interest is a different propagation mode. You are not likely receiving tropospheric ducting (although enhancement is possible), you are more likely receiving Sporadic E and F2 propagation in lowband.

The Near-Realtime MUF map that W7KEW gave you is closer to what you need.

 

[kayn1n32008]

Wirelessly posted (Mozilla/5.0 (BlackBerry; U; BlackBerry 9780; en-US) AppleWebKit/534.8+ (KHTML, like Gecko) Version/6.0.0.600 Mobile Safari/534.8+)

The darker the colours the longer the path

 

[GKolo]

Skip

Quote
Your interest is a different propagation mode. You are not likely receiving tropospheric ducting (although enhancement is possible), you are more likely receiving Sporadic E and F2 propagation in lowband.

The Near-Realtime MUF map that W7KEW gave you is closer to what you need.[/QUOTE]


Ok how does the MUF map work ?

 

[902]

The MUF map is generated from a number of variables, like A index, K index, solar flux index, geomagnetic activity. It is crunched in Proplab and placed online (automated). This is more of a product of solarterrestrial data. It's a prediction based on data. The other maps (Hepburn and the APRS network diagram) are based on higher-frequency conditions for VHF. Those are more weather dependent as opposed to solar/geomagnetic. They represent different levels of the atmosphere and very different mechanisms by which the propagation is created. The APRS map is actually displaying patent pathways based on analysis of a great volume of data sent to the APRS-IS.

 

[w2xq]

VHF Propagation Map

Can anyone explain the color codes and how the map works ?
I think the colors are different frequencies and shading on the map is where those frequencies are active, But i'm not positive what the freqs are and if thats how it actually works.

Thanks
Gary

Gary I think you might find this link easier to see what's going on. But... if everyone is listening and no one is talking... you know the drill.

QSO/SWL real time maps - NA - 50

I link directly to the 50 MHz map; the 28 MHz tab is just to the left. Compare the results to see the possibilities in VHF Lo. There also is an MUF (maximum usable frequency) map updated every 5 min here:

Near-Real-Time MUF Map

Looking at this map I would suggest that you look at the MUF reflection points more or less about 3000 km per hop; you can get multiples hops on the path. You want the MUF to be highest between you and the receiving target.

And, as commented elsewhere, a solar event expands the auroral zone and there will be absorption on the those signals whose paths that transverse the auroral zone.

Hope this helps.

 

[kb8qeu]

Who is doing this site....

Hi all

I have been following this map for quite a while and tried to find who is sponsoring it.

The site is : http://www.aprs.mountainlake.k12.mn.us/

It appears to me, it is in a Junior High School or High School.

Please enlighten me and I'll pas it along to others.

Thanks in advance

Ed - KB8QEU

 

[prcguy]

Not sure who is sponsoring the site but probably the school since its part of the URL. It could be they are getting data from the aprs.fi or similar site, which includes stations heard directly by APRS digipeaters and a propagation map was developed from that data.
prcguy

Hi all

I have been following this map for quite a while and tried to find who is sponsoring it.

The site is : http://www.aprs.mountainlake.k12.mn.us/

It appears to me, it is in a Junior High School or High School.

Please enlighten me and I'll pas it along to others.

Thanks in advance

Ed - KB8QEU

 

[ecps92]

In the lower right corner should be the Legend explaining the Colors, which indicate the distance for hearing the stations

VHF Propagation Map

Can anyone explain the color codes and how the map works ?
I think the colors are different frequencies and shading on the map is where those frequencies are active, But i'm not positive what the freqs are and if thats how it actually works.

Thanks
Gary

 

[902]

The originator of the map is Jon, NG0E who is the technology coordinator of the school. Extremely talented guy, judging by his product. The map is a skim of what goes into the APRSIS from various IGATES around the world. For example, I have a receiver at home that's tuned to 144.39 with a 5 dBd (15 ft. tall) VHF antenna. I also have a computer that runs as an IGATE server. It's currently down, but when it's running it is always sending data about what it hears into the APRSIS cloud.

The code behind the map decodes beacon text along with whatever coordinates are supplied and then puts points on the map and makes blob associations between points that actually receive each others' call signs on 144.3900 MHz. It's pretty much real-time. So one can look at the Hepburn site as a prediction and this one as real-time validation (at least at VHF high band).

Watch out for one thing - sometimes you have very high sites that hear a bunch of stuff and may relay the packets to IGATES that report them. Some of the propagation might have an artificially big footprint because of exceptional sites that have characteristics an average or modest station won't have. Look for instances of multiple paths along the desired route to validate your findings.