Anyone use this website ve2dbe dot com?

[Murphy625]

Anyone ever play around with the Radio Mobil Online webpage?
Radio Mobile WEB Site

You plug in antenna, wattage, frequency, location of transmitter and receiver, elevation of antenna, etc, and it predicts signal strength coverage.

I've been playing with it on and off all day today, plugging in different numbers, antenna height, playing with frequencies, etc.

I'm wondering if its generally accurate?

Some things I've learned playing with 13 miles between the Tx and Rx stations over minor hills and valleys..

*On the 2 meter band, there is absolutely no substitute for antenna height.. nothing even comes in close second.

*On 40 meters, just 2 watts goes a very long distance and goes everywhere.. Small hills and valleys may as well be flat land. 2 watts can easily make the 13 miles of distance I need.

*On 20 meters, its almost the same as 40 meters so far as a 13 mile distance is concerned.


So now I'm wondering how accurate and reliable the Radio Mobil site is. It seems to use google maps and topographical information to calculate for the terrain.

Any opinions?

 

[nd5y]

I use the Radio Mobile Windows program all the time. On VHF and UHF it appears to be reasonably accurate if you know what you are doing. It isn't perfect and it can't take into account shadowing or attenuation from individual buildings, trees, etc.

I haven't tried HF or microwave frequencies so I don't know how well it works for those and I haven't used the web based app so I don't know how it works.

The terrain elevation data is from NASA. I don't know if Google uses the same data. The RM PC app allows you to generate different types of map overlays from different sources. You can also make cool google earth overlays. I don't know how the web app works.

There are several tutorial web sites:
http://radiomobile.pe1mew.nl
http://www.g3tvu.co.uk/Radio_Mobile.htm
http://www.pizon.org/radio-mobile-tutorial/index.html
These are for the Windows program and I don't know how much is applicable to the web app.

 

[NC1]

The Radio Mobile Online web page based program gives good results. Mostly I have checked 2 meter and 70 cm scenarios and their estimates fall short if you are trying to make a repeater (or another base station), your signal goes much further. This is probably because the program is assuming it's Base station to mobile unit, and the model you create comes very close to actual results if that is what you are looking to do.

In my opinion it is an excellent resource if you do not want to get too technical and just want a ballpark coverage map, or to compare different power levels, heights, and antenna gains. For those new to radio, this is a "Must Bookmark".

 

[Murphy625]

The Radio Mobile Online web page based program gives good results. Mostly I have checked 2 meter and 70 cm scenarios and their estimates fall short if you are trying to make a repeater (or another base station), your signal goes much further. This is probably because the program is assuming it's Base station to mobile unit, and the model you create comes very close to actual results if that is what you are looking to do.

In my opinion it is an excellent resource if you do not want to get too technical and just want a ballpark coverage map, or to compare different power levels, heights, and antenna gains. For those new to radio, this is a "Must Bookmark".

I spent much of the weekend playing with the Radio Mobile website software this weekend. Correct me if I'm mistaken, but it seemed to me that what VHF could do at 25 watts and requiring line of site (altitude) etc, the lower frequencies like 40 meters could do with just a couple of watts.

When punching in the 13 miles I need, the VHF antenna at both locations had to be elevated at least 30 feet and minimum power was around 5 watts for 70% reliability. But with the 40 meter band, I was able to leave the antenna 6 feet and use only 2 watts to achieve far better coverage over the entire area.

Then I learned about NVIS antennas but not sure if I'd really need one of those for only 13 miles.

Am I missing something the software is not making obvious?

 

[nd5y]

At 13 miles on 40 meters in the daytime you probably have a combination of NVIS and direct propagation that will enhance or reduce signal levels depending on whether the signals are in phase or out of phase and the phase can change a lot with changes in the ionosphere.

Radio Mobile does not calculate NVIS, regular skywave or tropo propagation so it will not accurately predict that situation. You will also probably have a higher local noise level on HF than VHF.

Radio Mobile requires you to know a lot about radio to begin with in order to come up with realistic parameters to put in the program to get meaningful results. Otherwise it can give exaggerated or reduced distances.

 

[Murphy625]

At 13 miles on 40 meters in the daytime you probably have a combination of NVIS and direct propagation that will enhance or reduce signal levels depending on whether the signals are in phase or out of phase and the phase can change a lot with changes in the ionosphere.

Radio Mobile does not calculate NVIS, regular skywave or tropo propagation so it will not accurately predict that situation. You will also probably have a higher local noise level on HF than VHF.

Radio Mobile requires you to know a lot about radio to begin with in order to come up with realistic parameters to put in the program to get meaningful results. Otherwise it can give exaggerated or reduced distances.

When I was playing with it, I was also changing the db gain on the antenna's. For VHF, I was setting it at 2dbi, and for 7mhz, I brought it down to -3 at one point. For the 40 meter band, it didn't seem to matter too much what I did, the green coverage area was pretty solid all the way out to 25 or 30 miles in the worst case scenario.

A few nights ago, I was listening to a local guy about 20 miles from me talk to another guy 3000 miles away, I could hear them both, but the local guy sounded like he was in the chair next to me.

I'm thinking maybe 20 meters might be better since that bottom layer (i forget which letter it is) of the upper atmosphere seems to reflect that band all the time.

I still have my heart set on 2 meters since the antenna is so easy to set up. All I need is a tall tree, a wrist rocket, fishing line, and a roll up j-pole.. its lightweight, simple, fast, and easy to deploy.