how to calculate the range of an NDB

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I found a table with some antennas and their power is rated in dBW. How can I calculate the range at which I still can pick up the signal with an avarage ADF? Is there some sort of formula?I know the signal will drop distance squared, but I assume that air and lots of other things will be relevant. I also have mast height and frequency if that's necessary.Cheers, Christian

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Instead of trying to "calculate" anything just look up a typical NDB reception range in one of the many aviation handbooks.Michael J.[link:jdtllc.com]http://jdtllc.com/images/RCsupporter.jpg

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Christian,The reception range, or service volume, of an NDB will fall in to one of four categories.Compass Locator - 15NMMedium-High - 25NMHigh - 50NMHigh-High - 75NMSee table 1-1-2 from the Aeronautical Information Manual.http://www1.faa.gov/atpubs/AIM/Chap1/aim0101.html#1-1-8Regards,Michael CollierDispatcherSystem Operations ControlAmerica West Airlineshttp://jdtllc.com/images/RCbeta.jpg

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EDITED: I misread the original post. The others answered it pretty well.

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Sorry, your answers don't help at all. I knew those NDB ratings.I'm trying to add AM radio stations to MSFS, so I want to get an approximate range value for those. I know I can't get a good range value, because it depends on lots of things, but there must be some relationship between transmitted energy and range that I could use.I found this which helps me come up with some very rough estimates though:MH - <50 wattsHH - >2000 wattsH - in betweenWould be good to have a formula instead though. I know the the Bendix/King ADF can still receive at a s/n ratio of 6dB (4:1). If I would know how much energy (watts) background noise typically has, then I could calculate an approximate range like this:range[metres] = sqrt( mast energy[watts] / 4 * noise energy[watts] )I know the reality is more complicated since the range is dependent on frequency, antenna shape and height, etc, but would be good to get an approximate.Cheers, Christian

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Oh, sorry. I thought you were asking about NDB service volume. Michael CollierDispatcher System Operations ControlAmerica West Airlineshttp://jdtllc.com/images/RCbeta.jpg

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I know on my instrument cross country from Daytona to Gainsville, we picked up an AM station from Alabama. We were cruising about 7000 feet halfway along our route.

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When trying to figure the range of a Broadcast AM station typically in the frequency range of 550khz to 1600khz, there are so many variables to the problem. For instance you must take into account the power of the station, the type of antenna to get the ERP or effective radiated power, and most importantly the time of day. In the daytime a 50,000 watt clear channel station such as KOMA or KSL or KFI, may be picked up for as far away as 100 to 200 miles, at night these same stations may well be heard in excess of 2,000 miles depending on the conditions in the ionosphere. Smaller stations 10,000 watts and smaller may be pushed to be heard 25 miles away again depending on the ionosphere.Of course broadcassting companys do use some really heavy engineering techniques, (MATH), extemely complicated and EXPENSIVE electronic measuring devices and still usually miss what they were aiming for.I would guess that if you set your AM stations for an average of 250 miles reception it would not be totally unrealistic, I have picked up KOMA in the daytime in Dallas Tx at any altitude. KOMA is in Oklahoma City OK or about 200 miles. It is a 50,000 watt station and plays Oldies :) Or i can pickup WBAP in Fort Worth from Oklahoma City quite often.

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It's great if you can get yourself some elevation while travelling at night. On more than one occassion, I have picked up AM broadcasts from Minneapolis (WCCO), Chicago, Fort-Worth, and Santa Fe while driving along I-80 in Wyoming (which is more or less a plateau at ~6000-7000 MSL).J

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Thanks, that helps a bit. My stations have a range between 2000 and 150,000 watts, so quite a difference. I may just have to come up with some approximate guesses.Cheers, Christian

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In the U.S. AM broadcast stations are limited to 50,000 watts maximum and there are not too many of them. Mexico limits there AM stations to 100,000 watts.

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I love where flight simulator is goingthis is way more concern than any of my real world pilots have to anything... I am very impressedif we all listened to the beatles, and really kicked mr. gates in the bum to get things going on something that could promote the real industry, we could really start to have a lot of fun...be well, y'all, I'm off to iceland tomorrowmy question is how much difference line of sight makes with AM, I thought that made little difference versus FM, and it was more daytime versus night time, and errors like shoreling effect and dawn/dusk effect for the errors in AM/NDB freqs....this is a great thread for fs and real life:)

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