Goblin Posted January 17, 2016 Share Posted January 17, 2016 ? Its still just a radio signal. Yes, but NDBs are normally in the KHz frequency band and the VOR is in the MHz band. The lower the frequency the better it will bounce and travel longer. Link to comment Share on other sites More sharing options...
Havner Posted January 17, 2016 Share Posted January 17, 2016 ? Its still just a radio signal. It's been a long time since I remembered the frequencies, but very low frequency radio waves that's been used over the world for normal radio (maybe they still are) could travel to the opposite side of the Earth because they bounced of off the upper layers of atmosphere. No LOS there. No idea whether this is the case with NDB, but physically it's completely possible. [sIGPIC][/sIGPIC] Link to comment Share on other sites More sharing options...
Xtrasensory Posted January 18, 2016 Share Posted January 18, 2016 HF radios require a precise tweak of the frequency used to actually succesfully go over the horizon. The usable frequency differs for each specific time during the day and enviromental conditions. Eventhough a NDB might be a shortwave frequency its still not a dedicated over the horizon beacon and requires LOS. Those few times I usee them when they were still in commision, you already got a weak and fluctuating direction at 20nm, ofcourse dependig on the power output of the station. http://1stcavdiv.conceptbb.com/ 229th Air Cav, D Coy, Gunships Link to comment Share on other sites More sharing options...
Goblin Posted January 18, 2016 Share Posted January 18, 2016 Naturally the reception range depends on the output power of the transmitter. If your needles fluctuate at 20NM you're probably tuning a locator... We still have NDB here in Norway, and I can track them much farther than that. Link to comment Share on other sites More sharing options...
Xtrasensory Posted January 18, 2016 Share Posted January 18, 2016 (edited) Those were just regular enroute and airfield ndb's. What ranges are you tracking them and at which altitudes? Edited January 18, 2016 by Xtrasensory http://1stcavdiv.conceptbb.com/ 229th Air Cav, D Coy, Gunships Link to comment Share on other sites More sharing options...
Goblin Posted January 18, 2016 Share Posted January 18, 2016 We don't use them for navigation anymore, other than their position in the FMS. :) So I can't remember specifics. I can test it tomorrow though. Scheduled on the redeye... X-/ But NDB signals are generally considered beyond LoS. Depending on the equipment of course. https://en.m.wikipedia.org/wiki/Non-directional_beacon Link to comment Share on other sites More sharing options...
Xtrasensory Posted January 18, 2016 Share Posted January 18, 2016 Ah I see what you mean. http://1stcavdiv.conceptbb.com/ 229th Air Cav, D Coy, Gunships Link to comment Share on other sites More sharing options...
Goblin Posted January 19, 2016 Share Posted January 19, 2016 I received a NDB 270NM away at 15000'. The horizon should be around 150NM away at that altitude if you use the old approximation formula of 1,23x SqRt (Alt.). I also received an NDB 40NM away when on ground at the airport. And there' a 4000' high mountain range between me and the beacon, so no LoS there. Link to comment Share on other sites More sharing options...
Huesudo Posted February 13, 2016 Author Share Posted February 13, 2016 From the first paragraph on Wikipedia NDB signals follow the curvature of the Earth, so they can be received at much greater distances at lower altitudes, a major advantage over VOR. However, NDB signals are also affected more by atmospheric conditions, mountainous terrain, coastal refraction and electrical storms, particularly at long range. 1 Link to comment Share on other sites More sharing options...
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