charlie@oakhill.UUCP (Charlie Thompson) (11/28/90)
Across the USA there are hundreds of VLF aircraft navigation beacons know as NDB's (non-directional beacons). They operate in the 200 KHz to 400 Khz range. Does anybody know what output power NDB's utilize? I can hear the CW identifier from them as much as 200 miles away and I am trying to determine whether this is excellent reception or just typical. My antenna is a homemade 'active' whip which is about 10 feet long. I was told that NDB's are low power in order to minimize interference between beacons operating on the same frequency in different geographical locations. Knowing the answer to this question will help me determine the effectivness of my active VLF whip. WWVB comes in so-so at 60 KHz. Thanks in advance, Charlie WB4HVD
jmaynard@thesis1.hsch.utexas.edu (Jay Maynard) (11/28/90)
In article <4251@radio.oakhill.UUCP> charlie@oakhill.UUCP (Charlie Thompson) writes: >Does anybody know what output power NDB's utilize? I can hear >the CW identifier from them as much as 200 miles away and I am >trying to determine whether this is excellent reception or just >typical. My antenna is a homemade 'active' whip which is about 10 >feet long. I was told that NDB's are low power in order to minimize >interference between beacons operating on the same frequency in >different geographical locations. The output power of NDBs vary widely. NDBs are divided into four classes: 1) HH - high power homing beacon, over 2 KW. These have a designated service radius of 75 nautical miles at all altitudes. 2) H - medium power homing beacon, between 50 watts and 2 KW. 50 NM. 3) MH - low power homing beacon, less than 50 watts. 25 NM. 4) LOM/LMM - compass locator beacon. These are located at the outer marker (LOM) or middle marker (LMM - these are rare) of an Instrument Landing System. LOMs and LMMs have a service radius of 15 NM, though their power output isn't specified in my reference. Unfortunately, the only way to find out what class a given NDB is in is to figure out where it is, and then look it up in the Airport/Facility Directory for your area, available for $3 (I think) at your friendly neighborhood pilot shop. The classes above are also described there. -- Jay Maynard, EMT-P, K5ZC, PP-ASEL | Never ascribe to malice that which can jmaynard@thesis1.hsch.utexas.edu | adequately be explained by stupidity. "With design like this, who needs bugs?" - Boyd Roberts