W3EEE - Finding NDBs

Finding NDBs

A 'Quick and Dirty' guide to finding NDBs

This presumes that you want to find and stare at an NDB in the first place. It is a perverse twist to an already peculiar hobby (avocation?) (obsession - yes, obsession) called 'radio'. Relax. You are not alone. There are lots of sick people just like you out there.

Basically any NDB in the 190 - 535kHz band you can hear during the daytime is almost certainly within reasonable travelling distance. Any you can hear unaided on a portable is really close, say within 25 miles. Of course, if it is a maritime NDB, it could make for interesting insurance claims, but nevertheless... Note daytime. At night these things can be audible for hundreds and thousands of miles; this is the basis for yet another splinter radio hobby, NDB DXing.

You may wonder why, in this day and age of GPS, Google Maps and ready access to Lat./Long. data for these beacons, the following seemingly laughable 'stone age' hard-way beacon location methods are described here. Two reasons: Firstly, this piece has grown in fits and starts over the last couple of decades, in the earlier phases of which little of the above obtained. Secondly, there will be occasions where available data LIES TO YOU, or approximate to the point of making these approaches suddenly germane once more. So, spin on down to "How To Cheat (a bit)" or "How To Cheat (A Lot)" if you must, but don't say I didn't warn you!

Requisites:

(a) A good map, preferably topographic and as high a scale as possible of where the NDB is suspected to be,

(b) A decent road map to get you to that area from home. (I combine (a) and (b) with state-wide topographic map books, such as published by DeLorme in the US, and available at any good bookstore. They are fascinating, regardless of their usefulness in this application.) Yes, these are available online or on CDROM, but paper tends to work better when 'on the hunt'. Likewise, in the UK, if you aren't already a gibbering devotee of 'Ordnance Survey' maps, you're missing a major life-enhancement; they're perfect for this, too.

(d) A transportable radio with a ferrite-rod antenna that covers the NDB band. My favourite is the excellent Radio Shack DX-398 (a 'badged' Sangean ATS909).

(e) If you're really being hoity-toity, a compass. As I shall describe it's entirely possible to DF an NDB without a compass; in the absence of good landmarks though a compass will help. I've even done it without a map, but then again some people ski across the North Pole for fun. The best sort of compass is the clear plastic sort used by orienteering, available at sporting-goods shops. They're inexpensive (<$10), well damped, easy to use and they have straight edges, a plus when it comes to plotting bearings on the map.
My favourite though is a 'Pocohantas' burger-joint giveaway toy. My daughter is very chuffed that Daddy wants to borrow her compass. She's also probably the only three-year-old who's learnt how to use one as a result. Ascertain the magnetic deviation for your part of the world; a local topo map should show this.

(f) Non-essential, just useful for when zig-zagging through country roads or city streets, one of those dashboard compasses. Get the tackiest one they have in the shop, with 'go-faster' stripes and all that.

(g) If you really want to spoil the fun, a GPS unit (see later).

(h) Just once, a Loran unit. So that you, too, can have the "Duh" realization that LF Loran receivers don't work very well near LF transmitters . . .

Taking bearings.

Check first of all that you can even hear the NDB on the portable where you are; they are typically not stunningly sensitive on their internal antennas. Avoid anywhere within say 50 - 100 ft of any building and or especially power lines; stand well away from the car; these will all distort the bearing, and power lines add noise, too. Finding such unencumbered places can be harder than you think in any kind of populated area; even out in the country it's surprising how many power lines there are all over the place once you start noticing. Cemeteries are good(!) as are big corporate-building parking lots which *don't* have lighting poles dotted all over.

Find exactly where you are on the map; relate any obvious topographic or man-made features to the map. Find the 'null' direction of the beacon as the radio is rotated; chances are the signal will be insufficient to deflect the radio's signal level meter (if it has one) but it should be easy enough to tell by ear. The ferrite-rod antenna is usually lengthwise within the radio, so the radio will 'point' end-to-end at the NDB when nulled. Either note the bearing from the compass (correcting for deviation, Virginia) or relate the direction to any mapped feature - a hilltop, a gap in the hills, chimney stacks etc. Failing that note the angle of the null in relation to the road (assuming you're parked roadside. (If you're being stunningly efficient, take bearings of any other beacons and everything else you may ever think you may possibly need bearings for, now you've actually found an RF-friendly spot.)

Pencil-line (soft, easily erasable) the bearing line onto the map from where you are; along the derived compass angle or in accordance with topographic features or even the estimated angle against the road. (Don't knock it, it works really well with practice.)

Sometimes, particularly if you know the area well, just jumping out of the car, legging it a little way, and twisting the radio is enough to get a "yep, thataway!" feel for direction. Fifteen seconds and you're done. (Must have found half-a-dozen NDBs just doing that.)

If you're uncertain in which direction the NDB may lie along this initial bearing line, it's time to move sideways; drive 5 miles or so away at right angles to it to take a triangulation cross-bearing. This should be sufficient distance to get a bearing line cross close to the NDB. Then charge off in that direction.

Take further bearings every couple of miles or so if it's loud or 5-10 miles or so if weak (assuming you know you're heading in the right general direction).

There'll come a time when the signal is big, loud and healthy, driving the signal-strength meter well but still with a clearly definable null.

Stop! Don't move in for the kill just yet. Do yourself a favour and take another cross-bearing. Chances are you've been approaching from pretty much one direction and most of your bearing angles are close to each other; this gives a pretty long and thin area of agreement on the map. Move 'sideways' (right-angles) again off your primary (most detailed) bearing lines for a mile or two to get a good cross bearing.

Now. Drive straight to the cross-hatch on the map.

Once you're really close, the radio'll be as good as useless. The signal will swamp it, there'll be no apparent directionality to be had. If there IS any, take a bearing! Every one helps. The only purpose left, if the rf gain will crank down far enough, is to use brute signal strength as a 'warmer/colder' guide. Basically, though, just listen to the plaintive beeping morse. You're relying on eyeballs at this point.

A warning. (Actually, a couple of warnings.) NDBs can sometimes be tricky to spot. I cruised slowly backwards and forwards a few times past my nearest one before I twigged it. It was well disguised; at an old military base undergoing long throes of closure, in amongst acre after acre of cheap huts and 'phone poles, a cheap little hut and a couple of 'phone poles hardly stood out - true meaning to the phrase 'hiding in plain sight'. More often though they're somewhat easier to spot. The same cheap little hut and 'phone poles all of a lonesome at the edge of an airfield are a bit more of a giveaway. More modern ones tend to 'stick out' more, sometimes having purposeful-looking pre- fab equipment trailers and fibreglass 'stick' monopole antennas which actually look a bit more like a radio-navigation aid, if less characterful, than a hut-and-sticks.

Oh, yes. The other warning. NDBs often live near airfields. Bigger 'commercial' airports and in particular military bases often take security fairly seriously, especially nowadays. At the aforementioned army base, It was some while before I noticed the Chevy Suburban following me around... And just don't remind me of the 'friendly reception' I got at a local airfield the weekend after 911 . . .

How To Cheat ( a bit )

Well, quite a lot actually. Get a GPS unit and access to an NDB database.

There are numerous listings of NDBs for North America, Europe, and elsewhere. Some are available on the web: perhaps the best well-known is Airnav . It, along with most of the web resources tends to be a bit hit-and-miss in its content - for instance it lists main NDBs, but not 'two-letter' ILS compass-locator beacons - but it does make for a very good start. An unbelievably good stand-alone PC program is Alex Weicek's 'WWSU' which allows finding information on pretty much every NDB in the world by callsign or frequency. Best $15 you'll ever spend. For North America, a very complete and up-to-date listing is to be found at William Hepburn's excellent website. The better databases will drown you in data about the beacons' locations, lat/long, frequency, name etc.

And it is all to be taken with a grain of salt.

It would seem, to the less worldly, that a database and a cheapo GPS unit is nirvana. Not quite. (Other than the fact that doing it 'the hard way' is just plain fun.) It would seem that it would just be a matter of plugging in the lat/long to the GPS and let it tell you where to go, or alternatively plotting on the map the listed lat/long and toodling off there. Well, all this does mean you would ordinarily get a lot closer, quicker. However, there are a few less-than-obvious gotchas to just lying back and letting technology have its way with you . . .

. . . things aren't always as they seem.

(A) Firstly, a GPS may point you in the right direction, but it won't tell you what might be in the way, like, for example, the Cape Fear Estuary (and a 25 mile detour) if you're heading to 'CLB' at Carolina Beach.

(B) Amazingly the listed lat/longs are on occasion just plain wrong. Maybe they were determined pre-GPS by a guy with muddy boots squinting at a smudgy map in the rain, maybe they were done by Loran, maybe they were made with GPS pre-Selective Availability disabling, maybe they were just made up, 'placeholder' values until they get real ones; maybe it's some sort of paranoid 'security measure'. In some cases, the published lat/longs will just not agree with your neat little GPS thingie. You get the idea; the beacon will sometimes not obligingly be where the technology says it ought. Naughty beacon!

(C) The place names can be even more misleading. In fact, it can all be a bit misleading. Don't scream "Gotcha!" just because you've found the beacon's associated location name on a map. By way of an example, a local NDB to me is 'BZJ' on 328kHz. In the database the placename is 'Bellgrove'; fine. There's a village near here called Bellegrove; Aha! Bingo! But ten miles north of there, there's an old disused grass airfield on the map, too, called 'Bellgrove'; the Lat/Long indicate that it's somewhere in Fort Indiantown Gap army camp, nowhere near either; DFing it down found it actually near the Air National Guard's 'Muir Field'. Remind me to take GPS out there sometime to find out where it _really_ is.

It seems a general rule that place names in the databases are always not quite where the beacons actually are. Another local example: COMLO 'MD', 204kHz, location ENOLA. Only Enola is miles up the road (maybe in another county, even); the beacon's actually in the middle of a town called Camp Hill. Just thought I'd let you know . . .

A database is good for identifying and getting close to nearby airport marker beacons that are too weak to hear on a portable except close in. These can be real fun to find. These ILS (Instrument Landing Syatem) markers are usually directly in-line with the principal runway of a nearby airport, from about 5 to 10 miles out. A good clue here is that these 'two-letter' beacons are, as mentioned, by design exactly in line with the runway; this gives you a 'free' and accurate triangulation radial line to mark on the map.

Beware the frequency. NDBs transmit using one of two 'standards' both in olde-fashioned Amplitude Modulation (AM). The transmitted carrier is constant on the indicated frequency. The morse ID is modulated (usually) at 1kHz (1020Hz-ish) on the carrier, but sometimes nominally 400Hz. This is fine for DFing, because you're usually listening in AM, but if you're identifying a weak NDB using a radio in SSB or CW mode, you are probably listening to one or other of the AM sidebands, ie a kHz (or 400Hz) above or below the indicated frequency. Some beacons transmit one sideband only (one continuous carrier on the nominal frequency, one ID keyed). The point is your received frequency indicated on your radio may not be what the carrier frequency (and database frequency) is. So if you search by frequency, try also 1kHz up and down in the database.

How To Cheat ( A Lot )

Ooh - isn't technology wonderful? Assuming one is already cheating to the extent of relying on an NDB database or three, plugging the lat/long for a beacon into Google Maps ( http://maps.google.com ) will allow the generation of maps of varying scale centred on the beacon, wide scale for navigating towards it, tight scale for deciding which side of the road to park so you don't scuff your Guccis when you get there. (Attitude? Moi?) And, at least in the US and major European countries, photo-satellite overlays to show terrain and environment. Sometimes you can even zoom in enough to SEE the wretched beacon! Look: just print out the maps - and even the bloody driving directions to get there, if you insist - then tell your butler to go and get the damn photographs and tell you what it was like, OK?

This approach can, however, be just as fraught and misleading as lower-tech approaches if the data is suspect. A recent real-world example. In preparation for a little trip back to Blighty I thought I'd prepare some GoogleMap printouts to some beacons close to my intended line of travel, just in case I got the chance to pop in and say hello. After printing a few, it seemed suspiciously as though the Lat./Long. data in the database were 'rounded' to 00/15/30/45 seconds increments. So a test case to establish possible error ranges was done with "WOD' (Woodley, Berkshire) which I know how to find both blindfold and using GoogleMaps. The database said 'WOD' was at 51 26 15 N, 00 52 30 W. Which landed ever-so-slightly-exactly where 'WOD' isn't, to the tune of being on the far side of two gravel-pit lakes and a motorway; daunting obstacles indeed. Nudging GoogleMaps to align on the readily identifiable 'WOD' determined real co-ordinates of 51 27 10 N, 00 52 44 W. Difference: over a kilometer. And, after tracking a few down on the ground, that turned out to be a GOOD one!

The Small Print . . .

A good friend once remarked that nearly all laws could be struck off the books if only 'stupidity' was made prosecutable. Well, 'stupidity' may be a bit strong word, but a lost perspective of how one's actions may seem to 'normal' people comes really close, and oft-case crosses that line. Let's face it: Beacon hunting is weird. Secondly, the objects of the hunt are of security interest.

Beacons sit on property. The property is owned by an entity, like either the local airport or the Feds, or a guy who breeds pitbulls. Even outside the fence you are still probably technically trespassing. Now, for a large proportion of sites, whether rural, suburban or city-centre, access is easy and open and few folk are likely to pay much attention to you paying a short visit. But don't bet on it. Obvious idiot criminalities aside, like climbing over fences or opening locks to get a better look, your mere presence sniffing around the fence will get any security guard's juices going, or may well cause a concerned neighbour to hail the constabulary. Again - at the very least you are likely trespassing. It should go without saying that beacons that are within an airfield's boundaries *require* permission and probably accompaniment to visit - you *will* get spotted. Shuffling around with a radio redolent of Concorde's flight-deck and a camera worthy of an Angelina Jolie paparrazoid is going to look way suspicious; leave the radio in the car (you *know* what it sounds like by now, don't you?) and, frankly, any beacon pictures you can't get with a modest little digital camera, you shouldn't be taking anyway. If a gentleman in a uniform does assail you, be prepared for an uphill battle; with today's National Security Awareness Level at 'Fuschia' or 'Throbbing Purple' or whatever, you not only have explaining to do, you are already Guilty Of Being Weird and, worse, probably The Most Fun The Uniform Has Had All Week. I'm not going to patronise and tell you how to best squirm out of situations like this other than say Be Polite, and, as preparedness, have a set of printouts of pictures / write-ups about beacons you've already visited to hand in the car. This will at least help to establish some parameters for your bizarreness, and help show it's benign. A ham radio licence in your wallet may help (inasmuch as a scruffy badly-printed little bit of card can - they really aren't very impressive-looking). But just understand that at this point things will only proceed in varying degrees of not your way. Rest assured the guy's report to his boss is not going to conclude " . . . and then I said, 'Sure, take all the pictures you want! Here, let me open the gate for you! Need a hand with that?'".

Some states have 'scanner laws' (limiting possession of radios capable of listening to public service transmissions, i.e. cops) which coupled with a very low degree of understanding of technology in the world generally, sadly even amongst law enforcement, has led to some alarming situations. A chap in NY with all the right credentials (like possessing a for-real licence) was cited for having a ham radio in his vehicle. Although the charge was ultimately thrown out by a judge and the cop admonished, that doesn't strike me as a particularly low-stress way to spend a hobby.

Preparation for a hunt nowadays should involve checking out the likely beacon position on a high-res map (paper or 'puter); it could save a trip, some embarassment, or worse. F'rinstance - a loud beacon recently showed up, 'BUH' on 360kHz. Ripe for documenting, aha! The database location is given as 'Anne Arundel'; really useful considering that's the name of an entire county. Just a variation on the 'name it somewhere close but not actually here' apparent system of beacon-naming. Checking the lat/long out closely on GoogleMaps showed the beacon to be about 1000 feet inside the perimeter of an airfield. Bummer - too far in to even get a long-shot, and what looked suspiciously like a line of trees in the way anyway. Zoom out a little. It is obviously the 'private' airfield of a military facility - double no-no. And that facility is called Fort Meade. Interpreted for the sweet, naive and innocent, that is the National Security Agency. Triple no-no. Stay home. Read the funnies instead, or at least pick on someone your own size.

Some NDB Listings, databases and like resources

Go immediately to Alex Weicek's website and download and run his WWSU database.

William Hepburn's excellent, and most importantly current, North American NDB and DGPS station listing.

'myAFD' - everything you ever wanted to know about US airfields, including their navigation aids.

Airnav a convenient if incomplete online database of North American beacons.

Canadian NDB online database.

BeaconWorld a British web-site thoroughly covering the European beacon scene, but also with reported listings of North American beacons, too. Well cool.

Michael Oexner's paperware Euro and NA beacon listings.

Kevin Carey's 'Beacon Finder', loose-leaf binder paperware. Available only from the author: contact. - wb2qmy (at) arrl.net - for details.