| KFI - 640kHz - Los Angeles |
A very rare combination of happenstance and circumstance led to the opportunity to identify an MF AM broadcast station from thousands of miles away that would ordinarily be inaudible and unidentifiable. In early August 2003, Dale Rice in Oregon posted an 'Argo' plot to the 'Lowfer' e-mail reflector of KFI, Los Angeles carrier, which was not only off designated frequency by a surprising amount (some 8Hz) but had a case of the wiggles, cycling up and down about 1Hz every 12 minutes or so. A hypothesis that this was messaging for telemetry or whatever seemed to be supported by reports of some WWII and later RTTY-like modulation of the carrier by many big AM stations, including it seems KFI.
However it seemed clear to this observer and many others that the cyclical wiggles were probably an artifact of the station's transmitter's frequency stabilisation scheme, either by accident or design. John Andrews, W1TAG, contacted engineering at KFI, who were intrigued, and between them cooked up the idea of seeing just when and how far the unique signal could be identified.
Reception reports in the form of 'Argo' plots such as above came within the first couple of days not only from predictably within the US, even the east coast, but from New Zealand (a truly stunningly clear plot) and Tasmania. A few of those captures are visible here. As yet, nothing from Europe, but one suspects this is just a matter of time. Here in Pennsylvania, the 'wiggle' is visible throughout the period of mutual darkness with the west coast; the above is a typical plot. Reception was on a vertical for 160m (self-resonance 1650kHz) on an Icom R-75, and of course, 'Argo'.
Frequency stabilisation.
One can see some really scary things looking at AM broadcast carriers. For another interest and project lately I've been looking at *lots* of them. (Yes, there are even weirder and more arcane pursuits than LFing.) One would have thought that as mature as AM broadcast is and the sci-fi level of technology in general it would be entirely possible for them to generate stable carriers on their assigned frequencies.
Of course, Virginia.
Many are solid and on frequency, but many just aren't. Depending on the transmitter's age and quality, the carriers originate with anything from crystals 'au naturel', ovened crystals or synthesisers. These latter are similarly referred to any of raw crystals, TCXOs, ovens or in very, very rare cases an external source; their lock characteristics vary from rock-solid PLLs, through long time-constant frequency comparison/correction, to the downright accidental, depending on design, maintenance and ageing. It is common to see seasonal changes, diurnal variations as the transmitter cools and warms, and periodic effects such as exhibited here.
I fell upon this by accident a few years ago when tuning into the Beeb World Service from Antigua on 5975kHz, with a radio off which was hanging 'Spectran' after a session looking for EU on 136kHz. Before I switched the radio to AM, 'Spectran' drew Auntie's carrier. Which was, um, moving . . ? In a sorta-parabolic curve of some 10Hz width and 40-odd seconds period. I contacted Merlin who politely dealt with whom they must have regarded as a total nutter, but shortly thereafter fixed or replaced the synthesiser.
KFI's artifacts are curious. Firstly, they are using a modern switching transmitter (Harris DX-50) which one would expect to have impeccable synthesis, so it is almost certainly a non-fatal fault. It seems to be a regular periodic step-function (actually, more a slightly assymetric square-wave) being modified by an under-damped lowpass filter set about twice in frequency. Now, whether each or any of these are electrical or thermo-mechanical effects is the mystery.
The above 'Argo' plot shows a couple of typical (dare one say 'classic'?) stability system woes from other carriers accidentally caught along with KFI; above KFI and below the 'noisy' phase-hammered carrier of an AM-stereo station (either XENQ Mexico or more likely WGAC, Blountsville TN) is the tell-tale assymetric triangle wave of an ovened oscillator; oven slowly cools down, frequency drifting with it, until the oven clonks on more rapidly re-establishing the 'hot' frequency. Perhaps tellingly, the oven's period is very similar to that of KFI's synthesiser's main period. Below KFI is a rather dithery and 'noisy' PLL on another station.
About KFI
KFI is a 50kW former clear-channel, now Clear Channel station, its antenna being aside Interstate 5 as one hurtles down to DisneyWorld from LA. In the days when clear-channel stations had, well, clear channels, KFI was clearly audible nighttime over most of the western US.
All right, all right . . . translated from radio-industry-tongue-in-cheek into English: Many years ago several of the AM broadcast channels in the US were designated "clear channel", and were each inhabited by one behemoth station only, giving listeners all over the country chance to listen in of an evening to say WLS Chicago, WSM Nashville, KSL Salt Lake and yes, indeed, KFI Los Angeles, amongst others. No co-channel interference. With the pressure on spectrum, near non-existence of such consumer 'DXing', and steadily withering relevance of AM radio, the "clear channel" concept is now pretty well completely blown. On the other hand, "Clear Channel" (note the capitalisation) is a monstrous radio broadcast organisation in ascendance, owning presently over 1200, that is one-thousand-two-hundred, radio stations in the US alone, and many elsewhere. Several in any market of any size. Put into perspective, that's more legit radio stations than in Europe, total. The 'consolidation' and homogenization of recent years which Clear Channel epitomises has both saved many stations from oblivion and provided a standard of radio previously unknown or unaffordable in many markets, but at the cost of a coast-to-coast uniform blandness. Predictability and consistency cut both ways. Some also argue that it is close to a monopoly, a word that raises major hackles in the US.
A nice pictorial and description of KFI's inner workings, by a former chief engineer. Another brief history, also largely pictorial. A small private plane crashed into and destroyed the KFI's tower on December 19th., 2004; sadly the pilot and passenger died.
A post-scriptum of bizarreness (Jan. '04)
O-o-o-oh, Boy . . . .
Suddenly, in early January, a flurry of e-mails started. One was very nice and complimentary about the site. Those are always nice to get. A couple were 'techno-cagey', trying to find out "what I really know", or ostensibly reasonably establish my sources. But many were just plain loopy and / or downright weird. Other than those imploring me for more details, I had blatant accusations of being "a dupe and lacky of the Military Industrial Complex, spreading their falsehoods and duplicity", being responsible for "ham-handedly exposing truths that dare not be exposed", and conversely being "at long last a voice of scientific reason validating what we have known all along". I kid not.
"Huh?" inquired my sole remaining unrent synapse. . .
To cut quite a long story short, from clues in the e-mails I back-tracked this (for paranoid conspiracists they're about as stealthy as a State Fair) - to a simple absurd reality: If one Google's for "beaconing for aliens", guess which web-page comes out at the very top of the list? Go on, try it! People pay huge GOBS of money for top listing on Google, yet *this* intensely narrow-interest abstruse KFI page on tinky-winky dear little w3eee.com astoundingly sweeps the field in, um, this. . .
In the first paragraph of this page I attempted to encapsulate what led up to the capturing and analysis of KFI's anomaly. Some postulations as to what the carrier's frequency shifting might 'represent', never mind what it actually 'was' got a little odd. This I tried to touch on lightly (being that it is after all a southern California station, home of the comet folk and such), with a throwaway "Astonishingly, beaconing for aliens was never mentioned. . ." remark at the end of the paragraph.
So this really boils down to three things. Firstly, I shouldn't try to be funny; secondly, that the architects of Google's search engine need tracking down and seeing to with a thick rubber hose; lastly that if you are of a conspiratorial or other-worldly bent, I have no issue with your belief systems but you now know exactly and explicitly what that lightweight remark actually meant, and you can safely go on your way and leave me the f*** alone.
© Steve Dove, W3EEE, 2003,4