[IRCA] Perseus captures from 1986 and 1991

[Mark Connelly <markwa1ion@xxxxxxx>]

That's basically it Bill, though I think that 2 MHz would be about the 
top of the baseband range.  Storing higher frequency blocks would 
require a downconverter stage.  That, as far as I know, was the NSA 
method employed at places like Menwith Hill (UK), Resolute Bay 
(Canada), Thule (Greenland), Incirlik (Turkey), the Aleutian Islands, 
and numerous other monitoring outposts in the '60s as we snooped on the 
Russian bear (and probably the ChiCom's too).

Regarding Craig's comment, I have identified that his recording starts 
at 0859 UTC on 1 MAY 1986.  Lots of news about the Chernobyl nuclear 
reactor accident a few days earlier.  Fun to hear 1560 WQXR doing 
classical, as well as hearing contemporary hit music and oldies on 
numerous other stations that are now boring talk ... aah the good old 
days!  No TA's or Latin Americans, but what do you want with only about 
40 dB of dynamic range?

So, besides my 1991 stuff, now we have Perseus files from 1986!

Mark Connelly, WA1ION
South Yarmouth, MA

-----Original Message-----
From: Bill Nollman <billct97@xxxxxxxxxxx>
To: CapeDX <CapeDX@xxxxxxxxxxxxxxx>; badx <badx@xxxxxxxxxxxxxxx>; am 
<am@xxxxxxxxxxx>; irca <irca@xxxxxxxxxxxxxxxx>
Sent: Fri, Feb 21, 2014 8:32 pm
Subject: RE: [CapeDX] Perseus captures from 1991

OK, let me understand this… the idea was to take 0-150MHz add a 60Hz 
sync signal to keep the VCR happy, store it to tape through the Video 
IN jack then on output simply remove the 60Hz and you basically have 
coming out what you put in? So simple its silly! I once used a Hi-Fi 
VCR to capture 8 hours of FM DX audio. Hardly genius.
 

From: CapeDX@xxxxxxxxxxxxxxx [mailto:CapeDX@xxxxxxxxxxxxxxx] On Behalf 
Of Mark Connelly
Sent: Friday, February 21, 2014 4:56 PM
To: badx@xxxxxxxxxxxxxxx; am@xxxxxxxxxxx; CapeDX@xxxxxxxxxxxxxxx; 
irca@xxxxxxxxxxxxxxxx
Subject: [CapeDX] Perseus captures from 1991

I finally got around to going through a box of VHS videotapes from the
late '80s / early '90s spectrum capture experiments, as originally
developed by Craig Healy (NG1U), and mentioned in this article:
http://chowdanet.com/markc/webpage/WA1ION/vcrdx.pdf

There were about 6 tapes in the box. Two of these, when played into a
receiver, had reasonable performance.

One of these was the tape Craig had originally supplied me. This was
made at his QTH near Providence, RI. The whole AM band is captured.
Sensitivity on the lower half was quite low so it's primarily the local
stations such as 630, 790, and 920. Some skip signals can be heard on
the upper half of the dial. I still have to review the tape to 
determine the exact date and times of recording. Items on a news /
sports station, possibly with some Google follow-up, will nail down the
date. At some point in the recording there should be a time check on
one station or another. I looked into the lower shortwave spectrum but
noted little in the way of "real" (non-birdie) signals, so no CHU or
WWV assistance on the time.

The second tape was one I made at Billerica, MA in April 1991 during
the "wee hours" of the morning: 0643-1043 UTC. Because 50 kW WRKO on
680 is only 2.8 miles / 4.5 km from the receiving site, a notch filter
for 680 was inserted ahead of the VCR input. Usable sensitivity for
the capture came in starting around 800 kHz and up.

One thing that must be kept in mind is that this primitive version of
spectrum capture had a rather small dynamic range: only about 30 to 40
dB from a hashy noise floor up to the level of a strong local  on the
verge of causing distortion and spurs. The tapes, obviously, are not
going to produce much in the way of weaker signal DX.

Before the tapes have a chance to deteriorate, I'm porting at least
some of the contents over to Perseus files. This also gives a ready
method for sharing the experiment results with others. I reset the
computer date/time so that the Perseus time-stamping is relatively
close to the occurrence of the original recordings.

After I get all this stuff digitized, I'll go over it for any
interesting audio clips.

Though the "VCR DX" method became known to the MW DX world about a
quarter century ago, it is widely believed that, as far back as the JFK
administration, "spook" agencies such as the NSA were able to store
substantial RF bandwidths for later review. Broadcast studio grade
videotape, or something similar but custom-designed, was used.
Converters allowed any chunk of spectrum to be heterodyned to the
baseband range (0-3 MHz?) the tapes could accommodate. The late Gordon
Nelson (WA1UXQ) seemed aware of it. Maybe some tapes will show up at a
Fort Meade, MD fleamarket / yard sale so we can tune around and hear
stuff like Belize 834 and Bermuda 1235 once again, as well as
Murray-the-K on WINS proclaiming his status as the Fifth Beatle.

Mark Connelly, WA1ION
South Yarmouth, MA







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