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DL2KCL > VLF 29.06.97 10:24l 113 Lines 4425 Bytes #-10607 (0) @ DL
BID : 296705DB0MKA
Read: DL5MCG DL1TS DL3MGQ DL4DSS DL5MAV GUEST
Subj: LOWFER-DX-Rekord
Path: DB0KCP<DB0KFB<DB0CZ<DB0LJ<DB0ACH<DB0MKA
Sent: 970629/0720z @:DB0MKA.#NRW.DEU.EU [Hennef OP:DL3OE] $:296705DB0MKA
de DL2KCL @ DB0MKA.#NRW.DEU.EU (Andreas)
to VLF @ DL
Hier eine Info aus dem Internet ueber einen Reichweitenrekord der
in dem in USA allgemein zugelassenen LW-Bereich aufgestellt wurde.
Man sieht, was mit geringstem Antennenaufwand und qrp moeglich ist.
Digital DX Records Set On 1750 Meters
Recent experiments at HDO, a 1-watt transmitter at Cuesta College in
Morro Bay, California, have produced remarkable results. Using BPSK, one
of its two advanced digital modes, the beacon was heard in the last few
weeks at distances of 923 and 1600 miles!
Binary Phase Shift Keying (BPSK) and Coherent CW (CCW Morse) are two
methods currently employed by longwave experimenters to achieve
respectable communication range with their miniscule signals in the
noisy "basement" of the radio spectrum. These techniques involve precise
control of transmitter and receiver frequencies, and accurate timing of
data transitions.
Until recently, these requirements were too expensive and awkward for
casual experiments, but that has changed. Personal computers with an
inexpensive A/D converter and free software can easily handle the
modulation and demodulation chores. The RF hardware...transmitters and
receivers...are not a major problem, and kits are presently under
development for both license-free longwave use and for the amateur radio
bands.
HDO's operator, Clifford Buttschardt (W6HDO), sent the following
messages to a group of experimenters and correspondents who have been
following the work closely:
California to Colorado
Date: 96-01-24 20:38:52 EST
From: cbuttsch@slonet.org (Clifford Buttschardt)
Late last night, John West of Longmont, Colorado,
called and said that he was printing HDO(null)
very well! I asked for further details in which
John indicated that there was no signal to be heard,
rather the synchronization was obtained by the computer
and relying upon the synthesized frequency for accuracy.
The signal was obtained just before dawn in Colorado,
purposely done to avoid intermodulation signals when
the broadcast stations commence daytime operation.
John's grid square is DN70KD while the Cuesta College
beacon is located in San Luis Obispo, CA, at CM95NI. This
proved to be a path of 923 miles. HDO(null) is on the
air 24 hours a day and it should not be too long before
others in the Mid-continent obtain copy. Many thanks
to John for the effort and report!!
Cliff
California to Minnessota
Date: 96-02-03 20:27:37 EST
Just a few minutes ago on Saturday 3 Feb 96, I
received a letter from Lyle Koehler (Aitkin, MN)
indicating partial printing of the HDO(null) BPSK
beacon! As before, there was no audible signal and
Lyle did have to make adjustments after first noting
that consistency was present in what jumbled
characters he was receiving. A slight adjustment,
part of the DeCarle BPSK program, fixed that. Then
the usual happening----a computer birdie swept past
and wiped things out. These observations seem best
just before dawn at the receiving location, in this
case 1200 UTC. Whether this is propagation or simple
lack of broadcast intermodulation is one of the items
all this experimentation is about!
Lyle was not using exotic gear at all but rather an
Icom IC706 just gotten, with a good whip and preamp in
a 250 Hz filter. The key again is good frequency
stability and recall. John West has shipped a sample Max
Carter MAX800 receiver to Lyle for further tests.
Congratulations!!
Cliff
------------------------------------------------------------------------
Obtaining Further Information
If you'd like to know more about CCW, BPSK, and the effect of these
modes on low-power radio experiments, you can obtain both general data
and program files at the following FTP sites and Bulletin Board Systems.
•ftp.uni-wuppertal.de:/pub/pc/lowfer (Maintained by Robert Schneider,
this site archives quite a few longwave related files.) •The
Longwave/Part 15 BBS 706.672.0360 (Free. Many radio related files and
programs. No on-line browsing of library, however; download ALLFILES.TXT
when you connect, and browse it at your leisure in any good text
editor.) •VE2IQ BBS 514.226.7796 (Operated by Bill de Carle, author of
the COHERENT software package for BPSK and CCW, and maker of the
delta-sigma A/D board that works with the software.)
------------------------------------------------------------------------
73
de Andreas in Rheinbach, dl2kcl@db0mka
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