The "TEXAS" Beacon will remain on the air throughout the summer, as always,
but I had to roll up the chicken-wire groundplane around the tower. I can't
mow the grass unless I roll it up first. Rolling up 800 feet of chicken wire
(4,000 sq. ft.) is just too exhausting, especially when the grass grows
through it over the septic field.
Looks like the signal strength will be down by 6 dB or so as a result. Of
course with the summer static levels . . .
I will let you know when I roll it back out this Fall or make any changes. Happy DXing!
Subj: LF Notebook
Date: 97-05-29
From: pthomson
I'm working on improvements to RI, including a more extensive ground
system and better guy insulators, which should make it more audible
when it goes on the air on October 1. I don't plan any change to the
format (5 Hz CCW) and only minor tweaks to the transmitter circuit.
73, Pierre
Subject: North American HF maps
Date: Tue, 27 May 1997
Effective immediately, we have a new E-mail address. We can be
reached at: monitor@rac.ca
You might be interested in looking at the following pages:
http://www.ips.gov.au/asfc/usa_hf/
Jacques d'Avignon - Radio Propagation Forecaster for
"Monitoring Times" "The Canadian Amateur" "Shortwave Magazine"
"DX Ontario" "RAQI"
Subj: GWEN
Date: 97-05-21 01:47:18 EDT
From: wfowler (Walt Fowler)
The plan to cover the USA with DGPS beacons was announced at a European conference by
the assistant secretary of DOT. GWEN conversion
should be a feather in the politicians cap for converting a cold war system
to civil use. The cost savings are tremendous when you consider 22 sites
which will cover almost the whole USA in daytime conditions with antennas
and buildings already in place. The minimum field strength the Coast Guard
considers adequate is 75 Microvolts/meter, these are fairly strong signals
but are required to receive digital data in thunderstorms.
I can describe the MSK modulation which is used on the DGPS beacons.
MSK modulation is the most efficient form of modulation when you consider
bit rate verses bandwidth, for example for 200 baud data only 200 Hz of
bandwidth is required. MSK can be looked at as FM or FSK, a digital 1 is
defined as an advance in carrier frequency of 1/4 the baud rate. Example
for 200 baud shift frequency up for 5 milliseconds by 50 Hz this will
appear on the carrier as an advance of 90 degrees in the bit time of 5 ms.
A zero is a shift down by the same amount. The data bits are synchronized
with the carrier frequency so the bit rate must be a sub-harmonic of the
carrier frequency. A simple way to demodulate MSK is to use a narrow band
discriminator just like an FM receiver. The output of the FM detector will
be the data bits. This detection method will suffer at least 3dB and more
like 5dB of sensitivity loss when compared to a phase lock loop but is a way to
decode the data with out DSP.
I will find the documentation on data formats and see if I can get it
posted, I don't know how to do this but it will be a learning experience.
73, WALT KC5ZDX
- Reply 1:Thanks very much again, Walt. Your efforts are much appreciated!
73, John Davis
Subj: Re:GWIN
Date: 97-05-20
From: wfowler (Walt Fowler)
I work at Starlink Inc. We installed a 1Kw transmitter and coupler that we
designed for DGPS transmissions. The transmitter went on the air last week
with an incredible efficiency of 50 percent. The high efficiency is due to
the antenna being 300 feet tall with 12 ea 200 foot top load radials. The
next best efficiency DGPS beacon was at Sallisaw, OK, with 25 percent
efficiency. Our DGPS beacon receivers decode the MSK modulation which
includes a transmitter identification number as well as Latitude and
Longitude of the Transmitter. The receivers are quite expensive because of
the DSP required to demodulate the MSK modulation; however the guy that does
DSP programs on a PC with multimedia analog input could write a program
that would decode the data with a receiver that converted the signal into
the audio band. The bit rates for DGPS beacons in the USA are 100 and 200
baud (100 for the Appleton beacon). I design receivers and transmitters
but computer programming is not a strong point with me. If any one is
interested I could explain the MSK modulation.
There is a plan to turn all the GWIN sites over to the Coast Guard or
some federal agency we think by the end of 1998 depending on how the
testing goes on this site. Appleton was put on the air for at least a year
for a Federal Railroad test designed to improve railroad safety and allow
more trains on the same track by using exact position information provided
by DGPS.
Starlink has a web page at starlinkdgps.com. Information about DGPS
beacons across the world can be found there.
Walt Fowler KC5ZDX
- Reply 1:Thanks very much, Walt. That's the first clear technical information we've had on the possible conversion of the GWEN sites. The antenna system they use should be highly efficient, indeed, especially at the higher frequency of the Appleton site. I expect it should have splendid coverage, and wish Starlink much success in these tests. (I might add that it's a welcome relief to us LowFER enthusiasts to have them moving to regular beacon frequencies, too.)
Any light you could shed on the MSK format would certainly be welcome. Longwave beacon hunters have been looking for ways to identify DGPS transmitter sites for verification purposes. As you say, if one understands the format, it should be feasible to write a computer program to extract the transmitter ID.
Thanks again for a most informative message!
73, John Davis
Subj: GWIN
Date: 97-05-18 23:37:20 EDT
From: wfowler (Walt Fowler)
The GWEN station at Appleton WA has been converted to 300KHz and is
transmitting DGPS corrections. The station is delivering 500W ERP at
300KHz. How far can it be received??
Walt.
- Reply 1: If that 500 W is actually ERP, they should be audible over most of the continent at night! Wonder if you could enlighten us as to the source of this information, as several members are curious about the fate of GWEN. Do you know whether it continues to be operated by the Air Force, or will this site come under Coast Guard jurisdiction, as most of the other DGPS stations already are?
Thanks and 73,
John Davis
Subj: RL update and other stuff
Date: 97-05-14
From: RLLaney
I will try to have RL on this summer, but it will be intermittent because of the usual shut downs for T-storms and the threat there of. We have had more threats so far than actual storms. Seems like spring will never get here.
Regards, Bob
Subj: End of GWEN in sight?
Date: 97-05-14
From: mmommsen (Pierre Thomson)
I just ran across this sentence on p. 46 of May 1997 QST:
"The introduction of Milstar will also permit the
retirement of older and less capable systems such
as the Ground Wave Emergency Network."
This is written by Charles Keene of the US Strategic
Command. He ought to know what he's talking about.
So let's hope we will soon have the full 160-190 KHz
band for Lowfer activity!
73 de KA2QPG, Pierre Thomson
Subject: beacon BOB
Date: Tue, 13 May 1997
From: "bob a. hoffswell"
Just a quick note to say I've decided to leave BOB on the air through the
summer. I made a test with and without the radial wires on the antenna
system, leaving only a ground-screen composed of five pieces of 2' by 30'
chicken wire laid on the grass. My test with the full system gave a
pretty good, 569 signal at about 60 mi using my portable rx. A few weeks
later, the signal at about the same place was nil. A few weeks after
that at a Hamfest 90 mi from here, the signal was weak, but pretty good
copy, despite the fact that I was near Chicago and a lot of AM stations.
So, what can I say! As time permits, I'll upgrade BOB for next season
and fool around with movable/mowable grounds, and I'd be pleased to hear
from anybody that hears BOB. I still remember that BA was great here
last August before he added his winter ground system, and even with the
extended grounds last winter, BA was not much better here, and was often
pretty weak or uncopyable. Go figure, as they say!
Despite it all, and few reports, I still enjoy LF work. It's a real QRP
endeavor. Most of the time, I'm the only one listening to BOB, but it
still is a joy to hear it as DX!
73 de Bob Hoffswell,AA9DH
Subject: LEK Longwave report for May
Date: Sun, 11 May 1997
From: Lyle Koehler
This will be a very short report because we're going into the summer
slump in LowFER/MedFER activity. Beacon OK was still readable here until
lightning took out Bill's transmitter at the beginning of May. I'm still
hearing local beacons SAM and I. Haven't checked for STLMO for a couple
weeks on MF, but his BPSK signal was still copyable on 1690.798 the last
time I listened.
Regarding BPSK activity on the ham bands, the only news to report is a
successful 6-meter BPSK QSO with Clair, K0CJ, who lives about 115 miles
south of me. Clair's rig had an intermittent modulation problem that
would cause the output to drop from 50 watts down to a level that hardly
showed up on his wattmeter, but his BPSK signal kept printing. We may
run a more controlled test when his radio comes back from the repair
shop.
73 from Lyle, K0LR
Subject: TEXAS Beacon
Date: Sat, 10 May 1997
From: JWRIGHTsosu.edu
Sunday afternoon, May 4, 1997, I went out to the "quiet site"
about 2 miles SW of my home (out in the prairie and away from power
lines) and searched for the TEXAS beacon using a regenerative
preamp fed by a 12 ft whip antenna. I still use the little Sony
ICF-2002 receiver. I found TEXAS on the published frequency, a
strong signal of communications quality at my distance. TEXAS
transmits its ID twice, then goes key-down for several seconds,
after which the process repeats, etc. Does he have BPSK in the
key-down part? I also searched for but did not find OK. There was
some static today, and Davenport is further away.
Rick Wright
KA5YWH and R
Geezer Pilot (age 58)
Subject: Summer beacon update for DJL
Date: Fri, 9 May 1997
From: DarwinLoon
I just wanted to update you on my new beacon location and schedule for
the summer. As of today, I have begun operating my beacon from a new location, about
five miles southwest of the former location. The transmitter is now in Newbury Park, CA. (still grid location DM04). A much-improved antenna and ground
system is now being used (30' T-antenna with four-wire 8'x20' top-hat).
My mailing address remains the same. At this point, the schedule will remain 24 h exc. rain. The frequency
and transmit mode also remain the same (188.920 kHz, CCW format).
As you may have noted, my e-mail address has changed to
DarwinLoon@aol.com (GNN has become AOL since I submitted my last beacon
update for the Western LF Beacons section).
Have a pleasant summer!
Darwin Long IV (DJL)
Subject: Longwave BBS
Date: Tue, 6 May 1997
From: Tim Brannon
John,
I just read about the "decommissioning" of the Longwave BBS, and wanted to
give you another heart-felt thanks for your contribution to our hobby. I
remember trying to log on to another "longwave" bbs back in 1991 and being
so disappointed about it being out of service, only to find your BBS a few
years later. It served its purpose admirably, but technology marches on,
in keeping with other developments in the hobby today. There certainly is
no substitute for the printed word and I hope Bill Oliver will continue to
recognize this, but the usefulness of a forum like this is beyond measure.
Tim Brannon KF5CQ
- (Thanks for the kind words, Tim. Yes, one has to keep up with the times in order to communicate effectively. Thankfully, I don't think print communication is on its way out any time soon, and The LOWDOWN will still be the prime means of reaching LWCA members well into the future. Print gives an author time and space to develop thoughts, and to archive information of moderate longevity far better than electronic means. The Web, of course, provides faster dissemination of information, and less expensive distribution to a wide audience. So, I think they complement each other nicely. I'm glad we live in an era with both means of communication. -John Davis)
Subj: RE: CONSOL Station
Date: 97-05-01 19:01:00 EDT
From: monitor (Jacques d'Avignon)
The CONSOL station left in Stavanger is the last one left from a group
of 3 that were operating in Europe. One station was at Bush Mills in
the UK and the other was in Ploneis in Spain.
To get direction from this station you need a special chart and you
count the number of dots and dashes between the ID signals. Then by
looking at the chart you get one azimuth. So if you have 3, you get a
good fix.
The CONSOL range is 1000 nautical miles.
For "older" people, TUK on 194 was originally set up as a CONSOLAN...
Long range CONSOL station, there was another one on the West coast, I
beleive that it was LAX on 196.
There is very little left in the literature on this. Even older listeners in Europe are not aware of this, and the station is
still on the air.
- (Thanks, Jacques, for enlightening us on this most interesting piece of radio history! --John)