More information about this interesting communication path is referenced below.
On the morning of March 3, 2004 signals were reasonably strong and little doppler shift
between Ernie and Larry, so it was decided to attempt an SSB contact.
Modes were switched to SSB and surprisingly copy was Q5 with very recognizable voice
inflections. Larry rebroadcast on 75 meters a portion of one of Ernie's transmissions
and Bob W7PUA, Jimmy W7CQ and John W7FPK and myself, W7SLB, as observers heard what sounded to me
as similar to a 75 meter SSB signal using a carbon button microphone!
Quality was exceptional. Antenna and power levels at the stations were:
W7LHL- 10' dish, 4W; W7SZ- 10' dish, 10W.
Larry Liljeqvist, W7SZ, on the left and Ernie Manly, W7LHL, on the right,
along with Mike Reed, KD7TS, for several years have been running tests on 10GHz
exploring the upper troposphere as a communication path using DSP-10 transceivers
with transverters and various size dishes. Many times signals were nonexistent or
so weak they were barely detectable using long-term integration (LTI) and at other
times quick PUA-43 contacts were made when signals were stronger. Click on the pics
for full pictures.
The second 10 GHz SSB contact occurred on May 18, 2004 between Mike Reed, KD7TS (CN87ui) and
Bob Larkin, W7PUA (CN84io) over a distance of 197.95 miles (318.58 KM). Again, the upper
troposphere was used as a communication medium. Antenna and power levels at the
stations were: KD7TS- 3' dish, 1W; W7PUA- 4' dish, 4W.
Bob wants to point out the contact was not aircraft, but "upper tropo."
This is also not rain scatter, by any traditional definition.
Bob adds: "There were thunderstorms in the middle of the path causing moisture to be
lifted into the common volume at about 30,000 ft. We had been
transmitting back and forth every 5 minutes for weeks, and most often see
aircraft signals. But Monday night at about 0200Z we both started to see
strong tropo signals with the tones audible to the ear. We worked a quick
CW contact, and then I heard Mike coming through on SSB, weak but almost
Q5. The SSB contact took only a few seconds, and I could copy Mike asking
to QSY to 3818 kHz. The signals had fast QSB, but were narrow band and not
"aurora sounding," as is rain scatter."
At the left is the DSP-10 screen image of Mike's SSB transmission received by Bob at
Corvallis, OR. The big blobs are LTI with the beacon on 5 min intervals. The CW contact is
at about 0252 and the SSB can be seen at 0254. It is a bit confusing as
the spec width was wider during the CW and SSB, causing them to appear to
the left. Air planes are at the top. The small specs are due to LTI timing
errors, using random spread. Click on the pic to make full size.
"The point of all this is that we were only using 3 and 4 foot antennas, 1
and 4 Watts of power and a path with a big hill in the way (about 4
degrees as I look North). The only "exotic" capability might be having our
frequencies completely locked to GPS so that no tuning ever occurs.
Otherwise, we are pretty much ordinary home stations. By waiting for the
right moment, we have been able to catch some fun QSO's. We encourage
other microwave (and lower-frequency) types to explore this sort of
operation. A path such as Seattle-to-Boise or Spokane-to-Eugene may be
workable at the right time."
"Microwave Propogation in the Upper Troposphere" a paper summarizing the findings and
work done by Larry, Ernie, Mike and Bob Larkin, W7PUA to that date was published by the
American Radio Relay League in their QEX magazine for July/August, 2003.
The paper is available from the League by clicking
here .
(1,312,280 bytes, PDF file)
Two SSB contacts on 10 GHz of some interest occurred recently between W7LHL in Graham,
Washington and W7SZ in Washougal, Washington and second, between KD7TS in DesMoines,
Washington and W7PUA in Corvallis, Oregon. These contacts were significant in that
normal line of sight paths weren't available. The path was in the upper troposphere
with antennas elevated and pointed to a common volume area between the stations. 
"Interestingly, at this same time W7LHL was reporting below average tropo
signals from the Kelso and Canadian weather signals at 162 MHz. We have
observed before that the upper tropo is poorly correlated with the VHF
propagation, and even with 1296 MHz tropo."
Operating details for the DSP-10 have always been arranged, more-or-less, in cronological order in V1.6 notes, V2.0 notes plus various postings. This has not been very convenient, especially for people that are new to the project. They had to review old material that no longer applied, just to figure out what was happening today. Mike Reed, KD7TS, and Bob, W7PUA, have rearranged this material into HTML format, removed the parts that don't apply and added sections to make this up-to-date for version 3.8. The User's Manual can now be accessed on-line. This manual can also be used from PC files, without Internet access needs, after the initial download. You can download all the HTML files in "ZIP" format from a link near the bottom of the opening Manual page.
On January 16, 2001, I completed the first 2-Meter EME (Earth-Moon-Earth) contact with Bob, W7PUA,
using the PUA43 code in Version 2.0 just released. My equipment consisted of a DSP-10
driving an 8-watt Brickette amplifier (see June 2000 QST and this web page), followed by a KLM
PA10-160BL amplifier, running 100 watts output at the amp. The antenna was a home brew 12-element Yagi
mounted on a 4x4 post. Alignment with the moon was via "moon az/el data" at the bottom of the DSP-10 screen.
I also used a Janel QSA-5 preamplifier at the antenna to improve the S/N ratio. The ladder in the
picture aided in adjusting the az/el. The Janel QSA-5 preamp can be seen just below the feed
point between the ladder rungs. Bob's equipment consisted of a DSP-10, amplifiers for 500W
and 4x12 el Yagis. See Bob's DSP-10 page for a screen shot of his signal received here.
Click on the small picture to make it larger.
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