For the past several years a few of us in the Pacific Northwest have been observing propagation on 10 ghz using the DSP-10 2 meter IF radio. This has been a lot of fun and the results have been surprising. What makes these observations possible are the excellent weak signal capabilities of the DSP-10 and the use of a GPS disciplined station reference oscillator. All observations have been done among home stations without the need for portable operation.
August 2004 A/C scatter screensaves from DSP10 on 10368 MHz
More screen saves from Aug, 2004, on 10368 MHz
More
recent contact ( 24, March 2003 ) 0n 10 ghz using JT44
DSP-10
Screen saves of the W7CQ 10 GHz beacon
Path profiles on 4/3 Earth path profiles- 122 KB
At the outset, little was known of the role weather plays with propagation. Through many observations over a period of a few years it has become apparent that there is enhanced propagation when there is higher than average water vapor at high altitudes.
Weather indicators on FEB 26, 2003
Observations are done on the direct heading, with dishes elevated as required by local terrain. A slight amount of frequency shift seems to be present, but has not upset the usefulness of the path. In the case of shorter paths the antennas may be elevated as much as 25 degrees and seem to indicate a common volume between 20 and 30,000 feet altitude. This is around the same altitude as the commom volume on the longer paths observed which will be published in QEX.
Enhancements (WINTER 2002-2003) have been observed at lower altitudes as well. On clear, cloudless days signals are 10 to 12 DB above the noise. The enhancement seems to range from 20 to 30 DB and has been as high as 50 db above "flat" conditions. 95% of the time four degrees of elevation at both ends seems to work well for this enhanced path. Common volume seems to be around 6,000 feet. This coincides with periods of high humidity and low clouds. In the case of "flat conditions" one end is on the horizon, while the other is up two degrees for terrain clearance. There is no definite correlation btween any data we have and the short path we have been observing.
On 26 February 2003, we had favorable conditions for testing the
WSJT
program on 10 ghz between Ernie, W7LHL and Mike, KD7TS over a 31 mile
path.
Antennas were elevated to 15 and 26 degrees respectively. Results were
very good, with 100% copy in 10 minutes. This test was done to
illustrate
the use of common equipment and sound card programs in receiving weak
signals.
As this test was in progress signal strength was also observed using
the
Spectran waterfall program. This agreed quite well with the
waterfall
display of a DSP-10. This test was repeated again on February 28 with a
brief and weaker enhancement. The test was successful, but near
the
lower limits for this mode.
Some station details 5 KB
The use of a sound card and waterfall program is very useful for peaking and observing signal levels which would otherwise be undetectable.
As the signals increase in strength a CW contact can be easily accomplished.
Here's a WAVE
recording of Ernie from 6000 ft common volume 03 MAR 03(approx 142 KB)
Here's another WSJT
test done by Ernie and Larry on 10 GHz. This is a from an E-Mail
report to Gene Zimmerman, W3ZZ.
NOAA WV2 images available on the WWW.
http://www.wrh.noaa.gov/satellite/
East Coast, Central US : http://sat.wrh.noaa.gov/satellite/east4km/WV4E.GIF
West Coast, Central US: http://sat.wrh.noaa.gov/satellite/4km/WR/WV4.GIF
There are other 2KM products with greater detail, but the 4 KM has plenty of detail for our purposes.
