One Stop Pacific Northwest Weather by W7CQ
Back To : W7CQ Home Page
GOES Water Vapor
|KUIL Weather Balloon - Quillayute, Washington|
|KSLE Weather Balloon - Salem, Oregon|
|West Coast Radar|
By Studying all the above weather data,
We are trying to understand and predict the RF scattering media for VHF/UHF signals here in the Pacific Northwest.
A group of hams here in the Northwest are using the incoming weather from the Pacific ocean as a scattering medium of UHF signals for making 10 GHz and 24 GHz contacts. This is being done from the comforts of our homes in normal ham settings, not on hill tops. Two stations aim their antennas at a common spot of sky. This spot is a Common Volume and is usually ( but not necessarily) half way between the two stations and from 10k to 30k feet in altitude.
This propagation is called scattering and is been observed often by UHF hams and all we need is some sort of weather related signal scattering media. This is what we are studying. This is the same scattering media observed in the middle of the US during their large thunderstorm build ups. But alas, here on the west coast, we don't get this type of weather very often. The one thing we do have is eastward flow of Pacific storms into our area to provide the media to scatter our signals. More information on this subject is available in a pdf file from the July/August 2003 QEX article , authored by W7PUA, W7LHL (sk) and W7SZ
We also have the main west coast north south commercial airplane traffic pattern inline with our test area and an occasional airplane flying through this common volume makes for a large signal reflector of our signals back down to let us know our equipment is up and operating. This provides peace of mind when no signals have been observed for a long time and we start to think the equipment on either end may have failed.
This group of hams, W7PUA, W7SZ, KD7TS, W7YOZ, W7GLF, W7HXM and W7CQ meet almost every morning at 8:30am on 3,818 kHz to discuss ideas, what is going on UHF and what we have observed and the weather. That brings us to the reason for this page.
Here on this web site we are gathering weather data to try and make some sense of the signals we are seeing or not seeing and making this data available to the group. Some of these observations come from just looking out the window, and other data is gathered from weather balloons KUIL and kSLE that are launched from several spots around the northwest every 12 hours. Other gathering is done with Isobar Maps of the most of the Northern Hemisphere, Portland Rain Radar, and Composite West Coast Radar.
We use information from the above data on this page, signal data from our DSP-10's, a Software-design Radio by W7PUA, and audio files saved from Spectrum Lab by DL4YHF to gather info. Many hours of semi automated transmitting and receiving are required. Lots of Excel files and charts are being passed back and forth. Screen grabs of signals on the DSP10 saved to study. All these go together to help us in our search for information and understanding of the relationships involved.
Common Volume Explanation
Since none of us can "see" each other line of sight at UHF frequencies, due to mountain ranges and the curvature of the earth and we all don't live on mountain tops, we are aiming our antennas at the common volume atmosphere between our home stations and are reflecting our signals of this common volume water vapor back to each other. This works when the weather cold fronts roll in from the Pacific Ocean and pass thru our common volumes. Signals will slowly rise out of the noise to levels that allow CW and or SSB contacts and then slowly fade back into the noise as the fronts pass thru. This can be minutes or hours depending on the temperature and water vapor in the weather fronts. Weak CW signals have a distinctive sound that is due to Doppler shift by the moving front. When the fronts are not there we only see an occasional airplane for a short time while the plane is in the common volume. Airplanes show a distinctive pattern on the DSP-10 waterfall display and make for quick CW contacts but are not what we are studying.
Taking into consideration the curvature of the earth, the calculated Common Volume between KD7TS and W7CQ, a distance of 239 miles (385km), is located at an altitude of 9500 feet (2.9km) and at a distance of 119 miles (192km) from each station when their antennas at 0º of elevation and aimed at the horizon. If KD7TS were to elevate his antenna the intersect point in the common volume will move higher in altitude and closer to him. This allows KD7TS, with his elevation control, to choose a point in the sky that possibly has better reflecting media. Maybe a higher cold front that is closer to him as seen in the current green GOES satellite pictures of the moment. W7CQ would not have to move his elevation control. This very situation is being used with the 10ghz W7CQ/b beacon presently aimed at Seattle where KD7TS lives.
We used the picture and data files posted at top of this page to estimate temperature and water vapor content in the Common Volume to judge if a UHF signal could be reflected off the incoming weather front between the two stations. It is working!
The idea for this page was born out of necessity, as we all tried independently to observe weather data as it related to our UHF contacts. To all the gang on 3818 who have made suggestions, offered criticism, found links to things they wanted on this page, proofread, and helped improve this page, THANKS! UHF contacts and beacon reports by Mike KD7TS, Larry W7SZ, Bob W7PUA, Ernie W7LHL (sk), Beb W7SLB (sk) and many others who like my wife, who just wants to see what the weather is doing on a regular basis in our Pacific Northwest,.
I especially wish to thank Bob, W7PUA who, while trying to teach me Python, did most of the computer programming necessary to get all the information on this page. This idea has been in the works for a couple of years. Now it is here!
As time goes on we will continue to study scatter propagation here in the Pacific Northwest. Jimmy W7CQ
Back to W7CQ Home Page
Copyright 2007 - Jimmy Oldaker Last edited: 06 January 2017 04:26 AM GMT