Posts Tagged ‘tropo’
KL7 Tropo?
July 3rd, 2015 | 
Author:  |
| courtesy: http://www.nrlmry.navy.mil/ |
Like our unprecedented early hot and stable weather pattern over the West coast, this path is fairly rare and has never really been explored ... this one appears to be forming a stable path towards Alaska. The predicted conditions can be viewed on Bill Hepburn's World Wide Tropospheric Ducting Prediction page. Select the Eastern North Pacific from the 'Region' drop-down menu and see the map for Saturday.
Perhaps there are some KL7s near the water, or not too far inland and with a clear shot towards the southeast, that would be interested in running some possible tropo tests over the next few days if the path shapes up as predicted in the Bill Hepburn maps for the weekend. Not ever having explored this possible path before might yield some interesting results ... and who knows how far south into Puget Sound a tropo signal from the north might reach? Maybe it's time to find out. Of course, any stations between here and northern KL7 (Prince Rupert?... Juneau? ... Ketchikan?) might also be interested in trying a possible 2m path.
KH6 On VHF
I notice that the long distance records for terrestrial QSO's on 2.3 and 3.4GHz were recently broken. The records were set by veteran VHFer N6NB, Wayne Overbeck and W6IT, Greg Campbell. N6NB was operating portable in Hawaii while W6IT was operating Wayne's home station near Orange, California. Both contacts were on SSB. In Overbeck's own words as posted on the Tropo Ducting Reports reflector:I'd like to post something about my trip to Hawaii for the current tropo duct. This trip has really turned out well so far.
Last week the Hepburn forecast suggested that a duct might form in a few days. So I bought an airline ticket and packed a station for
all bands from 144 MHz through 10 GHz in two large suitcases plus a roll-aboard and a backpack (total weight: 150 pounds). When I got here, I rented a small SUV and built a station in/on it. I made several trips to Home Depot for parts to build a rotating roof platform.
When the duct began on Tuesday, I drove all over Mauna Loa while listening to my own 222.030 MHz beacon in Orange County, Calif. It was a thrill just to hear it 2,500 miles away. By Thursday, the duct seemed to be at its best. Greg, W6IT, activated my hilltop station near Orange, CA and we worked Thursday night on six bands, including 2304 and 3456 MHz, both for new world DX records. I heard Greg well on two more bands, 902 and 5.7 GHz, but so far local QRN in Orange County has prevented him from hearing me on those
two additional bands. Let's hope the duct continues for a little longer so we can try again and also work more stations on the west coast.
I intend to write at least a conference paper and create a PowerPoint show about what I've seen and heard in Hawaii. I've noticed that the KH6HME beacon site, as good as it is, sometimes seems to be above the cloud layer that forms the top of the duct. Thursday night it was about 2,000 feet above the cloud tops. Seeing that, I drove down to 5,200' elevation to work Greg on all those bands. (The beacon site is about 8,200 feet above sea level.) My 222 beacon was definitely louder at lower elevations than at the beacon
site at that time. Friday night I operated at 7,300', which was near the cloud tops and where my beacon seemed loudest then. The size and elevation of the duct seems to vary a lot, perhaps explaining the way the KH6HME beacons vary in relative signal strength, with 432 being a louder at certain times while the 144 beacon is louder at other times. There are some very interesting natural phenomena at work here.
If anyone would like to watch a video of the record-setting 2304 QSO with W6IT, it's online on my website:
www.n6nb.com/2304rcrd.mp4 Thanks to Greg, W6IT, for his able operating on the other end of these QSOs.
73, Wayne, N6NB/KH6
With the present extremely hot stable weather on the west coast, chatter on the PNWVHF reflector suggested that operators on the coast as far up as Washington state should be watchful of any possible DX opportunities should a suitable ducting pattern form between KH6 and the coast.
The difficult and rare path between Washington state and Hawaii has been worked in the past ... lastly in 1995, when some alert '7's' found themselves in KH6HME's logbook. Paul, K7CW and Merle, W7YOZ described an exciting day from Washington state:
Then the JA's on 6 the following evening was almost too much to believe.
Merle W7YOZ
Although the KH6HME VHF/ UHF beacons are still in operation, sadly, there appears to be no VHFers able to visit the beacon site and work the mainland, should an opening occur. Fred, KH7Y, the most recent beacon caretaker, has since moved back to California, leaving a giant hole in the VHF scene on the big island. I wonder if there is a replacement capable of activating the station?
Even without any operators at the far end, it would be exciting to just hear the VHF beacon(s) in this region. The 2m beacon, now on 144.277MHz, has even been heard here in BC, by Mike, VE7SKA, listening from his hilltop location on SaltSpring Island. Unfortunately no two-way contact was established at the time. Tropo of any kind is a rare event east of Vancouver Island's west coast because of the mountainous terrain.
One of the best ways to follow the formation of favorable conditions is to watch the tropo prediction maps on Bill Hepburn's website as well as the visible west coast weather patterns available here.
An interesting summary of the 1995 openings, as well as the associated weather pattern pictures, makes for fascinating reading on the PNWVHF Society's website, A Brief History of the KH6 Duct Into The Pacific Northwest.
Signal and Noise
“One man’s signal is another man’s noise,” began Dr. Kudeki as he derived incoherent scatter radar theory from Nyquist’s noise theorem in ECE458. I think of that statement often, whether it be QRM on the ham bands or sifting through the pocket litter of web users looking for their consumption preferences.
This morning, I admired just such an example of signal and noise while watching the NOAA Doppler weather radar. Undesired targets of a radar that return echoes are termed “clutter” in the radar parlance and one simplistic way of eliminating clutter, especially when you expect the desired scatterers (“targets”) to move, is to assume that all of the stationary returns are clutter. In the weather radar, we get clutter from all sorts of stationary things like trees, hills, and buildings. Of course, what causes the clutter to move?
You see, it was one of those humid August mornings when a ham’s mind wanders to…tropospheric ducting. Yes, indeed the clutter returns were moving, intensifying before and after sunrise. I was fixated on this and watched the loop over and over again before noticing an even more interesting bit of clutter!
Beginning at 0958 UT on 4 August 2014, there is a small ring forming out over the Elk River area. The ring, which is indicated by the downward-pointing vertical arrows, expanded over the next >40 minutes. I was puzzled and watched the loop over and over. I considered and discarded a number of theories before resorting to Google. Apparently, it’s very likely a flock of birds. Sure enough, the epicenter of the ring is Elk Neck State Park. Fascinating.
The slanted arrows in the figure above indicates the ground clutter that I was originally noticing as a signature of tropo ducting, obviously now of secondary interest in this sequence of images!
Epilogue: I sent these frames to my father, who is an avid observer of the natural world. He passed them along to two friends back home who are birders. At press time, one reported that he had learned of these “bird circles” from Greg Miller, another birder from the area who got famous as one of the subjects of the book (and movie of the same title) The Big Year. I haven’t read/seen it, but I guess they went to Adak, which has a special place in my heart. Anyhow, it’s a funny small and interesting world in which we live.
10m Es and early morning MS?
LB9YE and I have been exchanging WSPR spots since 0458z this morning. In both directions there is considerable Doppler. On another signal (not currently decoding) there are clear signs of meteor reflections as the signals are strong but in short bursts. I wonder if MS was playing a part in LB9YE’s decodes?
Earier in the night PB0AIC (288km) was decoded STRONGLY at -8dB S/N . At this range I assumes this was early morning tropo or again possibly MS? At the very same time 0404z, G8VDQ (93km) , was decoded strongly at -12dB S/N.
Otherwise all quiet on the Es front.
I do wonder sometimes about Es (SPORADIC E-layer) reflections. Many signals do come into this category with fleeting, often quite localised, strong openings, but many others are anything but sporadic. Are these really Es as we know it or some other propagation?
Odd start on 6m today
As 0438z OZ7IT (853km) spotted my 1W ERP 6m WSPR signal by very early morning Es I assume. Then, just spots from local G4IKZ (18km) until I spotted G3RCE (185km) a little while ago, presumably by tropo with some aircraft reflection (2Hz Doppler). Interesting that a lot of the local spots by G4IKZ had a fair bit of Doppler too.
