I think I probably mentioned this last year and indeed, I was going to take part and then forgot all about it! Anyhoo, from the 1st December to the 31st, there is the TOP DX Radioclub contest. Essentially, receive 10 different stations from 10 different countries. Scoring is based on distance from RX QTH to TX QTH (in Km) divided by the TX power.
For more details see: TOP DX Radioclub
And this year, I’m going to attempt it!
From SpaceWeather.com
When a stream of solar wind hits Earth, magnetometers around the Arctic Circle normally go haywire, their needles swinging chaotically as local magnetic fields react to the buffeting of the solar wind. On Nov. 18th, however, something quite different happened. Solar wind hit Earth and produced … a pure, almost-musical sine wave:
Rob Stammes recorded the event from the Polarlightcenter, a magnetic observatory in the Lofoten Islands of Norway. “A very stable ~15 second magnetic oscillation commenced and persisted for several hours,” he says. “The magnetic field was swinging back and forth by 0.06 degrees, peak to peak, with the regularity of a metronome.”
Imagine blowing across a piece of paper, making it flutter with your breath. The solar wind can have a similar effect on magnetic fields. The waves Stammes recorded are essentially flutters propagating down the flanks of Earth’s magnetosphere excited by the breath of the sun. Researchers call them “pulsations continuous” — or “Pc” for short.
“A very sensitive magnetometer is required to record these delicate waves,” says Stammes. “I use a mechanical magnetometer with bar magnets suspended from a special wire. LEDs and light detectors in an isolated dark box record the motion of the magnets, while vanes in oil damp out non-magnetic interference.”
Pc waves are classified into 5 types depending on their period. The waves Stammes recorded fall into the range 15 to 45 seconds–that is, Pc3. Researchers have found that Pc3 waves sometimes flow around Earth’s magnetic field and cause a “tearing instability” in our planet’s magnetic tail. This, in turn, can set the stage for an explosion as magnetic fields in the tail reconnect.
A quartet of NASA spacecraft recently flew through just such an explosion. Last week, researchers from the University of New Hampshire reported that four Magnetospheric Multiscale (MMS) spacecraft spent several seconds inside a magnetic reconnection event as they were orbiting through Earth’s magnetic tail. Sensors on the spacecraft recorded jets of high energy particles emerging from the blast site. One jet was aimed squarely at Earth and probably sparked auroras when it hit the upper atmosphere.
Stammes has recorded many Pc waves in the past, “but this is the first time I have detected category Pc3,” he says. “This was a very rare episode indeed.”
I came across this via a link from the Extreme Shortwave Listening group and posted from the blog of nw7us.
There is an ITU paper which discusses the problems of reliable ship-to-shore comms using only satellites, and a design for moving them back to HF. The paper includes architectural design for the system, along with explanations of the type of transmission, in this case, OFDM or Orthogonal Frequency Division Multiplexing. No, me neither.
A few quotes from the paper:
The NAVDAT HF system can use a simple time-slot allocation similar to the NAVTEX system which could be coordinated by IMO.
That NAVDAT HF system can also work on single frequency network (SFN) as described in Annex 4. In this case, the transmitters are frequency synchronized and the transmit data must be the same for all transmitters.
The NAVDAT HF digital system offers a free broadcast transmission of any kind of message from shore‑to‑ships with possibility of encryption.
That last one is telling “a free broadcast transmission”. That reads to me that one of the reasons to return to HF is the cost of renting satellite time, whereas HF is “free to air” with no ongoing costs other than maintenance.
Its not a large paper, but worth the read. The link to the pdf file is here: NAVDAT
CHANCE OF STORMS ON OCT. 7-8: NOAA forecasters say there is a 75% chance of minor G1-class geomagnetic storms on Oct. 7th and 8th when a stream of high-speed solar wind is expected to hit Earth’s magnetic field. The storms could intensify to G2-class–that is, moderately strong. If so, sky watchers in the United States could see auroras along a line from Maine to Michigan to Washington. Arctic sky watchers are almost certain to get a good light show. The gaseous material responsible for the coming storms is flowing from a large hole in the sun’s atmosphere, shown here in a false-color UV image taken by NASA’s Solar Dynamics Observatory.
|
Date |
TimeOn |
Call |
Freq |
Mode |
RST_S |
|
Name |
QTH |
QS |
QR |
QSL_VIA |
| 2018-09-26 | 17:44 | OD5VB | 14.18 | SSB | 59 | EA5GL | |||||
| 2018-09-26 | 17:32 | CS7APD | 14.209 | SSB | 57 | ||||||
| 2018-09-26 | 17:29 | OD5UI | 14.244 | SSB | 56 | Mohammed | |||||
| 2018-09-26 | 17:27 | CT1ASM | 14.244 | SSB | 59 | ||||||
| 2018-09-26 | 17:18 | CU3AN | 14.292 | SSB | 4,4 | ||||||
| 2018-09-26 | 16:53 | 9W2SAF | 7.145 | SSB | 56 | ||||||
A new callsign logged on 40m. 9W2SAF managing a big pileup. 20m was also in good shape.
Some interesting news on QRZNEWS.COM regarding a number of records of stations working Cape Verde Isands on 2m. No real details of power used/antenna, but clearly an excellent tropo-duct. For more details see: http://qrznow.com/g3smt-works-cape-verde-islands-to-set-new-144-mhz-tropo-record/
