Tag Archives: Propagation

ARRL reports California earthquakes disrupted west coast HF propagation

The ARRL reports earthquakes in California disrupted HF propagation on the west coast

British Columbia radio amateur Alex Schwarz, VE7DXW, said that an Independence Day magnitude 6.4 earthquake in California’s Mojave Desert and multiple aftershocks negatively affected HF propagation on the US west coast.

Schwarz, who maintains the “RF Seismograph” and has drawn a correlation between earthquake activity and HF band conditions, said the radio disruption began at around 1600 UTC on July 4, and continued into July 5. He said that on July 4, the blackout was total except for 20 meters, where conditions were “severely attenuated,” Schwarz said. The RF Seismograph also detected the magnitude 7.1 earthquake on July 6 in the same vicinity, Schwarz reported. The distance between the monitoring station in Vancouver, British Columbia, and that quake’s epicenter is 1,240 miles.

“Things are back to normal after the strong quake, as far as the ionosphere is concerned, but the unrest has not stopped yet,” Schwarz told ARRL on July 8.

Read the full ARRL report at
http://www.arrl.org/news/view/report-california-earthquakes-disrupted-hf-propagation-on-west-coast

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Free Advice: Stop worrying about solar minimums and just play radio!

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Lately we’ve been getting some pretty dismal news about the upcoming solar cycles and the potential for a pretty dismal trend according to some researchers.

We report this news on the SWLing Post because the sun and space weather play an important role in radio signal propagation and one’s ability to snag elusive DX.

After publishing news items like this, though, I always receive a number of emails and comments stating that these trends surely marks the end of all radio fun. After all, if there are no sun spots whatsoever, why bother!?!

Truth is, it’s sort of like saying, “the weather looks lousy, I don’t think I’ll be able to have fun.”

I lived in the UK for several years. If I let the potential for lousy weather stop me from having fun, I’d have never gotten anything done!

The same goes for space weather in our radio world.

A couple weeks ago, I made a Parks On The Air (POTA) activation running 15 watts with the Elecraft KX3 into a simple 20 meter vertical in SSB mode. Even though propagation was poor, I logged a new contact, on average, once per minute over the course of 30 minutes! It was non-stop!

The GE 7-2990A (left) and Panasonic RF-B65 (right)

I also listened to the Midwinter Broadcast to Antarctica with two portable radios. Propagation was poor and I didn’t even use an external antenna…but I caught the broadcast and had a load of fun hanging out on the Blue Ridge Parkway!

My advice?

As I said in a post last year, use the sunspot low as an excuse to explore frequencies and modes you’ve never used before. Use this as an opportunity to improve your listening skills and the most important part of your listening post or ham station–your antenna system!

I often receive email from people who’ve found the SWLing Post and take the time to write a message to me complaining about the death of shortwave radio: the lack of broadcasters, the prevalence of radio interference and the crummy propagation. They wonder, “is it all worth it?”

My reply?

“Hey…sounds like radio’s not your thing!”

While this same person is moaning and complaining, I’ll be on the radio logging South American, Asian and African broadcast stations.

I’ll be working DX with QRP power, even though everyone tells me that’s not possible right now.

I’ll be improving my skill set and trying new aspects of our vast radio world.

You see: I’ve learned that the complainers aren’t actually on the air. They gave up many moons ago because someone told them it wasn’t worth it, or they simply lost interest. That’s okay…seriously…but why waste time complaining? Go find something else that lights your fire!

While these folks are complaining, I’ll be on the air doing all of the things they tell me I can’t do.

In the words of Admiral David Farragut: “Damn the torpedoes, full speed ahead!”

Go out there and play radio!

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Radio propagation may improve soon with region of solar flux

Don’t buy into the doom-and-gloom: Low sunspots are not the end of DXing!

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In response to the spaceweather.com article about a lack of sunspots I posted yesterday, SWLing Post contributor, Rob Wagner (VK3BVW), replies:

Oh Thomas! Really?
It’s not all doom-and-gloom, you know! The low-frequency part of the SW spectrum is proving very good value at the moment. And the mediumwave guys are telling me that there’s plenty of DX to be had in that part of the RF spectrum.
And yesterday, I had some FT8 success!
From southeastern Australia on a dipole with 5w getting into Plymouth, Minnesota on 14mHz in the mid-afternoon here. Not bad at all for the bottom of the sunspot cycle!

Ha ha! Thanks for your reply, Rob! Honestly, I wasn’t trying to spread doom-and-gloom, rather I was pointing out how low this sunspot cycle has gone. (Okay, so perhaps I was also shaking my fist at our local star!)

I completely agree with you Rob. It’s not all doom-and-gloom! Here are a few strategies for working DX during sunspot lows:

Go low!

Sunspots really enhance propagation on the higher HF bands: especially 17 meters and higher. Without supspots, you’re not going to reliably snag serious DX on 10 meters, for example–there will be the occasional opening, but it might not last long. During sunspot cycle peaks, the higher bands provide outstanding DX opportunities even with a modest setup.

During one peak, I’ll never forget sitting in my car in North Carolina, with a RadioShack 10 meter mobile radio connected to a mag mount antenna, and having a three way chat with a ham in Sandiego, CA and one in Glasgow, Scotland.

With that said, even this year I’ve snagged some excellent DX on 17 meters (my favorite HF band). And, as you point out Rob, 20 meters is a great band for snagging serious DX even with no sunspots giving you a boost.

Openings between the US and Australia happen routinely on the 40 meter band as well, although some of us might have to wake up early or go to bed late to participate.

Of course all of this same advice applies for SWLing. Most of the DX I snag these days is found on the 25 meter band and lower. I’ve also been using this opportunity to explore Mediumwave DXing.

Digital Modes

Kim Elliott and I had an exchange about this yesterday on Twitter. Some digital modes are so robust they seem to work regardless of propagation.

Kim knows this well as he receives reception reports from Shortwave Radiogram listeners across the globe each week.

If you’re a ham radio operator, I strongly encourage you to check out the latest “weak signal” digital modes: JT65 and, especially, FT8.

In fact, SWLing Post contributor, Robert Gulley (AK3Q), wrote an excellent introduction to these modes in the June 2017 issue of The Spectrum Monitor magazine.

Robert and I talk about the FT8 mode frequently. Since I discovered this mode at the 2017 W4DXCC conference, I’ve been hooked. Sure–it lacks the nuances of phone and CW, but it’s incredibly fun to watch my flea-powered signal acknowledged by someone on the other side of the planet with a flea-powered signal.

As Robert will tell you, FT8 seems to defy propagation theory. I agree wholeheartedly.

I’ve worked some of my best DX with this mode during the sunspot low and have never used more than 15 watts out of my Elecraft KX3 and KX2.

Don’t give up!

Although propagation was poor, I worked more stations during National Parks On The Air than I had worked the entire time I’ve been a ham radio operator. All in the field with modest portable antennas and 15 watts or less.

Use the sunspot low as an excuse to explore frequencies and modes you’ve never used before. Use this as an opportunity to improve your listening skills and the most important part of your listening post or ham station–your antenna system!

I regularly get email from people who’ve found the SWLing Post and take the time to write a message to me complaining about the death of shortwave radio: the lack of broadcasters, the prevalence of radio interference and the crummy propagation.

My reply?

“Hey…sounds like radio’s not your thing!”

While this same person is moaning and complaining, I’ll be on the radio logging South American, Asian and African broadcast stations.

I’ll be working DX with QRP power, even though everyone tells me that’s not possible right now.

I’ll be improving my skill set and trying new aspects of our vast radio world.

You see: I’ve learned that the complainers aren’t actually on the air. They gave up many moons ago because someone told them it wasn’t worth it, or they simply lost interest. That’s okay…but why waste time complaining? Go find something else that lights your fire!

While these folks are complaining, I’ll be on the air doing all of the things they tell me I can’t do.

Rob, thanks for your comment!

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Guest Post: Eclipse 2017 – Shortwave Propagation Observations

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A map of the United States showing the path of totality for the August 21, 2017 total solar eclipse. (Source: NASA)

Many thanks to SWLing Post contributor, Bob LaRose (W6ACU), for the following guest post:

Eclipse 2017 Propagation Observations

by Bob LaRose (W6ACU)

DXers know that the reception of overseas Shortwave Broadcast stations offers one of the best ways to immediately gauge shortwave radio propagation conditions from your location to distant areas of the world. For the eclipse of 2017 I decided to see how reception of SW broadcast stations on lower shortwave broadcast frequencies (and to a smaller extent medium wave AM) reacted to the short term effects of the eclipse.

Going into this experiment I suspected that since the eclipse should temporarily reduce ionization to D-layer of the ionosphere, there might be some reduction in corresponding typical D-layer daytime absorption on lower frequencies. The hope was that this would enhance lower frequency propagation, particularly on the path between Asia and Western North America, which is normally totally absorbed at that time of day. I also monitored for propagation on other HF stations such as WWV as well as US-based SW Broadcast Stations in Alaska and Tennessee, and to a lesser extent AM MW broadcast stations. Here are the results of my experiment.

EQUIPMENT:

The Icom -IC-7300

For these tests I was using an ICOM IC-7300 Transceiver as a receiver connected to my standard antenna for lower frequency use – a Carolina Windom with the center about twenty feet off the ground. The antenna works reasonably well over a wide frequency range, including the lower SW and the medium wave AM broadcast bands. Because of my high local electrical noise level and proximity to several local AM broadcast transmitters, I turned off the built-in RF amplifier of the IC-7300 for all the tests. I used the uncalibrated S Meter of the radio to measure relative signal strengths in S units and dB above S-9.

BASELINE TESTS

The day before the eclipse I took baseline measurements at about the time of the eclipse. Because of normal summer daylight absorption, there were no signals present on either the 49 or 41 meter SW broadcast bands. At this time of year signals on those two bands generally fade below the local noise level at my QTH San Diego by about 1500 UTC.

I also checked the reliable daily beacons on SW at that time are the WWV frequencies of 5 and 10 MHz, The baseline for WWV was a signal strength of S5 on 5 MHz and S7-9 on 10Mhz.

I also took some baseline measurements of AM broadcast stations in Los Angeles (KFI 640 and KNX 1070). I was not able to receive any of the San Francisco, Sacramento, Las Vegas stations or points further North.

THE DAY OF THE ECLIPSE

According the Internet sources the eclipse began in San Diego at 1607 UTC, peaked at 1723 UTC and ended at 1846 UTC. It reached 66% of totality.

My first observation was at 1550 UTC. The strength of all signals were at the nominal readings from the day before. At 1630 I still did not hear any SW broadcast stations above the local noise level.

By 1640 the HF broadcast stations had begun to break through the noise. Here is a chart of my reception observations during the observation period:

Freq KHz	Station and Location	Time in UTC vs. Relative Signal Strength (S Units)
		1550	1630	1640	1650	1710	1725	1745	1800	1815	1830
640	KFI Los Angeles	9	9	9	9	9	9	9	9	9	9
1530	KFBK Sacramento, CA	0	0	0	0	3	6	2	0	0	0
5000	WWV Ft Collins, CO	5	5	7	9	9	9	6-7	7	5	5
5845	BBC Singapore (ends at 1700)	0	0	0	9	0	0	0	0	0	0
5995	Korea – Echo of Hope (presumed)	0	0	0	0	6	0	0	0	0	0
6015	Korea (presumed)	0	0	0	5	0	0	0	0	0	0
6045	Korea (presumed)	0	0	0	6	0	0	0	0	0	0
6125	China National radio	0	0	0	6	0	0	0	0	0	0
6155	Taiwan (1700-1730)	0	0	0	0	S9+10	5-7	0	0	0	0
6165	Yamata Japan for Korea (1600-1700)	0	0	6	7-9	0	0	0	0	0	0
6175	China National Radio	0	0	0	0	5-7	7-9	7-9	0	0	0
6195	BBC Singapore (open carrier – presumed tune-up for next morning	0	0	0	0	S9+10-20	0	0	0	0	0
7300	Radio Taiwan	0	0	7	0	0	0	0	0	0	0
7385	China National Radio	0	0	9	0	0	0	0	0	0	0
7465	BBC Singapore (ends at 1700)	0	0	S7-8	0	0	0	0	0	0	0
7485	VOA Thailand (started 1700)	0	0	0	0	7-8	3	0	0	0	0
7540	VOA Thailand (started at 1700)	0	0	0	0	0	S5-7	0	0	0	0
9355	Radio Free Asia (Marianas Islds, starts at 1700)	0	0	0	0	5-7	0	0	0	0	0
9475	WTWW Lebanon, TN	0	0	0	0	0	0	7-9	7	4-6	0
9655	KLNS Anchor Point, AK	0	0	9	6-7	7-8	0	0	0	0	0
9965	Radio Free Asia (Marianas Islds, starts at 1700)	0	0	0	0	9	5-7	0	0	0	0
9980	WWCR Nashville, TN	8	7-9	7-8	7-8	7-8	7-8	7-8	9	7-9	7-8
10000	WWV Ft Collins, CO	7	S9+10	9	9	9	5-7	9	9	6-8	7-9
12160	WWCR Nashville, TN	S9+20	S9+10	S9+10	N/R	N/R	N/R	N/R	S9+10	S9+20	N/R

N/R = Not recorded

REVIEW OF RESULTS

As the results show, there was a very significant improvement in lower frequency shortwave propagation between San Diego and Asia during the eclipse. The 49 and 41 meter SW broadcast bands in particular went from below the noise level to providing good reception of a number of Asian and Pacific broadcast stations, starting at around 1640 UTC. Stations were received from China, Korea, Mariana islands, Taiwan, and Singapore. All stations fell back below the noise level by 1745UTC.

Reception of WWV Ft Collins, CO on 5 MHz also greatly improved around 1700 UTC. The 10 MHz signal was not significantly affected.

As the eclipse moved East, Reception of WTWW on 9475 kHz and WWCR on 9980 kHz from Tennessee peaked at around 1745 UTC. There was no major effect to the WWCR transmission on 12160 kHz.

On mediumwave AM the only long distance station that I could hear was KFBK Sacramento,1530kHz. The distance is roughly 475 miles. It went from below the noise to an S-6 at peak at 1725 UTC. (Note – I tried the clear channel stations in the Bay Area, Portland, Boise, etc. but none of them were heard. Many of these frequencies have either low power daytime stations or are right next to high power local stations here in Southern California). Reception of KFI 640 kHz Los Angeles (about 90 miles) was unchanged with no sign of typical nighttime selective fading.

This was an interesting once-in-a-lifetime opportunity for this propagation experiment and the results show that the eclipse conditions can significantly improve certain types of radio propagation over long distances!

Fascinating results! Thank you so much for sharing your report of shortwave radio propagation during the 2017 Solar Eclipse, Bob!

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RadioWorld free eBook: Propagation Analysis for Profit

Visualising shortwave band activity throughout the year

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This article originally appeared on the London Shortwave blog.

24-hour shortwave spectrum image, showing activity for a single day in the first week of February 2017 (©PA3FWM, Twente WebSDR).

As many of my readers and followers will already know, these days I mostly enjoy listening to shortwave radio via the outdoor spectrum captures I make in my local park. Although I have built a system that helps me deal with urban radio interference at home, some of the weaker signals still can’t make it through the indoor noise. Since I have a limited amount of time for making outdoor trips, capturing entire portions of the spectrum allows me to record a lot of shortwave signals simultaneously, which I can then explore individually at a later time. However, these trips still need to be carefully planned because the time of the day and the time of the year both affect long-distance signal propagation, and do so differently depending on the frequency range. For example, signals on the 16 meter band are usually at their strongest during the daylight hours, whereas the 31 meter band is at its busiest around sunrise and sunset. Because my current portable recording set-up allows me to capture only 10% (3 MHz) of the shortwave spectrum at any one time, I decided to carry out a systematic exploration of activity on the shortwave bands to help me time my outings so as to capture as many signals as possible during each trip.

Capturing the shortwave spectrum out in the field with a portable SDR set-up.

Luckily, I didn’t need to make any of my own measurements for this. For over a year, the wide-band WebSDR at the University of Twente has allowed its users to see what the shortwave spectrum has looked like over the past 24 hours in a single image. More recently, however, the creator of the service, Pieter-Tjerk de Boer PA3FWM, has opened up his spectrum image archives, so it is now possible to see the past conditions of the bands on any single day in the last two years. Intrigued by how band activity changes depending on the time of the year, I created a timelapse animation of these images by taking two from each calendar week and lining them up in sequence. With Pieter-Tjerk’s kind permission, I share this animation below.

First, a really fast version to illustrate the broad effects the time of the year has on peak activity times across the bands:

Click here to view on YouTube

The X axis represents the frequency and the Y axis is the time of day, starting at the top. Conventional wisdom about band behaviour can be easily confirmed by watching this video: the 60m, 49m and 41m bands are mostly active after dark, with the 60m and the 49m bands being generally busier during the winter months. The 31m band is most active around sunset, but carries on all night until a few hours after sunrise. The 25m band is active during sunrise and for a few hours afterwards, and around sunset during the winter months, but carries on all night during the summer. Peak activity on the 22m and 19m bands is also clustered bi-modally around the morning and the evening hours, though somewhat closer to the middle of the day than on the 31m and the 25m bands. The 16m band is mostly active during the daylight hours and the 13m band is quiet throughout the year except for the occasional ham contest.

It almost seems as though someone positioned in the middle of the image’s right edge (corresponding to noon UTC) is shining two flashlight beams on the bands in a V-shaped pattern, and is changing the angle of this pattern depending on the time of the year: wider in the summer and narrower in winter. Here’s a slower version of the animation that shows some finer week-on-week changes:

Click here to view on YouTube

Thanks to this data being made freely available, visualising and understanding these dynamics will help me schedule my spectrum capture outings in the weeks and months ahead.

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