Log: FM E-skip, May 14th and 17th

Successfully hearing and identifying a distant FM radio station via meteor scatter, is a very hit and miss proposition. The other main mechanism by which FM signals can travel long distances is very hit and miss in general, but when it is “in”, it can be fairly stable for many minutes. Sporadic E-layer propagation, or “E-skip”, is a condition in the upper atmosphere whereby electrons are stripped from atoms, creating an electrically charged “cloud” that can reflect radio signals back to Earth. Under normal circumstances, the E-layer is transparent to FM and TV frequencies, but as a stronger cloud develops, higher and higher frequencies are reflected, and the maximum usable frequency (MUF) can reach the FM radio band and even higher at times. (In particular, there is an amateur radio frequency band at 144 MHz, and those operators eagerly anticipate strong E-skip conditions to log distant contacts. Operators on the 50 MHz band have much more frequent openings from E-skip.) The formation of these clouds is poorly understood, but they are very seasonal, mostly occurring within 6-8 weeks of the summer solstice. Unlike meteor scatter, the clouds can be fairly large and long lasting.

FM radio stations in North America run as high as 100 kilowatts of power, and for line-of-sight coverage they mostly need that much power to penetrate into buildings. With true line of sight, even much lower power stations can be clearly received for tens of miles. Thus, with a good reflection of a signal by an E-cloud, there’s still enough energy available to produce a clear signal from hundreds of miles away. In fact, the typical reception distance for E-skip is around 1000 miles! Basically, you can hear stations that are exactly the same distance on the other side of the E-cloud as you are from the cloud, within a margin depending on the size of the cloud. Clouds drift and evolve, so one might get E-skip from a sequence of cities during an opening, but if the cloud is in the wrong direction (i.e., giving you a path into the ocean or otherwise middle of nowhere), you might not notice anything unusual.

Okay, that was pretty long-winded, you can use your favorite search engine to get more info. Apparently, this season has gotten off to a poor start, but I was able to log a few stations with some automated recordings with my RTL-SDR dongle and FM6 yagi antenna set up indoors.

March 14

I did a 3-hour recording covering 87.9-89.9 MHz from about 7-10am MST (14-17UT). My clearest frequencies in this range are 88.3, 88.5, 88.7, and 89.1. I had some apparent meteor skip during the recording, but the main “star” was 88.9 with some significant flare ups. I had a station in and out from about 8:55am (1555UT) through about 9:30am (1630UT).
I never managed to get call letters, but I got the “88.9 Shine” slogan, which is quite rare (I could only find stations in Calgary and Ohio), and an ad for the Royal Canadian Circus, which was indeed appearing in Calgary at the time. Thus:
88.9 CJSI, Calgary AB, decent at 9:18am, 100kw, slogan and ad (new; FM6 indoor, 1147mi, Es)
Here are two audio files:

 

Without knowing what I had, I started a new recording and went to work. This recording covered 94.5-96.5 MHz from 10:20am-3:21pm MST (1720-2221UT). My best frequencies there are 94.9, 95.3, 95.5, and 95.7. E-skip was already in progress on 95.7 at the start and this lasted for at least a half-hour. Again, no call letters, but I got just about everything else I could hope for, repeated mentions of their “Easy Rock” slogan, repeated mentions the “Kootenay Boundary” region in Canada, many ads for the town of Trail and surrounding towns, and other reference to British Columbia and Canada. Thus:
95.7 CJAT, Trail BC, good at 10:22am, 13.5kw, slogan and ads (new; HD6 indoors, 1036 mi, Es)

This recording is 4 minutes long, but illustrates just how persistent E-skip can be and how listenable the signal can be from more than 1000 miles away:
After this faded out, I was getting an over-the-horizon signal from KWKM in Saint Johns AZ at 166 miles, but that’s a lower-atmosphere effect that is fairly common; upper atmosphere effects are always several hundred miles or more.

Interestingly, while CJAT was in, I was also getting a signal on 95.3. This only lasted from around 10:30-10:40am (1730-1740UT), and I was unable to clearly identify the station. There was an ad for Walker’s Furniture and Mattress, which has several outlets in Washington and Idaho, and at some point there was a mention of Coeur d’Alene. The only station I can find on 95.3 that serves Coeur d’Alene is KPND out of Sandpoint, but I just don’t feel quite right about counting it without a station slogan or something like that.

May 17th

I made some attempts on the 15th and 16th to no avail. On the 17th, there wasn’t anything in my morning automated recording, but I did some live DXing in the evening. From 7:10-7:50pm (0210-0250UT on the 18th) I was flipping back and forth between 92.7 and 93.7. I was getting a couple of stations on 93.7, but not sure if those were E-skip or just usually weak Arizona stations. However, on 92.7 I heard (and recorded) “(something) country 92.7” at 7:36pm, and while trying to decipher that, I kept recording. Lo and behold, in my next audio recording at 7:39pm, I caught “Saint Joe’s Q Country 92.7”! Combined with checking their webcast, that is certainly:
92.7 KSJQ, Savannah MO, good at 7:39pm, 50kw, slogan (new; HD6 indoors, 1031mi, Es)
And the recording:
(Savannah is a town just north of St. Joseph MO.)

This faded out, but I was also getting a station playing the syndicated “Sunday Night Slow Jams” program, which was definitely not a country station! But, there are too many affiliates to be sure about the ID, and I didn’t hear anything specific when the station was in.

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2 thoughts on “Log: FM E-skip, May 14th and 17th

  1. Steve

    Nice FM catches! Do you watch 6m for early indicators of possible FM openings on Es? I often start to hear Es on FM when the skip on 6m Es becomes a little shorter than normal.

    Steve VE7SL

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    1. azswdxing Post author

      Steve, thanks for your comment. I’ve looked at the dxmaps and G7IZU maps for indications of skip from 6m reports, but I haven’t tried directly tuning in to 6m. I’m not even sure if I have a good antenna for 6m. Something I should try, though. One issue is that a lot of my Es monitoring is through SDR recordings while at work and the single catch on the 17th was my first live Es/Ms log. But, my schedule is more flexible this time of year.

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