Mid-Atlantic AM DX

[BRNout]

Now pianoplayer, what you're saying is true to an extent - however, the OP did as most of us would like to do under similar circumstances: he took a barefoot ultralight portable out on the deck of a noisy ship and came away with incredible catches. Yes, I've read tales of dxpeditions where dxers would string up a kilometer of wire along a select coastline in Newfoundland or a desolate part of northern Finland, connect it to a $10,000 rig, and pick up the likes of Iran or a graveyarder from Battle Creek, Michigan. But, in some ways, that's cheating.

KR4BD dxed in the purest sense: by taking a good consumer grade portable out there and tuning around to hear what's there. 1,000 miles of groundwave given those circumstances, IMHO, is pretty damn impressive and perhaps a 'record' when it comes to pulling in signals barefoot like that.

For David E.: I didn't realize that you once owned a station in Guayaquil. I've traveled there dozens of times. Have you been there recently to see the Malecón along the Guayas River? Very nice. They've done a lot with that city over the past 10 years! Not a good place to dx, by the way; too much noise!

 

[gar hi]

KR4BD dxed in the purest sense: by taking a good consumer grade portable out there and tuning around to hear what's there. 1,000 miles of groundwave given those circumstances, IMHO, is pretty damn impressive and perhaps a 'record' when it comes to pulling in signals barefoot like that.

That's exactly how I see it too which makes 1000 miles impressive.

Like you said, one can use all kinds of special equipment and pull in stations that wouldn't even show up with any trace on an ordinary receiver.

And speaking of DXing in the Bahamas, I remember finding this neat video where someone was getting a good steady strong signal from WCBS in the daytime.

http://www.youtube.com/watch?v=-W_RgQogINQ

Yes, it's special equipment but we now know the signal would still be listenable even with a portable radio there.

 

[radioman148]

KR4BD dxed in the purest sense: by taking a good consumer grade portable out there and tuning around to hear what's there. 1,000 miles of groundwave given those circumstances, IMHO, is pretty damn impressive and perhaps a 'record' when it comes to pulling in signals barefoot like that.

That's exactly how I see it too which makes 1000 miles impressive.

Like you said, one can use all kinds of special equipment and pull in stations that wouldn't even show up with any trace on an ordinary receiver.

And speaking of DXing in the Bahamas, I remember finding this neat video where someone was getting a good steady strong signal from WCBS in the daytime.

http://www.youtube.com/watch?v=-W_RgQogINQ

Yes, it's special equipment but we now know the signal would still be listenable even with a portable radio there.

I've seen this video before and the fact is that the reception is at 5PM EST which means this was most likely a skywave signal in January.
I'd like to see a video of this at noon or 1PM, then I'd be really impressed. Hearing skywave signals at 5PM in the winter months is very common.
I've heard them as early as 2:30 in Dec & Jan.
In the 80s I heard WLS in Miami at 4:15 and that's not over water.

 

[gar hi]

But was the signal completely steady like in that video?

 

[DeadElvis]

In the dead of the Winter, one can often hear skywave -- ALL DAY. The top of the band does much better, of course. Here in Memphis, WTDY/Madison, WI is pretty common on 1670 midday. Sometimes, it can be quite listenable. 50 kW KXEL/Waterloo, IA is another station that might be heard all day. A 5kW daytimer on 1500 from Indianapolis also pops in and out (they're directional -- three towers pointing right at me. ERP in my direction is a lot higher than 5 kW.)

In those cases, of course, you have a nice combination of big power and a high spot on the dial.

DE

 

[wffm78]

This may be a dumb question, and I am not an engineer, but usually isn't the lower part of the AM band where signals go out the farthest? Why would it be different for skywave?

 

[rfry]

This may be a dumb question, and I am not an engineer, but usually isn't the lower part of the AM band where signals go out the farthest? Why would it be different for skywave?

The groundwave of AM broadcast stations has less loss for lower frequencies.

The reflection coefficient from the ionosphere for nighttime skywaves is about the same for all AM broadcast frequencies, but the higher power, higher frequency AM broadcast stations may have useful (but weak) skywave reflections during daylight hours, especially in the winter months.

RF

 

[davideduardo]

For David E.: I didn't realize that you once owned a station in Guayaquil. I've traveled there dozens of times. Have you been there recently to see the Malecón along the Guayas River? Very nice. They've done a lot with that city over the past 10 years! Not a good place to dx, by the way; too much noise!

I used to say that if the planet needed an enema, it would be administered via Guayaquil. I particularly enjoyed the week or so of the "cricket invasion" where bugs that were not really crickets would cover the walls, your nose and clothes, the streets. Unfortunately, the major ad agencies and one of my stations were there, so I went once a week for about 8 years.

The place was made nicer only because my partner in Guayaquil was Jaime Nebot, now mayor of Guayaquil and one of the major movers and shakers in the country.

In the early years, I stayed at the Hotel Humbold on the Malecon, where I could watch the raposas jump off the banana boats; that was a miserable hotel and by the late 60's there were many nice options where "air conditioning" did not mean "air on the condition you open the window."

I would occasionally DX from Salinas, up the coast and out of the Cuenca del Río Guayas. Excellent reception, even on a portable, ranging from Chile to California. And because the area is literally a sandbar, bad conductivity so the Guaquil and Manabí stations were not that strong on groundwave.

I don't go back; places where I have been ejected by soldiers with big rifles do not appeal to me very much. Still, my oldest daughter and her family live there, amid the horrible economy and the "equality is achieved via universal poverty" president.

 

[davideduardo]

This may be a dumb question, and I am not an engineer, but usually isn't the lower part of the AM band where signals go out the farthest? Why would it be different for skywave?

In non-technical terms, the higher on the AM dial you get, the closer you are to being a short-wave station.

 

[gar hi]

In the dead of the Winter, one can often hear skywave -- ALL DAY.

I'm aware of that and I've seen it happen even here in Florida midday but the dead giveaway that it's a skywave is the fading in and out.

I've heard many northern stations start to come in here around 5 pm in the winter (the time that WCBS video was done) but again, the fading is there.

but usually isn't the lower part of the AM band where signals go out the farthest? Why would it be different for skywave?

Because of the difference in frequency, the stations at the lower part of the AM band go a much greater distance on a groundwave than those at the upper end.

The stations at the upper end don't go nearly as far on the ground but have much better skywaves than the lower frequencies.

A good example of that is the .880 kw station from Brownsville, KVNS.

It often booms in here at night from 936 miles away just as strong as any big 50 kw station from the same distance.

Here, it starts out weak and then comes in strong around the 30 second point in the video.


http://www.youtube.com/watch?v=Y1H_pn43AdU

It's even heard in Europe at night.

http://www.youtube.com/watch?v=YwRJc2fsauY

 

[DeadElvis]

In terms of high frequency AM stations tending to do better with daytime skywave...

It's important to remember that the lower one goes, the greater the D-layer absorbs the signal. Therefore, higher stations get absorbed LESS. Thus, one is far more likely to see skywave at the top of the band in daylight.

DE

 

[pianoplayer88key]

Yes, I've read tales of dxpeditions where dxers would string up a kilometer of wire along a select coastline in Newfoundland or a desolate part of northern Finland, connect it to a $10,000 rig, and pick up the likes of Iran or a graveyarder from Battle Creek, Michigan. But, in some ways, that's cheating.

Also, from what I understand, they do most if not all of their DXing at night. I was talking about in the middle of the day... and due to the multiple time zones traversed, I should mention that it should be solar noon at the middle of the path, and preferably at a time of the year where at the ends of the path it's still at least 2 hours after sunrise / 2 hours before sunset.

... DXing in the Bahamas ... video ... good steady strong signal from WCBS in the daytime.

http://www.youtube.com/watch?v=-W_RgQogINQ

I've seen this video before and the fact is that the reception is at 5PM EST which means this was most likely a skywave signal in January.
I'd like to see a video of this at noon or 1PM, then I'd be really impressed. Hearing skywave signals at 5PM in the winter months is very common.
I've heard them as early as 2:30 in Dec & Jan.
In the 80s I heard WLS in Miami at 4:15 and that's not over water.

I've heard many northern stations start to come in here around 5 pm in the winter (the time that WCBS video was done) but again, the fading is there.

Also, for example here in San Diego, 5pm is actually 15 minutes after the time that local stations change patterns at sunset this month and next. (They change at 4:45pm.) Even in summer, I've heard skywave an hour after sunrise and an hour before sunset, sometimes longer.

In the dead of the Winter, one can often hear skywave -- ALL DAY.

I'm aware of that and I've seen it happen even here in Florida midday but the dead giveaway that it's a skywave is the fading in and out.

Another dead giveaway, for me at least, is that even if the signal is not fading, if I can receive it well enough to identify using a barefoot portable at noon in January, but can't detect more than a carrier with the Select-A-Tenna in July, I'd think it's probably skywave.

This may be a dumb question, and I am not an engineer, but usually isn't the lower part of the AM band where signals go out the farthest? Why would it be different for skywave?

The groundwave of AM broadcast stations has less loss for lower frequencies.

The reflection coefficient from the ionosphere for nighttime skywaves is about the same for all AM broadcast frequencies, but the higher power, higher frequency AM broadcast stations may have useful (but weak) skywave reflections during daylight hours, especially in the winter months.

RF

So what time of the year (and local time of the day) would there be at least an hour-long window when it be absolutely impossible for someone in the 20-70° (preferably 32-35°) latitudes to detect any trace of skywave reception on 1700 kHz in QRSS CW or PSK31 (whichever requires the less field intensity to be detectable)? To attempt to ensure that "if it doesn't happen under these conditions, it will NEVER happen", assume that the nearest source of QRM/QRN is the moon, any manmade spacecraft beyond that is completely powered off, the ionosphere is exhibiting maximum blocking of extraterrestrial mediumwave signals, the transmitted signal is still strong enough to spontaneously boil tungsten as it's arriving up to the lowest regions of the ionosphere (and the groundwave is virtually nonexistent), and the receiver cost the factory $1M just for the physical components to build the radio, and the antenna is a tuned beverage.

In the dead of the Winter, one can often hear skywave -- ALL DAY. The top of the band does much better, of course. Here in Memphis, WTDY/Madison, WI is pretty common on 1670 midday. Sometimes, it can be quite listenable. 50 kW KXEL/Waterloo, IA is another station that might be heard all day. A 5kW daytimer on 1500 from Indianapolis also pops in and out (they're directional -- three towers pointing right at me. ERP in my direction is a lot higher than 5 kW.)

In those cases, of course, you have a nice combination of big power and a high spot on the dial.

DE

It's still only November, but I was getting some skywave at around 1:15 to 1:45 pm today. I recorded these clips in my back yard at 32°45'38.6" latitude...

PL-606 (1k BW, SAT) - 1290 @ 1:31pm PST - first minute is KKDB San Bernardino (5kW DA {edge of lobe toward me} @ 95 mi N, signal indicating 34/01-17), next half minute is KZSB Santa Barbara (500 watts ND @ 195 mi NW)
GE Superradio III barefoot - 1290 @ 1:35pm PST - starts with KKDD, then at 1:05 is rotated to bring in KZSB
In summer, KZSB Santa Barbara (500 watts ND @ 195 mi) usually dominates the frequency throughout most of the day.

PL-606 (1k BW, SAT, aimed E/NE) - 1290 @ 1:41pm PST - Radio Disney (KMIK Tempe, AZ - 50kW @ 300 mi) is in there faintly, along with KBLA Santa Monica (more noticeable later in the clip; 50kW @ 119 mi). Normally it seems KMIK is not receivable at midday in summer here with the equipment I'm using.

PL-606 (1k BW, SAT) - 1670 @ 1:44pm PST - KHPY Moreno Valley, CA, indicating 34-39/08-25 on the signal display
GE Superradio III barefoot - 1670 @ 1:47pm PST - KHPY
Do I definitely hear skywave fading on KHPY, or is it just my imagination or is there some extremely slightly off-frequency (maybe less than 0.1 Hz for example) co-channel interfering carrier causing that fading?



P.S. slightly OT, but would it be better if I break up my multiple replies into separate posts in the future? I was just thinking (and reminiscing) about one of the reasons why I (from my observation) seem to say a lot in one post, but go longer between individual posts (based on people who registered well after me having much higher post counts and not just on this forum)... I remember a decade or so ago I got banned from a computer gaming forum for spamming - not advertising, just posting too often with short messages to get my post count up (maybe that's flooding not spamming?) so I could reach a certain level that provided extra priveleges (specifically a custom avatar and message below my avatar as that's how the forum was set up), so it left a bad taste in my mouth.

 

[radioman148]

But was the signal completely steady like in that video?

It's impossible to tell from a one minute video how really solid that signal was. Any skywave signal can be very solid for far more than a minute.
I used to hear WBZ in the Chicago area as early as 3PM in the winter very well and very solid for long periods.

 

[gar hi]

If you've heard something like that for a long period then I see your point.

I guess I'm going from only what I've heard where there's always been fading even if it's not in rapid cycles.

 

[radioman148]

If you've heard something like that for a long period then I see your point.

I guess I'm going from only what I've heard where there's always been fading even if it's not in rapid cycles.

As others on this board pointed out, this time of year skywave conditions can exist for a great part of the day especially on the high end of the band where in northern latitudes they almost always exist in the winter.

 

[davideduardo]

Another dead giveaway, for me at least, is that even if the signal is not fading, if I can receive it well enough to identify using a barefoot portable at noon in January, but can't detect more than a carrier with the Select-A-Tenna in July, I'd think it's probably skywave.

Maybe...

But consider that winter noise levels tend to be much lower than summer ones, even at lower latitudes, in temperate climates. That's why in the 60's in Cleveland, OH, WLS was very listenable in the daytime in the deeper winter months, but just too noisy in the summer ones.

 

[pianoplayer88key]

Another dead giveaway, for me at least, is that even if the signal is not fading, if I can receive it well enough to identify using a barefoot portable at noon in January, but can't detect more than a carrier with the Select-A-Tenna in July, I'd think it's probably skywave.

Maybe...

But consider that winter noise levels tend to be much lower than summer ones, even at lower latitudes, in temperate climates. That's why in the 60's in Cleveland, OH, WLS was very listenable in the daytime in the deeper winter months, but just too noisy in the summer ones.

Interesting.... In my clip above of the KKDD/KZSB reception, KKDD is usually only audible midday in winter (in summer it might be a infrasonic-heterodyning carrier but with no recoverable audio), and KZSB is usually about the same quality reception in summer as in winter around midday.

 

[rfry]

Here is a link to a short paper on the differences in the groundwave coverage of MW broadcast stations as functions of radiated power, frequency and earth conductivity.

http://www.radioworld.com/article/am-coverage-frequency-vs-conductivity/23739

//

 

[gar hi]

Those charts really explain the difference between the lower band and the upper band.

I'd like to see a chart for sea water conductivity of 5,000 mS/m.

I take it those color lines represent the limit of listenable 'distant' coverage and not actual 'fringe' distances.

 

[pianoplayer88key]

Those charts really explain the difference between the lower band and the upper band.

I'd like to see a chart for sea water conductivity of 5,000 mS/m.

I take it those color lines represent the limit of listenable 'distant' coverage and not actual 'fringe' distances.

So I guess I'm not the only one who wants to know what the absolute limit of coverage is under the best conditions (maximum extra-terrestrial radiation absorption by the ionosphere, nearest noise source being 200k miles away, spacecraft limiting emissions to 3dB above galactic noise level at 0.1 m), with the best receiving equipment (for example individual components of a receiver costing the factory $1B just for the parts to make it, high-Q tuned beverage or other good antenna), highest transmit power & antenna efficiency (for example a circle-group aerial using Franklin antennas, each segment of which is fed by a 2.5-megawatt transmitter)?

Also I'd like to know if there's a resource where I can find out the range of ambient noise levels (natural and manmade listed separately) from 150kHz to 1700kHz in various parts of the world at various times of the year, as well as factoring in various bandwidth? (If I understand correctly, a QRSS CW signal can be copied at much lower field intensities than a broadcast FM IBOC signal, for example.)

Also would this article contain useful information (formulas, for example) on how to calculate surface wave fields over distances, as affected by ground conductivity and frequency (hopefully I could set a "reference" of 100 mV/m @ 1 km for example)?