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Author Topic: White Noise on 75m  (Read 4291 times)
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k4kyv
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Don
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« on: December 10, 2006, 11:49:20 PM »

I have noticed last few weeks that most evenings there is a white noise type of signal on 3855 and 3865.  At first I thought it was probably a slopbucketeer broadcasting the blower noise from his leenyar, but it seems to be more like the DRM signal on 3990-4000.  The one on 3855 had some kind of dittily signal right in the middle of it.

The signals  stay on the frequencies all evening long.

Is anyone else hearing this?
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Don, K4KYV                                       AMI#5
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W1ATR
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« Reply #1 on: December 11, 2006, 12:32:03 AM »

Yeah, I have it here as well right on 55 at about an S5. There's a slopbucket on 60 right now making it tough, but if I switch the receiver to rtty/narrow, and fiddle with the filters and passband tuning, I can pull it in nice and clear. I don't know what type of digicrap it is, however, but it is fairly steady in signal strength.
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K1JJ
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« Reply #2 on: December 11, 2006, 01:00:49 AM »

I just tuned it in and determined it's coming from Europe.

It's PW to the West and SE on the bevs and directional quad arrays.

There is similar noise on 3823... in addition to 3858 and 3865 - all from Europe.  It's been going on for many years now. We are more aware of it in the Winter cuz of condix and esp now with the superb solar minimum low band condix. When beaming NE, all three are about the same strength at S9+ 15-20 over.

Sounds like some kind of digital telemetry to me. 

The way to find where in Eur it's coming from is to watch when it peaks and fades out at its sunrise in a few hours. (watch between now and 3:30AM est)  This is a pretty good indication. There are many hours between Moscow's and London's sunrise...

73,
T
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Sam KS2AM
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« Reply #3 on: December 11, 2006, 01:11:04 AM »

The one on 3855 had some kind of dittily signal right in the middle of it.
The signals  stay on the frequencies all evening long.
Is anyone else hearing this?

The one on 3855 is kind of weak here right now but it sounds like the weather fax station in Hamburg that operates on that freq.
When I'm in Europe I hear lots of this stuff all across the US 75 meter phone band ... occasionally punctuated by one or two east coast AM stations  ... you know who you are ...  Wink


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K1JJ
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« Reply #4 on: December 11, 2006, 12:10:26 PM »

Well, I have some results.  Last night I went to bed at about 3:30AM and could hear all three white noise stations at S9 +15 over on the bedside receiver hooked to the NE quads.  Within minutes, the 3823 station peaked and started to fade out. It was probably in the UK, since they were then into daylight and the last land mass until open ocean.

At 5AM, I awoke for a quick listen and the other two stations on 3858 and 3865 were still there, but down to S7. The 3823 station was completely gone. This shows the two were probably in eastern Canada, Nova scotia, etc, (less likely) or more likely in extreme southern Greenland. (antenna pattern tells that) Normally, Greenland can be one hour into daylight and still be heard.

Being in the Canary Islands was unlikely cuz it would have been too far into daylight at the time.

The reason I feel Canada is unlikely is because the two were dropping off too fast while Canada was still in darkness... unless it had something to do with skip getting longer at that time of the morning.

73,
T
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
Sam KS2AM
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« Reply #5 on: December 11, 2006, 06:16:42 PM »

The signal on 3855 appeared again right after sunset here and yielded this fax image.  So I'm pretty sure this one is "DDH3" in Hamburg @ 10 KW:





* Hamburg-3855-2.jpg (26.38 KB, 152x448 - viewed 409 times.)
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K1JJ
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« Reply #6 on: December 11, 2006, 07:38:28 PM »

Yep , it's possible that's it's Germany, of course.  It was a little weaker than the UK big guns.

What amazes me is that it faded out at about 6AM here. That would make it like 12 noon? in Germany? That's what makes me wonder. Even though it's winter and the bottom of the cycle, it's a pretty tough thing to pull off on 75M at that time of day.... 

In addition, the signal on 3823 faded out much earlier at 3:45 AM. Maybe that was coming from farther east, like Russia. There was a 3 hour difference in fade-out times between the 3823 and the other two signals.

One way to find out.. many of my DX window buddies from Europe run beverages and vertical four squares. I could axe them to take a fix on them. I'll do that when I get back on in a few weeks.

73,
T
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
W2JBL
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« Reply #7 on: December 12, 2006, 08:57:46 PM »

that stuff has been on there about 5 years. you guys must not get around much...
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K1JJ
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« Reply #8 on: December 12, 2006, 09:10:37 PM »

that stuff has been on there about 5 years. you guys must not get around much...

You musta skimmed the thread too fast, Chris... Wink

Seven posts back:

"There is similar noise on 3823... in addition to 3858 and 3865 - all from Europe.  It's been going on for many years now. We are more aware of it in the Winter cuz of condix and esp now with the superb solar minimum low band condix."
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
Sam KS2AM
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« Reply #9 on: December 12, 2006, 10:27:44 PM »

that stuff has been on there about 5 years. you guys must not get around much...

5 years ?  Utility and broadcast stations have been on the US 75 meter phone band for decades !

5 years ?  If Don is correct about some of the signals perhaps being DRM, and they do sound like it, they surely were not there five years ago when there were no DRM broadcasts on shortwave.

You must not get around much ...   Wink
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