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Registered Member #286
Joined: Mon Mar 06 2006, 04:52AM
Location:
Posts: 399
The schedual is here
Planned transmissions SAQ is planned to be on air on Wednesday 24th December 2008 at 08.00 UTC and 08.15 UTC. The frequency is 17.2 kHz CW. Running up an tuning of the transmitter begins about 07.30 UTC.
The last transmittion did not make it in the US, maybe we will get lucky this time.
Anyone who has never tried to pick up the transmittion before. They can get some ideas from these sites on building a reciever. Or they can simply hook up an antenna to their sound card with a band pass filter. Then using a spectrum analyser like Spectran or Spectrum Lab to view the message.
UPDATE: I have finished my reciever. It has two 17.2khz bandpass LC filters on the input with transistors to give the signal some gain. Then the signal is mixed with a 19khz local oscillator. The 1.8khz IF is then passed through a 1.8khz bandpass filter to attenuate the strong 19khz component. Finally the IF is fed to the line in on my sound card.
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
Good luck! I'm too busy to make an attempt this year. I'm hoping Dave and myself can combine our efforts for the next transmission in June. Last year I was able to receive only faint traces, despite a miraculous power outage that dramatically lowered my noise floor. As good as my antenna is, there's just only so much it can do at ~8ft above the ground, surrounded by trees. One of these times, I need to take a trip to somewhere that I can set up my antenna well above nearby conducting objects.
If you're using a length of wire, remember that altitude will be critical. At these frequencies, any practical-sized length of wire will act like an e-field probe. Nearby buildings and trees will significantly impact your reception.
By the way, if anyone wants to test their weak-signal-fu, I have a 675MB file that represents one hour of data, covering 0-48kHz, captured last Christmas. Plenty of sferics to listen to, as well as military MSK transmitters, some weak alpha stations, and very faint traces of SAQ. There are some other odds and ends, like an FSK-CW message from the Russian Navy, and test tones from NPM in Hawaii. I keep meaning to make a long graph of it.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I can see a power-station chimney from my window, with all the lines of giant pylons and switch-gear farms clustered around it, so I haven't a hope on VLF, much as I'd like to listen in.
Registered Member #1389
Joined: Thu Mar 13 2008, 12:50AM
Location: Pittsburgh, PA
Posts: 346
Perhaps this may be something for me to try in the future, but how much do power plants screw up reception? I've got a nuclear plant visible from the top of the hill near my house. I would guess that it is no more than 15 miles away.
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
Local noise sources are much more of a concern than something 15 miles away. If you can get into a clear area that's free of power lines and mains wiring for a few hundred feet in any direction, you're in pretty good shape. Alternately, if you can simply get *above* the noise sources and construct a ground plane that will screen out noise coming from below, you're also in pretty good shape. Or, if you're prepared for low impedance, you can use a loop rather than a run of wire, and height above ground becomes a lot less important.
If all else fails, head on over to , and look for the signal on the spectrograms. The Sheffield spectrum usually shows SAQ well enough that you can see the smaller amount of power delivered to the antenna when the key is not even down.
Registered Member #286
Joined: Mon Mar 06 2006, 04:52AM
Location:
Posts: 399
If you're using a length of wire, remember that altitude will be critical. At these frequencies, any practical-sized length of wire will act like an e-field probe. Nearby buildings and trees will significantly impact your reception.
It looks like i am screwed. I was going to make a loop antenna for the reciever but I have been to busy developing a mario like game. I may have time wednesday to put it together.
Chris, I would like to listen to that 675MB capture from last year, and use it as a test source for my reciever.
I have calculated 08.00 UTC to be 3AM on the east coast. Is this right?
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
ShawnLG wrote ...
If you're using a length of wire, remember that altitude will be critical. At these frequencies, any practical-sized length of wire will act like an e-field probe. Nearby buildings and trees will significantly impact your reception.
It looks like i am screwed. I was going to make a loop antenna for the reciever but I have been to busy developing a mario like game. I may have time wednesday to put it together.
Chris, I would like to listen to that 675MB capture from last year, and use it as a test source for my reciever.
I have calculated 08.00 UTC to be 3AM on the east coast. Is this right?
Yes, 3am EST is the starting time for the SAQ transmission. Warm up begins around ten minutes before, and nearer to 3am, it should be at or near full power, so it's a good time to start really paying attention. Keep in mind that's 3am Wednesday morning, so you're not going to have much time to do anything on Wednesday.
I'm uploading the SAQ capture now. It's in there, but only just. Not enough to make out any of the code. However, there's no shortage of strong signals in there to listen to. Several MSK stations, and the alpha stations are very weak but present. If you're lively with a filter, there's a copyable FSK-CW message on 18.1kHz near the beginning of the recording, just below the MSK station on 18.3kHz. About 15 minutes in, NPM switches from MSK to a beautifully narrow and stable dashed signal.
I will PM you with the URL for the file when it's uploaded.
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
Harry wrote ...
There are all sorts of interesting and very inventive VLF/ELF antenna projects on the Radio Waves Below 22kHz site here:
I second that. Definitely a great site. I exchanged a few emails with the owner of the site, and he's a great guy. Hope all goes well with tonight's reception attempt!
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Alexanderson transmitting on December 24, 2008
