SAQ Transmission - December 24th, 2007 - 0800 UTC
Chris Russell, Fri Nov 30 2007, 07:18AMAnyone who hasn't had a chance, get your VLF antennas ready! SAQ will be firing up the historical Alexanderson alternator and transmitting on 17.2kHz on December 24th, 2007, at 0800 UTC. For anyone who doesn't know, SAQ is a VLF transmitter in Grimeton, Sweden, and transmits at a frequency so low that it would probably be audible to most people if it were sound instead of electromagnetic radiation. A radio is not required for reception -- just a big loop of wire, a sound card, and a program like Speclab.
I haven't had any luck with this so far, but Steve Conner was able to get great reception last time, and posted the results here. I'm hoping that my active whip antenna will finally be able to bridge the gap. Anyone else up for a go this time around?
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Spedy, Fri Nov 30 2007, 04:22PM
This sounds fun. I'll have to see if my sound card will work, and then how to hook it up properly.....
Anyway, thats cool. It took me a bit to realize what VLF meant.
Spedy, Fri Nov 30 2007, 04:22PM
This sounds fun. I'll have to see if my sound card will work, and then how to hook it up properly.....
Anyway, thats cool. It took me a bit to realize what VLF meant.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Chris Russell, Fri Nov 30 2007, 08:08PM
Yes, VLF is very low frequency, the name for the band of frequencies between 3kHz and 30kHz. It's a great place to get started with radio in this day and age, since nearly everyone already has the equipment to receive 0-22.5kHz or 0-24kHz. Unfortunately, most of the man-made signals in this range are encrypted data links for use with submarines and other naval vessels -- doesn't make for interesting listening. The bright side is that there are many interesting natural signals to listen for, and once in a while SAQ fires up their transmitter, giving everyone a chance to receive some morse code.
Chris Russell, Fri Nov 30 2007, 08:08PM
Yes, VLF is very low frequency, the name for the band of frequencies between 3kHz and 30kHz. It's a great place to get started with radio in this day and age, since nearly everyone already has the equipment to receive 0-22.5kHz or 0-24kHz. Unfortunately, most of the man-made signals in this range are encrypted data links for use with submarines and other naval vessels -- doesn't make for interesting listening. The bright side is that there are many interesting natural signals to listen for, and once in a while SAQ fires up their transmitter, giving everyone a chance to receive some morse code.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Chris Russell, Thu Dec 06 2007, 12:53PM
Update! The time of the SAQ transmission has changed to 0800UTC. The message will be repeated at 0815UTC.
Chris Russell, Thu Dec 06 2007, 12:53PM
Update! The time of the SAQ transmission has changed to 0800UTC. The message will be repeated at 0815UTC.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
ShawnLG, Fri Dec 07 2007, 06:35AM
Is this starting at 3:00AM for the US east coast?
ShawnLG, Fri Dec 07 2007, 06:35AM
Is this starting at 3:00AM for the US east coast?
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Chris Russell, Sat Dec 08 2007, 01:16AM
That is correct. However, the transmitter will be tuning up from 0730 UTC, which would be 2:30am.
Chris Russell, Sat Dec 08 2007, 01:16AM
That is correct. However, the transmitter will be tuning up from 0730 UTC, which would be 2:30am.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
ShawnLG, Tue Dec 18 2007, 04:37AM
I am ready! My antenna is a longwire running across the roof of the house. Also, I have also put together a 17.2khz active bandpass filter to filter out most of the other junk such as 60hz mains. Below is a snapshot of Spectran and I am picking up the 15khz horizontal frequency from a TV in the house.
ShawnLG, Tue Dec 18 2007, 04:37AM
I am ready! My antenna is a longwire running across the roof of the house. Also, I have also put together a 17.2khz active bandpass filter to filter out most of the other junk such as 60hz mains. Below is a snapshot of Spectran and I am picking up the 15khz horizontal frequency from a TV in the house.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Chris Russell, Wed Dec 19 2007, 05:47PM
Looks good! I'll post a screenshot of what I see in that area later this week, so you can see how they compare. At night, do you see any sign of the big military msk transmitters operating on 18.6, 19.6, and 22.1 kHz?
Chris Russell, Wed Dec 19 2007, 05:47PM
Looks good! I'll post a screenshot of what I see in that area later this week, so you can see how they compare. At night, do you see any sign of the big military msk transmitters operating on 18.6, 19.6, and 22.1 kHz?
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
ShawnLG, Wed Dec 19 2007, 08:05PM
This is what I can find around 2PM. I do not know what they are.
ShawnLG, Wed Dec 19 2007, 08:05PM
This is what I can find around 2PM. I do not know what they are.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Bjørn, Wed Dec 19 2007, 09:42PM
Generally anything that drifts in frequency is unintentional transmitters, usually local. Some times you can clearly hear that it is a circular saw or something similar by just listening to the signal.
The intentional transmissions are usually fairly narrow in bandwidth and at a very constant frequency. This picture show a typical and strong transmission at 18.6 kHz.
Bjørn, Wed Dec 19 2007, 09:42PM
Generally anything that drifts in frequency is unintentional transmitters, usually local. Some times you can clearly hear that it is a circular saw or something similar by just listening to the signal.
The intentional transmissions are usually fairly narrow in bandwidth and at a very constant frequency. This picture show a typical and strong transmission at 18.6 kHz.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Chris Russell, Thu Dec 20 2007, 01:00AM
Thank you, Bjoern, for an excellent example. Here is what is visible from my location -- your location should be able to see most of these signals. This capture was made at 11pm EST, about one month ago.
MSK signals are visible at 18.1kHz, (Russia), 19.6kHz (Anthorn, UK), 20.9kHz (Rosnay, France), 21.4kHz (Laualualei, Oahu, Hawaii), 22.1kHz (Skelton, UK), 22.7kHz (North West Cape, Australia -- a rare catch), 23.4kHz (Rhauderfehn, Germany -- almost obscured by the signal at 24kHz), 24kHz (Cutler, Maine -- appears so broad because it is the most powerful VLF transmitter in the world, and is less than 150 miles away), 25.2kHz (North Dakota, US), and 37.5kHz (Keflavik, Iceland). In order to have a fair shot at SAQ, you should be able to see some of these in the evening. During the day, nothing will be visible except perhaps the signal at 24kHz from Cutler -- that is strong enough to be received during daylight throughout the northeastern US.
I'm not sure what the pulsing carrier you see there is. It is probably local noise. At some point each night, the 21.4kHz signal from Hawaii switches to a long dash format, something like 15 seconds long with 5 seconds between dashes, but that is the only dashed signal I have ever seen on VLF.
The wandering carrier is fairly typical of an electric motor -- they radiate a lot of noise. The most common source for that sort of noise around here is a vacuum cleaner, though I have picked up similar noise from electric saws, as well as cars driving by. Some cars produce a surprising amount of alternator noise.
Chris Russell, Thu Dec 20 2007, 01:00AM
Thank you, Bjoern, for an excellent example. Here is what is visible from my location -- your location should be able to see most of these signals. This capture was made at 11pm EST, about one month ago.
MSK signals are visible at 18.1kHz, (Russia), 19.6kHz (Anthorn, UK), 20.9kHz (Rosnay, France), 21.4kHz (Laualualei, Oahu, Hawaii), 22.1kHz (Skelton, UK), 22.7kHz (North West Cape, Australia -- a rare catch), 23.4kHz (Rhauderfehn, Germany -- almost obscured by the signal at 24kHz), 24kHz (Cutler, Maine -- appears so broad because it is the most powerful VLF transmitter in the world, and is less than 150 miles away), 25.2kHz (North Dakota, US), and 37.5kHz (Keflavik, Iceland). In order to have a fair shot at SAQ, you should be able to see some of these in the evening. During the day, nothing will be visible except perhaps the signal at 24kHz from Cutler -- that is strong enough to be received during daylight throughout the northeastern US.
I'm not sure what the pulsing carrier you see there is. It is probably local noise. At some point each night, the 21.4kHz signal from Hawaii switches to a long dash format, something like 15 seconds long with 5 seconds between dashes, but that is the only dashed signal I have ever seen on VLF.
The wandering carrier is fairly typical of an electric motor -- they radiate a lot of noise. The most common source for that sort of noise around here is a vacuum cleaner, though I have picked up similar noise from electric saws, as well as cars driving by. Some cars produce a surprising amount of alternator noise.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
ShawnLG, Thu Dec 20 2007, 07:27AM
So thats what those MSK signals are. I can see several of them through out the spectrum.
7.25khz
18.3khz
21.4khz
23khz
24khz
"I' m not sure what the pulsing carrier you see there is. It is probably local noise."
They are not noize. The 23.74khz one shifts it's frequency down three dashes every few minuits.
There are many VLF stations out there and it could be one of them.
ShawnLG, Thu Dec 20 2007, 07:27AM
So thats what those MSK signals are. I can see several of them through out the spectrum.
7.25khz
18.3khz
21.4khz
23khz
24khz
"I' m not sure what the pulsing carrier you see there is. It is probably local noise."
They are not noize. The 23.74khz one shifts it's frequency down three dashes every few minuits.
There are many VLF stations out there and it could be one of them.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Bjørn, Thu Dec 20 2007, 02:14PM
The pulsing carrier seems to be drifting a lot so it is not a proper transmitter. Even a RC oscillator would be a lot more stable. Looks like electric noise to me. Maybe a regulator of some sort.
Bjørn, Thu Dec 20 2007, 02:14PM
The pulsing carrier seems to be drifting a lot so it is not a proper transmitter. Even a RC oscillator would be a lot more stable. Looks like electric noise to me. Maybe a regulator of some sort.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Chris Russell, Thu Dec 20 2007, 06:05PM
Here are the spectrograms of more than two dozen VLF receivers, updated every ten minutes: . None of them are showing any similar signals. Closest thing is the Russian Alpha stations, but they are much lower in frequency and the pulses are not constant. If it is a VLF transmitter, it is an extremely short range one, with a curiously unstable signal. It's certainly possible, but I can't imagine what purpose it would serve.
At any rate, mysteries aside, if you are seeing the MSK signals, you're in a good position to be able to hear SAQ, so that's good news.
Chris Russell, Thu Dec 20 2007, 06:05PM
Here are the spectrograms of more than two dozen VLF receivers, updated every ten minutes:
. None of them are showing any similar signals. Closest thing is the Russian Alpha stations, but they are much lower in frequency and the pulses are not constant. If it is a VLF transmitter, it is an extremely short range one, with a curiously unstable signal. It's certainly possible, but I can't imagine what purpose it would serve.At any rate, mysteries aside, if you are seeing the MSK signals, you're in a good position to be able to hear SAQ, so that's good news.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
HV Enthusiast, Thu Dec 20 2007, 08:29PM
The thing is, you really need a very narrowband filter to properly isolate it from all the surrounding noise (if you are using a PC etc...)
HV Enthusiast, Thu Dec 20 2007, 08:29PM
The thing is, you really need a very narrowband filter to properly isolate it from all the surrounding noise (if you are using a PC etc...)
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Chris Russell, Fri Dec 21 2007, 03:10AM
To decode SAQ by ear, yes, a very narrow filter will be needed, as the band in this region is extremely noisy. 50Hz would be good, 30Hz would be better. Good results have been reported with 15Hz filters, but keep in mind that SAQ is powered by an RF alternator, so the frequency can drift a bit. Also, at 15Hz, you are pushing things close to the Nyquist limit... dots and dashes may start to run together a bit. Probably the best approach is to just capture the full 48kHz (or 44.1kHz) sampled audio, and try different filters at your leisure.
For visual decoding, a wide filter will suffice, since the FFT and your eyes do the work of a filter -- so long as you have selected an appropriate bin width. Your eyes will easily be able to pick SAQ out from the powerline harmonic that is 20Hz below, even if it is significantly stronger. Your ears probably won't be able to do that without the aid of a narrow filter.
Chris Russell, Fri Dec 21 2007, 03:10AM
To decode SAQ by ear, yes, a very narrow filter will be needed, as the band in this region is extremely noisy. 50Hz would be good, 30Hz would be better. Good results have been reported with 15Hz filters, but keep in mind that SAQ is powered by an RF alternator, so the frequency can drift a bit. Also, at 15Hz, you are pushing things close to the Nyquist limit... dots and dashes may start to run together a bit. Probably the best approach is to just capture the full 48kHz (or 44.1kHz) sampled audio, and try different filters at your leisure.
For visual decoding, a wide filter will suffice, since the FFT and your eyes do the work of a filter -- so long as you have selected an appropriate bin width. Your eyes will easily be able to pick SAQ out from the powerline harmonic that is 20Hz below, even if it is significantly stronger. Your ears probably won't be able to do that without the aid of a narrow filter.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Steve Conner, Fri Dec 21 2007, 04:20PM
Spectrum Lab's own FFT filter worked great for me. I just set it to a few hundred Hz bandwidth and had it output the down-converted signal from my PC speakers.
My code is pretty rusty, but I made out the callsign and the word "Alexanderson." I can't remember if I posted a MP3 last time.
I've also demodulated AM radio using a similar setup with a VFO and Tayloe downconverter before the soundcard inputs. Speclab is a complete software-defined radio transceiver, though the user interface tries pretty hard to hide it.
Steve Conner, Fri Dec 21 2007, 04:20PM
Spectrum Lab's own FFT filter worked great for me. I just set it to a few hundred Hz bandwidth and had it output the down-converted signal from my PC speakers.
My code is pretty rusty, but I made out the callsign and the word "Alexanderson." I can't remember if I posted a MP3 last time.
I've also demodulated AM radio using a similar setup with a VFO and Tayloe downconverter before the soundcard inputs. Speclab is a complete software-defined radio transceiver, though the user interface tries pretty hard to hide it.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
ShawnLG, Mon Dec 24 2007, 07:56AM
It is 3AM and I see nothing. EMI is high tonight and the 4hv chat is not working for me.
ShawnLG, Mon Dec 24 2007, 07:56AM
It is 3AM and I see nothing. EMI is high tonight and the 4hv chat is not working for me.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Bjørn, Mon Dec 24 2007, 08:25AM
I did not get anything either that I can say for sure was not noise, thousands of people getting out of bed and turning on their appliances made it very messy.
The signal was received very well in Hungary.
Bjørn, Mon Dec 24 2007, 08:25AM
I did not get anything either that I can say for sure was not noise, thousands of people getting out of bed and turning on their appliances made it very messy.
The signal was received very well in Hungary.
Re: SAQ Transmission - December 24th, 2007 - 0800 UTC
Chris Russell, Mon Dec 24 2007, 09:08AM
I definitely received it, but I do not believe any of the code is copyable. I would not have received it at all, but by an amazing coincidence, there was a blackout from about 0750UTC until 0850UTC. I saved a raw dump of the soundcard output. I will try to clean it up and post it. For now, I've got to get to bed!
Chris Russell, Mon Dec 24 2007, 09:08AM
I definitely received it, but I do not believe any of the code is copyable. I would not have received it at all, but by an amazing coincidence, there was a blackout from about 0750UTC until 0850UTC. I saved a raw dump of the soundcard output. I will try to clean it up and post it. For now, I've got to get to bed!
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