The AM Forum

For the past week I have been experimenting with a QRP CW rig on 3.579 mhz and almost every night I hear what sounds like someone playing a recorder or flute but it is with CW. The BFO has to be on to hear it so someone is keying their transmitter on/off but each beep is at a slightly different frequency. How many of you out there can hear it? I hear it in East Hartford, Ct. Kinda spooky!

I once heard someone on 80m playing with a hand key and CW rig with VFO.  He played a perfect rendition of "Dixie", by judiciously shifting the VFO while manipulating the key.  Maybe he was a master of the Theremin.  He certainly had more skill in that department than I could ever achieve.

Sounds like digital...

MFSK8 or 16    sounds just as you describe

are you sure it isn't someone's TV 3.579???

I can hear something like that on 3579 too.  Not sure if it's the same one. I hear more digital stuff up on 3580-82 too.

After DFing it with the beverages, the 3579 signal at 8:30 EST is coming from the West. I'm in the Hartford, CT area.

It's very weak to the SE and very weak to the NE.  About S9 +10 to the West.

For what it's worth.

Tom, K1JJ

Yes I heard it all through December too. You closet CW elitists make me sick.  ;)

Actually I heard it during the AWA 1929 QSO Party mostly on the beverage so it is not super strong dunno...

Mike WU2D

Right , 3.579 is the freq of the "color burst" xtals and may be a give away to what is being heard.
Seems that a TV would be the likely culprit given that it is right on 3.579, the digital tones might be explained by the nature of how the colorburst works, see below.

There is also a kit from Small Wonder Labs called the "Warbler" that uses ~3.579, see the link and photo below.
http://www.smallwonderlabs.com/Warbler.htm

I'll listen here and see what I hear and report back.
Good question and posting, there seems to be an ever increasing amount of RF byproducts from consumer electronics on our band, yikes!

In composite video, colorburst is a signal used to keep the chrominance subcarrier synchronized in a color television signal. By synchronizing an oscillator with the colorburst at the beginning of each scan line, a television receiver is able to restore the suppressed carrier of the chrominance signals, and in turn decode the color information.

In NTSC, its frequency is 39375/11 kHz or 3.579545 MHz with a phase of 180°



(http://smallwonderlabs.com/img/Warbler.jpg)

Yep, probably many people are using the ever-popular and available 3579 crystals for homebrew  PW rigs or digital experimentation.

I think that's the same reason 3885 became so popular -  due to WWII xtal surplus.  The story goes that Chuck/WA1EKV handed 3885 xtals out one day, back in the 60's.

T

Positive

Try Pepto Bismol

Answer for yourself... easily....

I am sure you're describing MFSK.... but hey, I've been wrong LOTS of times!

Go hear  ( not mispelled)

http://www.kc0tks.org/index.php?option=com_content&task=view&id=38&Itemid=45


Scroll down and listen to MFSK  either 8 or 16

No, it's not that. I am familiar with how digital communications sound; heard them a thousand times. What I heard was single notes each lasting about 1 second followed by another & another, each with the exact time duration but a different frequency; as if someone was playing a recorder. I could not identify a tune but it sounded as if someone was trying to produce one. I will keep monitoring from time to time and log the time & date.

Why not record it and post it here?

Perhaps one of the readers may recognize it.

Getting my low power draw transistorized receiver & tape recorder set up so I can leave it on all the time when I am home. I hope now that I hear it again. The only other 3 times that I heard it was when I was calling CQ & I didn't want to hear it. I only have one xtal in the CW section of the 80 meter band & it is on that frequency so I couldn,t get away from it.

Okay, reverting to my old specialty while with Uncle Wiskers Forces...

The signal you guys appear to be hearing is NOT on 3579.+ kcs but down slightly at approximately 3577.35 kcs (center) with a repeating program lasting approximately 46 +/_ seconds every 2 minutes within a preset time block...

In this case, the on period appears to be about 25 or so minutes with an off time of 35 minutes...  I have a very weak signal here with my fixed antenna so I have not been able to actually check the "on/off" periods yet during daylight hours.

I suspect this is coming somewhere from the open water off the east coast someplace. It could be a variation of the "drift net" signals we hear on 160.

It is a simple form of "Telemetry" , early technology

This sort of signal consists of a start (sync. signal) followed by a tone matrix used to convey data from selected sensers in a remote device, usually to report on the health , etc of the remote device...

Each tone within the segments of the matrix is calibrated for the "normal" resting condition of the data being observed and will shift plus or minus  from that base tone with variations in the monitored  data point.

Additional information...7:45pm 1/11/09

At 7:25pm this evening the signal came on and sent in the form stated above for only 13 minutes, I.E. 5/6 cycles of data ...  I would say the signal was what I would expect from a low power beacon on this frequency to be within 150 to 200 miles from my location. Direction? No idea!

Called CQ from 15:00 EST to 15:37 EST on Sunday, 11 Jan.& after every CQ the signal repeated; at least it seemed to each time. It was as if someone heard my CQ & answered with the "music"  It also played a couple of times when I didn't send a CQ.I recorded it & will make an mp3 file so I can share it with anyone who is interested.

Can you post the file here?

I'll try to get on this evening and see what happens on my end.

Intriguing!

trivia.. what color is the colorburst signal?