I'm waiting with bated breath to see how this one comes out! (It's better than watching CSI!) Whatever it is, I'm amazed that the timing is so precise, especially if it's not a commercial station of some sort. Of course, I guess if it were a PC tied to some sort of packet station, and the PC was set to update the clock at regular (and frequent) intervals, the timing may be pretty good.
Can't wait for the next installment! -- de WM4B Mike Kathleen, GA _____ From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Nate Duehr Sent: Tuesday, December 12, 2006 9:18 PM To: [email protected] Cc: Scott Overstreet; Dave Platt Subject: Re: [Repeater-Builder] Mystery Signal Scott Overstreet wrote: > Hello All > > An interfering mystery signal has suddenly appeared on the input > (144.670 mhz.) of our repeater. Using a five kc. wide FM detector---The > signal is approximately one second in duration----opens with 100 hz. PL > (which continues throughout) and then three DTMF "zeros" follow in rapid > succession and then possibly a short period of some sort of data. The > signal repeats exactly two times an hour and the source is off in > between transmissions. This goes on continuously without interruption or > apparent change. Our area is between urban and big city and the signal > is strong enough to be heard over a wide area using only an HT. > > A wave file of the mystery signal is at: > > http://www.radagast <http://www.radagast.org/~dplatt/hamradio/Signal_3.wav> .org/~dplatt/hamradio/Signal_3.wav > > using an FM detector with wide open squelch. > > We are obviously very interested in identifing this signal and its > origin---- > > What is it ? > > Thanks-- > > Scott, N6NXI Scott, After someone else mentioned packet, I cranked up the audio real high and listened closer. It sounds like a bog-standard packet station (1200 bps) with a radio (Kenwood or Yaesu) with the DTMF paging function turned on. The default in the Kenwood's is "000" if I remember correctly for DTMF paging/alerting. If you listen real hard with the audio cranked up on good speakers, you can hear packet "transmitter warm-up" tones and a packet burst behind the DTMF. The radio is sending the DTMF over the top, muting the packet audio... but not quite enough to completely cover it up. I bet if you could filter out 941 Hz and 1336 Hz and then amplify that file a *whole* lot, you could probably "copy" the packet burst. Of course, you might go through all that trouble and find it's set to "NOCALL". Ugh. Let's see... what else could you try... if it's got NOCALL in it? You could try to force it to transmit by trying to digipeat through the various default digipeater names if their software responds to those... like the APRS "WIDE" name... and see if their transmitter responds to those. Just fire up a packet station on your repeater input and try a few of the common digipeater names built into various software and TNC's... a packet oriented group would know all of these. If you could find a way to get it to transmit, even if you can't copy the packet, at least you could DF it easier. Or maybe you'd get the ham's attention if you hammered on it for a while. I bet it's someone's APRS software on a PC connected to a radio that either was bumped or purposely tuned to your repeater frequency that they monitor through or that they left a memory channel in... and then somehow they got the DTMF paging turned on too. That or a TNC-based digi that the radio whacked out a bit on... or someone bumped. You could ask the local packet gurus if anyone they're used to seeing fell off the air recently... something that used to beacon at :23 and :53. Maybe some packet guy keeps his logging turned on around there, and you can go back to a date before you started hearing it on the repeater input. You could also just start announcing around on various repeaters that you've figured that it's someone's packet station with a misconfigured radio, and maybe the person with the "new" packet station they just hooked up will pay attention and see that their radio is transmitting. Nate WY0X
