Hello All
By this time all of you who have been following and or helping with the
identification and location of our mystery signal have probably figured that
something has happened due to the silence from this end. Well, if so, you
figured right----the signal quit last Wednesday evening and hasn't been heard
since.
To add some details-----we made ---seems like about the fourth---- contact
with a related arm of our emergency com. organization that has a station using
the large municipal tower that I have mentioned previously as being in the
approximate center of our Doppler DF convergence. This time, in spite of their
repeated assurance that all was well within, they agreed to shut down their
station in total. I also ask that they make contact with other hams in their
area of their town and particularly those running packet gear of any sort in
the hope of finding the signal source. In amazing coincidence to when the tower
station was shut down, the mystery signal quit. Nobody is admitting
responsibility yet---and the signal has not returned -----yet ---in spite of my
being told that the tower station is all up again.
Looking back at all that happened in identifying the signal is amazing. It
started with one of our hams (N6NFI) making a waterfall audio frequency
spectral analysis of the signal's modulation which identified the presence of a
100hz. PL tone and the three tone bursts as being DTMF zero's-----this
explained why our repeater was opening and announcing errors. Next, N6NFI made
a wave file recording and sent it on to all of us locals and one of our guys
(KR6DD) who was in Maryland on vacation. He analyzed for a while using a
borrowed computer finally announcing that he thought that he could see some
buried data---he then ask for another recording with open squelch to be sent to
him. This was done by N6NFI and I, at this point, put my first message on
Repeater Builder (I'm a member of this group) offering the wave file for
identification at AE6EO's server.
You are all up on the flurry of RB messages that followed this. Most
outstanding was Nate Duehr's (WY0X) successful extraction of "Packet" data from
deep in the modulation. He, using computer filtration and blanking techniques,
removed the DTMF zeros and brought the packet data up by what must have been at
least 30 db.. He then put this on his server for any and all to try to decode.
AE6EO back here went to work on it and determined that the format was
definitely ham packet format but wasn't able to decode much more than that the
origination station was coded as a ? mark-----the rest of the data was
interrupted by the DTMF tones.
About this time, Bill, K6TYO, near here, precisely measured the frequency of
the mystery signal as being almost dead on channel and stable which together
with several comments from RB people about some Kenwood and Yaesu radios for
the ham market being capable of producing the DTMF preamble made it pretty
clear that we were looking for a radio of this sort with the DTMF preamble
inappropriately activated that had been some how shifted in memory channel to
what was in a previous application used to talk to our repeater---what a
mouthful! ---and--- that was now connected to a packet controller that was set
up to announce the station's presence every half hour.
Now, this and back to the top you have the whole picture to this point.
And, finally, I want to thank all who participated ,no mater how----you all
helped and I and we all appreciate your efforts and suggestions. I would like
to list all of you but there are to many to do that. Thanks again!
Scott, N6NXI
SPECS----Southern Peninsula Emergency Repeater System----
Mountain View, Calif. 145.270,---224.140,----440.800