Ditter network, multiple frequencies, June 14, 2013

[Token]

All,

It looks like one of the past mystery ditter networks is active again.

Starting at about 1710 UTC I noticed a ditter on 15550 kHz that looked familiar.  The pulses were about 124 msec long and the pulse spacing was 6.0 seconds.  This pulse width and spacing is twice what one of the past ditter networks used, so the search was on.

I found ditters on 10050, 10575, 13250, 13325, 13875, 14400, 15100, 15550, 15625, 16000, 16725, 17475, 17975, 18050, 18625, and 19300 kHz.  They all appear to be between 20 and 38 Hz low in frequency.

The dits do not look simultaneous, but rather they appear sequenced, from low freq to high freq, so that it pulses one freq and then moves up to the next one.  From holes in the timing I am probably missing a few frequencies, I will look closer at the wideband recordings later and see if I can find them.

At this time (2000 UTC) the pulses all appear to still be up, but if past history is an indicator they will not stay up long, I am suprised they have been up this long.

T!

(edit)  Off air 2145 UTC.  Other frequencies found before the signal went off were 11025, 11150, 11225, 11300, 12025, and 13350 kHz.  Based on the signal strength and timing of the 13325 and 13350 kHz signals there might have been more than one network active with those two freqs being in seperate networks.

[Token]

Here are some timing relationship images. For today’s ditter network.  The Excalibur only has 3 receivers on it, so the max frequencies I could audio sample at one time to make the spectrograms is 3.  A couple of images only have 2, and that was because I was not far sighted enough to better plan my recordings to make sure that everything has at least 4 overlapping signals.

In each image I have tuned each of the receivers for a slightly different audio pitch on each freq.  This way the signals show on the spectrograph separated in frequency.  If they were each tuned correctly 2 or 3 dits would look like one longer line.

Image one will be 10050 and 10575 kHz, you can see that 10575 lags behind 10050.

Image 2 will be 13250, 13325, and 13875 kHz, and you can see the timing relationship there.  Image 3 will start where image 2 left off, at 13875 kHz, and will include 14400 and 15100 kHz, so that by combining image 2 and image 3 you have the timing relationship of 5 frequencies.  I continue from there overlapping the lowest frequency on each image with the highest frequency of the preceding image, so that in the end 7 images will show the timing relationship of all 14 different signals, despite any one image having no more than 3 signals on it.

You will see in image 3 that there is a gap in time between the 14400 and 15100 kHz signals.  This likely means there is a ditter in between those two that I am missing.

I hope these make as much sense to people looking at them as they did when I was doing it in my head

Image 1, 10050 and 10575 kHz.


Image 2, 13250, 13325, and 13875 kHz.


Image 3, 13875, 14400, and 15100 kHz.  Note the gap in timing between 14400 and 15100 kHz.


Image 4, 15100, 15550, and 15625 kHz.


Image 5, 15625, 16000, and 16725 kHz.


Image 6, 16725 and 17475 kHz.


Image 7, 17475, 17975, and 18050 kHz.


Image 8, 18050, 18625, and 19300 kHz.


T!