pipper network up 1520 UTC

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n0nhp

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Due to time and band conditions I am probably only hearing a portion of the network at the moment.
D= double pip. There are two different transmitters / sites operating and both are hitting this freq.
17475, 16725D, 16550, 16000, 15625, 15100, 14400, 13875, 13325, 13250, 12025, 11300, 11225, 11150, 11025, 10575, 10500, 9225D, 9050, 8975, 8825, 8275, 7700, 6725, 6550, 6225, 5575, 5450, 5225, 4900

All frequencies in KiloHertz. Center Frequency. To hear on USB setting tune 1KHz lower for 1KHz note.


Bruce
 
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Token

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Bruce,

I see two new, or at least previously unreported, frequencies in your list, 5225 and 10500 kHz.

The Pips network used approximately this same frequency list in June of 2013, August 2013, and February 2014. In all three of those past events the pulse duration was 0.125 sec and the pulse interval was 6 seconds, do you have a feel for what it was today? Also during these past events they ran off and on through the day until about 2300 UTC.

T!
 

Token

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What is the pipper network?
This networks, called “Pips” in my log book, is a bit of a mystery. It has been seen periodically since early 2012 but no one is really sure what it is or what it is for. In my opinion some kind of network test or an ionospheric test program are most likely.

The network typically sends a short pulse of CW, a “pip”, on multiple frequencies. The pip or dash duration used has been seen to be anything from about 0.063 seconds length to about 1.5 seconds length. The duration between pips is some multiple of the pip length, and durations from 3 to 10.5 seconds have been noted. Typical combinations are 0.0625 (pip length, in seconds) x 3.0 (interval, in seconds), 0.125 x 6.0, 0.7 x 7.0, and 1.5 x 10.5. 0.125 x 6.0 is possibly the most reported.

As I said, the interval is some multiple of the pip length, so that I the 0.125 x 6.0 example the interval is 48 times the duration. This becomes important.

I said it appears on multiple frequencies, and you see from Bruce’s list it was when he reported it. How it hits these freqs is sequential. Typically hitting the lowest frequency first with a pip, then stepping up to the next highest and transmitting a pip there, next highest another pip, etc, to the top frequency, then back to lowest to start over. It sequences through the frequencies from low to high. In the example of a 0.125 x 6.0 pulse it would be possible to hit 48 frequencies in the cycle.

An example of this action can be seen in the following image. In this example three receivers are used to listen to three frequencies at the same time and plot them on the spectrogram. If each were offset form the pulse frequency by the same amount it would create one long pulse sound, so RX 1 is tuned 900 Hz low, RX 2 is 1000 Hz low, and RX 3 is 1100 Hz low, this makes three different pulse audio tones, of 900, 1000, and 1100 Hz, so that the three pulses can be seen visually on the spectrogram. The appearance of overlap in the image is caused by the AGC delay time used, there is no real overlap.



I said in the 0.125 x 6.0 example that up to 48 frequencies were possible, however more than 48 frequencies have been seen in use. This is because it is strongly suspected that at least two different locations (based on frequency occupation, DF cuts, and propagation) transmit these pips, and each location uses a different set of frequencies. So far I have seen no indications of more than two locations. Sometimes a frequency will be shared by the two sources, this results in synchronized, but out of cycle, double pulse on the frequency. Notice Bruce indicates one on 16725 kHz and 9225 kHz in his report.

Working backwards from these double pulse frequencies (compare next highest and lowest freq for sequential pulses) you can determine which frequencies belong to which source, and also find “holes” in your coverage, indicating possible unnoticed frequencies in the sequence.

T!
 

n0nhp

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Thank you Token!
I was wondering how I was going to answer the question. You did a magnificent job.
I have been busy since I reported this and have not had time to find more or get the timing. If it is still up I'll try to get you the info requested.
Bruce
 

n0nhp

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Thanks for making me take a second look at my log T!
The 10500 was a lysdexic typo on my part. That should have been 10050.
The 5225 however is a good freq.
The network had gone down by the time I got back to the rx and I did not get a recording (I know, why have the toys if you are not going to use them).
I'll keep an eye out for it to pop back up.
Bruce
 

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This networks, called “Pips” in my log book, is a bit of a mystery. It has been seen periodically since early 2012 but no one is really sure what it is or what it is for. In my opinion some kind of network test or an ionospheric test program are most likely.
Thanks for all the info Token! Now I'm going to have to try and find some Pips! ;)
 

Token

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If you are going to look for Pips here is a table of most of the past transmissions I have logged. This is not a complete list, but it is pretty representative. I post it because this network typically returns to frequencies, and this is almost all the freqs I am aware of it having used.

Pips Frequencies


The network has never been active 24 hours a day, it typically does less than 8 hours of activity in a 24 hour period. It often changes frequency sets during a given day, it might be up for say 45 minutes in one set of freqs, go off the air for a period, then come back up on a different set of frequencies.

T!
 
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