We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations. Always consult with the appropriate authorities if you have questions concerning what is permissable in your locale.

Author Topic: Pips Network, multiple frequencies, 0905 to 1020 UTC, 29 January, 2020  (Read 493 times)

Offline Token

  • Global Moderator
  • DX Legend
  • *****
  • Posts: 1917
  • Karma: +16/-0
    • View Profile
Was insomniac this morning, so had a chance to radio at hours I normally don't ;)

And I ran into what appears to be the sequencing frequency Pips Network that has been reported on these forums in the past.  In this case it seemed to be a 0.25 second long pulse every 7.5 seconds (the most common seen is a shorter pulse, often about 0.125 seconds every 6 seconds).  A possible anomaly with this set of transmissions is that the pulses looked like they may have been doubled, I mean two back to back pulses on each freq.  Among several possibilities this could be a phase shift in the middle of the pulse (BPSK for some reason) or it could be two transmissions on each freq.

As is indicative of this network the pulses sequence through frequencies, low to high.  However, another anomaly, in this case each frequency seemed to be pair, in time, with one other freq.  I don't think I have ever seen this before.  For sure in the past there were two networks working together, synchronized in time and sometimes overlapping on one or more frequency, but never, that I remember, with paired (coincident in time) frequencies.

What I mean is that in the following list of freqs 2000 and 2275 kHz were transmitting at the same time, and then the signal sequenced up to the next higher pair, 2575 and 2800 kHz at the same time.  And then up to the next pair, etc.  Typically in the past it would have been more along the lines of sequencing 2000, then 2275, then 2575, then 2800, etc.

Freqs observed:

2000
2275
2575
2800
3150
3550
4200
4525
4800
5400
5775
6375
6700
7050
7450
7725
7950
8275
8575
8700
9375
9600 ?
9950 ?
10250 ?

The last freqs (with the ? marks) may have shown up just before the signal ended, I have not had time to confirm they are related in time but they looked like they possibly were.  I have not had time to go through my recordings and see if I can locate other frequencies I might have missed.  I suspect there were more frequencies in use at the high end, however propagation above 8000 kHz dropped of very quickly.

Eventually I will go through the recordings and confirm the timing of all freqs, probably locating one or two more I missed under other signals in the process.  I want to see if the pairing of freqs holds up across the entire working set.

T!
T!
Mojave Desert, California USA

Offline KM0NAS

  • Jr. Member
  • **
  • Posts: 33
  • Karma: +0/-0
  • Minnesota
    • View Profile
I heard today on these frequencies. Was a strong signal from my QTH in MN. Ended around 20:24 UTC. Was in progress when I tuned in around 19:59 UTC.

5775
6375
6700
7050
7725
7950
8275
8575
8700
9375
9600 -not heard but possible interference
10250
« Last Edit: February 22, 2020, 1604 UTC by KM0NAS »
*KM0NAS*
Kenwood TS-570D
Soft66RTL2
40 meter dipole @ 40' height
20 meter dipole @ 40' height
10 meter vertical @ 16' height
Beacon MN on 13562.8

Offline Harmony

  • Jr. Member
  • **
  • Posts: 38
  • Karma: +0/-0
  • NW Europe
    • View Profile
    • Email
Isn't this 'pips network' actually transmissions from STANAG transmitters? As I occasionally see those pips around 5700, but other times I see a STANAG there which looks the same on an SDR and is similar strength.

Its very strong, so I think close to the SDR location (UK south coast), so its not skywaving.

H

Offline Token

  • Global Moderator
  • DX Legend
  • *****
  • Posts: 1917
  • Karma: +16/-0
    • View Profile
Isn't this 'pips network' actually transmissions from STANAG transmitters? As I occasionally see those pips around 5700, but other times I see a STANAG there which looks the same on an SDR and is similar strength.

Its very strong, so I think close to the SDR location (UK south coast), so its not skywaving.

H

We are probably talking about different signals.  When these Pips have been seen they have almost never been detected in Europe, and when they were seen there they were not very strong, in fact typically very weak.  Since there are many different STANAG signals and formats, which specific one are you talking about?

T!
T!
Mojave Desert, California USA