HFU HF Underground
Loggings => HF Mystery Signals => Topic started by: JustGreg on April 21, 2022, 2353 UTC
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I am seeing some strange signals near the Russian Buzzer Frequency. Here is a screen shot from my SDR showing them:
(https://i.imgur.com/NnHF9wW.jpg)
In the waterfall, one can see a sweeper that goes from a high frequency (4587) to a lower (4562) frequency. Most Ionosphere sounds go from a low to higher frequency. So this is a bit strange for me. Any thoughts on it?
The other at 4643 looks like an analog tv signal with a carrier and one sideband, but much narrower. I have tried to demodulated it, but, only get white noise. Any thoughts on these will be appreciated, since I do not have a clue on what they are.
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The sweeping signal is a CODAR. CODAR is a specialized coastal radar that monitor ocean wave and current activity. CODAR can, and do, sweep either direction, up or down.
The other signal you describe is STANAG 4285, a digital modem used by NATO forces. Normally it does not have a carrier present, why it is there I can't say. Maybe someone selected the wrong mode, or maybe it is an unrelated signal on the same frequency.
T!
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Thanks for the information :) I will check to see if the carrier disappears. Please take care in these strange times.
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I just check to see what signals were on now (4/22 2247Z). It looks like two CODAR signals are on. The one in my screen shot is definitely closer to me. The STANAG 4285 with a carrier is also present, but, much lower in signal strength. I wonder if the carrier may be a fault within the generating equipment.
I expanded the STANAG 4285 signal. The carrier is definitely not part of STANAG signal. It is about 600 Hz below the STANAG signal. Thanks Token for the help.
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I just check to see what signals were on now (4/22 2247Z). It looks like two CODAR signals are on. The one in my screen shot is definitely closer to me. The STANAG 4285 with a carrier is also present, but, much lower in signal strength. I wonder if the carrier may be a fault within the generating equipment.
I expanded the STANAG 4285 signal. The carrier is definitely not part of STANAG signal. It is about 600 Hz below the STANAG signal. Thanks Token for the help.
I have seen part time CODARs, that do not transmit all the time, and of course normal propagation can bring one up or down for your location. It is common for a given CODAR frequency to have multiple CODARs around the world on it. Overlapping or intermingled CODAR is not uncommon.
Re the STANAG 4285 with possible carrier, the carrier may still be part of the transmission. If the transmitter was in USB+carrier mode (H3D, H3E, or H3W) the carrier would be roughly 600 Hz below the bottom edge of the data. The carrier is not part of the data, there is no pilot tone or Doppler tone in S4285, but still could be part of the same transmission.
Most often S4285 is sent USB or LSB, and no carrier is present, but the presences of the carrier might just be an operator mode selection (accidental or intentional) to USB+carrier.
T!
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Thanks for the information. I am bit surprised the presence of the carrier has not been noticed by the operators. The signal seems to be on constantly. Thanks for the help.
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As an addendum, S4285 is coded to tolerate a number of interfering carriers. I presume this carrier is not organic to the S4285 signal in question.