unfamiliar signal

[pinestone]

Hi all.

I just joined in hope someone would recognize this signal. I believe it to be the atmospheric heater at Arecibo but haven't had confirmation. My research shows their system was scheduled for maintenance during the period I logged this transmission, but no scientists were using the array.

https://forums.radioreference.com/attachment.php?attachmentid=66449&stc=1&d=1542119520

 

[Token]

No, that is not the heater at Arecibo. What you have there appears to be an OTHR (Over The Horizon Radar). Which specific OTHR it is will basically be impossible to confirm, there are several sources that use the same basic waveform. Those are probably bursts of FMCW, and they appear to have differing rep rates. Without an audio example I cannot be 100% sure on either factor, but that is what it looks like. Good candidates would be the JORN in Australia, or one of the Chinese sky wave radars.

T!

 

[k7ng]

Actually, based on the frequency range shown, I would guess that's a 'Coastal Ocean Dynamics Radar' or "Codar" for short. They are in use widely around the world. They're for monitoring of ocean wave heights and directions. If you tune in to one in USB or LSB mode you'll hear a 'wheep' 'wheep' sound coming about 1/2 second intervals.

The ocean dynamics radars operate in several HF bands but I hear them the most in the 5 MHz range. I haven't been able to reliably determine which signal belongs to which radar, but there is information on the Web on where these emitters are located, who operates them, and what specific frequencies each radar is authorized for.

 

[Token]

Actually, based on the frequency range shown, I would guess that's a 'Coastal Ocean Dynamics Radar' or "Codar" for short. They are in use widely around the world. They're for monitoring of ocean wave heights and directions. If you tune in to one in USB or LSB mode you'll hear a 'wheep' 'wheep' sound coming about 1/2 second intervals.

The ocean dynamics radars operate in several HF bands but I hear them the most in the 5 MHz range. I haven't been able to reliably determine which signal belongs to which radar, but there is information on the Web on where these emitters are located, who operates them, and what specific frequencies each radar is authorized for.

CODAR does not transmit in such short bursts as seen in the image (time scale on left). Also CODAR is not as narrow as this signal (8 kHz shown in the image). This signal is not CODAR.

As for reliably IDing CODARs, in the US this is not too big a problem, there are some nice lists that define center freq, bandwidth, and direction of sweep. Between those I can normally figure out who is who. The rest of the World can be a pain to ID though.

As I said, this is probably (almost certainly) an OTHR of some kind, and I often see the Pacific OTHRs (JORN, Chinese, and others) in this frequency range.

T!