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HF Doppler RADAR Signal Examination

Discussion in 'Amateur Radio News' started by KA0KA, Feb 4, 2019.

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  1. N1SZ

    N1SZ QRZ Lifetime Member #233 Platinum Subscriber Life Member QRZ Page

    No problem. Concepts are nearly identical....except for the range and propagation issues.:)
     
    WA1ZMS likes this.
  2. KA0KA

    KA0KA Ham Member QRZ Page

    Had some time to re-edit this, thanks to N1SZ & K3DCW for helping with ID I think this should provide a basic sample of the signature.
     
    N1SZ, W1YW and KX0DW like this.
  3. KY5U

    KY5U Ham Member QRZ Page

    I'd like to record that 3 pulse 2000hz (aprox) tone and play it back on the FCY to see if the radar responds. :)
     
    K6LPM and KA0KA like this.
  4. KX0DW

    KX0DW QRZ Lifetime Member #212 Platinum Subscriber Life Member QRZ Page

    That 3-pulse emission right before the ROTHR (AN/TPS-71) burst is used to make sure the antenna is properly tuned. As one can imagine, when beaming massive amounts of power into a wideband antenna array, you want to make sure you won't blow-up or melt any components. You see similar emissions with a lot of frequency agile radars.
     
    N1SZ, WA1ZMS and KA0KA like this.
  5. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    BTW, when the first test USN ROTHR was installed at Comm Station Northwest (Southeast of Norfolk, VA), a friend of mine had the job of surveying the receiving antenna element locations. Extreme accuracy was required, within 1/10th of an Inch. The array had the appearance of dozens of square, white 'croquet hoops" on concrete pads, over a mile long, oriented towards the Caribbean. GPS was just coming into place and was used for the surveying.

    There was an auxiliary video display of the radar in the intelligence center at Atlantic Fleet Headquarters for a few months, where I was stationed. The appearance was that of large colored 'blobs" ranging across the Southern US, Gulf of Mexico and the Caribbean which seemed to be similar to propagation maps. I never saw any active target detection or tracking. Following the end of the Cold War, the array was dismantled and removed sometime in the mid 1990's. b.

    p.s. The term "Relocatable" OTH Radar, was widely winked at, since the antenna was no more relocatable than any permanent building or structure. The word in the intelligence community was that it was dreamed up as a way to differentiate the Navy program from other ongoing USAF OTH programs, in order to sell it to Congress. ;)
     
    Last edited: Feb 9, 2019
  6. KY5U

    KY5U Ham Member QRZ Page

    The OTH reminded me of a ham I knew many years ago that had a QTH radar. At his house on his tower was a radar scanner with the indicator unit in his house. It was the "QTH" radar.
     
  7. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    I always appreciate Tyler's videos he puts a lot of work and effort into them and explain thngs so that most hams should be able to understand. Tyler is highly Technical and skilled. The one Navy radar that he was referring to is still being used for surveillance and Central and South America and can be heard regularly on 60 and 40 m
    Thank you
     
  8. KA0KA

    KA0KA Ham Member QRZ Page

    It is all new to me, I did not even know the name of the signature until Jim N1SZ and Dave K3DCW helped out. They also helped me ID a new video clip I found of the JORN in Australia, it was pounding into Colorado and made a great video. I found a new RADAR again today, it was on 6.4MHz lasted about 15 secs each transmission, sounded like a electric razor in SSB. I was able to video it, sounded Russian but I will have to have Jim and Dave help with ID...Having this state of the art Amateur SDR systems has been a true gift, without it I think I would have finally lost interest in this hobby and moved on to other related things.
     
    N1SZ likes this.
  9. KA2IRQ

    KA2IRQ Ham Member QRZ Page

    What are some of the factors that go into picking a frequency spectrum for these radars?

    Most hams (like myself) don't understand what goes into the physics of the radar frequency vs. the target they are looking to hit (like ocean waves or missiles) and therefore the choice of frequency spectrum appears haphazard... and when in amateur bands, an intrusion.

    Old OTHR systems, like The Woodpecker, probably were there to disrupt rather than detect, but I'm sure that is not the case for all systems.
     
  10. KA0KA

    KA0KA Ham Member QRZ Page

    Way too high tech and costly just to 'jam' - they are engineered to the best precision current tech allows, lots of this has to do with finding the target, so frequency, PRI/PRF are big factors. There are a lot of variables that are all trade offs when using this tech, It is all quite fascinating, I think... But to really understand this, one would have to have prob worked in it as a career for a few decades, most of us did not have those type of paths...well I did not.
    Jim N1SZ and Dave K3DCW know more about this then anyone I have found...
     
    N1SZ and W1YW like this.
  11. KA0KA

    KA0KA Ham Member QRZ Page

    Just posted the JORN video, really great sample all the way from Australia!!! Thanks to K3DCW & N1SZ as well for their help!!!
     

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