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Author Topic: Iranian Radar 11 meters 27 Sep 2013  (Read 6291 times)

Offline ChrisSmolinski

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Iranian Radar 11 meters 27 Sep 2013
« on: September 27, 2013, 1355 UTC »
Here is a waterfall, I will leave it to Token to 'splain this:

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Offline Token

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Re: Iranian Radar 11 meters 27 Sep 2013
« Reply #1 on: September 27, 2013, 1610 UTC »
This radar has been active for about a year that I know of.  I first saw it in January of 2013, but others had been hearing it for a while before that.  I very seldom hear it here at the house direct, I normally have to use a remote to see it.  Correspondingly I have yet to grab an I/Q recording to look at in detail.  If someone could eventually grab a 10 or so second I/Q recording 100+ kHz wide and make it available I would appreciate it.  Such a recording would let me look at the signal in greater detail.

This radar is suspected of being Iranian.  That is not confirmed but strongly supported by receive bearings including those taken by “official” ITU Monitors.  Also propagation conditions and reports support it being from the area of Iran.

The radar uses at least 4 different repetition rates.  I have seen it anyplace from 25000 kHz to 29000 kHz, including inside the 10 meter ham band.

Video of it inside 10 meters here:
http://www.youtube.com/watch?v=FgfFKwQ5p9g


Not much is known about the radar for sure.  There are a couple of suspected locations.  Occasionally the radar appears to use active beam steering, and that means there must be a noticeable array someplace.

T!
T!
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Offline RickF

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Re: Iranian Radar 11 meters 27 Sep 2013
« Reply #2 on: October 02, 2013, 2123 UTC »
Possibly related to this T?



http://theaviationist.com/2013/09/22/irans-air-defense-radar/



By David Cenciotti
On Sunday Sept. 22, 2013, during the annual military parade in Tehran that marks the anniversary of the outbreak of the 1980-88 Iran-Iraq war, Iran displayed a new indigenous passive phased array radar system for detecting stealth targets and cruise missiles.

According to Iran’s FARS News Agency, the radar systems was developed by the experts of Khatam ol-Anbia Air Defense Base in order to detect fast moving targes at any altitude and speed.

The tactical radar system has been dubbed “Silent Radar System” because it acts passively: it does not emit any radar wave and can’t be detected by the enemy systems.

Furthermore, it can be moved quite easily and can be installed in a short time.

Commander of Khatam ol-Anbia Air Defense Base Brigadier General Farzad Esmayeeli said “The radar is capable of detecting stealth (radar-evading) targets and cruise missiles and enjoys a high movement and mobility capabilities and acts in different ranges,” FARS reported.

Actually, this is not the first time Iran announces a new radar system capable to detect radar-evading planes, cruise and ballistic missiles: in May 2012, the IRGC (Islamic Revolution Guards Corps) Aerospace Commander Brigadier General Amir Ali Hajizadeh announced a 1,100 km range radar system, called Gahdir, designed and built to identify aerial targets, stealth planes and low-altitude satellites.

Still, at least according to what the U.S. Air Force has recently disclosed, in March 2013, Iranian radars were unable to detect F-22 Raptors flying a few miles off their coastline: one the U.S. stealth fighters intercepted two F-4 Phantoms without them noticing it until the American fighter jock radioed: “you really ought to go home!”

In December 2011, Tehran announced that the country had installed advanced radars capable of detecting Unmanned Aerial Vehicles (UAVs): according to what Iran claimed, they could detect, track and shoot down any drone violating their airspace.

Anyway, in December 2011, Iran somehow managed to capture an RQ-170 Sentinel and later they proved to have put their hands on some smaller ScanEagle UAVs.




« Last Edit: October 02, 2013, 2126 UTC by RickF »

Offline Token

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Re: Iranian Radar 11 meters 27 Sep 2013
« Reply #3 on: October 02, 2013, 2238 UTC »
No, completely unrelated.  The one in Chris’s example is a traditional radar operating in the HF spectrum.  A traditional radar transmits some kind of signal (there are many possible radar waveforms and techniques, although this radar, like most, uses only a few) and then listens for that signal to be reflected off a target.  The transmitter used can either be co-located with the receiver (called a mono static system, such as a police officer’s radar gun or an NWS weather radar) or the transmitter and receiver can be geographically separated (called a bistatic system, like many HF radars, such as the British Chain Home system, the Russian Woodpecker, or the US AN/FPS-118 in Maine).  It then processes and uses the reflected energy to detect whatever target parameters (range, bearing, elevation, altitude, size, speed, etc) it is capable of based on its specific design.

The system defined in that article is a “passive radar”.  I have had many discussions of if such a system should be called radar at all, I say it should not (to me a radar has a transmitter, and passive radars do not have a specifically associated transmitter), but I am in a minority, so passive radar it is ;)

A passive radar (not a new idea, been around a long time) works by using someone else’s transmitted signal as the source of energy, it does not have a transmitter of its own.  The specific transmitter used will depend on the design of the system, but it can be many things.  You could, for example, use the transmitted energy of FM broadcast radio, TV stations, cell phone towers, etc, etc.

So think of a passive radar as a bistatic radar (transmitter and receiver separately located) but the transmitted energy used might be energy of opportunity.  So the passive radar might use the broadcasted energy of a TV station as its source.  It then looks for reflected energy off of targets.  Using a variety of techniques it either measures or calculates angle of arrival (direction) and motion.  Using other techniques it might directly measure distance based on reflected energy from more than one transmitter or it might perform target motion analysis to determine position.  So on and so forth (a complete description is probably beyond what should be in a thread like this, it can run to pages and pages of potential techniques…and still be incomplete).

Here is a similar application of the passive radar techniques.  In this image I am using the transmitted energy of a TV station (Channel 7 out of LA).  The ATSC pilot for this channel is a CW signal (and I mean CW as it applies to the rest of the world, not ham radio, CW means continuous wave, an unbroken carrier) transmitted at 174.310 MHz.  I can look for the Doppler shift of this energy to detect things in motion.  It just so happens that the location of the transmitter is pretty nice for me to get significant reflected energy off of aircraft in the LA basin.  So, the “squiggly” lines on this picture are Doppler shifted energy from aircraft in and out of LAX.  The ones slanting up to the right (bottom to top, left to right) are aircraft on departure, the ones slanting down to the right (top to bottom left to right) are on approach.  The one almost straight up and down was probably something transiting across and above the LAX pattern (but that is just a guess).  I am only pulling Doppler data, and that amounts to radial velocity in reference to the transmitter source, but with a bit more effort I could start to pull more information.



So, what are the advantages of a passive radar vs a “normal” radar?

A traditional radar radiates energy to operate, this means any time it is tracking you, you know it is on the air, and probably know if it is or could be tracking you.  Think of a radar detector in your car, a similar system can be used to detect any radar, or even one system that can detect all radars.  So, a passive radar can be tracking you and you have no idea it is doing so.

The radiated energy of a traditional radar also provides great targeting if you desire to remove that radar from operation.  An ARM (Anti Radiation Missile) can literally ride the energy to its source and destroy the transmitter or transmit antenna, if not the entire system.  The radiated energy can be used with detection systems and geolocation techniques to provide a point in space for delivery of munitions or sub-munitions…it can tell you were to drop a bomb or put cannon rounds, if you don’t have an ARM handy.  A passive radar does not give away its position like that.

Passive radar systems can be smaller, lighter, more mobile / portable, and use less energy.  The transmitter of a traditional radar is often a large part of its physical makeup.  To handle the transmitted power it generally requires waveguide instead of coax (if higher than VHF), it requires more cooling to disepate the heat load of the transmitter, it requires a circulator or something along those lines to isolate the receive energy and path from the transmitter side, and it requires larger and heavier power supplies / sources since the transmitter almost always uses many times as much (often by orders of magnitude) primary power as the rest of the system does.

And passive radar often can have some counter-stealth applications that a traditional radar might not have.  I will not go into them but a Google search (or your favorite search engine) of “bistatic radar and stealth” or “passive radar and stealth” will give some of the basics.  Remember what I said above, a passive radar can be thought of as a bistatic radar.

T!
« Last Edit: October 02, 2013, 2252 UTC by Token »
T!
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Offline SingleSideburn

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Re: Iranian Radar 11 meters 27 Sep 2013
« Reply #4 on: October 03, 2013, 0338 UTC »
All I have to hear is "Iran" and "radar" and I'm headin' straight to the White House bomb shelter.

Heh, we keep some pretty good stuff down there, uh,

Corona, and maybe some, uh, Balvenie, or Macallan.

Drinkin' some Dalmore right now, whew! Courtesy of United States taxpayers, wherever you may be.

Gettin' ready to fill up some water balloons in case the Iranians get too close,

pretty scary, heh! God Bless,

God Bless the U. S. A., especially ME

Alpha Victor

Yankee Zulu

Romeo Register Void
« Last Edit: October 03, 2013, 0717 UTC by SingleSideburn »
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Offline SW-J

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Re: Iranian Radar 11 meters 27 Sep 2013
« Reply #5 on: October 08, 2013, 0301 UTC »
This radar has been active for about a year that I know of.  I first saw it in January of 2013, but others had been hearing it for a while before that.  I very seldom hear it here at the house direct, I normally have to use a remote to see it.  Correspondingly I have yet to grab an I/Q recording to look at in detail.  If someone could eventually grab a 10 or so second I/Q recording 100+ kHz wide and make it available I would appreciate it.  Such a recording would let me look at the signal in greater detail.

This radar is suspected of being Iranian.  That is not confirmed but strongly supported by receive bearings including those taken by “official” ITU Monitors.  Also propagation conditions and reports support it being from the area of Iran.

The radar uses at least 4 different repetition rates.  I have seen it anyplace from 25000 kHz to 29000 kHz, including inside the 10 meter ham band.

Video of it inside 10 meters here:
http://www.youtube.com/watch?v=FgfFKwQ5p9g


Not much is known about the radar for sure.  There are a couple of suspected locations.  Occasionally the radar appears to use active beam steering, and that means there must be a noticeable array someplace.

T!

Actually, sounds like one of the polar ionosphere 'radars' with an unusually high sweep rate. Normally, as you know, they sweep a LOT slower, but, I have seen them fairly fast before well below 10 meters ... a couple years back I noted the 'sweepers' active between 27.5 and below 28 MHz ...

As a practical matter, a bistatic CW RADAR can (and does) operate at a LOT lower RF power level and can do so on account of the BWs (bandwidths) involved, what with noise power being proportional to BW and all ... meaning short PW radars require a LOT more power on account of maybe a 1 MHz or 5 MHz occupied BW ... I would expect to see simple 'carriers' as opposed to sweeping for a simple Bi-static CW detection radar ... but then one enters into the area of FM or 'swept' radars and a two (or bistatic) site setup, where the range can now be calculated knowing when the sweep started ... unambiguous range being associated with the starts of successive sweeps ...

Unless this radar is used constantly, it's pretty useless as a detection radar as well (right?). The angular resolution would be poor at 27 MHz ... multiple receivers could yield position much as a GPS receiver computes a position looking at the Doppler shift from GPS several birds and working the 'math' for a fix. What does not figure is the sweep, unless it is a simple two-site only bi-static detection FM (swept freq) radar which then gives range resolution with some sacrifice of Doppler speed determination (really useful only for known "to or from" radial courses anyway).
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Offline Echo_One

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Re: Iranian Radar 11 meters 27 Sep 2013
« Reply #6 on: October 08, 2013, 0827 UTC »
All I have to hear is "Iran" and "radar" and I'm headin' straight to the White House bomb shelter.

Heh, we keep some pretty good stuff down there, uh,

Corona, and maybe some, uh, Balvenie, or Macallan.

Drinkin' some Dalmore right now, whew! Courtesy of United States taxpayers, wherever you may be.

Gettin' ready to fill up some water balloons in case the Iranians get too close,

pretty scary, heh! God Bless,

God Bless the U. S. A., especially ME

Alpha Victor

Yankee Zulu

Romeo Register Void

*chuckles*

And people called me annoying
Echo One - Bringing An English Eccentricity To The Air Waves

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Offline Token

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Re: Iranian Radar 11 meters 27 Sep 2013
« Reply #7 on: October 08, 2013, 1901 UTC »
Actually, sounds like one of the polar ionosphere 'radars' with an unusually high sweep rate. Normally, as you know, they sweep a LOT slower, but, I have seen them fairly fast before well below 10 meters ... a couple years back I noted the 'sweepers' active between 27.5 and below 28 MHz ...

The ionospheric radars you describe most often use an FMCW waveform, typically LFM, although not all of them, the SuperDARN, for example, uses a simple pulse.

The slower sweep rates of the ionospheric radars are specifically chosen to work with the anticipated ranges targeted by the radar.  The repetition rate of an uncoded sweep (or uncoded pulse, for a pulse type radar) sets the maximum unambiguous range.

However, stepping outside the area of ionospheric radars, to HF radars looking for missiles, ships, and aircraft, the LFM / LFMCW waveform is still the most common used.  For a variety of reasons simple pulse type systems are a minority on HF.

This radar could indeed be swept vs pulsed, I do not have enough information to tell for sure.  The shape of the spectrum does not support a rectangular pulse transmission, but it might support a shaped pulse envelope to reduce bandwidth (as is done with the pulsed SKiYMET HF Meteor radar, there is a video on my Youtube channel if you are not familiar with that radar).  By the same token the spectrum does not really support an FMCW transmission either, I would expect that to be more flat topped, however every time I have received it the SNR has been too low for me to place a lot of confidence in that.  I simply don’t know if it is swept or pulsed, but if it is pulsed it is a shaped pulse.

The ionospheric radars and “real” radars (looking for aircraft, ships, etc) can use identical waveforms, and it can be extremely difficult or impossible to tell them apart.  Some are on continuously (such as the British PLUTO radar) and others jump around, frequency hopping and hitting different frequency ranges to tailor the illumination area.  If you have not seen and identified a specific radar or sounder before sometimes the best you can do is make a “best guess” at what it is.  In general if I see something hitting a specific frequency range once every 5 minutes or less often I think of it as a probable ionospheric radar.  If I see it revisiting a frequency range every few seconds I think of it as a probable radar.  And just to show there is always an exception, the SuperDARN radar is on nearly continuously, frequency hopping around a fairly confined range of frequencies (although were in the spectrum this range in varies with conditions).  And the SuperDARN is looking at atmospherics, not man made targets.

As a practical matter, a bistatic CW RADAR can (and does) operate at a LOT lower RF power level and can do so on account of the BWs (bandwidths) involved, what with noise power being proportional to BW and all ... meaning short PW radars require a LOT more power on account of maybe a 1 MHz or 5 MHz occupied BW ... I would expect to see simple 'carriers' as opposed to sweeping for a simple Bi-static CW detection radar ... but then one enters into the area of FM or 'swept' radars and a two (or bistatic) site setup, where the range can now be calculated knowing when the sweep started ... unambiguous range being associated with the starts of successive sweeps ...

Pulsed radars with a BW of 1 to 5 MHz (3 dB points, approximation BW@3dB point ~ 1/PW, this is not exact at all, but gives a rough working number) would have pulse widths from about 200 nanoseconds to about 1 microsecond.  While that kind of pulse width is common at microwave frequencies I don’t think I have ever seen an HF pulsed radar with such a short PW.  Again using the SuperDARN or the HF TIGER as an example of HF pulsed radar those systems use a 300 microsecond pulse, or about 3.3 kHz of BW (3 dB).  The old Russian Woodpecker used a 3.1 millisecond pulse, and should have had about a 322 Hz BW (3 dB), however the Barker coding used caused this pulse transmission to not exhibit the typical sin (x) / x shape of a simple rectangular (or trapezoidal) pulse.

Not 100% sure I understand what you are getting at with the rest of that paragraph, so if I have misunderstood forgive me.

Pure unmodulated CW radars are rare on microwave frequencies (outside of things like speed guns and as missile illuminators), and I don’t think I have ever seen or heard of one on HF, at least not inquite a while, maybe not post WW II.  An unmodulated CW radar (either semi-monostatic or bistatic) can only yield two things, bearing (with a directional antenna and something like a monopulse feed) and radial velocity based on Doppler.  It cannot yield distance or any target detail.  They do bring to the table high average power on the target and the ability to notch out non-moving objects, a good form of MTI if you will.  By using a source / transmitter with low phase noise, and a notch filter with steep skirts on the CW transmitted frequency, your ability to discriminate slow moving targets from the clutter is limited by the notch width and the spectral purity of the transmitted signal.  You can detect anything with a radial velocity relative to the transmitter that is great enough to produce a Doppler shift outside the notch filter.

HF FM radars can be either bistatic or monostatic.  Bistatic is most common because it is easier to do, easier to protect the receiver from the transmitted energy and to notch out the transmitted frequency, resulting in lower Doppler target detection.  And although it is not very common, you can encode the swept FM so that you can detect nth time around targets, extending the unambiguous range while not requiring slower sweep rates.

Unless this radar is used constantly, it's pretty useless as a detection radar as well (right?). The angular resolution would be poor at 27 MHz ... multiple receivers could yield position much as a GPS receiver computes a position looking at the Doppler shift from GPS several birds and working the 'math' for a fix. What does not figure is the sweep, unless it is a simple two-site only bi-static detection FM (swept freq) radar which then gives range resolution with some sacrifice of Doppler speed determination (really useful only for known "to or from" radial courses anyway).

The radar can be seen for hours on end, and the burst rate seen is high enough for good detection of targets.  It is a much faster burst rate than something like the US ROTHR (AN/TPS-71 radar).  This suggests, to me, the Iranian radar is looking for something that moves faster than the ROTHR looks for.

The angular resolution does not have to be poor at 27 MHz, we have no idea of the size of the array.  It is quite possible to get reasonable beam widths at such frequencies, it just takes a larger aperture.  And it also depends on what their spec is, what is desirable or acceptable for resolution.  A res of 3 or 4 degrees might be all they need for their application, which is possibly to queue another system.

What I find interesting about this radar is the combination of frequency and the repetition rate.  As we both indicated above, the rep rate (be it pulsed or swept) limits the unambiguous range of an unencoded pulse.  Although I have not been able to look at the signal in detail I have not yet seen anything leading me to believe it is encoded.  If it is not encoded we can look at its PRI’s and calculate a maximum possible usable range.  The two PRI’s in my video are roughly 872 Hz and 308 Hz (I did not actually measure them, just eyeballed the spikes on a spectrum display, but should be close).  308 Hz would yield a maximum possible range of about 487 km, and 872 Hz would be about 172 km.  Both of these ranges seem odd to me when combined with the observed frequencies, I just do not normally think of the 25-30 MHz area as a good choice for 170 to 500 km paths, not when 4 to 10 MHz will probably do it better.  I suppose this range would be good to detect objects high in the Earth’s atmosphere, so that propagation becomes less of a player, but then why not move up in freq and shrink the antenna?  Or maybe I am missing something about this radar, having not really seen it very much at all.

T!
« Last Edit: October 09, 2013, 1405 UTC by Token »
T!
Mojave Desert, California USA