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AWG-10 WCS and APG-59 Radar

Arjen

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It looks like maximum detection range plotted against altitude of target.
From left to right:
1) Cyrano IV detection of MiG-23M
2) Saphir-23D-III detection of Mirage F.1
3) AN/APQ-120 detection of MiG-23M
4) Saphir-2[3]D-III detection of F-4E

<edit>Vertical axis (H): altitude in kilometres, horizontal axis (D): range in kilometres</edit>
 

stealthflanker

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oeno said:
HI folks!



2.What high jitterd in the PRF column means?

Jittered or Staggered PRF there means that the PRF (Pulse Repetition Frequency) is changed during transmission in some intervals (say ..60 Khz 1st pulse burst ..then changed to 70 Khz in 2nd pulse burst).

This change is to allow detection of target that its velocity falls in the "blind region" of the RADAR's velocity respond (perhaps for example.. airplanes that moves slow or maneuvering).

For that "highly jittered" PRF however i'm not really sure but i think in those modes using that PRF setting in your table , the PRF are changed quite rapidly to satisfy the detection requirement .
 

overscan (PaulMM)

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From McDonnell-Douglas F-4K Report - thanks to Ron @ http://aviationarchives.blogspot.com.

Note that the 4th diagram seems to be Lookdown performance against a Blinder but is labelled as a MiG like the preceding image. The diagrams are especially interesting in conveying just how much typical radar ranges vary with aspect ratio.
 

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overscan (PaulMM)

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Radar photos on https://commons.wikimedia.org/wiki/Category:AN/AWG-10
 

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Blaze1

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Does anyone know what the differences between the AWG-10A and AWG-10B were, particularly from an operator's (RIO) as well as performance standpoint?
 

DucatiDan

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I stumbled on this site while looking for some info on the AWG-10. As an AQ in the US Navy 69-72 i was responsible for maintaining the AWG-10 on the F4s for VF-213 deployed on the Kitty Hawk. This was a very interesting read. Especially SgtWookie. I see that most of these posts are over 10 years old but contain a lot of great information
 

overscan (PaulMM)

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Thanks - it's an interesting radar, along with the Soviet Sapfir-23 - part way to a modern pulse-doppler but not quite there.
 
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crossiathh

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What I still do not understand about the AN/AWG-10 and its derivations AN/AWG-11/12:
Did this radar used Monopuls or Conical Scan for Lock-On? Or was it a mix depending on different radar modes? I ask, because in some posts here the use of "monopulse detection techniques" was mentioned.
In the book "Phantom in the Cold War: RAF Wildenrath 1977-1992" the Ferranti license build AN/AWG-11 is indicated that conscan was used for Lock-On, which is different in comparison to the Sapfir-23 (btw. the R-23R missile also had a monopuls seeker) radar just mentioned.
 

overscan (PaulMM)

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What I still do not understand about the AN/AWG-10 and its derivations AN/AWG-11/12:
Did this radar used Monopuls or Conical Scan for Lock-On? Or was it a mix depending on different radar modes? I ask, because in some posts here the use of "monopulse detection techniques" was mentioned.
In the book "Phantom in the Cold War: RAF Wildenrath 1977-1992" the Ferranti license build AN/AWG-11 is indicated that conscan was used for Lock-On, which is different in comparison to the Sapfir-23 (btw. the R-23R missile also had a monopuls seeker) radar just mentioned.
AWG-10 used conical scan angle tracking. Monopulse signal processing was used in some modes and purposes but not for air/air target tracking. It had a CW illuminator for Sparrow - the Sparrow used a conical scan seeker up to AIM-7F - it was AIM-7M which added this.


Radar system designed in USA by Westinghouse
Radar (e.g. AN/APG-59) includes IFF and CW Illuminator for Sparrow missiles
Conscan tracking and FM-ICW ranging/velocity measurement
Variants modified and maintained by Ferranti

Sapfir-23 was indeed monopulse - so was the Lightning's AIRPASS radar even earlier.
 

crossiathh

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AWG-10 used conical scan angle tracking. Monopulse signal processing was used in some modes and purposes but not for air/air target tracking. It had a CW illuminator for Sparrow - the Sparrow used a conical scan seeker up to AIM-7F - it was AIM-7M which added this.

Hi Overscan,
many thanks for the clarification.

Radar system designed in USA by Westinghouse
Radar (e.g. AN/APG-59) includes IFF and CW Illuminator for Sparrow missiles
Conscan tracking and FM-ICW ranging/velocity measurement
Variants modified and maintained by Ferranti.

Sapfir-23 was indeed monopulse - so was the Lightning's AIRPASS radar even earlier.
True, as well as the French Cyrano I/II and the Soviet RP-22 family.
And that is what I was wondering about, that a, for its time, modern and capable AWG-10/11/12 radar complex, was still using Conscan as well as the AIM-7, up tp the F version, still was using Conscan.
Especially I see the aspect or let's say advantage of the monopuls technique in terms of ECM.
During the "Have Pad" evaluation of the MiG-23MS with the RP-22 radar set the US rated the radar as two technology generations behind the radar sets of the Phantom F-4 (namely APQ-120 and AWG-10), but in term of ECM the found the weapon system (namely RP-22 together with the Lazur data link) as nearly jam-proof for the 1978 standards. I need to add that in 1978 the RP-22 family was already about 15 years in services.
The comparison of the AWG-10 family with the Sapfir-23 family is of course very interesting too. Eventually for me, the urban legend, that the Sapfir-23 derived from the AWG-10 (found in a Phantoms shoot down in the Vietnam war), is nowhere near true; except some possible smaller adaptions of different technology aspects.
 
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overscan (PaulMM)

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AWG-10 used conical scan angle tracking. Monopulse signal processing was used in some modes and purposes but not for air/air target tracking. It had a CW illuminator for Sparrow - the Sparrow used a conical scan seeker up to AIM-7F - it was AIM-7M which added this.

Hi Overscan,
many thanks for the clarification.

Radar system designed in USA by Westinghouse
Radar (e.g. AN/APG-59) includes IFF and CW Illuminator for Sparrow missiles
Conscan tracking and FM-ICW ranging/velocity measurement
Variants modified and maintained by Ferranti.

Sapfir-23 was indeed monopulse - so was the Lightning's AIRPASS radar even earlier.
True, as well as the French Cyrano I/II and the Soviet RP-22 family.
And that is what I was wondering about, that a, for its time, modern and capable AWG-10/11/12 radar complex, was still using Conscan as well as the AIM-7, up tp the F version, still was using Conscan.
Especially I see the aspect or let's say advantage of the monopuls technique in terms of ECM.
During the "Have Pad" evaluation of the MiG-23MS with the RP-22 radar set the US rated the radar as two technology generations behind the radar sets of the Phantom F-4 (namely APQ-120 and AWG-10), but in term of ECM the found the weapon system (namely RP-22 together with the Lazur data link) as nearly jam-proof for the 1978 standards. I need to add that in 1978 the RP-22 family was already about 15 years in services.
The comparison of the AWG-10 family with the Sapfir-23 family is of course very interesting too. Eventually for me, the urban legend, that the Sapfir-23 derived from the AWG-10 (found in a Phantoms shoot down in the Vietnam war), is nowhere near true; except some possible smaller adaptions of different technology aspects.

This is an interesting point. The British were very hot on adoption of Monopulse and ECCM techniques in their radars and tended to design their gear with the assumption that the adversary would have access to ECM of near parity or parity capability. AI23 even had a passive radar direction finding mode. The US seems to have largely ignored the possibility of Soviet ECM capability until presented with firm evidence of its widespread adoption.
 

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This is a fantastic thread and I was quite pleased that it has been active recently, it has taken away my excuse for not finally registering after being a lurker for a long time.

I've got a question about the AWG-10 relating to inverse monopulse guided missiles.

The RAF F-4Js were apparently equipped with Skyflash missiles soon after entering service (from what I understand - this may be incorrect and I don't have a firm source), and of course these were guided by PD illumination vs CW with the Sparrows prior to and including the F. The USN tested the Skyflash with an F-4J in 1976. So my question is: What (if any) modifications did an AWG-10 need to be made compatible with the Skyflash? Or was that included as part of the AWG-10B upgrade?

My assumption is that something was required to guide an inverse monopulse missile that did not exist natively in the -10B as I haven't seen much documentation to suggest that the F-4S ever carried an AIM-7M.
 

overscan (PaulMM)

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This is a fantastic thread and I was quite pleased that it has been active recently, it has taken away my excuse for not finally registering after being a lurker for a long time.

I've got a question about the AWG-10 relating to inverse monopulse guided missiles.

The RAF F-4Js were apparently equipped with Skyflash missiles soon after entering service (from what I understand - this may be incorrect and I don't have a firm source), and of course these were guided by PD illumination vs CW with the Sparrows prior to and including the F. The USN tested the Skyflash with an F-4J in 1976. So my question is: What (if any) modifications did an AWG-10 need to be made compatible with the Skyflash? Or was that included as part of the AWG-10B upgrade?

My assumption is that something was required to guide an inverse monopulse missile that did not exist natively in the -10B as I haven't seen much documentation to suggest that the F-4S ever carried an AIM-7M.

I.'m pretty certain the Skyflash inverse monopulse seeker still used the same CW illumination signal as the AIM-7E, and hence needed no modification for the AWG-10. The US preferred Pulse Doppler illumination for the AIM-7M, which was a more complex and advanced system.
 

overscan (PaulMM)

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The homing head seeks reflected continuous-wave (CW) radiation, this having been selected in preference to pulse-Doppler (PD) because of the emphasis on fighting in European conditions. A continuous-wave radar has better clutter rejection and target discrimination for low-level work, as well as improved performance in bad weather. The likely presence of heavy ECM (electronic countermeasures) in Europe has been a major consideration, and Sky Flash has been designed specifically to operate in heavy jamming.

 

yellowaster

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Another consideration (other than ECM resistance) was apparently that CW homing could use the existing AWG-11/12 CW illuminator (with minor modification). That meant that a target could be engaged with the radar in either non-coherent pulse (apparently preferred by aircrew) or PD radar modes. If they'd used PD homing then engagement would be restricted to radar in PD mode.
 

Biggus

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I was under the impression that an inverse monopulse seeker required PD illumination by default. Assuming the Skyflash worked similarly to the AIM-7M seems to have been a misunderstanding on my part, after learning that the AWG-9 on the Tomcat had separate PD and CW illumination modes. Thank you for clearing that up for me.

I think this likely answers my question regarding the F-4S/AIM-7M potential pairing, although I'd love to read more about the modifications undertaken to the CW illuminator on the 11/12 units if there are any available sources.
 

yellowaster

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Biggus, the documents I've seen date from development period, so may not reflect actual production missile. But they suggest the AWG-11/12 CW illuminator used FM, apparently providing range-to-go and coherency-check modulation (not quite sure what that is) which would need to be supressed for Skyflash, to obtain maximum benefit from its narrow-band phase lock loop doppler tracking system.
 

overscan (PaulMM)

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Yes - AWG-10 was still a hybrid between a pulse radar and a true modern pulse-doppler radar. You used the PD modes when you needed to, but the pulse modes gave longer range and better performance for lookup engagements. PD modes didn't even give target range, just closing velocity and direction.

Not being able to engage in all modes would be an issue. Also the peak power available in PD mode on the AWG-10 was lower than that for the CW illuminator once you factor in the duty cycle (PD KPA = 1525 watts * 0.5 duty cycle = 762 watts, CW illuminator KPA is around 900 watts). AIM-7F could use both CW and and pulse-doppler illumination.
 
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Biggus

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Overscan and Yellowaster, thanks for the information. I might try and hunt down one of the later Phantom NATOPs manuals for further reading.
 

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Recently posted by Periscope Film on YouTube, a formerly "CONFIDENTIAL" technical film regarding testing of the AWG-10, produced by the US Navy's Naval Air Systems Command.

It is entitled, "F-4J BIS Guided Missile Trials." "BIS" is the abbreviation of Board of Inspection and Survey. According to the caption at YouTube, the film dates approximately to 1967.

YouTube: Periscope Film "DOUGLAS F-4J PHANTOM AWG-10 GUIDED MISSILE TRIALS PT. MUGU, CALIFORNIA 80254"
*McDonnell F-4J Phantom II, BuNo 153074 (c/n 1541), "stars" in much of the film. She is still extant today, on display at Lakehurst Naval Air Station Air Park, in Lakehurst, New Jersey.
 

RHVERNON

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Biggus, the documents I've seen date from development period, so may not reflect actual production missile. But they suggest the AWG-11/12 CW illuminator used FM, apparently providing range-to-go and coherency-check modulation (not quite sure what that is) which would need to be supressed for Skyflash, to obtain maximum benefit from its narrow-band phase lock loop doppler tracking system.

Coherency Check is the system that the missile uses to confirm that the signal it is picking up on its forward receiver its that of the target being illuminated by its launch aircraft and not that of a target being illuminated by another aircraft. Its used when the doppler tracking loop search system locks on to the target after missile boost or if it has to reacquire the target during flight after losing lock. Sparrow may not have been able to do the later, but its a good bet Skyflash could.
 

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Interesting that you found my old post up there.

I was an MOS 6657, airborne missile fire control technician on F-4J and F-4S Phantom II's during my six-year tour in the Marine Corps.

In the top photo, the radar antenna (LRU-1, LRU=Line Replaceable Unit)) has no IFF antennas (Identification, Friend or Foe). On the port side of the antenna (or right side as you're looking at it) is a rectangular funnel-shaped object, which is the CW illuminator feedhorn. The main KPA (Klystron Power Amplifier) is 1525 watts, and the CW illuminator KPA is around 900 watts. It was necessary to provide the illuminator KPA for the AIM-7 Sparrow missiles' guidance, as even though the illuminator KPA was rated at a much lower power than the main KPA, the most the main KPA could be on for TX/RX was less than a 50% duty cycle, reducing it's effective power to well below that of the CW KPA. Signal from the CW KPA was also fed via coaxial cable to the rear of the four onboard missile stations, for the Sparrows to get a "lock" on. Early Sparrows had mechanical tuners, which were problematic; one ordinance technican found that you could get them "unstuck" using a large hammer, which action caused the rest of us more cautious and sane types to scatter in all directions.

The APG-59/AWG-10 radar had three basic modes:
1) Short Pulse - a 0.65 uSEC pulse triggered the transmitter to send out the same length pulse. This was the 10 NM mode.

2) Chirp - A 0.65 uSEC pulse was sent through a "delay line" - basically, an inductor which was grounded on one end. This caused the inductor to "ring" as a struck bell, and would cause the transmitter to fire for approximately 65 uSEC. Upon returning, the signal would be fed back across this same delay line, which would compress the pulse back down to about 0.8 uSEC pulsewidth prior to being fed to the receiver (LRU-2A8, bottom starboard side). This meant a slight loss in resolution, but a huge gain in range due to the increased return signal.

3) Pulsed Doppler - the most powerful mode. The transmitter would fire for approximately 40 uS, and then the system would receive for approximately 40 uS. The PRF (Pulse Repetition Frequency) would be varied constantly to avoid a phenomenon known as "target eclipsing" (when the transmitter is on while the return signal comes back.)

Back to the LRU-1 photo at the top: Notice that there is a rectangular panel about 1/3 of the way down the antenna? That is the Beam Spoiler, and was used for PPI/MAP mode (Plan Position Indicator) - it would extend about 1" to "spoil" the radiation pattern to scan the ground. On the scope, the sweep would scan back and fourth 120º (+-60º) and the bottom of the scan would be fixed, the top (furthest away) would look like a Japanese fan, or a section of pie, if you will.

In combat modes, the sweep was vertical, traversing the entire screen.

In the 2nd picture, the eight black T-shaped items on the front of the antenna are IFF antennas. They are white on one end (the top) of the "T" to indicate the polarity of the antenna; as putting some of them on backwards would foul up the signal.

The feedhorn is the long projection from the center of the antenna. At the forward end, there are thin fiberglass covers epoxied over the feedhorn, enabling the waveguide system to be pressurized with dry air to 14 lbs/in2 so that the RF energy wouldn't arc (short out) in the waveguide. The feedhorn directed the transmitted energy back against the dish, and received the signal the same way. When the RIO (Radar Intercept Officer) initiated a lock, the feedhorn support would begin to rotate at 66 RPM, causing slight rotational shifts in the position of the feedhorn; this was known as "nutating the feedhorn." This shifting would cause the radar to "paint a donut" around the target. The radar would detect the difference in signal return around the "donut", and re-orient the antenna so that the signal strength was equal all around.

The antenna was controlled by servos and resolvers, but driven by hydraulic pressure. The Phantom's hydraulic system was pressurized to 3,000 PSI, but the antenna's supply was regulated down to 1,200 PSI.

Of all the radars' modes, PD (Pulse Doppler) was the mode that was the hardest to get used to, and somewhat more difficult to fix.

In PD mode, targets were not displayed in range, but in terms of closing velocity, or Vc! Targets near the top of the scope were closing very rapidly, while targets near the bottom were going away. The range was about 1,600 knots closing to about 500 opening. In order to determine the range, the pilot or RIO would have to lock on to the target, and then a range gate would appear as a blip to show range.

The AWG-10A was a big improvement; LRU's 15,16,and 17 (analog computers) in the turtleback (panel 19 behind the RIO) were changed, the new LRU's 15 and 16 were digital, LRU-17 deleted. The analog
version described the missile's envelope as a truncated cone, which was grossly inadequate. The AWG-10A's missile envelope was more like a mushroom, if you will - and much more accurately described the lethal zone of the missiles.

Back to the 2nd picture: the "6" equipment rack is down. LRU-6A2 is on the bottom, LRU-6A1 on top. The 6A1 dealt mostly with antenna control, the 6A2 with the CW illuminator.

To the left (forward) is the "5" equipment rack, and just behind the X-frame is the "4" equipment rack.
On the top of the "4" rack is LRU 4A1, down from there is LRU-4A2, and on the bottom is the LRU-4A3
Inside the LRU-4A2 are 290 crystal ovens, each a different frequency, which resonated to signal returns in the PD mode, thus giving the Vc (velocity closing) range (roughly -500kts to 1500kts)

I realize now that I misspoke in my prior post - it was the 4A1A7 board, not the 4A3A7, that needed to be changed for frequency selection. The 4A3A7 board had it's own problems - there was a block of Zener diodes, which if blown, would cause an effect known as "picket fencing" on the display; the PRF would change every 60 ms causing the display to have vertical streaks on it.

VTAS - (Visual Target Acquisition System) In later versions, VTAS was implemented. The pilot wore a special helmet with four IR transmitters on it, and there were IR receivers mounted around the pilot's cockpit. The pilot's helmet had a reticle; he would extend it over his right eye, and look at the target while pressing half-action on the acquisition switch on his stick. The radar would sweep out in range, and acquire the target. As far as I can remember, this only worked in 10-mile range, or "short pulse". But, like I said - it's been a long time since I've worked on them.

[edited for minor corrections]
I worked on all versions of the AWG-10 for more than 12 years. This is a very good description of the system operation. It sure brings back some good and bad memories.

The good was shooting down drones at Barking Sands at 26 miles. I had a special way of tuning the KPA that gave a couple of our birds detections up to more than 100 miles in PD. The RIO had to use Pause to Range mode to see the target as Velocity mode only went to 100 miles. No E-plane or detuning of the 3rd cavity was used and the KPA's lasted just as long. Of course we did not do retuning for flight interference.

The bad was taking 1200 vdc up my arm to my shoulder and back down it to ground when I was tuning the STALO while holding the shaft of the screwdriver. I made sure to put my left hand in my back pocket as the manual had a warning not to hold the metal shaft of the scewdriver. I guess those warnings were in the manuals for a reason. They said that someone died for each warning and someone was injuried for each caution, I guess the good Lord was watchig over me that day. I was also lucky enough to get a backseat license when I was in a training squadron and had quite a few chances to use the system in the air. It was not that easy to find a target with that pencil beam and both aircraft chasing after each other.

Note: The VTAS sytem was pretty much negated when Pilot Lock-on Mode (PLM) was incorporated in the AWG-10B. Most pilots did not like the added weight of the helmet receivers.
 

overscan (PaulMM)

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I think Pause to Range mode would pause the search pattern and enter single target track mode briefly to measure range.

Correct?
 

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