AWG-10 WCS and APG-59 Radar

overscan

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I'd really like to learn more about the F-4J avionics, including the APG-59 radar and the VTAS helmet mounted sight.

Here's two shots of the APG-59 radar; the first is a McDonnell-Douglas provided promotional picture, showing a prototype radar, the second picture is an operational radar.

Source:
  • Bert Kinzey Detail & Scale 012 F-4 Phantom II (3) - USN & USMC, Arms & Armour Press, 1983
 

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overscan

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t was always fun when we got a "new" bird - nOT! You F/A-18 fixers don't know what you missed; it doesn't even concern you nowadays. If the pilot or RIO sees co-channel interference from another plane, he just pushes a button to change channels. That wasn't so in the good ol' F-4J's and F-4S's, as they were "manually" tuned.
There were 18 frequencies used, all X-band (9ghz), and since you had 12 birds in a squadron, the odds of getting a new bird in a "wrong" frequency was really high. You wouldn't want to send out a flight of Phantoms that were closer than 2 channels from each other, because the radars would pretty much "jam" each other, or overload each other's receivers with radar energy. So, we'd get to re-tune 'em, which meant a buttload of work:
1) Open the radome, insert the package extension rail.
2) Extend the radar package after removing the 4 nuts from the X-frame.
3) Connect air conditioning from the -8 and power from the -60
4) Select the channel range on LRU-6A2
5) Select the channel range on the 4A3A7 board.
6) R&R the two filters out of the 2A8 (Receiver)
7) Wait for COM/NAV to replace the filters in the turtleback
8) Fire up the radar, warm it up until the transmitter kicked in (5 minutes)
9) Re-tune the main KPA (Klystron Power Amplifier, 1,525 watts) by adjusting the four struts, de-tune strut #3 to obtain maximum power
10) Re-tune the CW Illuminator KPA using same procedure (the CW Illuminator generated the RF signal the Sparrow missiles followed to their target)
11) Button it up, and you're done ... but put a new set of KPA's on order, because they don't like being tuned to a new frequency, and you can bet your arse you'll be putting in a new set within two weeks. Oh, joy! Roll Eyes Wink

Such were the joys of a 'Nam-era F-4 radar tech We busted are azzes, and learned a lot.
Funny, I hadn't worked on one of those birds in 25 years, but still have the routine pretty well down pat Wink

S/F,
Wook
http://forums.military.com/eve/ubb.x/a/tpc/f/5671946761/m/254105031
 

overscan

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AWG-10 (APG-59)

Provides pulse and pulse doppler air/air search/track, high/low map modes, and air to ground ranging.
First deployed in 1968
29 LRUs

AWG-10A

Enhanced reliability part digital version. Only 3 LRUs unchanged, 6 new, 7 deleted, 9 modified in varying degrees. Adds one air/air [close combat] and three air/ground modes. Improved built-in-test capability.

AWG-10B
Final "all-digital" version of F-4S

Source:

Jane's Weapon Systems 1981
 

overscan

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the APG-59 is credited with 1 kw, but that's Pavg, with a 44% duty cycle. Avg.
detection range on a 5m.^2 target is 60nm. I don't know if that's for a
50%, 90% or other % probability of detection.
Guy Alacala, Usenet discussion.

32 in (810mm) diameter antenna

Heavier and bulkier than APQ-72
Jon Lake ed. McDonnell-Douglas F-4 Phantom: Spirit in the Skies Aerospace Publishing, 1992
 

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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]
 

overscan

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A very interesting post indeed., Thanks for sharing!
 

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SgtWookie, that was the single most informative post I have read about AN/AWG-10 in my forum's life, many many thanks!

Could you comment more on that radar, per example:

a) How many radar modes did the RIO has for air combat (BVR and ACM) and how were the scan patterns in azimut and elevation (bars).

b) You commented that the PD mode was the most difficult to use and based on velocity closure (range rate) and not in range vs azimut. That means something like "VS" mode on AN/APG-68 I mean, that's a HPRF mode isn't?. Do you remind any interesting peculiarity of those modes, per example how did they worked according to different clutter environments and target profile?, was that mode only LD or it was also available as a Look up option?

c) Can you comment on the MTBF of the radar set, compared to other radars on Phantom and vintage aircraft you know?, it introduced LRU philosopohy?, how it was to mantain?, would be delighted (and guess most of us) to hear more about your job ;D

d) Did the radar interfaced with advanced con scan Sparrow (AIM-7F) and monopulse Sparrow (AIM-7M) missiles?...

Thanks a lot for any answer and for the last post.
 

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Pit said:
SgtWookie, that was the single most informative post I have read about AN/AWG-10 in my forum's life, many many thanks!
You're welcome - although, in retrospect, I incorrectly corrected my first post! (are you confused yet, because I am ;)) The numbering system for the WRA's/LRU's (same thing) was just a little bit confusing, because on the port side of the radar, the numbers increased from forward to aft, (eg: antenna=LRU 1, then LRU 4 was the entire pallet (but never removed as an entire unit), LRU 5 (never entirely removed as such) and LRU 6. Then, on the 4 pallet, 4A1 was the topmost 3rd, 4A2 was the center unit, and the 4A3 was on the bottom. You can see on the 4A1 and 4A3 units what looks like ribs, those are actually removeable "boards", sort of the shape of a watermelon slice. They're held in place by one (slotted and hex-head) captured screws, one on top and one at the bottom.

On the starboard side, the LRU 2A1 was the transmitter control box, on the top of the package. It was long and relatively thin, shaped rather like a piece of wall to floor molding, only thicker (and aluminum) Below that was "the hat" - a large aluminum cover that was held on with what seemed like a zillion #8 Phillips-head screws. This "hat" was the cover for the pressurized (air, to 14 lbs/in2) transmitter power supply compartment.
There were two separate power supplies, one for the CW illuminator KPA, and one for the main KPA. I believe the LRU 2A2 CW supply put out 22,000 volts, and the main 2A3 supply put out 25,000 volts - at high power. Those supplies were about the size of a loaf of bread each, but were VERY heavy. There were high-power rectifier tubes in those supplies that had large cooling fins on the bottom - as a matter of fact, they made very cool ashtrays when the tubes went bad (I had one for many years, and the wife threw it out!! Arrrgh!)

Could you comment more on that radar, per example:

a) How many radar modes did the RIO has for air combat (BVR and ACM) and how were the scan patterns in azimut and elevation (bars).
There were six "bars" that I remember. I don't recall the starting bar, but if the bars were numbered as such:
1
2
3
4
5
6
I believe the vertical scan pattern went something like: 2,4,1,5,6,3
It wasn't quite what one would expect. I don't recall it changing the bar scan pattern - but remember, the last time I worked on those things was 27 years ago.

As far as modes - they could select PULSE, PD (both ACM modes) A/G (which was the ground mapping feature, 120º PPI (Plan Position Indicator) mode) and I believe T/C or TERRAIN - this last very obscure feature was very difficult for aircrew to understand; it was supposed to indicate to them the likelyhood of collision with terrain features when proceeding at high speed, low altitudes (eg:bombing runs). The antenna scan pattern was that of a "+" - Full Up, Full Down, Center, Full Port, Full Starboard, Center (repeat) The scan displays on both scopes was also a "+". However, a number of crashes occurred while using this mode, and it's use was discouraged by modifying a card in the LRU-10 (Cockpit Display Unit, aft cockpit, port side, just under the canopy rail) to display a large "X" on the screen. As mentioned above, the pilot could select DOGFIGHT mode, which would override the RIO's controls, select short pulse, 10 mile range, and enable VTAS acquisition by sweeping out the range gate upon the pilot's pressing the lower button on his joystick.

The RIO had his own joystick, mounted to the right of the scope and above it. The RIO's stick was about the size of a screwdriver handle, or straight sausage-shaped on a ball mount. It had an "action" button under the middle finger, and a thumbwheel on the top. The thumbwheel controlled the antenna's elevation. The elevation was indicated on the scope as a short horizontal blip on the right side of the screen. Pressing the button halfway down was called "half-action", this would cause the antenna to be slaved to the RIO's stick, and would initiate 60ms PRF switching to prevent target eclipsing.

There was also the "taboo" mode, "EMERGENCY". This mode was to be used ONLY if you were in actual combat, and you had a transmitter failure. This mode overrode all of the thermal sensors, and a number of other protection circuits. Selecting this mode might enable the transmitter to work for a short period of time, but at the likely cost of destroying a number of radar components. When a RIO selected this mode, it tripped a red flag on the knob, which could only be re-set by removing the knob with a small Allen-type wrench. That was one of the very first things we would check after a flight - if that flag was out, the RIO got a trip up to the Skipper's office for an ass-chewing.

There may be more modes that I've forgotten. The last couple of years I was on active duty, we got F-4S's with the AWG-10A's in them, then I transferred to VMFA-122 which had the older F-4J's with AWG-10's again. One can't remember everything from 27 years ago ;)

b) You commented that the PD mode was the most difficult to use and based on velocity closure (range rate) and not in range vs azimut. That means something like "VS" mode on AN/APG-68 I mean, that's a HPRF mode isn't?. Do you remind any interesting peculiarity of those modes, per example how did they worked according to different clutter environments and target profile?, was that mode only LD or it was also available as a Look up option?
PRF was approximately 40ms in PD mode; but remember there still was minute adjustments made to the PRF at the end of every scan, and it would switch every 60ms during half-action or acquisition.

One interesting aspect of the PD mode was the ground clutter notch. This looked rather like an inverted arch. The faster the aircraft was travelling, the taller and narrower the arch was. It was, literally, a "black hole" - the radar would not "see" anything in that notch. It would take digital signal processing to make use of that ground clutter return, which wasn't until later. Remember, the electronics in the AWG-10 were quite crude by today's standards - their idea of an integrated circut back then was a collection of discrete components surrounded by a black cube of epoxy. This is also what made it so difficult to repair, and gave it a low MTBF.

c) Can you comment on the MTBF of the radar set, compared to other radars on Phantom and vintage aircraft you know?, it introduced LRU philosophy?, how it was to mantain?, would be delighted (and guess most of us) to hear more about your job ;D
The MTBF on the original AWG-10 radars we had was quite dismal; if an aircraft was still "up and up" (airframes/radar) for three "hops" (sorties) it was golden. Remember, these aircraft were doggone old by the time I got to operational squadrons back in 1975; they were all Vietnam Veterans, and had seen MANY launches/recoveries from aircraft carriers, and were very high-time airframes. A single F-4J Phantom had 15 miles of wire in it. That's a lot of wiring to maintain. Much of it involved the radar. And the radar had quite a few electro-mechanical relays. One of our most frustrating "gripes" would be, "Radar breaks lock under G's" to which we could only reply "G-force simulator on back order." They wouldn't let technicians fly in the backseat - so we couldn't begin to troubleshoot it.

The BIT box (LRU-8) was a troublesome piece of equipment (BIT=Built-In Test) - it was driven by a film strip with written instructions and frame numbers to tell you where it was in the test, and a grid of (logical) 1's or 0's (either black or see-through) that drove a series of either phototransistors or photoresistors, which controlled a "relay tree" above the antenna that would select various circuits to test. This thing was a nightmare in itself. The AWG-10A BIT box was infinitely better; it was all digital, and markedly faster.

When my 1st squadron got the very first F-4S's with the AWG-10A radars in them, we found them to be VERY reliable in comparison - we were getting 10, 20, 30 or more hops between repairs. However, the first time we went to swap out a computer (LRU15 or LRU16, can't remember which) in the turtleback (behind the RIO) we discovered that the computer harness had been made too short! We got the cables off OK, but they just wouldn't go back on the new computer. They'd made an error in measuring the "jig" used to build the cables.

The F-4S's had other teething problems. They changed from the old flammable hydraulic fluid to a new, non-flammable hydraulic fluid; however the old O-ring seals were not compatible with this new fluid. Well, they supposedly replaced all of the O-rings when the airframes were rebuilt, but they missed a few in the turtleback area, causing eventual massive hydraulic leaks and our squadron to nearly lose an aircraft after losing all hydraulic pressure during approach.[/quote]

d) Did the radar interfaced with advanced con scan Sparrow (AIM-7F) and monopulse Sparrow (AIM-7M) missiles?...
I left the Corps before those missiles were available. The Sparrow missiles I worked with connected to the missile umbilical using a 32-pin shear "wafer". When the missile was ejected from the rack (by firing what amounts to a blank shotgun-shell type device) the wafer would actually shear in half; one side would remain attached to the missle, the other half would stay with the harness. I have a couple of these "wafers" left from my tour in the Corps; I was using them to build Sparrow missile simulators so the aircrew could practice locking on the radar and firing when the missile was inside the envelope. Don't have any photos - yet. They're rather crude, we didn't have any circuit card material available - just soldered together a dozen resistors, capacitors and diodes along with a fuse holder, then potted the whole thing.

Thanks a lot for any answer and for the last post.
You're welcome - hope this is enough for the moment. It's after midnight here, it's been an event-filled day, and I have more to accomplish before hitting the rack.

More to come...
 

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OK, here's an attempt to label some of the components; at least the visible LRU's.

Slight mistake - the channel switch on the 4A3A4 board is actually slightly down and to the right of where I circled it. If you load the pic into an editor and enlarge it, you can faintly see a slightly brighter rectangular area - that is the instruction label for the switch, indicating what channel range each switch setting was for; I don't recall whether each position covered three or four channels.

At the top - "Package extension rail" - this was a long, heavy, rectangular bar made of stainless steel (the aircraft nose end) and aluminum (towards the antenna); it was nearly twice as long as the radar package (less antenna) is deep. The whole package weighed between 650 and 750 lbs, so the package extension rail had to be quite sturdy. The end has a funny-looking shape to it, because there was a lever in it that would swing 90° to lock the rail into position, and then a safety catch would pop out about 1/4" to prevent the lever from returning to horizontal by itself. Without the lever latching the stop in place, the momentum of the radar package could easily cause the entire radar set to over-extend, causing extensive damage to the umbilical and umbilical catenary (shown) The umbilical and catenary actually made nearly a full circle of the rear of the package, to assure the minimum flexing of the wiring without adding undue length (and resistance) to the harness.

The AOA probe (Angle of Attack) I found quite interesting. The probe was very hot when the aircraft was being readied for flight. The probe was basically a hollow cone, with two horizontal slots in it, both facing forward, one about 45º above horizontal, and one the same distance below horizontal. When at flight speeds, the probe could rotate, and the air pressure against the slots would cause the probe to rotate so that the slots were always eqidistant from the center of the airstream pressure, thus giving the angle of attack.

On the forward side of LRU 4A1 is the 4A1A1 board, which is smaller than all the rest. The dark rectangles below it are relays, the purpose of which eludes me after all these years. On the 4A2, the horizontal dark strip is a label. On the far right edge of the 4A2, there is a 50-pin D-type connector oriented vertically, with a white plastic cover on it. There are two more in the middle of the 5A2. Below that, there are dark areas on the 5A3. Believe it or not, on the left (forward) side of the 5A3 there are spare fuses; three of the spare fuseholders are occupied, the other three are empty. The dark rectangles to the right of the rib are more relays.

Just a portion of the relay tree is visible. The miserable thing seemed to cover the entire forward upper starboard quadrant of the package. As they aged, they would become unreliable and cause really odd malfunctions under G forces. I have a few samples of these relays from when I was constructing a special piece of test gear for the transmitter section; a light sequencer you could read from the rear cockpit to tell if all criteria were met for powering up the main and CW KPA's. Never got to complete the project, as by the time all the parts came in, we were changing to the F-4S's, and there were many changes to the transmitter section which negated the need for the special test gear.

These relays are probably 30 years old - but never been used. I'll bet they'll still work ;) I think I'll use some of them in an A-4B Skyhawk we're currently restoring ;D
 

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More on the 50-pin "D"-type connectors... (forgot to explain them in the previous post)

We had a piece of test gear we called a "50-pin box" - certainly not the correct nomenclature, but all the Radar techs called it that. This box had an umbilical cord about 8' long with a 50-pin male D-type connector on it, that we would plug into the matching female LRU connector.

The 50-pin box itself was painted yellow, was about 1'x1'x8", and had 5 rows of 10 numbered red buttons on the top, with a meter movement off to the right. Translucent plastic overlays with holes in them went over the buttons; each 50-pin LRU connector had it's own overlay to document the signal (that should be) present on each pin.

Manpower required: When the F-4J was initially introduced, the radar system was a quantum leap over what was previously available - and was a very complex piece of gear. I was told back in the 70's that when Marine squadrons were initially equipped with these aircraft, that Radar Shop was manned by 120 people - to maintain 12 aircraft! :eek: By the time I was trained to maintain these radars, each Radar Shop had about 20 Marines, or about 7 per shift (days, nights, mids/mid crew.)

Not much maintenance got done during the day; that's when the aircrew flew their sorties. Change a fuse, pressurize the Coolanol-25 (a very thin oil used for cooling, sort of like WD-40, VERY expensive at around $80/gallon in 1980) or something else simple. De-briefed aircrews returning from sorties, perhaps began troubleshooting failures.

Night crew was tasked with getting nearly everything fixed - if they ran into a really tough problem, that would be left for mids. But if there were more than a couple of aircraft left to fix by the time mid crew came in, it would not be a pleasant situation.

Mid crew was the "tiger team" - they would fix the really tough problems. Sometimes, these were buried deep in the wire harness, and many panels would need to be taken off of the aircraft. I really liked working mid crew.
 

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OK, now I'm really stretching my memory.

There were a number of versions of the AWG-10 radar. The versions I worked on were 1472 (AWG-10, later edition) and 1527 (AWG-10A). There were various changes between the versions, obviously. It looks to me like you found drawings from an earlier version than I worked on.

I'll attempt to address each image in order.
AWG10a.jpg
MAN VEL - I don't recall this control being present. It likely would've only been used in PD mode.
Vc LOW/HIGH - not present in 1472/1527. It would have manually changed the Closing Velocity (range rate) envelope.
SCAN - Funny I'd completely forgotten this control. We'd leave it in 3-bar scan during ground testing. SS would simply scan left and right, no elevation change (except for RIO's thumbwheel input)

AZ - this would control the X-azimuth scan of the radar; normally left in "wide" mode for a 120 degree scan. BST would force the antenna to "boresight", or aligned along the aircraft's centerline.

MSL GATE - Missile gate. If the aircrew wanted to take a chance, they could select "wide" which would allow the firing of a missile outside of the computer-plotted kill envelope. This could be a very valid tactic, such as scaring a bogie off the tail of a wingman.

VEL COV CTR - used in PD mode. Sort of like scrolling up and down this page, you could use this switch to scroll in three steps up and down the frequency spectrum.

ANT - Sometimes, the inertial nav gyros would fail. When they did, you'd select GYRO OUT to disable that input to the radar. The artificial horizon line on the scope would then remain fixed from left to right across the screen.

ERASE CLUTTER - this was a pushbutton, not a toggle switch in later models. The screen had a lot of persistence. The ERASE CLUTTER button was equivalent to CLS on a PC - just get rid of all of the persistent stuff to prepare for a fresh "paint" of the screen.

FUNCTION - Same modes as I remember. You'd have to put it into OPR in order to enable the transmitter - but there was a weight-on-wheels switch on the starboard landing gear which would prevent radiating RF on the ground (unless you manually jumpered across it or some such.) You'd have to push the switch in and rotate it to select EMERgency mode, which would deploy the tell-tale red flag below the switch. Had a RIO scratch most of the red paint off the flag trying to get it to go back up ;)

MODE - PD (Pulse Doppler), PULSE (both Short Pulse and Chirp modes) VI (Vis Ident, never used) H MAP / L MAP (the PPI modes) A-G (the antenna was locked in boresite in this mode) TERR (Terrain Clearance mode; X'd out)

AWG10b.jpg
The BIT box buttons!
The visual readout looked only vaguely like what is represented. Each frame had a test number in the top of the readout, and near the bottom, where the next tests were if failure or success occurred.

You could manually scan forwards/backwards through the tape, and select a random test if you desired.

You could press GO to force a "go" condition even if a test frame failed.
If a frame failed, the tape would stop, and the "NO-GO-FI" button would illuminate. Pressing the NO-GO-FI" would attempt a logical Fault Isolate to discover the area of the problem. It wasn't all that accurate.

The thumbwheel switch controlled the brightness of the buttons and readout.

AWG10c.jpg
Top image: this is a display of PD mode. Note the "main beam clutter" - this is the upside-down notch I was talking about; the clutter return from the ground. Since the notch is relatively flat, the speed of the aircraft is currently pretty low. See the "6" on the right? The tic mark is the antenna elevation strobe. The "blips" near the bottom of the screen are near Fo, or the frequency of the radar, which means their Vc, or speed relative to the aircraft, is near zero. The blips near the top of the screen are closing at a very high rate, perhaps 1,500 knots or better.

Center image: RIO has initiated half-action on his control stick. Radar is switching PRF rapidly, the antenna feedhorn is nutating at a 66hz rate, and the antenna is slaved to the RIO's stick. RIO controls antennas' azimuth by moving his stick left and right, and the range gate by moving the stick forward and aft. Elevation is still controlled by the thumbwheel.

Bottom image: Much is self-explanatory. Steering error dot - the direction the pilot should fly to get a better "bead" on the target, or improve the chances of hitting the target with a missile. ASE circle - the steering error dot needed to be inside this circle in order to fire a missile. As the aircraft neared the target, the circle would become quite wide, but beyond a certain point it would get much smaller again. It represented the kill envelope of the missile. RANGE RATE CIRCLE - you would find the RANGE RATE GAP to determine the Vc of the target. The range rate gap was usually 1/8" to 1/4" wide, but in this drawing you can't see it at all! The gap would rotate around from about the 1 o'clock position to roughly the 11 o'clock position. I don't recall offhand what Vc's the positions meant (27 years, remember?) but in most of the BIT tests, the Vc gap would be in about the 7:30 position.

That's enough racking my brain for the moment.
 

overscan

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The document they are from is an official report into the AWG-10 from 1967, probably connected with UK Phantom II acquisitions.

Paul.
 

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AWG10d.jpg - don't feel like commenting on this one at the moment, as this is not quite the same as the 1472 or 1527 mods looked like.

AWG10e.jpg
Pulse mode - basically, the same display for all pulse modes (whether Short Pulse or Chirp; the aircrew wouldn't need to be aware of the electronics involved.)

Top image: pulse scan mode. Note that the vertical line is labeled "B-SWEEP". This was the way the scope was swept for ACM; vertically rather than in a radial scan. This kept the display pretty evenly lit from top to bottom. Were it a PPI-type scan, it would've required constant fiddling with the brightness and contrast controls to detect close vs far away targets. The acq symbol was always present on the screen.

Center image: RIO is in half-action, ACQ SYM over target, ANT slaved to RIO's stick, feedhorn nutating @ 66Hz causing the dithering.

Lower image: Tracking. I don't recall the "contracted position of range rate circle" being present on our later systems. Basically, the information presented by that circle is redundant to the outer range rate circle, and clutters up the display - likely why it was removed. This same comment would apply to AWG10d.jpg.


AWG10f.jpg
Pretty much what I remember, except for 4) Bombing Range Strobe - don't believe our radars had them. We didn't spend much time testing in PPI mode. If our aircrew were going to drop bombs, they tended to use the gunsight instead.

AWG10g.jpg
What you see is what we got - not much information there, eh? About the best you could hope for would be a large return from a building, which you could lock on to - then you would be given the range to the target.

AWG10h.jpg
Terrain Clearance mode - guaranteed to turn your shiny Phantom into a smoking hole in the ground.
All 1472 and 1527 models I worked on were modified to the lower display.

AWG10i.jpg
VIS-IDENT mode display - hmm, this actually could've been the RIO's way of selecting VTAS for the pilot. I just don't remember; I didn't work on VTAS-equipped Phantoms for very long, and that was many years ago.

I've already explained the basics of acquiring the target using VTAS - but looking at this diagram, when the pilot went to half-action on his stick button, the range gate would sweep out from the bottom up to the target, and select the closest target on the pilot's visual az/el

That about covers it, well - what I can remember anyway.

Hope this helps...
 

overscan

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Well, that was really useful, as my document is dry technical stuff like frequencies, PRFs and the like, while your comments actually make sense. Thanks!

Paul.
 

overscan

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Points of interest

  • Report written after writer spent a month at Westinghouse for familiarisation prior to setting up facilities at Ferranti.
  • AN/AWG-10 greatly improved capabilities over previous systems
  • Target detection by pulse radar, or pulse doppler. Chirp/evaluation monopulse detection techniques.
  • In pulse doppler mode, targets are tracked in velocity, and range to target determined by auxiliary circuits. Mode used to discriminate target from clutter on the basis of velocity, improving downlook capability. Also very high average power (1KW) which increases range.
  • Normal pulse radar modes are present for short ranges but peak power is limited by the use of a klystron amplifier essential to pulse doppler operation. Pulse expansion and compression techniques (chirp) are used to achieve higher duty ratio and high effective power short pulses.
  • Elevation monopulse used for terrain clearance mode, which gives steering indications to avoid terrain obstacles in low level flight.
  • Monopulse also used in air to ground ranging mode.
  • In pulse doppler mode the antenna will update velocity by nodding to pick up ground returns, to improve navigational accuracy
  • Low altitude operation used for weather mapping and mapping from low altitudes using pencil beam
  • Beam spoiler used for better map presentation at high altitudes.
  • Two displays, for pilot and navigator. Lights used for mode & informational presentation, plus direct view greyscale radar displays.
  • 3 computers located behind RIO, to provide missiles with target data
  • CW transmitter for Sparrow illumination
  • Extensive Built In Test facilities
Thats just the first page.
 

overscan

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  • Uses solid state circuits to save space.
  • Packaged in LRUs for flight line replacement with few or no harmonisation adjustment required.(really??? - Overscan)
  • Most units in the nose behind the radome, in a structure with slides forward for easy access.
  • Indicator and optical sight in pilots cockpit. All controlling units in the radar operators cockpit. Three computers located aft of the operator's cockpit, above fuel cells.
  • Antenna AS1906 contains waveguide feed to a hybrid T which splits the transmitter energy equally between the two halves of a dual waveguide horn. The horn provides an elevation monopulse radiation pattern which is sharply focussed by a 32" paraboloid reflector. For reception, input to two channels are taken from the sun and difference arms of the hybrid T. The difference arm of the T is connected to a waveguide switch to permit selection of the difference signal or the input from an auxilliary waveguide horn located at the rime of the reflector. The selected signal is appiled to the receiever auxilliary channel. Signals from the sum arm of the T are duplexed part of the transmitter waveguide to the main channel receiver. Low power waveguide (not carrying transmitter energy) is half height to save space and weight.
  • Transmitter and microwave components are located on the right side of the radar assembly mounted in the nose of the aircraft. Power supply and transmitter pulse amplifier are housed in a pressure vessel, which has an air to liquid heat exchanger in its walls. Liquid coolant is pumped through the walls to cool the air, which is then used to cool the several units.
  • Transmitter Pulse Amplifier is commonly called the Pulser and is one of the units located in the pressure vessel. This LRU applies high voltage to the pulse transmitter power klystron during transmit interval and removes high voltages during receive intervals as determined by pulses produced in a timer antenna unit.
  • Radio Frequency Oscillator is an LRU mounted beneath the after part of the transmitter pressure vessel. It provides the system with very stable pulse transmitter and first mixer (local oscillator) frequencies. Since it also generates a CW transmiter frequency in another unit, this unit is the source of all microwave frequency used in the system except the parametric amplifier pump signal.
 

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OK, his comments need some "commenting up". I'll have to attack that later on, as it's 11:50 PM here in Florida, and I have a rather busy day tomorrow.

Yes, Paul - I try to make comments in layman's terms, as many folks who wish to have a basic understanding of the system just wouldn't get it if I went overboard into dry technical jargoneze - and that would defeat the entire purpose of my post! The material you're reading is more targeted towards someone whom already has a rather technical background.

OK, I really have to hit the sack! Goodnight!
 

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A little more on "chirp" mode:
When I first explained it above, I said that the 0.65 uSec pulse hit the delay line and "rang" it like a bell. That's not precisely what happened.

A bell, when struck, usually produces the same tone from when first struck until the oscillations/vibrations cease.

The delay line, when hit with the pulse, "rings" with a range of frequencies, starting quite high and rapidly decreasing, sort of like running your finger down a piano keyboard, or up a guitar's frets. This frequency shift was mixed in with the radar's Fo (Frequency Of the oscillator, or the Klystron frequency) and sent out towards the target.

When the reflected energy came back, the same frequency shift was still riding on the Fo, and was sent back through the same delay line. However, the higher frequencies were delayed more than the lower frequencies. That's why the compression scheme worked.

Average power:
The main KPA was rated at 1,525 Watts. I don't know how they came up with a 1KW average power rating, when the duty cycle was somewhat less than 50% even in PD mode. The most it could possibly put out in PD mode would be closer to 750 Watts. Perhaps they gave the CW illuminator KPA's average power by mistake.
 
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