The controls for these radars were housed in the Radar Control Van, which was located very near the Battery Control Van and the same size. John Porter, manager of SF-88, reports that "The Battery Control Van is 20.5 ft long, 8 ft wide, 7 ft high, with a 6.5 ft tongue."

	This is a Nike Hercules tracking radar. It could be a Missile Tracking Radar (MTR), a Target Tracking Radar (TTR), or a Target Ranging Radar (TRR). The details are hidden under the wind shield, which reduces wind pressures and buffeting. The wheeled transportation vehicle is still present, when removed, the antenna is supported by three removable legs in a triangle (shown attached even though the wheels are still attached).
	This Nike X-Band (about 10 GHz) Target Tracking or Missile Tracking radar antenna is without the wind screen. The picture is from a Nike site that recently (2016) came out of service at Folgaria, TN, Italy. It is now part of a great Nike Hercules museum at that site.
	Ft. Bliss, Texas, November 2017 Sad, forlorn, and almost forgotten, didn't get to move to Ft. Sill. :-(( All ready to party, and no where to go :-(( The end of a successful era and life - but technology moves on - In a more permanent situation, the wheels and fore and aft trailer can be removed, and sent to storage.

This information is grouped into the following sections:

• Tracking Antenna Towers
• Tracking Antenna Base Pictures
• Target Tracking Operator Positions
  - Target Tracking Operations
• Missile Tracking Radar
  - Missile Commands - Communication systems to command the missile
• How The Tracking Radar Points at an Object - Monopulse
  - Monopulse Wave Guide Schematic
• Target Ranging Radar
• Radar Receiver Cabinets
• Multi-path Problems & Work-arounds
• Radar Aiming Alignment including boresighting
• Radar Range Determination
• Radar Height Determination
• Radar Azimuth (horizontal direction)
• Tracking Radar Physical Support
• Simultaneous Tracking Test (the proof)
• Simulated Tracking (and jamming) using the T-1 System
• Resistance to ECM (Jamming)

Radar Receiver Cabinets

There are two cabinets, side by side, almost mirror images of each other, one for the Target Tracking Radar (TTR), and one for the Missile Tracking Radar (MTR).

Pre-Modernization, Vacuum Tubes The first door on cabinet on the left of the Target Tracking Consoles opens into the Target Tracking Radar Receiver Cabiner. The cabinet shown is for the Hercules, but the Ajax was very similar. At one time I could tell you the function and how to adjust/fix everything in here - The chassis on the door is the Test Chassis, used to test the correct functioning of everything in the cabinet. The closed door on the left is very similar for the Missile tracking radar. Each contains the 60 MHz Intermediate Frequency (IF) amplifiers for Sum, Elevation Error and Azimuth Error, Automatic Gain Control for the IF amplifiers, Range Unit, circuits enabling automatic tracking in elevation, azimuth and range, and a Test Panel which also can control the bore site mast electronics.

Post-Modernization, Solid State, Transistors All information and pictures from Mr. Ramiro Carli Ballola "I'm sending you some photos relevant to the BC Van actually located at Base Tuono, this is the last configuration frozen in 2005 (no more modification foreseen or authorized) for all Nations participating in the WSPC, As I already explained the three remaining Countries were ITALY-GREECE and TURKEY, end 2005 GREECE started phasing out the system, followed by ITALY in 2007, after that the WSPC entered in the liquidation phase." for both MTR/TTR subAssy starting from the top the items list is the following: 1) Beacon AFC 2) IF amplifier SUM 3) IF amplifier AZ 4) IF amplifier El 5) Video and AGC amplifier 6) Servo Error Converter AZ 7) Servo Error Converter EL On the two doors either MTR or TTR from the top the list is the following: 1) IF test generator (like the old chassy) 2) Error voltage Monitor (like the old chassy) 3) AZ Error Modultaor 4) EL Error Modulator TTR section right side LP/SP filters from the top: 1) SUM LP and SP filters 2) AZ LP and SP filters 3) EL LP and SP filters MTR section left side SP filters from the top: 1) Sum 2) AZ 3) El Relative to the LIN LOG circuits, still from the top: 1) IF Amplifier 2) Long Pulse filter 3) Lin Log amplifier

Various components in cabinets - TTR SubAssy - TTR Test IF signal generator - MTR Error Voltage Monitor - TTR Lin-Log circuit - MTR Angle error modulators

MTR and TTR RSPU's (Radar Signal Processing Unit) The RSPU's output Range, Azimuth, Elevation, Height and other 8 items of information - TTR RSPU front - MTR RSPU front - TTR RSPU cover removed

Multi-path Problems & Work-arounds

OK - You can get most of the above from any serious radar book. Now for a gory practical detail :-((

Radar waves are just a (VERY) low frequency light wave. This is both good and bad news.

• The good news is that radar waves reflect off of conductive surfaces, like aircraft.
• The bad news is that radar waves reflect off of surfaces you wish they wouldn't, like earth or water (with different dielectric constants relative to air) between you and the aircraft you are trying to track. Here are two stories one story and another story involving the Missile Tracking Radar "Locking-On" the reflection of a missile.

This is a visualization of the problem

and a graph showing tracking errors of a plane at unspecified height with a radar at unsspecified height and frequency with beam width about 3 times Nike 3 centimeter wavelength. This edition goes on for about 3 more pages about this effect.

The above "sample" is from the 1980 edition of "Introduction to Radar Systems" by Merrill I Skolnik. While trying to contact the author for permission to publish, (no contact yet) I found that he is alive, still lecturing and authoring. According to http://www.radarcon2008.org/bio_Skolnik.html , "Dr. Merrill Skolnik served as superintendent of the Radar Division at the US Naval Research Laboratory in Washington, D. C. from 1965 to 1996." and has all sorts of accolades. If you are seriously interested in modern radar (including Lidar) you should get one of his more modern books.

The above paragraph indicates a reason that the Nike mission was against "high flying" aircraft, and some motivations for developing homing missiles such as HAWK, and the more sophisticated methods in PATRIOT.

Good News

The chart can be interpreted to indicate that the error between two closely spaced radars, involved with low angles of elevation of the target, will have similar errors - that the error of the MTR tracking the missile into the Intercept Point will be largely compensated by the error of the Target Tracking Radar tracking the target into the same Intercept Point. - The two errors largely cancel -

Bad News

If the Missile Tracking Radar tracks the reflection or image - it will lose track of the missile, and there is no practical way to regain track before the missile self destructs after losing the tracking/command signal from the MTR.
Good News ;-))

The effect was known and corrected for until judged "not a problem". This was usually easy in the U.S. Rolf Goerigk reports from Germany

... A good example was the daily MSL {Missile Tracking Radar} acquire procedure. Because of the usually low grazing angle of the antenna beam, multipath effects were monitored in elevation. By using NIKE amplitude monopulse there was no cure. The MSL was rated non-operational. Just imagine, looking thru the mounted telescope seeing some cows instead of the auto tracked missile! But the view-point or directing point was not the reflection point, instead it was the sum of the direct and indirect RF energy from the MSL. The "reflection point" was changing with season and daytime and sometimes gone at all. It was a really interesting case and I learned a lot. I was engaged (again) in that "secret" story. That case was really hot and sensitive. This matter is discussed in some radar books. The wartime solution! Moving trucks between the MTR and MSL, it worked!

Radar Aiming Alignment including boresighting

A quick Wikipedia introduction

Radar alignment is reasonably complex. Each radar (target tracking & missile tracking) must be individually leveled and boresighted. Then the two radars must be aligned so that their potentiometers read the same when both are pointed in the same direction. Then the position difference of the missile tracking radar from the target tracking radar must be placed into the computer for that correction.

This is a bore site mast (15 K bytes). The test signal radar waves come out of the feed horn at the center of the X on top, and the 4 side things of the X on top are optical targets for the telescopes on the radars (TTR, TRR, and MTR). More details here

A little reflex klystron, such as this, was used to generate the echo pulse via the feed horn to the tracking antenna being boresighted. The radar receiver sensitivity could also be checked by attenuating the output of this tube. The tube is about 3 inches, 8 centimeters, from tube base to top. The long "pin" below the base is the coaxial output structure feeding a wave guide. The little screw assembly on the right permitted coarse (larger scale) frequency adjustment, fine frequency adjustment is accomplished by changing the reflector voltage, one of the pins in the base. We (site maintenance people) never touched this tube.

This is a bore site mast (34 K bytes) being lowered. When in place, the long pole is vertical. Image from Rolfs NIKE Pages by goerigk@onlinehome.de.

In list fashion, it can be organized into the following major steps:

• Individual leveling (all tracking radars)
  The level indicating instrument was a ruggedized version of the Precision engineers level mounted on the rotating part of the antenna. The instrument alignment was checked by leveling the antenna then rotating the antenna 180 degrees and assuring that the instrument still indicated level. If not, you readjusted the level until it indicated the same error "forward" and "backward". You then re-leveled the antenna and checked again. (This adjustment was quite stable.) The level of the antenna was generally not stable.
• Individual bore sighting (all tracking radars)
  • Turn on Bore Sight Test Mast oscillator
  • - When the test mast control box senses X-Band pulses,
  • -- it will generate echo pulses on the same frequency from the feed horn
  • Lock on oscillator
  • Track in automatic
  • Set telescope into mount, position 1, observe target
  • Set telescope into mount, position 2, observe target
  • Adjust telescope (not radar!) for correct bore sight
  • Shut down the Bore Sight Test Mast oscillator
• Aim missile and target tracking telescopes at each other's crosshairs
• Adjust potentiometer alignments
• Make sure the missile tracking radar position offset was in computer

The leveling adjustment was the most troublesome at many new sites. It would drift about quite a bit (require releveling several times a day) until the concrete pads settled down into the ground. Then the adjustments would not be required more than once a day.

Data Unit Adj

Elevation BoreSight

Azimuth BoreSight

This yielded a bore sight accuracy between the Missile Tracking Radar and Target Tracking Radars of about 1.5 inch in a thousand yards (assuming the bore site mast was at about 250 yards from the radars). At 110 miles (200,000 yards) that would be about 300 inches or on the order of 25 feet. There are many more error sources in the system - of course - but the system was/is interestingly accurate. In angular measure, the boresight error was about 0.0025 degrees, or about 10 arcseconds. The angular size of a star in a powerful telescope on the earth is about 1 arcseconds due to atmospheric problems. For an interesting comparison with the earlier (WWII) SCR-584, click here.

Frank E. Rappange points out that there is a check that demonstrates that all of the adjustments REALLY WORK. " ...the main test (that had to be performed every 6 hrs, when on 30' SOA) was the 'Simultaneous Tracking Test'. In this test the MTR was set to 'skin track mode' and both TTR (and TRR) and MTR locked on the same target. The BCO could read the voltage difference for the positions of the respective radars in the BC Van. Readings were made for both TTR and TRR in the difference pulse modes. It was the decision of the BCO to accept the system or not."

Return to beginning of Nike Radars

Radar Range Determination

Radar waves (and light and other electromagnetic waves) travel through air almost as fast as in a vacuum. Fortunately for engineers and users, air pressure, humidity, and other atmospheric variables do not affect the speed of travel very much. To make matters even easier for the Nike problem, any variations that do occur are largely canceled out at the end of the flight, as both the radar beams are traveling through very similar air conditions. Errors due to refractive effects due to differences in air pressure along the beams cancel out. So a common crystal oscillator was used to calibrate the range systems of both the missile and target radars. This adjustment was fortunately very stable, rarely needed tweaking unless a component was changed.

Analog - pre-modernization

There is a circuit called a "phantastron" that has a remarkably linear pulse delay time from a voltage input. The Range Operator (or range tracking servo system) operates a linear potentiometer which provides the range voltage for:

• Elevation potentiometers, see Height Determination below
• Azimuth potentiometers, see Radar Azimuth Determination below
• Range gate for displays and for servo gating

This diagram came as a shock when I was looking through technical manuals in 2015. I had never seen it in trainning nor on site. It must have been discussed on one of the days I was on KP. (The Army had a bad habit of making their slave wage students take their turns doing KP (Kitchen Police, washing pots and pans, mopping the mess hall, ...) during technical trainning. The Air Force is much more enlightened, hiring civilians to do kitchen chores instead of techie students.) Good thing the range units didn't fail on our site, would have taken me some time to fix things, or call in ordnance. (There were two range units, one for the Target Tracking, The other for the missile tracking.) Maybe Lopresti or Sizlak (the other two IFC techies) didn't have KP on their sequence.

Digital - post-modernization -

Return to beginning of Nike Radars

Radar Height Determination

Analog - pre-modernization Digital - post-modernization - from Ramiro Carli Ballola Note: during the post 1975 modernizations, including replacing many analog components with digital components, the elevation trig potentiometers were replaced by digital angle resolvers. Here is an explanation of a digital angle resolver. The output was sent to a little digital computer in the RC van where the height was computed from the digital_slant_range times the sin of this angle and the ground_range determined from the cosine of this angle. Gathering the details, and educating me (Ed Thelen) is an on-going effort (November 2015) by Ramiro Ballola :-)) Please be patient, these were major philosophical, data flow, and processing changes. going back to the RAEMOD, with the change of the potentiometers in the antennas, in the exploded view photo included at nr 26 you should see fisically the optical resolver inside the TTR azimuth encoder assembly, they were the same on the elevation and equally the same for TTR/MTR/TRR Inside the functional schematic photo you should see a little part of the RSPU Angle encoder section and you should read the input from synchro and resolver from the antenna and the first data conversion, to be sent to the Coordinate Converter Section (via PCS), than to the TDP (Track data processor) and to the Digital computer in the BC Van Ed Thelen here - The above two diagrams provide fascinating hints of the digitized (azimuth and elevation) angle data sent by the antenna circuitry to the RC van to help provide X, Y, and Z information of the radar target. Ramiro is continuing to collect photos, diagrams, and information. from Ramiro Nov 19, 2015 Ed, if you remember after boresight check before the Orientation, one check was mandatory to be performed and it was the KDP (Known Datum Point) to define the TTR (considered as System center) azimuth position respect to the North Geographic, this value recorded inside the TTR RSPU, together with the Orientation Elevation position and the Range zero check value SP and LP, was the reference you recall to intialize the system. Of course in the MTR RSPU the azimuth reference value was the Orientation value. Ed Thelen here - None of the above, except boresighting - done daily - , and determination of "north" - done once on Ajax sites -, is unfamiliar to this Ajax techie. I (and this description) have a long way to go - we had no "RSPU" to initialize - Return to beginning of Nike Radars

Radar Azimuth (horizontal direction) Determination

Analog - pre-modernization Digital - post-modernization Note: during the post 1975 modernizations, including replacing many analog components with digital components, the azimuth trig potentiometers were replaced by a digital angle resolver. Here is an explanation of a digital angle resolver. The output was sent to a little digital computer in the RC van where the ground_range and angle were used to compute the E-W and N-S ground values. height was computed from the digital_slant_range times the sin of this angle. Return to beginning of Nike Radars

Tracking Radar Physical Support

One of the many keys to precision tracking between the target and missile tracking radars is the fact that (small) identical errors of tracking by both the target and missile tracking radars "cancel out". Example, if both the target and missile tracking radars say that their respective tracks are both 100 yards higher than absolute height, the actual miss distance (if every thing else was perfect) would be 0 yards. **Very Interesting and Useful**

This way, errors due to radar wave (like light wave) refraction in the atmosphere cancel out if both radars are tracking the same point in space (in this discussion we ignore the slightly different paths due to the slightly different physical location of the two radars.

The Nike Ajax system "assumed" that wind buffeting of the two tracking radars would be sufficiently similar so that accurate enough tracking could be accomplished.

Since the Nike Hercules had an "effective" range more than 3 times the Ajax, and a real range more than 4 times the Ajax, errors due to wind buffeting and similar errors could be 3 or 4 times larger, and possibly render Hercules ineffective (too inacurate) at longer ranges.

Bubbble surrounds each tracking antenna
To counter the wind buffeting, the tracking radars were enclosed in an air inflated fabric "bubble". This greatly reduced the wind forces on the tracking antennas. Even if the wind gust shifted the bubble a few inches, the air forces on the antennas would be greatly reduced during the shift of the "bubble".

The "bubble" also protected the antenna from much of the differential heating due to the sun heating (expanding) one side of the mount and antenna relative to the other side (shady side) of the mount and antenna. Although both tracking antennas would likely be illuminated by the sun the same way, vertical alignment was usually made by one person at slightly different times (an error source) and one was never confident that everything was identical anyway.

Wind Force and Sun Heating on Tower Mount
Ideally, the radars could be located on high ground, well above surrounding trees, buildings, ... . However, in flater areas, towers had to be used to get the tracking radars high enough.

The wind also supplies forces and torques on radar towers. The forces and especially the torques shift the top of the tower in space, and shift its angle with the vertical. The shift in space (inches) is much much smaller than other errors, but the shift in angle from vertical could result in much more severe errors.

To provide improved resistance to angle errors due to torque in the tower, the tower was actually a double tower.

The outer tower was buffeted by the wind, and also the differential expansion due to the sun light heating it. The platform at the top of the outer tower also supported the bubble that protected the antenna from the wind.

The inner tower supported the antenna. The inner tower was largely isolated from the wind and the sun which resulted in much more stablity.

Image of tower showing: - outer tower platform - bubble base - foot pad from inner tower

Return to beginning of Nike Radars

Simultaneous Tracking Test (the proof)

Did all of the above boresighting adjustments and alignments REALLY yield a system that could get a missile within kill distance of the target? There is a way to check!

Have BOTH the target tracking radars and the missile tracking radar track the same target (aircraft). If both radars say the aircraft is in the same place, the tracking system is correctly aligned. Period. No guess work, no theory, no "it oughta", the tracking system IS correctly aligned. Assuming the computer works, the missile takes commands, etc., that NIKE system is capable of guiding the missile to the target!

However, you remember that the Missile Tracking Radar (MTR) tracks a beacon in the missile, not the skin of the missile. So, (FOR THIS TEST) the MTR is set to:

• a mode to track the MTR radar reflection from a target, not the missile beacon
• remove the delay of the beacon (a fixed delay between receiving the MTR radar signal and the firing of the beacon) from the MTR range system

The above two changes permit MTR to track the aircraft just the same as the TTR system.

An aircraft flies about, and the computer voltages representing N-S, E-W, UP-DOWN for the MTR and the TTR are compared. They ideally should be identical. Placing a sensitive volt meter between say the target radar N-S and the missile radar N-S should ideally yield zero at all times while tracking the same aircraft. In practice they rarely are completely identical due to at least the following error sources.

• different parts of the aircraft reflect (glint) differently at different angles
• different pointing servo gains and damping
• actual level errors
• actual boresight and alignment errors
• errors in the range, elevation, azimuth potentiometers
• errors in components in the computer
• a wide variety of mechanical errors such as binding, looseness, ...

In spite of the above long list of possible error sources, people at NIKE sites had to and did prove - frequently - that the tracking system errors were very few yards at ranges in excess of 50 miles. Unbelievable but true!

Simulated Tracking (and jamming)
using the T-1 System

Tracking aircraft with a NIKE system is trivial if the aircraft is not using jamming.

With no jamming, you can easily teach your junior high school kid to be a good NIKE radar operator in an afternoon. A group of afternoon trained junior high kids could do all the NIKE aircraft radar tracking operations necessary to shoot down a non-jamming aircraft.

The airforces of the world spend a great deal of time and money to try to defeat radar - and many interesting jamming methods have been developed and are used. How do you train NIKE people to track aircraft that are using Electronic CounterMeasures - ECM (jamming)? How do you maintain and enhance this difficult skill?

Using friendly aircraft for this training and skill maintenance has many disadvantages, including:

• The friendly air force is unlikely to wish to fly aircraft for hours per day around the various sites to assist in trainning and honing the friendly anti-aircraft forces. Occasional tests may be OK, but almost every day?
• The friendly air force may not wish to turn on their latest and greatest ECM (jamming) equipment for analysis by non-friendly agents.

I presume these, and other, reasons led to the development of the AN/MPQ-T1 Electronic Warfare Simulator (developed by ITT Baltimore, MD ) which was housed in one very large trailer. The operators in the T-1 trailer could exercise the radar operators in both

• the Battery Control (BC) van (acquisition operators and battery commander)
• and the Radar Control (RC) van (Target Tracking operators (azimuth, elevation, range) and Missile Tracking operator.

with many types and quantities of "interesting" ECM (jamming) problems.

Jamming/spoofing slides from the archives of "Association of Old Crows"
https://aoc.adobeconnect.com/jammingtechniques5-1-14recording/?launcher=false&fcsContent=true&pbMode=normal
(The introductory part, relative to the pulsed, non-coherent techniques used in Nike)
With the Improved Nike Hercules, the jammer/spoofer had to fool two different frequency radars in range.
Note the attempt to both:
     a) obscure/hide the target
     b) fool the range operator/system to track a fake target
Also note: this does not include "mechanical" jamming, such as chaff, corner reflectors, decoys, ...

	This is where ECM was for Nike Ajax
			and modern techniques are much more "interesting" ...

For more details on the T-1 unit, see

Lesson 8. Target Simulation - 1.2 megabytes

There is a T1 manual on-line at T1 AN/MPQ-T1 (another site)(.zip -> .pdf files)(10 files totaling 6 Mbytes)

For a more general discussion of jamming, go here.

From Steve Johnson

LOPAR/HIPAR target video and ECM was created using sync and preknock signals from the radar. Antenna rotation was slaved to the radar by a device called a "flying spot scanner" and video was triggered using a system called an "antenna pattern generator" which simulated not only the main antenna lobe but side lobes as well. By changing the position of the main lobe, the target could be moved in azimuth at will and the ECM would also be positioned along the main lobe. TTR and MTR video was generated {by the T-1} much the same as the IF test pulse except that the TTR was given sum, azimuth and elevation signals and long and short pulse. Azimuth and elevation signals were controlled through servos which were slaved to the antenna and range simulation was done by delaying the video from sync. The system could generate 6 independent targets with 4 types of Electronic jamming on 4 different carriers in addition to Acq and track chaff and angle deception.

From Bert Belfer

Army Navy Mobile Radar Signal Simulator. I worked on them for about 10 years, a great training device. Simulated up to 6 targets, ECM, and ground clutter. The Chaff cabinet was a bitch to maintain. The T1 also had a reusable missile. The T1 was heat sensitive and the IF strips had to be retuned as the trailer got warmer. The Simulations were injected at the RC & BC Vans not at the radars.

Resistance to ECM (Jamming)

from Doyle Piland < dpiland@zianet.com > his Nike ordnance web site

First, let me say something about analyzing the ECM/ECCM situation for Nike or any other system. That is somewhat akin to painting a moving train. Technology advances tend to make the advantage shift between ECM and ECCM. So, I?m not surprised that some point in time the SSKP was as low as 85%. However, I have watched as Air Force planes tried to break Hercules System lock after the TRR was added to the system and they could not do that. I have even read letters from Air Force organizations requesting that Nike not track their planes using their ECCM, because it tended to undermine the confidence of their pilots in their ECM equipment. I don?t know the time period that the simulations were done. Ability to do meaningful simulations developed as technology did, so the sophistication (accuracy) of the simulation could be called into question. Second, all simulations involve some approximations and assumptions. Thus, simulations have to go through a validation process to determine the accuracy of the simulation. I have never heard of any meaningful simulations involving the Nike Hercules systems. That doesn?t mean there weren?t any, just that if the 20+ or so years working with and around Nike, I would have expected to see something about it. I hope this helps. Doyle

If you have comments or suggestions, Send e-mail to Ed Thelen

Return to home page, Goto Next Section

Return to beginning of Nike Tracking Radars

Updated April 14, 2022