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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.
|
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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:
Also, TM9-5000-18 "NIKE I SYSTEMS - TTR TRANSMITTER AND RECEIVER CIRCUITRY" is available for another (more detailed) view of some of this material. (The Nike 1 [Ajax] was the predecessor of the Nike Hercules, but the same principles apply.)
Tracking Antenna Base Pictures
Equipment used for BoreSighting
This is the control box and cable used to do fine antenna pointing adjustments during bore sighting and other alignment procedures This is the telescope used in bore sighting and other alignment procedures.
The National Park Service has abscounded with this unit -Connectors at a tracking antenna
This could be called the connector side of a Nike Tracking Antenna. It also includes two storage compartments for frequently used equipment. Most of the connectors use low current (signal) connectors, here is a sample. The exposed connector is for the three coaxial cables carrying Intermediate Frequency (60 MHz) signals to the Radar Control Van for further amplification. They are the Sum, Azimuth Error and Elevation Error signals.
Tracking Antenna Base Electronics
These are magnetron and other high voltage power supplies, and the amplifiers used to drive the antenna azimuth and elevation motors. They are on the opposite side relative to the connector side.
Target Tracking Operator Positions
These are the Target Tracking Consoles, each with scope and controls as labeled. They looked very similar for both the Nike Ajax and Nike Hercules. In the Nike Hercules, an added (stand-up) position, the Tracking Supervisor, was added to help coordinate activities and operate the anti-jamming controls.
Picture of Radar Control van at Ft. Sill museum from Al HarvardPan-adaptor scope for anti jamming and controls
below left, TTR Magnetron controls
below right, Azimuth scope right
from Greg BrownThis image is of the A-Scope chassis of the target track elevation position pulled out.
(All A-Scope chassis are identical)This image is of the powered Target Tracking Consoles and anti-jamming controls of an Italian system,
from Ramiro Carli BallolaTracking Supervisor Controls
This was Nike Hercules only - a forth man stood behind the three tracking operators and used this detachable anti-jamming control panel. I have shown this in great detail as I am fascinated imagining what all could be done to dodge jamming signals.TTR - MTR Magnetron, type WE 5780
A magnetron is a specialized vacuum tube capable of making surprisingly powerful pulses ( 100s of kilowatts ) of microwave power from powerful pulses of high voltage ( about 30 Kv ) current ( about 30 amps ). The Western Electric type WE 5780 magnetron was used in Nike Target Tracking radars. This is a tunable magnetron with frequency centered on 10 GHz ( 3 cm wavelength ).
Jon Elson < elson @ pico-systems . com > sent these picturesHere is a data sheet from frank.pocnet.net/sheets/201/5/5780.pdf
from Jon:
ARGhhhh! &^%$ !!!I have had this magnetron with me for over 40 years, it's been sitting in a box in my current garage for 25 years. Take it out to take a picture, and I DROPPED it! DAMN!
I suppose I could fudge it back together for a picture...
This is the outside tuning equipment - off to the left is a little geared down motor, then a flexible cable with inside twisting mechanism, to 90 degree angle, to worm drive. This enabled the TTR to try to avoid interference and jamming by changing frequency +- 10%
The receiver automatically tracked the magnetron frequency changes (AFC)Beam width
Beam width is usually defined as the width between half power points of the main beam of an antenna. Wikipedia gives a formula for a typical parabolic beam width as:
Beam_Width_In_Degrees = 70 * WaveLength / AntennaDiameter
where WaveLength and AntennaDiameter are in the same units.Using factors of
- wave length = 3 cm
- antenna diameter ( about 5 feet ) = 152 cm
gives a Nike antenna beam width of about 1.4 degreesA small (narrow) beam width in a tracking antenna is a "good thing", giving:
- more radar energy on the target and gain (better range)
- better target angle determination
- better resistance to off axis jamming
Nike tracking antennas had a beam width of about 1.4 degree, that is, most of the transmitter power was concentrated in about 1.4 degree wide and 1.4 degree high. Although the TRR ( Target Ranging Radar ) had shorter wavelength, it was not used for angle determination.There were three types of Nike Target Tracking Radars
- the (earlier) Ajax Target Tracking Radar
- the Hercules Target Tracking Radar
- the Hercules Target Ranging Radar
The earlier Nike Ajax tracking radar had an effective range of about 50 miles.
Overview This antenna (next four pictures) is at the Historical Electronics Museum near Ft. Meade, MD. A great place to visit! :-)) It used a Fresnel lens type of focusing like this. Boresighting was identical with the later Hercules Tracking antennas. Leveling was of course a big deal. The Target Tracking and Missile Tracking radars MUST have a common vertical reference. Two levels at right angles are used for convenience. This was one leg of the tripod support of a tracking antenna. The cap covers a 1 inch hex bolt head to be turned to level the antenna. Bill Shaw Nike website noted an article
showing the evolution of the Fresnel form of the metal plate lens antenna. Chapter 3, METAL-PLATE LENS ANTENNAS by Paul Wade. This contains the following diagrams. Fig. 3-1&2 Fig. 3-1&2 Fig. 3-4&5 Fig. 3-6&7
A discussion of Metalic Delay Lenses, as used by Nike Ajax tracking radars, was presented in this issue of Bell System Technical Journal. Bell and Western Electric (a subsidiary) designed and built the Nike IFC equipment. A Life Magazine photo - at Red Canyon - possibly troops firing their Nike Ajax equipment before taking it to some site at some city. An other possibility is troops back for annual re-fire shooting from resident equipment. Hercules Target Tracking Radar
The Nike Hercules Tracking Radars had a maximum range of 200,000 yards, a little over 110 miles. (This was a hard limit as the tracking displays and computer scaling had that limit.) For an interesting comparison with the earlier (WWII) SCR-584, click here.The Nike Hercules systems had two Target Tracking Radars that were externally similar. Internal differences included using different frequency bands. The two radars were used instead of the usual one radar to help fight enemy jamming. A variety of strategies made the life of enemy jammers extremely difficult. (The Nike Ajax systems had one target tracking radar).
Nike Hercules Tracking Radar - internally setup for Missile Tracking.
Note that the wheels have been removed for a more permanent installation.
The black arrow points to the telescope support assembly, where a 30 power telescope is mounted for radar boresighting and alignment. This image was taken at SF-88 before the wind screen (a spherical green ball) was installed which protects the radar and rotating mount from wind buffeting and weather.
View of electronics in the rear of the radar.I was really impressed with the smoothness of the rotation in azimuth. The bearing had no apparent play, but was easy and smooth to move. In 2012 I asked Kennith Behr about this. He said this was a Kaydon Bearing and provided this picture. Gaston Dessornes wants to "... know the approximate weight of the MTR/ TTR mobile tower? (See picture attached) "
The following images are from scans of TM9-1430-253-34 by GoogleBooks Although there is considerable complexity, we rarely had problems with the radars (or the rest of the Nike IFC system). It was extremely well designed and manufactured :-)) Pretty much a joy to keep running. Unfortunately, Western Electric, the designer and manufacturer has been disassembled by the government -
All practical ( and heavy ) electronics were placed in the tripod base. This included power supplies, magnetic amplifiers to drive the drive motor, ... This is the back of the TTR antenna - made as light as practical - Electrical connection, i.e. controls, elevation angle voltages, power, intermediate frequency channels, ... were made with the base via "slip rings". Here is a slip-ring assembly, electrically connecting the rotating parts, used both in azimuth and another for elevation - The Azimuth Transmitter is a precision sine-cosine potentiometer which helps convert polar coordinates ( angles ) to Cartesian coordinates ( x,y ) :-)) In special situations, such as typhoon hazard or arctic conditions, a large protective cover was included which could provide additional protection. These covers were shaped like clam shells which could be closed in really bad conditions. See pictures Side view, Quarter view and Alaska location information Site Peter and Site Summit. I am guessing (please correct me) that if the clam shells were closed, the tracking radars could not be used.
From Rolf Goerigk, Specification for the Target Tracking Radar (TTR) include:
Antenna Gain 44 dB = 25,000 Freq. Range 8.5 - 9.6 GHz Pulse Width Short Pulse (SP) = 0.25 microseconds
Long Pulse (LP) = 2.5 microsecondsRF Peak Power Short Pulse (SP) = 201 kW
Long Pulse (LP) = 142 kWAverage RF Power
LOPAR-ModeShort Pulse (SP) = 25.1 Watt
Long Pulse (LP) = 177.8 WattInstrumented Range
from here200,000 yards (113 miles)
Nike Hercules Target Ranging Radar (TRR) (image is 33 K Bytes) (Photo credit Rolf Goerigk) The rope fence and supports are there only during maintenance to reduce accidents - removed during normal operations. During normal operations, a spherical wind screen surrounds the antenna to reduce wind forces and tracking errors. Note the more pointed cone, this antenna uses a different "optical" system. View of electronics (Photo credit Rolf Goerigk)
MMS Subcourse No 150 LESSON 5. TARGET RANGING RADARFrom Rolf Goerigk, Specification for the Target Ranging Radar (TRR) include:
Antenna Gain 49 dB = 79,000 Freq Range 15.7 to 17.5 gHz Average RF Power Short Pulse (SP) = 15.6 Watt
Long Pulse (LP) = 78 WattCW2 Robin E. Smith says that the TRR evolved considerably during its service life.
For more information, upgrades, and pictures, click here
- - 1st, manual frequency change (to avoid jamming)
- - 2nd, automatic and manual frequency change (to avoid jamming)
- - 3rd, the SAMCAT change, automatic "channel" frequency change, 400 times per second (to avoid jamming)
Francesco Ledda wrote April 20, 2022
Ruminations about the Nike TRR. It has been 37 years since the last time I put my hands on a TRR.
The TRR came about for the need to counter-interact possible ECM from the enemy that would “falsify” the real distance of the Target.
Advancement in electronics had allowed the enemy to design a circuit called Range Gate Stealer that could confuse the range circuitry of the TTR about the true slant range of the target.
The Range Gate Stealer circuitry synchronized to the PRF of the TTR and generated a return pulse coincident with the TTR return pulse. Once this was achieved, the pulse widened or split in two pulses that moved away from the original return pulse and tricked the TTR range gate circuitry to think that the target was at a different range.
To counter-interact this, the TTR incorporated a gated AGC and the Multi Pulse circuitry that staggered the PRF. Not being enough, and additional Ranging Radar was designed and introduced (TRR).
The TRR is an ECCM RADAR, It consists of a parallax computer, a dual receiver transmitter and a panoramic receiver.
The Parallax computer corrected for the errors due to the different physical position of the TTR and TRR. The parallax computer was located on the base of the TRR.
The TRR dual transmitter receivers operated on different frequencies, and, through some switching circuitry, the TRR could switch from one frequency to the other without delay. This required a very high level of complexity of the ECM gear that was difficult to achieve and difficult to maintain and operate.
The TRR also had a panoramic receiver that allowed the operator to identify, monitor and fight possible ECM jamming that the enemy could do. The panoramic receiver gave the TRR operator clues of hot to retune the TRR transmitters to avoid jamming.
The TTR and TRR operator could also switch between the TTR and TRR has the source of Range for the ballistic computer. The TRR and TTR, as a ranging system, was highly effective and very difficult to deal with.
Best, Francesco Ledda
Nike Hercules System Engineer
VitroSelenia from 1980 to 1985
The Hercules Target Tracking Radar, and the almost identical Hercules Missile Tracking Radar, are diagrammed below
The antenna shown above is pointed roughly level. As per Vasilis Bourantanis, The antenna could be depressed about -204 mils (about 11.6 degrees) at which point a microswitch prevents further motor drive in the down direction. A shock absorber stops further downward physical motion. The antenna can point straight up and a little beyond.
There is a special computer circuit to steer the missile so that it does not pass directly over the Missile Tracking Radar (MTR). This prevents the MTR from having to slew in azimuth at a high rate of speed. This is called an "over-the-shoulder-shoot". (This prevents the need for a special no-launch azimuth.) Although the recommended site configuration suggested the missile launch area be toward the direction of an expected attack, practical considerations sometimes caused the launch area to be "behind" the IFC (radar site).
As the diagram mentions, the fixed base was carefully leveled, and checked daily (or until the cement pad finally showed signs of adequate stability). The level system was extremely sensitive and accurate.
There was a method of "bore sighting" the radar beam to assure that the beam was parallel to a telescope system (with cross hairs). A special microwave transmitter and test mast with optical sights was used in this adjustment.
The telescopes of the missile and tracking radars then were pointer at each other to assure that the elevation and azimuth indicators (potentiometers) were correctly aligned.
Target Tracking Operations
The above Hercules A-Scope type image (thanks to Rick at ShoreRick@aol.com)
shows a tracking radar with a single target in the
middle of the range notch. This notch gives a range expansion,
meaning that although whole base line is 200,000 yards, the lowered
section is greatly expanded in range, being about 150 yards in length.
This provides a combination of whole picture,
The lower trace is the error channel signal. This shows the operator
the success of the servo system in keeping the antenna pointed at the
target. It is extremely useful (required) if the tracking is in
"MANUAL" or "AIDED MANUAL" due to ECM (jamming) problems.
In the middle of the range notch is the
unseen "range gate" which samples the target information and sends it to
the azimuth, elevation and range tracking servo systems. The servo systems
use this sample to move the hand wheels controlling the tracking antenna
in azimuth, in elevation, or the tracking range systems.
There are three target tracking operators seated in a row.
each looking at his own "A" scope. The one on the right is the range operator,
the one in the middle is azimuth operator, and on the left is the elevation operator.
Between the range and azimuth operator is a PPI scope showing the
same picture that the battery commander sees. This helps the tracking operators
find the target designated by the battery commander.
Each operator can also look at the error signal (mentioned above)
that goes into the servo systems. Each operator can
also select to use the following modes of tracking:
In the Hercules, the range operator used a separate antenna TRR
(the Target Range Radar). This radar used a selection of different frequencies
and had the most extensive anti-jamming equipment.
The three seated tracking operators (range, azimuth, elevation) were assisted/supervised by
a Tracking Supervisor who stood behind them and also operated the AntiJamming
equipment.
Anti-jamming control box used by tracking supervisor - in the hands of
SF-88 site volunteer Ezio Nuriso (who was a tracking supervisor)
from: "Frank E. Rappange" (f.e.rappange@pi.net)
"
The TTR had 3 different pulse modes: Short pulse, Long pulse, and
Multipulse, and the TRR had 2 magnetrons (for eccm reassons). That means
that we had to perform the simtrack for: TTR short, TTR long, TRR (both
magnetrons) with TTR long and short pulse."
again from: "Frank E. Rappange" (f.e.rappange@pi.net) while discussing
Nike sites in Europe "
The use of multipulse was strictly forbidden in peacetime, the switch
was sealed. By the way we were even supposed to avoid picking up targets
in an easterly direction. Before we could fire up the magnetrons we had
to check with HQ for the presence of 'Zombies' (= civilian aircraft from
Warsaw Pact countries). We had to stay clear 400 mils on both sides with
any tracking radar.
"
from Rick at ShoreRick@aol.com
"The Multipulse mode of the TRR was a ECCM feature that the Tracking
Supervisor could select. This was used however in cases of very strong ECM
where the operators were having difficulty in tracking. The TRR receiver
would "sample" the frequency spectrum and select a frequency that was free
from jamming signals and transmit at that freq. The multipulse feature was
added later in the life of Nike.
The IF freq of the TTR was still 60 MHz. The TRR operated in the 14 Ghz range,
and in fact used three Backward Wave Oscillators (BWO). One for each
transmitter, and one for the panoramic receiver. The TRR contained two
transmitters and three receivers. Since the TRR had two of everything, it was
a simple radar to maintain. (If one unit had trouble, the TRR could still
operate.)
The above display shows an a-scope with a single very weak target signal
in the range notch. The fuzz or "grass" is primarily receiver noise, similar the
"snow" on your TV screen when the TV station received signal is very weak.
When the range gated signal is strong, the Automatic Gain Control (AGC) reduces the
receiver gain and system and noise tends to disappear. When the range
gated signal is weak, the AGC increases the gain and system receiver and
other noise is also amplified more, and becomes quite visible.
Enemy or accidental jamming can/will cause these and many other interesting
displays on the tracking scopes. Go to jamming for
more information.
There are various unverified stories that in practice combat between the
Air Force with their jamming equipment, and the Nike with their anti-jamming
equipment, that the Nike successfully tracked the Air Force planes and would
have had successful intercepts with the Hercules missiles.
This was reputed to be true even when the Air Force used their best jamming equipment
to try to confuse the tracking.
From Rolf Goerigk,
Specification for the Missile Tracking Radar (MTR) include:
There is one interesting "got cha" - the MTR can lock on to the *ground reflection* of the
missile's transponder. (Radar waves bounce off the ground as well as metal and water.)
The missile tracking operator must observe that the elevation angle of the MTR is correct
when locking on the missile. This can be called "multi-path, a pest even for FM and TV reception.
If locked on the ground reflection, the MTR will slew *down*
when the missile is launched - causing loss of tracking of the missile during launch -
and things happen so fast that there is no recovery from this error. The missile will
go straight up, detect that it is not being tracked, and explode in about 4 seconds. :-((
Since the missile tracking radar is not pointing at the target until the last few
seconds, the airborne enemy jammers only "see" the MTR for the last few seconds and
have much more trouble jamming it, especially with the high signal strength
of the transponder on the missile. The possibility of an enemy plane tracking
a Nike missile in order to jam it (cause it to fail to see the MTR
or to act on false steering and burst commands) would seem to be slight.
The time delay between the missile receiving the missile tracking radar pulse pair
and the generation of the response is fixed, and allowed for in the MTR range system.
Missile Commands - Communication systems to command the missile
The command is a pitch command if the "command"
pulse pair is separated by one missile code plus one microsecond.
The Pitch and Yaw commands are sent alternately during normal tracking until 0.5
seconds before intercept. First the pitch, then the yaw, then the pitch, ... .
Due to the coding, the missile knows which command is which type.
During the boost phase (4 seconds) and the roll phase (1 second), zero g yaw and
pitch commands are sent to the missile. Then normal steering commands are
sent to the missile, which is normally starts as a dive (from vertical)
to the predicted intercept point.
The burst command is a special series of pulses starting 0.5 seconds before predicted
intercept. No steering is performed during this final 0.5 second interval.
The following images are all from the the RC van, by Greg Brown.
Hercules Command System - Battery Code
Page 18, section 15A of Lesson 4 of MMS SUBCOURSE NUMBER 150
The Missile Tracking Radar (MTR) pointing system had an added circuit to automatically
point the the MTR at the designated missile. If the MTR was not tracking a launched
missile, and this circuit was engaged, the MTR would slew (in azimuth, elevation,
and range) to the position of the designated missile. The Launch Control Officer
would select the next missile to be fired based on:
How The Tracking Radar Points at an Object - Monopulse
There are now interesting articles in Wikipedia about
Monopulse radar and
RCA AN/FPS-16 Instrumentation Radar.
The tracking radars use the system called monopulse. In this system, each returning
radar pulse provides pointing information by being focused at the antenna onto a group
of 4 radar openings. The focusing can be done by either a simple radar lens, as in
the original Nike Ajax system (similar to the long refractor telescope of newspaper
cartoon fame) or a more complex Cassegrain
(folded) system used in the Hercules, similar to many modern optical
Cassegrain telescopes.
Looking at it from the
transmitter out, the Magnetron generates a high power pulse, it travels down the
waveguide of the sum channel, hits the comparator, gets broken up equally into
each port, and travels out the 4-port feed as horizontally polarized RF.
Nike Hercules Tracking Antenna Polarization tricks
This design is beautiful in that
you have basically no aperture blockage by the sub-reflector, and the radome
design of the antenna means there are no supports to cause aperture blockage and defraction.
The four windows are connected to complicated microwave "plumbing"
(discussed in the Wave guide section)
which gives the following
3 outputs:
The Sum video signal is sent to the range servo system and is the signal usually
displayed on the a-scopes.
The elevation difference and the azimuth difference radar signals
are processed
by the receiver circuits, and available to be gated into the servo system by the
range gate circuits to control the antenna elevation angle and the azimuth angle.
The goal of the servo systems is to reduce the pointing error to zero (and also to remain
stable - not oscillate about the zero error signal).
The antenna pointing controls the elevation and azimuth potentiometers which feed
position information into the computer.
There are several advantages (and no disadvantages that I know of) of Monopulse
pointing system over the
older (?original?) nutating radiating dipole pointing system.
Monopulse Wave Guide Schematic
Comments from the designer of the Hercules tracking antenna.
Target Ranging Radar (TRR)
All the others have been taken on the Nike RC Van actually located in Sardinia
on the Monte Cardiga site.
It's used as a radar relay (TTR only due to the good target tracking) between
various kind of radars located in the Salto di Quirra Fire Range Site
(courtesy of Mr. M. Reccia under my request).
I Have specified the various kind of radar circuits.
1)the unexpanded base line
2)and the expanded (greater time detail) of the notch.
As mentioned above, the external appearance of the Missile Tracking Radar (MTR)
was identical with the TTR above.
In addition to needing a view of the target volume, into which it guides the missile,
the MTR also need a direct view of the missiles on the launchers.
photo courtesy of Greg Brown, of SF-88 launcher from the IFC area.
Antenna Gain 44 dB
RF Peak Power 158.9 kW
Average RF Power (PRF 520 pps) = 79.4 Watt
There is one missile tracking operator with one a-scope. The missile tracking signal
is a radar pulse generated by the missile in response to a pair of radar pulses
transmitted by the missile tracking radar.
The missile "echo" is quite strong and gives a high "signal to noise ratio" and
looks like the
strong target tracking signal above. The missile is always tracked in
"automatic" mode. When every thing is working correctly, the missile
operator observes the equipment for proper operation,
but does not have to touch the equipment during missile firing operations.
Missile Tracking is a little different from Target Tracking
The Ajax and Hercules missile systems use different communication systems
(using the Missile Tracking Radar) to command the missile.
- Ajax Command System
- Hercules Command System
- Hercules Command System - Battery Code
In the Ajax system, missile steering commands are sent to the missile by the
missile tracking radar
by changing missile tracking radar pulse rate. You can think of the commands as
"tones", one tone range for up/down, another tone range for left/right, another
tone for burst. The tone signals are combined and control the generation
of radar pulse pairs.
In the Hercules system, missile steering commands are sent to the missile as follows:
Pitch, yaw and burst commands are not mixed as in the Ajax but are sent out
individually. One command is send out each 2,000 microseconds (500 commands per second).
Pitch and yaw commands are sent as two pulse pairs. Lets call the first pulse pair
the "start" pulse pair, and the second pulse pair the "command" pulse pair.
The "start" pulse pair are separated in time by the site specific
delay (called "missile code").
The command is
a yaw command if the pulse pair is separated by one missile code plus two microseconds.
The delay time between the last pulse of the first pulse pair and the last pulse pair
is the value of the command. The delay time for -7 g is 52.5 microseconds.
The delay time for 0 g is 87.5 microseconds.
The delay time for +7 g is 122.5 microseconds.
Battery Code Panels
Command Origin Chassis
Battery Code Panel
Greg Brown found the following chassis and document dealing with "Battery Code". Since it wasn't mentioned in
the document above, and doesn't specify down to
the microsecond, I'm confused. Or maybe too old a puppy :-((
The Wikipedia monopulse article is reasonably accurate until it gets to its
History section where it states that monopulse was "very expensive, labor intensive,
and less reliable". Simply not true - I contend the nutation system had those
negative characteristics
vs the monopulse system. Once you fabricate the wave guide system in monopulse (which has
no moving parts and in the X band fits in a cube 10 inches on a side) you are home free.
The few extra tubes (if any) involved hardly ever fail. Consider that the nutation
detection system is replaced by a simpler synchronous detector and added IF strip.
(I have no clue how the
wave guide assembly was fabricated.)
Please note, this is a schematic drawing, actually the feed horns (left) are very close together.
This is a more detailed diagram from TM9-5000-18 (available on this web site)
showing the complete wave guide detail. Unfortunately, the Tracking Radar at the SF-88
restoration is missing this unit (actually the entire RF section) so I cannot show a picture.
The exit labled "AFC" goes to the Automatic Frequency Control circuitry so that the
receiver can track the magnetron in frequency
(the magnetron is tuneable about +=10% nominal frequency).
This drawing ( from Hercules ) ( maybe more realistic than the schematic above )
is from GoogleBooks.
You better believe we on site never got in this far - something for Ordnance ;-))
After the various upgrades made in Europe
(The pre-upgrade at SF-88 (north of San Francisco)
seems even more of a prototype.)
From Ramiro Carli Ballola of Italy
Hello Ed,
The TRR pictures numbers 1/2 have been taken at Base Tuono Site RC VAN
(courtesy of Mr. M. Mastruffi under my request).
1 TRR Control Panel
2 TRR TRR PowerSupply and circuits
3 TRR Front Bottom right Synchronizer,
a side PAN ACS (Automatic Channel Selector)
4 TRR Oscilloscope
5 TRR IF Test Generator
6 TRR Power Supplies (1-missing)
7 TRR Voltage Regulators
8 TRR Delay Timers
9 TRR PAN RNG Log Amps Video Amp LP Filter
10 TRR A-B and PAN IF Circuit, ACS_circuits
11 TRR Synchronizer
TTR - Expanded Sweep
Radar Receiver Cabinets
for both MTR/TTR subAssy starting from the top the items list is the following:
Multi-path Problems & Work-aroundsThere 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
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."
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
Radar waves are just a (VERY) low frequency light wave. This is both good and bad news.
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. |
Good News
Bad News
... 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:
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
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:
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 -
Analog - pre-modernization
Digital - post-modernization - from Ramiro Carli Ballola
from Ramiro Nov 19, 2015
|
Radar Azimuth (horizontal direction) Determination
Analog - pre-modernization
Digital - post-modernization
|
Tracking Radar Physical Support
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 |
Simultaneous Tracking Test (the proof)
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:
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.
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)
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:
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
Jamming/spoofing slides from the archives of
"Association of Old Crows"
For more details on the T-1 unit, see
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
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
Resistance to ECM (Jamming)
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,
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Return to beginning of Nike Tracking Radars
Updated April 14, 2022
The above two changes permit MTR to track the aircraft just the same as the TTR system.
using the T-1 System
with many types and quantities of "interesting" ECM (jamming) problems.
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"
...
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.
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.
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%.