Transcript RADAR - TalkTalk

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RADAR
Chuck Hobson BA BSc (hons)
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INTRODUCTION
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This presentation starts with the early beginnings of Radar in the United States
and Great Britain. It moves on from there to describe various military and civilian
radars, how they work and what they look like. In keeping with this, I shall first
kick off with my own early beginnings and how I fit into the picture.
I was born and raised in Pittsburgh Pennsylvania, which is located at the heart of
the US steel and coal mining industries. My early years were spent there during
the Great Depression. I graduated from High School at the age of 17 in 1944. Like
most young men in similar circumstances at that time, I contemplated my future,
which included the military draft and a life time working in Steel Mills. With such a
future to look forward to, I became very depressed indeed.
Then one morning while walking in down town Pittsburgh I spotted a US Navy
recruitment poster in a Post Office window. My spirits soared. “US Navy wants
young men in Radar!” I rushed into the Post Office where I suddenly found myself
confronted by a very intimidating US Navy Chief Petty Officer.”So you want to join
the Navy”, he asked? I mentioned the Radar poster and he said I would have to
pass a written test on mathematics and physics to get into the Navy’s Radar
school. I was really elated as those were my favourite high school subjects.
I said I would like to take the test please. The Chief said It was called “The Captain
Eddy Test”, which consisted of 80 questions, and that very few ever passed it. He
then handed me the test paper and told me I had two hours to complete it.
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INTRODUCTION
(continued)
I completed the test in an hour and 10 minutes and handed it back to the Chief.
He asked me, “What’s the matter, can’t you answer the questions?” I told him I
finished the test. He marked it and graded it a pass. The chief then handed me
an official looking US Navy form and told me to give it to the doctor in an
adjoining room.
The physical exam took about 5 hours, It was truly an ordeal. Having passed
that I found myself on my way to Boot Camp the following week with a Seaman
First Class rating (S1/c). After surviving four weeks of accelerated boot training,
I went on to attend a suite of US Navy technical schools. The first was called
“Pre-Radio School.” It was a gruelling four weeks of mathematics. I managed
that (30% survival rate). From there I went on to the next level, “Primary Radio
School” for 3 months. It included electronic theory, some higher math, and
building elementary receivers. After finishing and passing that, I went on to the
final level, “Secondary Radio School.” That lasted six months. This school
included a lot of electronic theory, which was taught in the mornings. The
afternoons were taken up with extensive hands on experience: Radar and Sonar
sets, Communication gear, and Navigation equipment.
I graduated in the top 10% of the class and was awarded a second class petty
officer rating. (RT2/c) It was not because I had a super brain, but because I was
adicted to electronics and completely immersed in my studies. (The Nerd mode)
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INTRODUCTION
(continued)
During the next 6 years I served aboard various Naval ships and on shore
stations repairing any and all kinds of Naval Electronic Equipment. If it
contained vacuum tubes (valves) magnetrons and klystrons, I had a go at it:
Fire Control, Air and Surface Search Radars, HF/VHF/UHF Transmitters and
Receivers, Loran etc. That experience along with the Navy’s education/training
in Radar set me up for life in the field of Electronics. In the process I became
quite familiar with many kinds of Radars, which is what this Radar presentation
is all about.
The next slide shows a picture of the USN Recruitment Poster I saw in
Pittsburgh, a photo of me taken in Boot Camp and and another of an early US
Navy Destroyer Escort. From there the presentation goes strictly into Radar.
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MY BEGINNINGS
S1/c Chuck Hobson Jan. 1945
US Navy Recruiting Poster 1944
US Naval Destroyer Escort DE-316
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WHAT IS RADAR
• RADAR: RAdio Detection And Ranging (American)
• RDF:
Radio Direction Finding (British)
• Doover: Australian equivalent to thingamajig
• Radar transmits short high powered burst of RF energy
• RF energy travels towards aircraft at speed of light
• RF illuminated aircraft re-radiates signal back to Radar
• Radar measures RF energy round trip time (12.3µs per nm)
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RADAR USERS
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NOTES: PAR = Precision Approach Radar
ASDE = Automated Surface Det Equipment
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HOW RADAR CAME ABOUT IN THE U.S.
• THE EARLY BEGINNINGS
• U. S. Naval Research Lab:
• 1934 – 1935 experimented with Pulsed Radar
• 1936 Demonstrated Pulse Radar
range (Air Search Radar)
25 mile
• 1937 Installed 200MHz Radar on
destroyer
• 1938 – 1945 Installed same radar on
DDE’s DD’s CA’s BB’s Carriers and
various other ships (SC series Air Search
Radar)
Typical Destroyer mast
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HOW RADAR CAME ABOUT IN BRITAIN
THE EARLY BEGINNINGS
1933 Ionosphere sounding
Experiments with HF
1. 1934 Examined HF fading
caused by aircraft.
2. 1935 Deventry Experiments
Demonstrated Feasibility
3. 1935 developed & demonstrated Pulsed
Radar at Orfordness leading to
construction of CH Radar
4. 1936 – 1939 Built the CH Radar system
Chain Home Radar
Transmitter Antennas
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THE TIZARD COMMITTEE
Scientific Survey of Air Defence Committee
Tizard Chairman Rector of Imperial College
Rowe Secretary
Air Ministry
Wimperis Member
Air Ministry
Watts
Radio RS Supt.
Member
This committee’s job was to. investigate new
technologies for defense against air attacks.
Their 1st task given to Watson Watts was:
calculate the amount of RF energy needed to
disable the pilot and aircraft in flight?
His results shown it to be impractical. Subsequently Arnold Wilkins was
asked via Rowe and Watts how he may help the Air Ministry with their
task. Hence, efforts to develop Radar began. (This was in early 1935)
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ARNOLD WILKINS
Scientific Officer at the Radio Research Station
Expert on antennas & the behaviour of radio waves
Conducted Deventy experiment
Participated in pulsed radar tests at Orfordness
ARNOLD WILKINS
(1907 – 1985)
RRS known as Home of the Invention of Radar
Credit for invention given to Sir Watson Watts**
** 1933 Wilkins familiar with pulsed RF techniques Ionosphere sounding
Noted flutter of VHF (60MHz) signals from nearby Aircraft
Subsequently mentioned this to Watts
Joint Watts Wilkins memo presented to Tizard Committee
Led to Deventry Experiment, Radar tests at Oxfordness & CH Radar
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THE DEVENTRY EXPERIMENT
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THE DEVENTRY EXPERIMENT
Heyford Bomber
RAF Long Range Bomber
Prototype Flown in 1930
Speed 229km/hr (142 mph)
Range 1480km (920 Miles)
Ceiling 6400m (21000 ft.)
Deventry Experiment Site
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ORFORDNESS
1. Radar proposal by Watts and Wilkins accepted and go ahead given
2. Highly secret work started Apr. 1935 at Orfordness an isolated place
3. A very austere operation
4. Test equipment 2 HF wave meters, 2 Avometers, & misc. VM & AM’s
5. Tech book Radio Amateur Handbook: Wilkins & other 2 were “Hams”
6. Erected two 75’ wooden towers for Xmtr and 4 others for Receivers
7. Transmitter problems: Flash over and pulse width Corona on ant.
8. Committee appeared on site expecting results (June 1935)
9. 50 metre freq. Used. Atmospheric noise problems.
10. Echo from Valencia A/C observed at 27km
11. Committee gave glowing report to Air Ministry
12. Shifted to 22MHz (14m) atmospheric problem went away.
13. Pulse width down from 50µs to 10µs
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CHAIN HOME (CH) RADAR
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Following Orfordness development work, a system of 20 CH radars
were strung up along the south and east coasts of England just
before World War Two.
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These radars gave the RAF a distinct advantage over the German
Luftwaffe.
•
These radars were able to detect incoming enemy bombers and
provide the RAF with their range, direction and altitude (position)
•
With this information the RAF could choose when and where, or
simply not to engage the enemy bombers (A distinct tactical
advantage)
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Map of Chain Home Radars
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CHAIN HOME (CH) RADAR
1. Pulse type radar operating at 20 to 30MHz Transmitter
peak power: 350kW/750kW
2. Large HF antennas strung up between two 100 metre
high steel towers for transmitting
Transmitted very broad beam to illuminate all aircraft in search area
Receiving antennas (not shown) provided azimuth and elevation data
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CHAIN HOME (CH) RADAR
1. Second set of cross type antennas on 60m
high towers for receiving.
Cross Dipoles mounted
on wooden towers
Antennas were used to DF on reflections from aircraft
DF was achieved by phasing cross dipoles with goniometers
Beam was shifted left, right, up and down with goniometers calibrated in
az. and el. Mechanical calculators converted elevation angle to altitude.
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LUFTWAFFE FLYING BELOW CH RADAR BEAM
1. Chain Home Low (CHL) Radars added (1939 - 1940
2. Picked up Luftwaffe flying below CH radar beams
3. Operated at 180 – 210MHz
4. Antenna broadside 32 dipole array
5. Horizontal Beam width 200
6. Antenna steered on pedal crank by WAAF
7. “A” Scope display. PPI introduced in 1940
8. Antenna rotated at ~ 1 to 2 rpm
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CHAIN HOME GCI RADAR ADDED
1. GCI = Ground Control Intercept
2. 500MHz –600MHz GCI Radar introduced in 1942
3. Peak Power 50kW PW 4µs Rep-Rate 500pps
4. Antenna beam width ~4.50 Hor. And 7.50 Vert.
5.
On 200’ tower detect bombers flying 500’ at 120miles
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IDENTIFICATION FRIEND OF FOE
Radar)
• PASSIVE REFLECTOR
• MARK I
• MARK I I
• MARK I I I
• MARK X
THIS SLIDE IN WORK
IFF (Secondary
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BASIC RADAR TYPES
CW DOPPLER RADAR
PULSED RADAR
PULSE DOPPLER RADAR
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CW DOPPLER RADAR
CW MICROWAVE TRANSMITTER (3cm 10GHz)
Compares Transmitted Freq to reflected signal frequency from moving
objects to get Doppler shift frequency. Radar sees only moving objects
Aircraft: GCA operations. Approaching aircraft
Doppler shift
speed determined from
Road Traffic: Police Radar. Traffic speed determined from Doppler shift
Meteorology: Sees moving cloud masses etc.
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PULSED RADAR
PROVIDES: Range - Azimuth- Elevation Information
USED FOR:
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Surveillance Radar (Surface and air search)
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Precision Tracking Radar. Provides accurate
Range information for:
Az El and
a. Ground Control Approach GCA
b. Military Fire Control and Gun Laying Radars
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Satellite Tracking Radar
Transponders)
(Sat. have
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PULSED RADAR SYSTEM
BASIC PULSED RADAR SYSTEM
Timer is sometimes regarded as a Synchronizer
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PULSED RADAR DISPLAYS
PPI: PLAN POSITION INDICATOR
N
W
E
S
• PPI Scope: Most popular display
• Provide maplike display in Azimuth and Range
• Polar coordinates: Range centre outward Azimuth 0 to 3600
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US NAVY SC RADAR CONSOLE
Probably USN Radar Operator’s School
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REPORTING RADAR SIGNAL STRENGTH
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PULSED RADAR TRANSMITTER
RADAR TRANSMITTER (MAGNETRON)
PFN charges up to 12kV (dc resonance Choke L and PFN C)
Energy stored in PFN = ½ V2C In this case 2 Joules.
Thyratron discharges PFN in 2µs which is stepped up to –27kV pulse
2 Joules of energy used in 2µs represents 1.0MW pk pwr input to Maggy
With pulse rate = 400pps, Duty Cycle = 2/2500. Average pwr. = 800W
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PULSED RADAR TRANSMITTER COMPONENTS
HYDROGEN THYRATRON VX2511
VX2511
Pk
I 350A
Ave. I
350mA Max V
20kV**
X BAND MAGNETRON (2J36)
Pk I 12A Pk
V 14kV Pk
Pwr 17kW
Freq. 9.1GHz
** Hold off Voltage
Used with 500kW
Radars
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L-Band Magnetron (5J26) tunable
Pk ~ I 35A
Pk V 27kV
Pk Pwr ~900kW
Freq.~ 1.25GHz
Z = 800
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PULSE DOPPLER RADARS
DISTINGUISHES BETWEEN FIXED & MOVING TARGETS
Surveillance Radars (Surface and air search)
Precision Tracking Radars
Relies heavily on digital signal processing (dsp)
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PULSE DOPPLER RADARS
SIMPLIFIED WEATHER RADAR SYSTEM
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MOVING TARGET INDICATOR (MTI)
STALO: Stable Local Oscillator
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MILITARY RADARS
US Navy 10cm Radar
Surface Search SG-1b
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BMEWS Radar Antenna
Navy Destroyer Escort Mast
USN Fire Control Radars
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US ARMY WW2 RADARS
AN/TPS-1B Range & Azimuth
Air Search Radar
Developed by Bell Telephone Labs
Produced by the Western Electric
Operated by crew of two
Detects bombers alt 10k at 120 nm
AN/TPS-10A Height Finder
Developed by MIT's Radiation Lab
Produced by Zenith
Operated by crew of 2
Detected bombers alt. 10k at 60 nm
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MILITARY RADAR STATION
X-Band Height Finder
Type: AN/TPS-10D.
Freq : 9230 - 9404 MHz.
Power output: 250kW
Range: 60/120 miles.
Pulse width : .5 & 2µs
RAF service Type 61 Mk2
L Band Search Radar
Type: TPS-1B
Freq. 1.2 – 1.3GHz
Power output 500kW
Range: 120nm
Pulse width: 2µs
RAF service Type 60
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GCA RADAR
(Ground Control Approach)
Gilfillan
Freq: 9,000 - 9,160 MHz
Pulse Rep. Freq. (PRF): 1,500 Hz
Pulse-width: 0.18 to 0.6µs
Peak Power: 150 kW
Displayed Range: 40 nmi
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MILITARY HEIGTH FINDER
Military AN/FPS-6 Height Finder
Frequency:2600 - 2900 MHz
(PRF):300 - 405Hz
Pulse-width (PW):2.0µs
Peak Power:2.0MW
Displayed Range:300nm
Range Resolution: 1000ft
beamwidth: 3.2 degrees Az 0.9 El
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AIRPORT RADAR
Frequency 10GHz
Antenna Rotates at 60 RPM
ASDE (Airport Surface Detection Equipment
Scans Airport Surface to Locate Vehicles and Aircraft
Limitation due to RF Multipath and Target ID problems.
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AIRPORT RADAR
Digital Airport Surveillance Radar
Primary Radar Frequency 2.7 – 2.9GHz
Peak Power 25kW
Secondary Radar (IFF) Top Array
Interrogator Frequency 1030MHz
Aircraft Transponder Freq. 1090MHz
Detects Aircraft and Weather Conditions in Airport Vicinity
Detection Range out to 60 Miles
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US NAVY RADAR
US Navy Air Search Radar
SPS-49A (MID 1990’s)
Frequency 850 – 942MHz
Antenna Size 8 X 24 ft.
Stabilized in Pitch and Roll
Beam width 3.30 Az 110 El
Parabolic CSC2
Rotation Rate 6 or 12 rpm
Peak Power 360kW
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Development began in the 1970’s by The US Naval Research Lab
Latest Version Determines radial speed of each Target
Uses Unique Digital Signal Processing Developed by the NRL
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POLICE RADAR
K Band Speed Gun
Range 3500 feet
Locks on Target
3 Digit MPH or kmH Display
DECATUR $1250
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FLAT ARRAY ANTENNAS
Used in MIG29 Zhuk-ME radar
Flat Slotted Array Antenna
Requires Mechanical Steering
Used in MIG29M2 NIIP BARS 29 Radar
Phased Array Electronic Steering
Scans and Tracks Multiple Targets
Considerable Losses in Phase Scanning
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ACTIVE ELECTRONIC STEERED ARRAY
Array APG-81 AESA (X-Band)
Picture Shows Grumman Test Bed
2000 TR Modules ($2,000 each)
Total cost of Antenna $2,000,000
AN/APG 79 AESA Radar
Fitted on USN F/A-18E/F Super-Hornet
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Thank you for viewing my Radar Presentation
I hope you found it informative and enjoyable
Chuck Hobson G0MDK
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