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Monopulse Technique

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shailendra gupta

on 4 October 2013

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Transcript of Monopulse Technique

Presented By
Shailendra Kumar Gupta
Manager (Elex)

Achieved by the design of
the antenna and deriving 3 different signals in receive path
SUM,
DIFF &
OMNI

Monopulse Technique
Primary Secondary

SSR MSSR

RADAR is an acronym for RAdio Detection And Ranging

in INDRA, monopulse table is generated dynamically using live targets. This value is added to or subtracted from the boresight azimuth to give a precise target azimuth
This table contains the relation between the digitized monopulse video and the number of ACP correction (Values on the table are represented in . ACPs).
The azimuth correction will be given by:
Δ Az = No. of ACP (in table) * 360 ⁰ / 16384 ACP (per scan).
Target azimuth = Antenna azimuth + Δ Az

Each value is further devided into 4 slots making total 8192 slots for higher precision.
Values on Monopulse table is represented in ¼ ACP in INDRA MSSR
For each processed received pulse, a monopulse value is assigned.
Each monopulse value is used to address an off-boresight table (OBT)







half-angle monopulse processor
which generates a single valued output over the entire range of sum/difference
ratios. The output is given by the approximate formula:
f(Δ, Σ)= 2 arctan (Δ/ Σ)

ACP Correction

Off-boresight angle as a function of sum and difference channel signals

A/D converter generates a 8 bit (12 bit in INDRA MSSR) monopulse data to the processor. This monopulse data divides the 4⁰ beamwidth into 256 bins or slots in NGOSCO and 4096 (212) slots in INDRA.
The voltage range is -2048mV to +2048mV on x-axis and the ACP values from -128 to +128 in y-axis is used in INDRA

To ensure accurate off boresight estimation ∆/ Σ should remain stable within 3 db beam width over all practical elevation angle

Off boresight angle of the target is estimated from ∆/ Σ ratio

on the other side of the boresight, Σ
is out of phase with ∆

At Off Boresight

At Boresight

Signal received at Antenna A & B are in phase.
Sum= A+B is Maximum (Σ)
Difference= A-B is Minimum (∆)
Ratio (∆/ Σ)= Zero
The Azimuth of the target is the ACP of the Antenna measured.

At Boresight

At Boresight

This technique requires two antennas or split antenna with each antenna or each section separately fed

This is achieved by the design of
the antenna and deriving 3 different signals in receive path namely, SUM, DIFF
and OMNI

Monopulse is a technique used for applying correction to the azimuth information
derived from the ARP / ACP

Logarithmic receiver is used to deal with wide dynamic range
Receiver uses matched channels (for ∆ & Σ) having stable gain and phase characteristic over entire dynamic range and third channel (control Ω) for RSLS function.

Monopulse Receiver

This technique requires two antennas or split antenna with each antenna or each section separately fed

Monopulse Antenna (Ex. LVA CSL-M used in Indra)
Twin Channel Monopulse RX (MRU in INDRA)
Monopulse off boresight angle processor (MRU in INDRA)
Plot Extractor ( MEX in INDRA)

Monopulse System

technique that allows the measurement of target azimuth from single reply pulse
simultaneous lobe comparison for measuring the direction of arrival of radiation.

Monopulse Technique

Range
Azimuth
Aircraft Identity (Mode A)
Flight Level ( Mode C)

Secondary Radar gives

Presented By:
Shailendra Kr Gupta
Manager (Elex)

MONOPULSE TECHNIQUE

Δ Az = 64*360 / 16384 = 1.4060
Target azimuth = Antenna azimuth + 1.4060

Off boresight angle (OBA) is calculated using this unit.
Azimuth of Aircraft= Antenna bearing+OBA
Sign of the ratio determines left or right side of correction form boresight.



Monopulse Extractor

By introducing a 90 degree phase shift in to the A, on one side of the boresight, Σ is in phase with ∆


At off boresight Σ decreses and ∆ increses

At Boresight

In SSR Azimuth measurement is through Sliding window technique

Σ- channel

Δ- channel

Monopulse Antenna

Primary Secondary

SSR MSSR

RADAR is an acronym for RAdio Detection And Ranging

in INDRA, monopulse table is generated dynamically using live targets.
This value is added to or subtracted from the boresight azimuth to give a precise target azimuth
This table contains the relation between the digitized monopulse video and the number of ACP correction (Values on the table are represented in . ACPs).
The azimuth correction will be given by:
Δ Az = No. of ACP (in table) * 360 ⁰ / 16384 ACP (per scan).
Target azimuth = Antenna azimuth + Δ Az

Each value is further devided into 4 slots making total 8192 slots for higher precision.
Values on Monopulse table is represented in ¼ ACP in INDRA MSSR
For each processed received pulse, a monopulse value is assigned.
Each monopulse value is used to address an off-boresight table (OBT)


A/D converter generates a 8 bit (12 bit in INDRA MSSR) monopulse data
to the processor. This monopulse data divides the 4⁰ beamwidth into 256 bins or slots in NGOSCO and 4096 (212) slots in INDRA.
The voltage range is -2048mV to +2048mV on x-axis and the ACP values from -128 to +128 in y-axis is used in INDRA




Half-angle monopulse processor

which generates a single valued output
over the entire range of sum/difference
ratios. The output is given by the approximate formula:
f(Δ, Σ)= 2 arctan (Δ/ Σ)

Δ Az = 64*360 / 16384 = 1.4060
Target azimuth = Antenna azimuth + 1.4060

Off-boresight angle as a function of
sum and difference channel signals

Off boresight angle (OBA) is calculated using this unit.
Azimuth of Aircraft= Antenna bearing+OBA
Sign of the ratio determines left or right side
of correction form boresight.



Monopulse Extractor

To ensure accurate off boresight estimation ∆/ Σ
should remain stable within 3 db beam width over all practical elevation angle

Off boresight angle of the target is
estimated from ∆/ Σ ratio

on the other side of the boresight, Σ
is out of phase with ∆

By introducing a 90 degree phase shift in to the A,
on one side of the boresight, Σ is in phase with ∆


At off boresight Σ decreses
∆ increses

At Off Boresight

Signal received at Antenna A & B are in phase.
Sum= A+B is Maximum (Σ)
Difference= A-B is Minimum (∆)
Ratio (∆/ Σ)= Zero
The Azimuth of the target is the ACP of the Antenna measured.

At Boresight

At Boresight

This technique requires two antennas
or split antenna with each antenna or
each section separately fed

This technique requires two antennas or split antenna
with each antenna or each section separately fed

In SSR Azimuth measurement is
through Sliding window technique

Range
Azimuth
Aircraft Identity
(Mode A)
Flight Level
( Mode C)

Secondary Radar gives

MONOPULSE TECHNIQUE

ACP Correction

At Boresight

At Boresight


Rx uses matched channels (for ∆ & Σ) having stable gain and phase characteristic over entire dynamic range and third channel (control Ω) for RSLS function.

Monopulse Receiver

Plot Extractor
( MEX in INDRA)

Monopulse System

Σ- channel

Δ- channel

Monopulse Antenna

Primary Secondary



RADAR is " RAdio Detection And Ranging"

Monopulse Antenna
(Ex. LVA CSL-M
used in Indra)
Twin Channel Monopulse
RX (MRU in INDRA)
Monopulse off boresight angle processor (MRU in INDRA)
Logarithmic receiver is used to deal with wide dynamic range
Technique used for applying
correction to the azimuth information
derived from the ARP / ACP

Measurement of target
azimuth from single reply pulse

simultaneous lobe comparison
for measuring the direction of
arrival of radiation

SUM OMNI & Difference
At Off Boresight

SSR
MSSR
Thanks
Full transcript