1. Integration of Pulse
The process of summing all the radar pulses to improve detection is known as “Pulse integration”
A search-radar beam scans, the target will remain in the beam sufficiently long for more than one pulse to hit it. This number is known as hits per scan.
For a ground based search radar with antenna scan rate 5 rpm, beam width 1.5o and PRF 300Hz, the number of hits would be 15/scan.

2. A pulse integrator is a improvement technique to address gains in probability of detection by using multiple transmit pulses.
Depending on location of the pulse integrator in the signal processing chain this process is referred to as
coherent integration.
non-coherent integration.

3. Coherent Integration:
Insertion of a Pulse integrator between the matched filter and amplitude detector.
The signal processor samples the return from each transmit pulse at a spacing equal to the range resolution of the radar set and adds the returns from N pulses. After it accumulates the N pulses, performs the amplitude detection and threshold check.
Non-Coherent Integration :
Integrator is placed after the amplitude or square law detector.
The name non-coherent integration derives from the fact that, since the signal has undergone amplitude or square law detection, the phase information is lost.
The non-coherent integrator operates in the same fashion as the coherent integrator in that it sums the returns from N pulses before performing the threshold check.

4. Non-Coherent Integration
Predetection Integration
Postdetection Integration
Phase information of the echo signal is preserved
Detector destroys phase information. Less efficient than predetection.
If n pulse are integrated, the SNR of integrated signal is nSNR.
If n pulse are integrated, the SNR of integrated signal is lesser than nSNR.
Difficult to implement
Easy to implement

5. The integration efficiency may be defined as
Ei(n) – Integration efficiency,
SNR(1) – Single pulse SNR required to produce a specific Pd if there is no integration,
SNR(n) – Single pulse SNR required to produce a specific Pd if n pulses are integrated perfectly.
The improvement in SNR if n pulses are integrated, (post detection) is nEi(n)
Ii(n) = nEi(n) is called as Integration improvement factor, or the equivalent number of pulses integrated (neq).
In Predetection, (neq) = n
In postdetection (neq) < n.

6. The integration loss is specified in dB.
The radar equation with n pulses integrated can be written as
Substituting IIF,

7. Radar Cross Section of Targets
Radar cross section is the area intercepting the amount of power and scatters in all direction.
A formal definition is,
RCS depends on the target shape, dimensions, materials, polarization etc.,

8. Resonance region:  is comparable with object’s dimension.
Rayleigh Region : The wavelength () is large compared to the object’s dimensions.
 is proportional to f4.
 is determined by the volume than its shape.
E.g: Echo from rain
Optical region: The wavelength () is small compared to the object’s dimensions.
 is affected by shape than projected area.
E.g: Scattering from Aircraft
Resonance region:  is comparable with object’s dimension.
 is larger in resonance region than the other two regions.

9. RCS of Sphere – simple target