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12 Radar Systems of Maritime Transport
Fig. 12.1 Structural diagram of shipboard pulse radar. MRF—microwave receiver former; MTF—
microwave transmitter former; Osc—oscillator; PA—power amplifier; IFA; TCG—time corrected
gain; M—modulator; ICM—interference compensation module; meteorological disturbances;
DPU—digital processing unit
Therefore, the reflected microwave pulses without preliminary amplification
directly at the receiver input are converted into intermediate frequency pulses. The
required in this case frequency converter, capable of operating at microwave frequencies, uses a klystron or a Gunn diode local oscillator and a diode crystal mixer, which
can operate not only at centimeter, but also at millimeter waves. The mixer receives
continuously generated oscillations of the local oscillator with a frequency f H and
reflected pulses from the antenna with an oscillation frequency equal to the frequency
of the magnetron f osc . As a result of two frequencies mixing, pulses of the intermediate difference frequency f IF = f H − f osc are generated, which receive the necessary
amplification in the intermediate frequency amplifier (IFA), and then are fed to the
detector, where they are converted into video pulses.
At the output of the receiver, due to detecting, video pulses are formed, mixed
with noise (interference), which are fed to the control electrode of the cathode-ray
tube (CRT) of the indicator, creating an amplitude or brightness mark on the screen,
depending on the modulation method of the CRT’s electron beam.
The main technical characteristics of the shipboard radar are: wavelength (carrier
frequency); pulse repetition or repetition rate; transmitter power; the sensitivity and
bandwidth of the receiver, the shape of the antenna directional pattern in the vertical
and horizontal planes; the suppression degree of side lobes; behavior of field polarization; method and rate of airspace survey; type of terminal unit (indicator); overall
dimensions and weight of the station; type of power supply and power consumption.
Technical characteristics, or parameters, are selected based on the requirements of
the radar operational characteristics.
12 Radar Systems of Maritime Transport
Fig. 12.1 Structural diagram of shipboard pulse radar. MRF—microwave receiver former; MTF—
microwave transmitter former; Osc—oscillator; PA—power amplifier; IFA; TCG—time corrected
gain; M—modulator; ICM—interference compensation module; meteorological disturbances;
DPU—digital processing unit
Therefore, the reflected microwave pulses without preliminary amplification
directly at the receiver input are converted into intermediate frequency pulses. The
required in this case frequency converter, capable of operating at microwave frequencies, uses a klystron or a Gunn diode local oscillator and a diode crystal mixer, which
can operate not only at centimeter, but also at millimeter waves. The mixer receives
continuously generated oscillations of the local oscillator with a frequency f H and
reflected pulses from the antenna with an oscillation frequency equal to the frequency
of the magnetron f osc . As a result of two frequencies mixing, pulses of the intermediate difference frequency f IF = f H − f osc are generated, which receive the necessary
amplification in the intermediate frequency amplifier (IFA), and then are fed to the
detector, where they are converted into video pulses.
At the output of the receiver, due to detecting, video pulses are formed, mixed
with noise (interference), which are fed to the control electrode of the cathode-ray
tube (CRT) of the indicator, creating an amplitude or brightness mark on the screen,
depending on the modulation method of the CRT’s electron beam.
The main technical characteristics of the shipboard radar are: wavelength (carrier
frequency); pulse repetition or repetition rate; transmitter power; the sensitivity and
bandwidth of the receiver, the shape of the antenna directional pattern in the vertical
and horizontal planes; the suppression degree of side lobes; behavior of field polarization; method and rate of airspace survey; type of terminal unit (indicator); overall
dimensions and weight of the station; type of power supply and power consumption.
Technical characteristics, or parameters, are selected based on the requirements of
the radar operational characteristics.