We have two radars on board one is S band JRC radar and the other is RAYTHEON radar.We do not use JRC radar. Ray theon is a X band , semi-arpa radar. The technical characteristics of the radar are counted below:
Frequency: 9410 ± 30 MHZ
Magnetron peak power: 25 KW
Pulse length/PRF: 0,05 µs/ 1200 Hz
0,25 µs/ 1200 Hz
1,00 µs/ 600Hz
Horizontal beam width: 1,3º
Vertical beam width: 24º
Display type: Colour, 15 inch
Scan form: Raster Scan
This radar meets all performans standards required by IMO
Factors Affecting the Radar Display;
There are four factors that are affecting the radar display these are namely, maximum range, minimum range, range accuracy and bearing accuracy. All these factors are effected that factors which I mentioned on the below.
Frequency;
The higher the frequency of a radar (radio) wave, the greater is the attenuation (loss in power), regardless of weather. Lower radar frequencies (longer wavelengths) have, therefore, been generally superior for longer detection ranges.
Peak Power:
The peak power of a radar is its useful power. Range capabilities of the radar increase with peak power. Doubling the peak power increases the range capabilities by about 25 percent.
Pulse Length:
The longer the pulse length, the greater is the range capability of the radar because of the greater amount of energy transmitted.
Pulse Repetition Rate:
The pulse repetition rate (PRR) determines the maximum measurable range of the radar. Ample time must be allowed between pulses for an echo to return from any target located within the maximum workable range of the system. Otherwise, echoes returning from the more distant targets are blocked by succeeding transmitted pulses. This necessary time interval determines the highest PRR that can be used. The PRR must be high enough, however, that sufficient pulses hit the target and enough echoes are returned to the radar. The maximum measurable range can be determined approximately by dividing 81,000 by the PRR.
Beam Width:
The more concentrated the beam, the greater is the detection range of the radar.
Target Characteristics:
Targets that are large can be seen on the scope at greater ranges, providedline- of- sight exists between the radar antenna and the target. Conductingmaterials (a ship’s steel hull, for example) return relatively strong echoeswhile nonconducting materials (a wood hull of a fishing boat, for example) return much weaker echoes.
Receiver Sensitivity:
The more sensitive receivers provide greater detection ranges but are more subject to jamming.
Antenna Rotation Rate:
The more slowly the antenna rotates, the greater is the detection range of the radar. For a radar set having a PRR of 1,000 pulses per second, a horizontal beam width of 2.0°, and an antenna rotation rate of 6 RPM (1 revolution in 10 seconds or 36 scanning degrees per second), there is 1 pulse transmitted each 0.036° of rotation. There are 56 pulses transmitted during the time required for the antenna to rotate through its beam width. With an antenna rotation rate of 15 RPM (1 revolution in 4 seconds or 90 scanning degrees per second), there is only 1 pulse transmitted each 0.090° of rotation. There are only 22 pulses transmitted during the time required for the antenna to rotate through its beam width. From the foregoing it is apparent that at the higher antenna rotation rates, the maximum ranges at which targets, particularly small targets, may be detected are reduced.
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