Problem of ambiguous range measurements encountered in Pulse Doppler Radar only.

Explanation:
The problem of ambiguous range measurements is encountered in Pulse Doppler Radar. This issue arises due to the presence of range ambiguity in the radar system. Range ambiguity occurs when the radar receives multiple echoes from different targets within the same range bin.

Causes of Range Ambiguity:
Range ambiguity can occur in Pulse Doppler Radar due to the following reasons:

1. Pulse Repetition Frequency (PRF): In Pulse Doppler Radar, the PRF is used to determine the maximum unambiguous range. If the PRF is too high, it can lead to range ambiguity because the radar pulses may overlap in time and cause echoes from different targets to be received within the same range bin.

2. Target Velocity: Another factor that contributes to range ambiguity is the target velocity. If the target is moving at a high velocity, the received echoes from different pulse repetitions can overlap in range and result in range ambiguity.

Effects of Range Ambiguity:
Range ambiguity can have several effects on the radar system:

1. False Target Detection: When range ambiguity occurs, the radar system may incorrectly detect multiple targets at the same range. This can lead to false target detections and inaccurate tracking.

2. Range Measurement Errors: The presence of range ambiguity can also introduce errors in the range measurement of targets. The radar system may not be able to accurately determine the true range of a target due to the overlap of echoes from different targets.

Solutions to Range Ambiguity:
To overcome the problem of range ambiguity in Pulse Doppler Radar, the following techniques are commonly used:

1. Pulse Repetition Frequency (PRF) Switching: By using multiple PRFs, the radar system can avoid range ambiguity. The PRFs are switched in a predetermined sequence, and the range measurements are obtained by comparing the received echoes with the corresponding PRFs.

2. Pulse Compression: Pulse compression techniques, such as matched filtering, can be employed to improve the range resolution of the radar system. This can help in resolving the range ambiguity and accurately determining the true range of targets.

Conclusion:
In conclusion, the problem of ambiguous range measurements is encountered in Pulse Doppler Radar only. This issue arises due to the presence of range ambiguity, which can be caused by factors such as PRF and target velocity. It can lead to false target detections and range measurement errors. To overcome this problem, techniques such as PRF switching and pulse compression are used in Pulse Doppler Radar.