EMS 5

Question 1

Explain Doppler Shift

Answer 1

The doppler effect for an observer is the apparent change in frequency of a wave when there is relative motion between the
source and the observer.
* The apparent change in frequency is called Doppler Shift.
* The amount of Doppler Shift is expressed in Hertz.

Question 2

Describe differences between Coherent and Non-Coherent waveforms

Answer 2

Coherent waveforms are phase consistent from one transmitted pulse to the next when compared to a continuous reference signal.
Non-coherent waveforms have phase inconsistencies from one transmitted pulse to the next.

Question 3

Describe the benefits of a Coherent radar

Answer 3

Received signals are sorted by Doppler shift.
* Identifying Doppler shift allows target speed to be calculated.
* Doppler shift is also employed as a background clutter reduction technique.

Question 4

Explain the applications of Doppler

Answer 4

• Sonar systems – Marine applications using sound waves
• Radar gun – Speed
• Space – Stars : Red shift/ Blue shift
• Echocardiogram – Medical imaging