GATE-2018 (24) :Wyllie – Time average equation

Gate_2019

76) An aeromagnetic survey is conducted over an area with outcropping magnetic sources. The aircraft is flying at a height of 250 m with a speed of 200 km/hour. In order to fully define the magnetic anomalies along the flight path, the largest sampling rate of measurement by a Proton Precession Magnetometer will be ________ seconds. (Round off to the nearest

Integer).

(Thanks to Chandra Sekhar, ANU)

 

Solution:

Given that height(h) = 250 m

Velocity(V) = 200 km/hour

            V =$\frac{200\times 10^{3}}{3600}$ m/sec

           V =55.55 m/sec

Sampling rate ($t_{s}$) = ?

The maximum time taken by the aircraft is $t_{max}$

$t_{max}= \frac{distance}{velocity}$

$t_{max}= \frac{250}{55.55}$

$t_{max}= 4.5 sec$

Therefore $f_{max}= \frac{1}{t_{max}}$

$f_{max}= \frac{1}{4.5}$

$f_{max}= 0.222 Hz$

The sampling Frequency $f_{s}= 2\times f_{max}$

$f_{s}= 2\times 0.222$

$f_{s}= 0.444 Hz$

The sampling rate is given by $t_{s}= \frac{1}{f_{s}}$

$t_{s}= \frac{1}{0.444}$

$t_{s}= 2.25 sec$

The sampling rate of the measurement is 2 sec by rounding off the 2.25 to nearest integer