Background to the problem: When an ambulance passes in the street the pitch of the siren drops suddenly as it passes by.

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Background To The Problem When An Ambulance Passes In The Street The Pitch Of The Siren Drops Suddenly As It Passes By 1 (65.98 KiB) Viewed 42 times

Background To The Problem When An Ambulance Passes In The Street The Pitch Of The Siren Drops Suddenly As It Passes By 2 (48.23 KiB) Viewed 42 times

note - you can just refer to the PI and individual number as'PI' and 'IN'

Background To The Problem When An Ambulance Passes In The Street The Pitch Of The Siren Drops Suddenly As It Passes By 3 (31.62 KiB) Viewed 42 times

Background to the problem: When an ambulance passes in the street the pitch of the siren drops suddenly as it passes by. This is because the sound waves are compressed as the ambulance approaches and decompressed as the ambulance moves away. This is an example of "Doppler Shift". Radio waves in cellular communications are subject to Doppler shift when the transmitter and the receiver are moving relative to each other. The importance of Doppler shift to mobile radio communications is that a large shift could move a transmission from one channel to another, especially when channels are closely spaced. A typical situation for cellular communications is when the cell phone is moving, as in the illustration below. The car with the cell phone is moving from A to B at speed or velocity v towards the cellular base station which is transmitting to the cell phone in the car. 2300 MHz A B Figure 1 A scenario where a car with a cell phone inside is moving towards the cellular base station.
The problem: Imagine you are a passenger in a car moving at velocity v either towards or away from a mobile phone transmitter broadcasting a signal at frequency fi in MHz. The velocity v in m/s will be multiplied by your individual number. Your algorithm should calculate f, in Hz that is the frequency at which your phone is receiving the signal (as a result of the Doppler shift). Step 1: The amount of the frequency change is dependent on the original frequency (f), the speed of the car (v) and the speed of light (c). This change is the Doppler shift (fd). The ft, converted XX 1.01XYZ C equation to calculate the Doppler shift is: f= = The speed of light is 3 x 10³ m/s Your individual number is tied to the velocity of the car throughout so that v is multiplied by 1.01XYZ at the start. For example, if the speed of the car is 15m/s, (just over 30 miles per hour) and the transmission frequency is 2300 MHz (2300 x 100 Hz) and the individual number is 1.01123 then: 2300×108 × 15 × 1.01123 3x108 fa = 116.29Hz Step 2: You can use a Boolean is_towards for the position of the car. If your car is travelling towards the transmitter then this frequency shift is added to the transmitter frequency, and if it is travelling away from the transmitter it is subtracted: • Car travelling toward transmitter: fr = ft+fd • Car travelling away from transmitter fr = ft - fd i. Develop an initial decomposition of the problem using the chevron notation (> and >>) from the module materials. Include your decomposition in your solution document. ii. Building on your decomposition for Parti, develop an algorithm for solving the problem. Include this algorithm in your solution document. In your solution document, in answer to this part, also write down your Pl and the individual number that you have obtained via Steps 1-3 from your Pl.
iii. Write a Python function definition following the instructions that are provided below. Save your function in a file called Q4_OUCU.py, where OUCU is your OUCU number. When you have completed your work on this part: o submit the .py file with your function o paste the function definition from your .py file as text (with indentation preserved) into your solution document Instructions for writing the function: • Provide a single Python function that implements the algorithm you wrote for part c(ii). Your function must be a translation of your algorithm from part c(ii), otherwise no marks will be awarded. • The function should have three arguments: one for the car speed v (m/s), one for the frequency of transmission f(MHz) and one for the direction of the movement of the car is_towards (to indicate whether it is moving towards or away from the transmitter). • The function should have one return value for the received frequency f, iv. Test the function by calling it in the Python with the arguments 15, 2300 and the car is moving towards the base station. Include the function call and the result. You should aim to use only the Python features that are introduced in the module. If you decide to use techniques or language features that TM112 does not cover, you must give a justification for your decisions, or marks will be lost. (10 marks) (Total 16 marks)