Controlling Traffic Lights Using the Siren Sound, Essay Example

The focus of the report is on the use of Lab View simulation to design a smart traffic system that detects emergency sirens and automatically change the traffic lighting to facilitate a freeway for emergency vehicles, for example, the ambulance. The resolution method via the implementation of Fourier analysis is explained below.

Solution Approach

The Fourier analysis performed on the signal enables to attainment of a favorable frequency pattern. Definitively named after Joseph Fourier, the Fourier transform can be described as a calculated transformation utilized to alter signals between the time domain and frequency domain.

In order to obtain the information signals required to execute the process, the power spectrum is used since it tends to view and analyze all the signal features. The spectrum is sometimes referred to as Fourier transform. The Fourier Transform swaps the dimension of time with that of the frequency.

Fourier transforms entails the combination of slow and fast oscillations that have different amplitudes. The presence of a very strong and slow component within the frequency domain infers that there is a great correspondence among the large-scale fragments of the signal with regards to time.

Lab View simulation

Since the project majors on detecting a siren sound, the tools needed to analyze the signal comprise of an integrated microphone for sound acquisition. The microphone feature is programmed using Lab View simulation tool. The microphone tool continuously scans for any voice or sound input. This is facilitated via the use of a voice card that has a time delay scan interval of two second.

The Lab View simulation offers the platform with the tool kits for running multiple tests. The tests included the playing of the different recorded siren sound clips. The circuit design within the lab tools is used play the siren signals which subsequently performs an analysis on sound to determine the characteristics of the signal. The resultant features given is supposed to provide the information required to perform further analysis, for instance, using the power spectrum tool to acquire the data about the signal frequency domain.

Result

The outcome of Fourier analysis performed established that the maximum frequency of sirens is generally between 800 and 2000 HZ. Furthermore, the sound pattern of the siren signal was unique enough to identify that the signal were siren sounds. To ensure the attainment of a high quality sound sample, a sampling rate of 44100 HZ was utilized to maintain the frequency above the Nyquist rate frequency.

Since the range variation is known, the information extracted offers valuable and conclusive data. To further simplify the analysis, these steps were followed:

The data gotten from the graph were further analyzed. This is initially achieved via extracting the arrays of data acquired from the simulation. The arrays were (f0, df, and magnitude), i.e.:

(f0) –  This is the initial frequency while,

(df) – is the frequency step

The magnitude of energy pulses.

So as to obtain the magnitude between the frequencies variations mentioned earlier, a sub array function was utilized in place of a filter so as to get rid of all the unwanted signal components. This task was to achieve done via calculating the length of the magnitude array, that is, between 800 and 2000 HZ, and the starting point.

The Lab simulation view interface offered information regarding the maximum energy pulse, that is, between 800 and 2000 Hz. This frequency was used as the threshold to compare and analyze the signal acquired by the microphone. The finalized and simple comparison made between the two signals aims at identifying if there is a hit or a match with the signal from a siren. Well, if a frequency match occurs then the traffic light start flashing yellow for three second before turning all the lights to red.

Traffic light simulation

• The traffic light signals are built based on a state machine. The state machine is an electronic device which stores and records the status of an electrical process at a given time and then operates on an input to alter the status by either performing an action or portraying an output of the given change.
• The task is achieved via the combination of a while loop and a case structure tools which facilitated the simulation of the case structure.
• No walk lane was considered in this experimental setup.

Status

The resultant status of the simulation confirmed that it successfully works. The emulation confirmed that the traffic lights will always follow the design pattern mentioned earlier. This solution comprised of playing a siren sound through a media device, in this case a cell phone, which the traffic lights essentially detected subsequently forcing the light regular sequence to change from yellow then to red.

Plan going forward

• Detecting the direction of the siren, this is accomplished by emulating human ears using two microphones instead of one.
• A warning sign should be including in the design to notify people further of the situation
• A signal to noise ratio (SNR)[8]

Conclusions

Conclusively, the simulation project was a success and we managed to acquire the requisite information as prior expectation.  Moreover, the lab simulation offered the group the experience and expertise in designing using lab simulation tools. Despite the success, there were a number of setbacks that slowed down the experimental process. These included the problem of setting up and scheduling the group meeting which had to be planned a couple of times to accommodate all the members’ routines. The supplementary meetings aided in the identification and resolution of bugs and errors within the project’s simulation environment.