Fm Radio Taimoor.docx

FM RADIO RECIEVER DESIGN Complex Engineering Problem

SUBMITTED BY: TAIMOOR KHAN M.HUSNAT KHALID BSEE 2015-19

Table of Contents 1.1. FM Broadcast: ..................................................................................................2 1.2. Frequency modulation: .....................................................................................3 1.3. Complex Engineering Problem: .......................................................................4 1.4. References: .......................................................................................................7

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1. Objectives: At the end of the project: i. ii. iii.

Students being able to design an individual circuit or device that make up of FM modulation/ demodulation systems and understand the function of each subsystem Students being able to construct and test their designed FM Radio. Students become familiar with the use of design and simulation tools in design process.

1.1. FM Broadcast: FM radio broadcast is one of the main types of radio broadcasting. FM usually denotes frequency modulation. This frequency modulation usually takes place on VHF airwaves in a frequency range of 88 to 108 around the world. This following article shares precise information on FM radiobroadcast. So, find out everything about FM radio broadcast whether its advantages or disadvantages right here.

Figure 1: Schematic representation of FM Broadcasting

Sources have revealed that FM radio broadcasting is very popular especially in developed areas including Europe and United States because higher sound fidelity as well as stereo broadcasting certainly became quite familiar in this format. During 1930s, Edwin H Armstrong invented FM radio. He invented it to overcome the interference problem associated with AM radio broadcasting to which is relatively immune. Going further with the details on FM radio broadcast, we come up with the point that for accommodating an audio signal in FM radio, it does not require a bandwidth of 200 kHz. What is all required is 20 kHz to 30 kHz for a narrowband FM radio broadcast or FM signal. The 200 kHz bandwidth enabled space for ±75 kHz signal deviation from the appointed frequency.

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1.2. Frequency modulation: Frequency modulation (FM) is the standard technique for high-fidelity communications as is evident in the received signals of the FM band (88-108 MHz) vs. the AM band (450-1650 KHz). The main reason for the improved fidelity is that FM detectors, when properly designed, are not sensitive to random amplitude variations, which are the dominant part of electrical noise (heard as static on the AM radio).

Figure 2: Schematic representation of FM Modulation.

In narrowband FM, commonly used in two-way wireless communications, the instantaneous carrier frequency varies by up to 5 kilohertz (kHz, where 1 kHz = 1000 hertz or alternating cycles per second) above and below the frequency of the carrier with no modulation. In wideband FM, used in wireless broadcasting, the instantaneous frequency varies by up to several megahertz (MHz, where 1 MHz = 1,000,000 Hz). When the instantaneous input wave has positive polarity, the carrier frequency shifts in one direction; when the instantaneous input wave has negative polarity, the carrier frequency shifts in the opposite direction. At every instant in time, the extent of carrier-frequency shift (the deviation) is directly proportional to the extent to which the signal amplitude is positive or negative.

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1.3. Complex Engineering Problem: As part of engineering curriculum, Complex Engineering Problem (CEP) was assigned to us by our communication systems course instructor. We selected FM radio because it was easy to implement in limited time as well as the components were easily available in market at low rates. We have described our project briefly:

Circuit Diagram:

Figure 3: Circuit diagram for our FM radio

Components:       

Arduino UNO FM Radio Module (RDA-5807m) Audio Amplifier Audio Jack Connecting wires Breadboard Male connectors

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Working: The Arduino UNO supplies power to all the components and control their operation through the programmed code. The radio module intercepts the selected FM radio channel and sends the signal to audio amplifier. Audio amplifier amplifies the signal and sends it to audio jack, from where; the broadcasted channel can be heard.

Programming Code of Arduino UNO: The code is obtained from open source Arduino library with some alterations as per our requirements: #include #include <Wire.h> #include #include // ----- Fixed settings here. ----#define FIX_BAND

RADIO_BAND_FM ///< The band that will be tuned by this sketch is FM.

#define FIX_STATION 10100 #define FIX_VOLUME 6

///< The station that will be tuned by this sketch is 101 MHz. ///< The volume that will be set by this sketch is level 4.

RDA5807M radio; // Create an instance of Class for RDA5807M Chip /// Setup a FM only radio configuration /// with some debugging on the Serial port void setup() { // open the Serial port Serial.begin(57600); Serial.println("Radio..."); delay(200); // Initialize the Radio radio.init(); // Enable information to the Serial port 5

radio.debugEnable(); // Set all radio setting to the fixed values. radio.setBandFrequency(FIX_BAND, FIX_STATION); radio.setVolume(FIX_VOLUME); radio.setMono(false); radio.setMute(false); } // setup /// show the current chip data every 3 seconds. void loop() { char s[12]; radio.formatFrequency(s, sizeof(s)); Serial.print("Station:"); Serial.println(s); Serial.print("Radio:"); radio.debugRadioInfo(); Serial.print("Audio:"); radio.debugAudioInfo(); delay(3000); } // loop // End.

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1.4. References:  http://www.radiocave.com/fm-radio-broadcast.html  http://www.theorycircuit.com/arduino-rda5807m-fm-receiver/  http://forum.arduino.cc/index.php?topic=37676.0

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