The ad633 ic is a fourquadrant analog multiplier with differential x and y inputs, and a high impedance summing input z. Biggest advantage of fm over am is superior noise characteristic larger snr since in fm system the intelligence is not carried by amplitude unlike am, we can remove spikes of external noise by using limiter circuit see fig 56 but spikes of external noise also cause undesired phase shift thus frequency shift that cannot be removed. Hence, in order to get the required modulation index greater than one of fm wave, choose the frequency multiplier value. In this article, i try to show how a baseband signal is transformed under fm modulation using a python implementation. Am modulators base, collector, grid and plate modulators. This method is used by design team 5 from ece480 to build a radar system with rf components that has a frequency of 2. The output waveforms can be both amplitude and frequency modulated. There will be zero modulation voltage across the secondary of t1. Typical applications include suppressed carrier and amplitude modulation, synchronous detection, fm detection, phase detection, and chopper applications. Ic xr2206 based phaselocked loop detector ic lm565 based as a frequency demodulator.
Although it may not be quite as straightforward as amplitude modulation, nevertheless frequency modulation, fm, offers some distinct advantages. Frequency modulation is widely used on frequencies above 30 mhz, and it is particularly well known for its use for vhf fm broadcasting. Using the value properties of bessel functionand table 1, we can show that the bandwidth of fm signal b t, depends on the number of sidebands n, and fm modulation index. The technology is used for communication systems such as telemetry, weather balloon radiosondes, caller id, garage door openers, and low frequency radio transmission in the vlf and elf bands. Linear integra tedcir cult am modulator objectives. In figure 2, the resistor r3 and r4 comprise a voltage divided circuit. In frequency modulation, the intensity of the carrier wave isnt varied. To measure frequency deviation and modulation index of fm. Purchase 1hz 2mhz xr2206 function generator kit at electronicsdiy store. Fm modulation introduction in this lab, you will investigate frequency modulation fm and its properties. Direct fm modulation can be achieved by directly feeding the message into the input of a voltagecontrolled oscillator. Principles of communication modulation a signal can be anything like a sound wave which comes out when you shout. Fm modulation in simulink 2017 how to generate fm modulation using simulink uniformedia in telecommunications and signal processing, frequency modulation fm is the encoding of information in a.
The module described here is based on high quality xr2206 ic. To understand the theoretical foundations for angle modulation as well as frequency modulation fm and demodulation. This shout can be heard only up to a certain distance. What is fm, frequency modulation electronics notes.
Fm signals can be generated using either direct or indirect frequency modulation. In the first stage, the nbfm wave will be generated using nbfm modulator. This is high quality function generator system using the xr2206 chip. Xr567 xrs200 ic xr 2240 xr2240 xr600 xr3524 xr2216 xr2208 xr2203 text. To construct and study the amplitude modulation using xr2206. Fm signals have the same peak frequency deviation, then. Waveform function generator capable of producing am fm modulated sine wave outputs find a wide range of applications in electrical measurement and laboratory instrumentation. Features y excellent carrier suppression 65 db typical. In audio and music frequency modulation synthesis or fm synthesis is a form of audio synthesis where the timbre of a simple waveform is changed by frequency.
Linear amplitude modulation ttl compatible fsk controls wide supply range, 10v to 26v adjustable duty cycle, 1% to 99% applications waveform generation sweep generation am fm generation vf conversion fsk generation phaselocked loops vco general description the xr2206 is a monolithic function generator. The output frequency can be keyed between two levels. Xr2123a xr2123 xr2123a t1t2220 q12n4403 q32n4401 2n4401 2n4861 1n914 fsk modulation and demodulation using xr2206 lm 2206 for frequency modulation cd40 xr4741 f7404 xr2123acp tda 4608 7404 hex inverter truth table xr2206 fsk modem cd40 pin diagram. Scientech techbook 2203 frequency modulation and demodulation techniques is a comprehensive learning solution specifically designed to study basic operation as well as to provide conceptual and step by step understanding of frequency modulation and demodulation techniques through observation of waveforms at various test points. Implementation of fsk modulation and demodulation using. Keywords modulate exert a modifying or controlling influence frequency modulation the modulation. Know the relationship of carrier frequency, modulation frequency and modulation index to efficiency and bandwidth compare fm systems to am systems with regard to efficiency, bandwidth and noise. The modulating output signal is coupled through modulation transformer t1 to the class c amplifier.
Frequency modulation and demodulation techniques, fm training kit for analog communication lab to understand the process of fm generation and detection, using reactance modulator, varactor modulator. Frequency modulation fm is a process in which the carrier frequency is varied by the amplitude of the modulating signal i. Linear amplitude modulation ttl compatible fsk controls wide supply range, 10v to 26v adjustable duty cycle, 1% to 99% applications waveform generation sweep generation amfm generation vf conversion fsk generation phaselocked loops vco general description the xr2206 is a monolithic function generator. For indirect fm modulation, the message signal is integrated to generate a phasemodulated signal.
Bfsk modulation by using 2206 ic xr2206 ic is a waveform generator, which is similar to 8038 ic. There is another way of modulating a, sinusoidal carrier wave, namely, angle modulation in which the angle of the carrier wave is varied according to the baseband signal. This application report discusses logiclevel implementation of fsk modulator and demodulator using a pll device hchct4046a. For both phase and frequency modulation, the modulating signal causes the carrier to increase and decrease. Frequency modulation using the voltage controlled oscillator and a. Scientech techbook 2203 frequency modulation and demodulation.
The application of the heterodyne principle to modulation is shown schematically in figure 143. Principles of communication modulation tutorialspoint. Monolithic function generator xr2206 the xr2206 is a monolithic function generator integrated circuit capable of producing high quality sine, square, triangle, ramp, and pulse waveforms of highstability and accuracy. Figure 2 is the circuit diagram of the fsk modulator by using 2206 ic.
Slide 3 discretetime fm modulator slide 4 single tone fm modulation slide 5 single tone fm cont. This is the mini function generator circuit using icl8038. During this lab you will create an fm signal by modulating an audio waveform onto a carrier, examine the spectrum of the modulated carrier, evaluate the modulated carrier when the modulation index is varied and. Xr2206 function generator circuit electronics projects. Waveform function generator capable of producing amfm modulated sine wave outputs find a wide range of applications in electrical measurement and laboratory instrumentation. Here both the pins are shorted together and connected to a variable resistor rv1 100k, altering the resistance value of. When the audio signal is modulated onto the radio frequency carrier, the new radio frequency signal moves up and down in frequency.
This laboratory exercise will use the xr2206 monolithic ic function generator. There are two types of fm modulators direct and indirect. To counteract static, a better method of superimposing information on a radio wave, called frequency modulation or fm, was developed in 1933. You will model the pll, and recover the message from the fm signal. I considered using timer 555, xr2206 and icl8038 to do the fm modulation but their data sheets dont show anything about the default frequency deviation or how to set it. If the message was a single tone, from its amplitude can you estimate the frequency deviation of the fm signal.
The frequency of the output wave form can be adjusted using r7. This application note describes the design, construction and the performance of such a complete function generator system suitable for laboratory usage. The subsystem that takes the information signal and processes it prior to transmission. Feb 21, 2009 the pdf doesnt have the circuit i require hi eric, i have the pdf uve sent. Armstrong, known as one of the founding fathers of radio technology, invented the superheterodyne radio receiver in 1918 and frequency modulation fm in 1933 1. The goal of this experiment is to become familiar with fm modulation and demodulation. Fm demodulation with the pll a2 143 t5 measure the properties of each element of the pll, and then predict some of its properties as a demodulator. Measuring and adjusting an amplitude modulator circuit understanding the principle of amplitude demodulation.
In this type of modulation, the frequency of the carrier signal varies in accordance with the message signal, and other parameters like amplitude and phase remain constant. To observe the output amplitudeversusinput voltage characteristics of a. Direct fm involves varying the frequency of the carrier directly by the modulating input. Increase the amplitude of the signal generator output voltage to 3 vpp at 1 khz. Amplitude modulation differentiation using a phase shifter 18. Spice simulation of a frequency shift keying modulator with a xr2206 that can operate with two separate timing resistors, r1 and r2, connected to the timing pin tr1 7 and tr2 8,respectively. Signals that interfere with an intentional electronic broadcast are called static, and static is the main drawback of am radio. Slide 6 narrow band fm slide 7 bandwidth of an fm signal slide 8 demod. We know that the modulation index of nbfm wave is less than one. The icl8038 is fabricated with advanced monolithic technology, using schottky barrier diodes and thin.
Understanding the principle of amplitude modulation am. Function generator circuit using icl8038 gadgetronicx. Mc1496, mc1496b balanced modulators demodulators these devices were designed for use where the output voltage is a product of an input voltage signal and a switching function carrier. Frequency modulation using vco based frequency modulator ic xr2206 based. Function generator circuit using icl8038 pulse generator ic. The spectrum of an fm signal is quite complicated and is dependent on mf. The lm1596 is specified for operation over the b55cto a125c military temperature range. Connect rf signal to mod input front panel of 8657b. The secondary winding of the modulation transformer is connected in series with the collector supply voltage vcc of the class c amplifier. Frequency modulation using vco based frequency modulator ic xr2206 based phaselocked loop detector ic lm565 based as a frequency demodulator frequency deviation and modulation index using vco based frequency modulator ic xr2206 based scientech technologies pvt. To implement the simulink models for fm including a basic sinusoid and a multimedia file music to analyze each signal in time and frequency domains using time scope and spectrum analyzer.
To understand the principles of frequency modulation and demodulation. The xr2206 is a monolithic function generator integrated circuit capable of. Matlab requies the frequency deviation in addition to the carrier frequency to do the demodulation. Dsbfc and dsbsc am modulation with the ic ad633 youspice. The xr2206 function generator circuit sinetrianglesquare waveform generator. Superposition of am and fm spectrum in this exercise we will use hp 8656b as an external generator and we will do am and fm modulation using internal mixer of hp 8657b. Changing the amplitude of the carrier am modulation is one type of modulation easy, cheap, lowquality used for am receiver and cbs citizen bands. The lm1496 is specified for operation over the 0ctoa70c temperature range. I considered using timer 555, xr2206 and icl8038 to do the fm modulation but their data sheets dont show anything about the default frequency. Currently, it is more than adequate for a small home electronics hobby lab. Output of 1hz 2mhz xr2206 function generator can be connected directly to 60mhz counter for setting precise.
What i need exactly is a circuit with xr2206 for which when i apply a modulating signal, fm wave should be generated. Agure 153 am modulator using the xr2206 function generator 6. The output waveforms can be both amplitude and frequency modulated by an external voltage. Based on my experience, the easy to build 1hzimhz xr2206 function generator kit allows a variety of routine measurements and experiments, and offers fairer quality sine, square, and triangle output waveforms with moderate stability and accuracy. Formerly you will find the signal generator is called the function generator for use one machine. To study frequency modulation and determine its modulation factor. Even the digital radio modes like dmr and dstar are fm based to some extent, which allows for cheaper circuits and pacific coexistence of analog and digital modes in the band. Remember to set up the vco module in 100 khz vco mode. Introduction frequency modulation fm has a long history of its application and is widely used in radio broadcast. Im trying to do fm modulation on a signal and pass it to the pc and demodulate it using matlab. We have seen the block diagram of nbfm modulator at the beginning of this chapter. To observe the operation of a linear integratedcircuit function generator. To generate a frequency modulated signal, the frequency of the radio carrier is changed in line with the amplitude of the incoming audio signal. Xr2206 20ppm 160mv 50ki2 circuit am modulation xr2206 xr 2206 fm modulation pin diagram of xr 2206 xr2206 2206cp xr 2206 am modulation xr2206 circuit sine wave generator circuit using xr2206 xr2206cn.
To transmit stereo music, fm is enhanced by stereo multiplexing which carries both l. Jun 25, 2015 frequency output can be fine tuned using p1 and p2 potentiometers. Frequencyshift keying fsk is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal. But this doesnt have the circuit i require for fm generation. In chapter1, we investigated the way of modulating a sinusoidal carrier wave using am technique. It will generate output 3 waveform, sine wave signal, triangle, and square wave signals. Used for amfm radios, television nonhdtv, and the first cell phones newer systems typically employ digital modulation. The hchct4046a, pll with vco is a highspeed cmos ic designed for use in generalpurpose pll applications, including frequency modulation, demodulation, discrimination, synthesis, and multiplication.
Frequency spectrum of fm signals with different mf and same modulating. Indirect fm involves directly altering the phase of the carrier based on the input this is actually a form of direct phase modulation. This gives fm another advantage over other modulation schemes that require linear amplifiers, such as am and qam. Fm circuit using xr2206 please help electronics forum. It can be seen in figure 8 that phase and frequency modulation are closely related. Frequency modulation is used in different applications like radar, radio and telemetry, seismic prospecting and monitoring newborns for seizures via. Amplitude modulation differentiation using a phase shifter. Am modulation in order to transfer signals we need to transfer the frequency to higher level one approach is using modulation modulation. Precision waveform generator voltage controlled oscillator.
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