FM Receivers Essay -- essays research papers

abstractionistThis paper pass on handle the creation of an FM receiver. It will approach with a brief historicbackdrop of FM broadcasting and its white plague in society. It will affect by providing thenecessary mathematical priming coat of the modulation process. Furtherto a greater extent, it willretell near of the advantages of FM everyplace former(a) forms of modulation, namely AM.Finally, the paper will discuss the design of a sancti hotshotd FM receiver as well as introducesome circuits and circuit components which the reader whitethorn not be familiar with. submissionFrequency modulation (FM) was invented in 1936 by an American electrical calculate/inventor named Edwin H. Armstrong. Posses netherworldg numerous advantages over the existingAM broadcasting placement, as will be discussed later, in combination with relatively lowmonetary value of implementation, resulted in its rapid growth. In the years following World warTwo, there were 600 licensed move broadca sting in the U.S. By 1980, the topic grewto 4000. On another historic note, in 1961 stations began broadcasting in stereo.The basic receiver design consists of the following components. An antenna is utilize to win over electro-magnetic waves into electrical oscillations. Amplifiers are rehearsed by dint ofout the receiver to boost predict power at radio, baseband and middlingfrequencies. The core of the FM receiver, the discriminator, comes in non-homogeneous circuitforms and is used in detection and demodulation. Basically, its role is to extract the parole or message from the toter wave. Another component, essential in someelectronic circuits, is the power furnish (DC or AC converted to DC). Finally, atransducer (speaker in the case of Radio) is mandatory to convert the message signal into its terminal form (audio, mechanical, etc). Other components more specific to FM receiversare mixers have with local oscillators used for oftenness manipulation, limiters tocontrol a mplitude, de-emphasis and other filter out circuits.2Mathematics of FM strange amplitude modulation (AM) where the message or modulating signal, call it m(t),is used to strengthen the amplitude of the carrier signal, frequence modulation, as thename implies, uses m(t) to transform the frequence of the carrier. The amplitude of anFM signal should lie constant during the modulating process an key propertyof FM. A general FM signal can be described by the following1FM(t) = Acos(... ...n its output proportional to s(t).oer a short cadence interval, this version C(wc-wo)t. Thus, the system continues to loopuntil the frequency of the VCO output matches or locks onto the incoming frequency.The time it takes for the system to lock is called the skill time. formerly thefrequencies match, s(t) becomess(t) = AB/s sin(c-o)For an incoming FM signals(t) = AB/2 sin(c(t)-o)= AB/2 sin (kf m()d Co)Running s(t) through with(predicate) a differentiator results in an AM signal which can be easilydemodulated using envelope detection.Once the signal has been demodulated, it is then passed through a de-emphasis circuit,as mentioned earlier. Typically, it is then amplified one last time onward heading to theoutput transducer.ConclusionIn conclusion, the modulation/demodulation process for FM signals has proven to bemuch slight straight forward than unsophisticated AM modulation. However, FM has considerableadvantages and its use in radio, satellite and microwave radar applications make it indispensable.Many methods of signal and system analysis along with filter and feedback design areemployed in the building of an FM receiver, whether it be analog, digital or otherwise. FM Receivers Essay -- essays research papers AbstractThis paper will discuss the design of an FM receiver. It will begin with a brief historicalbackdrop of FM broadcasting and its use in society. It will continue by providing thenecessary mathematical background of the modulation pro cess. Furthermore, it willenumerate some of the advantages of FM over other forms of modulation, namely AM.Finally, the paper will discuss the design of a basic FM receiver as well as introducesome circuits and circuit components which the reader may not be familiar with.IntroductionFrequency modulation (FM) was invented in 1936 by an American electrical engineer/inventor named Edwin H. Armstrong. Possessing numerous advantages over the existingAM broadcasting system, as will be discussed later, in combination with relatively lowcost of implementation, resulted in its rapid growth. In the years following World WarTwo, there were 600 licensed stations broadcasting in the U.S. By 1980, the number grewto 4000. On another historical note, in 1961 stations began broadcasting in stereo.The basic receiver design consists of the following components. An antenna is used toconvert electro-magnetic waves into electrical oscillations. Amplifiers are usedthroughout the receiver to boost signal p ower at radio, baseband and intermediatefrequencies. The core of the FM receiver, the discriminator, comes in various circuitforms and is used in detection and demodulation. Basically, its role is to extract theintelligence or message from the carrier wave. Another component, essential in mostelectronic circuits, is the power supply (DC or AC converted to DC). Finally, atransducer (speaker in the case of Radio) is needed to convert the message signal into itsfinal form (audio, mechanical, etc). Other components more specific to FM receiversare mixers combined with local oscillators used for frequency manipulation, limiters tocontrol amplitude, de-emphasis and other filter circuits.2Mathematics of FMUnlike amplitude modulation (AM) where the message or modulating signal, call it m(t),is used to modulate the amplitude of the carrier signal, frequency modulation, as thename implies, uses m(t) to transform the frequency of the carrier. The amplitude of anFM signal should remain constant during the modulating process an important propertyof FM. A general FM signal can be described by the following1FM(t) = Acos(... ...n its output proportional to s(t).Over a short time interval, this variation C(wc-wo)t. Thus, the system continues to loopuntil the frequency of the VCO output matches or locks onto the incoming frequency.The time it takes for the system to lock is called the acquisition time. Once thefrequencies match, s(t) becomess(t) = AB/s sin(c-o)For an incoming FM signals(t) = AB/2 sin(c(t)-o)= AB/2 sin (kf m()d Co)Running s(t) through a differentiator results in an AM signal which can be easilydemodulated using envelope detection.Once the signal has been demodulated, it is then passed through a de-emphasis circuit,as mentioned earlier. Typically, it is then amplified one last time before heading to theoutput transducer.ConclusionIn conclusion, the modulation/demodulation process for FM signals has proven to bemuch less straight forward than simple AM modulatio n. However, FM has considerableadvantages and its use in radio, satellite and radar applications make it indispensable.Many methods of signal and system analysis along with filter and feedback design areemployed in the building of an FM receiver, whether it be analog, digital or otherwise.