Fm Transmitter And Receiver Project Pdf
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File Name: fm transmitter and receiver project .zip
The rear side of the page has the silkscreen, as well as a poorly reproduced version of the schematic. Some of the This kit is a nicely designed 8 IC circuit that generates about 10 mW of output mW if wired for export use. Keywords: FM transmitter, wireless microphone, single transistor, The photo shows a wireless FM transmitter, pocket radio and yellow disk for size comparisons. Speak into the transmitter and others hear you on any FM radio.
In radio communications , a radio receiver , also known as a receiver , a wireless or simply a radio , is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna.
The antenna intercepts radio waves electromagnetic waves and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information.
The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation. Radio receivers are essential components of all systems that use radio. The information produced by the receiver may be in the form of sound, moving images television , or digital data.
The most familiar type of radio receiver for most people is a broadcast radio receiver, which reproduces sound transmitted by radio broadcasting stations, historically the first mass-market radio application.
A broadcast receiver is commonly called a "radio". However radio receivers are very widely used in other areas of modern technology, in televisions , cell phones , wireless modems and other components of communications, remote control, and wireless networking systems. The most familiar form of radio receiver is a broadcast receiver, often just called a radio , which receives audio programs intended for public reception transmitted by local radio stations.
The sound is reproduced either by a loudspeaker in the radio or an earphone which plugs into a jack on the radio. The radio requires electric power , provided either by batteries inside the radio or a power cord which plugs into an electric outlet.
All radios have a volume control to adjust the loudness of the audio, and some type of "tuning" control to select the radio station to be received. Modulation is the process of adding information to a radio carrier wave. In amplitude modulation AM the strength of the radio signal is varied by the audio signal.
AM broadcasting is also permitted in shortwave bands, between about 2. In frequency modulation FM the frequency of the radio signal is varied slightly by the audio signal.
The exact frequency ranges vary somewhat in different countries. FM stereo radio stations broadcast in stereophonic sound stereo , transmitting two sound channels representing left and right microphones.
A stereo receiver contains the additional circuits and parallel signal paths to reproduce the two separate channels. A monaural receiver, in contrast, only receives a single audio channel that is a combination sum of the left and right channels. Digital audio broadcasting DAB is an advanced radio technology which debuted in some countries in that transmits audio from terrestrial radio stations as a digital signal rather than an analog signal as AM and FM do.
Its advantages are that DAB has the potential to provide higher quality sound than FM although many stations do not choose to transmit at such high quality , has greater immunity to radio noise and interference, makes better use of scarce radio spectrum bandwidth, and provides advanced user features such as electronic program guide , sports commentaries, and image slideshows.
Its disadvantage is that it is incompatible with previous radios so that a new DAB receiver must be purchased. As of , 38 countries offer DAB, with 2, stations serving listening areas containing million people.
Broadcasters can transmit a channel at a range of different bit rates , so different channels can have different audio quality. The signal strength of radio waves decreases the farther they travel from the transmitter, so a radio station can only be received within a limited range of its transmitter. The range depends on the power of the transmitter, the sensitivity of the receiver, atmospheric and internal noise , as well as any geographical obstructions such as hills between transmitter and receiver.
AM broadcast band radio waves travel as ground waves which follow the contour of the Earth, so AM radio stations can be reliably received at hundreds of miles distance. However FM radio is less susceptible to interference from radio noise RFI , sferics , static and has higher fidelity ; better frequency response and less audio distortion , than AM. So in many countries serious music is only broadcast by FM stations, and AM stations specialize in radio news , talk radio , and sports.
Besides the broadcast receivers described above, radio receivers are used in a huge variety of electronic systems in modern technology. They can be a separate piece of equipment a radio , or a subsystem incorporated into other electronic devices. A transceiver is a transmitter and receiver combined in one unit. Below is a list of a few of the most common types, organized by function. A radio receiver is connected to an antenna which converts some of the energy from the incoming radio wave into a tiny radio frequency AC voltage which is applied to the receiver's input.
An antenna typically consists of an arrangement of metal conductors. The oscillating electric and magnetic fields of the radio wave push the electrons in the antenna back and forth, creating an oscillating voltage. The antenna may be enclosed inside the receiver's case, as with the ferrite loop antennas of AM radios and the flat inverted F antenna of cell phones; attached to the outside of the receiver, as with whip antennas used on FM radios , or mounted separately and connected to the receiver by a cable, as with rooftop television antennas and satellite dishes.
Practical radio receivers perform three basic functions on the signal from the antenna: filtering , amplification , and demodulation : . Radio waves from many transmitters pass through the air simultaneously without interfering with each other and are received by the antenna. These can be separated in the receiver because they have different frequencies ; that is, the radio wave from each transmitter oscillates at a different rate.
To separate out the desired radio signal, the bandpass filter allows the frequency of the desired radio transmission to pass through, and blocks signals at all other frequencies. The bandpass filter consists of one or more resonant circuits tuned circuits. The resonant circuit is connected between the antenna input and ground. When the incoming radio signal is at the resonant frequency, the resonant circuit has high impedance and the radio signal from the desired station is passed on to the following stages of the receiver.
At all other frequencies the resonant circuit has low impedance, so signals at these frequencies are conducted to ground. The power of the radio waves picked up by a receiving antenna decreases with the square of its distance from the transmitting antenna. Even with the powerful transmitters used in radio broadcasting stations, if the receiver is more than a few miles from the transmitter the power intercepted by the receiver's antenna is very small, perhaps as low as picowatts or femtowatts.
To increase the power of the recovered signal, an amplifier circuit uses electric power from batteries or the wall plug to increase the amplitude voltage or current of the signal. In most modern receivers, the electronic components which do the actual amplifying are transistors.
Receivers usually have several stages of amplification: the radio signal from the bandpass filter is amplified to make it powerful enough to drive the demodulator, then the audio signal from the demodulator is amplified to make it powerful enough to operate the speaker.
The degree of amplification of a radio receiver is measured by a parameter called its sensitivity , which is the minimum signal strength of a station at the antenna, measured in microvolts , necessary to receive the signal clearly, with a certain signal-to-noise ratio.
Since it is easy to amplify a signal to any desired degree, the limit to the sensitivity of many modern receivers is not the degree of amplification but random electronic noise present in the circuit, which can drown out a weak radio signal.
After the radio signal is filtered and amplified, the receiver must extract the information-bearing modulation signal from the modulated radio frequency carrier wave. This is done by a circuit called a demodulator detector. Each type of modulation requires a different type of demodulator. The modulation signal output by the demodulator is usually amplified to increase its strength, then the information is converted back to a human-usable form by some type of transducer.
An audio signal , representing sound, as in a broadcast radio, is converted to sound waves by an earphone or loudspeaker.
A video signal , representing moving images, as in a television receiver , is converted to light by a display. Digital data , as in a wireless modem , is applied as input to a computer or microprocessor , which interacts with human users. In the simplest type of radio receiver, called a tuned radio frequency TRF receiver , the three functions above are performed consecutively:  1 the mix of radio signals from the antenna is filtered to extract the signal of the desired transmitter; 2 this oscillating voltage is sent through a radio frequency RF amplifier to increase its strength to a level sufficient to drive the demodulator; 3 the demodulator recovers the modulation signal which in broadcast receivers is an audio signal , a voltage oscillating at an audio frequency rate representing the sound waves from the modulated radio carrier wave ; 4 the modulation signal is amplified further in an audio amplifier , then is applied to a loudspeaker or earphone to convert it to sound waves.
Although the TRF receiver is used in a few applications, it has practical disadvantages which make it inferior to the superheterodyne receiver below, which is used in most applications.
The bandwidth of a filter increases with its center frequency, so as the TRF receiver is tuned to different frequencies its bandwidth varies. Most important, the increasing congestion of the radio spectrum requires that radio channels be spaced very close together in frequency.
It is extremely difficult to build filters operating at radio frequencies that have a narrow enough bandwidth to separate closely spaced radio stations. TRF receivers typically must have many cascaded tuning stages to achieve adequate selectivity. The Advantages section below describes how the superheterodyne receiver overcomes these problems. The superheterodyne receiver, invented in by Edwin Armstrong  is the design used in almost all modern receivers     except a few specialized applications.
In the superheterodyne, the radio frequency signal from the antenna is shifted down to a lower " intermediate frequency " IF , before it is processed. The mixing is done in a nonlinear circuit called the " mixer ". The result at the output of the mixer is a heterodyne or beat frequency at the difference between these two frequencies.
The process is similar to the way two musical notes at different frequencies played together produce a beat note. This lower frequency is called the intermediate frequency IF. The IF signal also has the modulation sidebands that carry the information that was present in the original RF signal. The IF signal passes through filter and amplifier stages,  then is demodulated in a detector, recovering the original modulation. The receiver is easy to tune; to receive a different frequency it is only necessary to change the local oscillator frequency.
The stages of the receiver after the mixer operates at the fixed intermediate frequency IF so the IF bandpass filter does not have to be adjusted to different frequencies. The fixed frequency allows modern receivers to use sophisticated quartz crystal , ceramic resonator , or surface acoustic wave SAW IF filters that have very high Q factors , to improve selectivity.
The RF filter on the front end of the receiver is needed to prevent interference from any radio signals at the image frequency. Without an input filter the receiver can receive incoming RF signals at two different frequencies,.
A single tunable RF filter stage rejects the image frequency; since these are relatively far from the desired frequency, a simple filter provides adequate rejection. Rejection of interfering signals much closer in frequency to the desired signal is handled by the multiple sharply-tuned stages of the intermediate frequency amplifiers, which do not need to change their tuning.
The RF filter also serves to limit the bandwidth applied to the RF amplifier, preventing it from being overloaded by strong out-of-band signals. To achieve both good image rejection and selectivity, many modern superhet receivers use two intermediate frequencies; this is called a dual-conversion or double-conversion superheterodyne.
Some receivers even use triple-conversion. At the cost of the extra stages, the superheterodyne receiver provides the advantage of greater selectivity than can be achieved with a TRF design. Where very high frequencies are in use, only the initial stage of the receiver needs to operate at the highest frequencies; the remaining stages can provide much of the receiver gain at lower frequencies which may be easier to manage. Tuning is simplified compared to a multi-stage TRF design, and only two stages need to track over the tuning range.
The total amplification of the receiver is divided between three amplifiers at different frequencies; the RF, IF, and audio amplifier. This reduces problems with feedback and parasitic oscillations that are encountered in receivers where most of the amplifier stages operate at the same frequency, as in the TRF receiver.
The most important advantage is that better selectivity can be achieved by doing the filtering at the lower intermediate frequency.
In order to reject nearby interfering stations or noise, a narrow bandwidth is required. Modern FM and television broadcasting, cellphones and other communications services, with their narrow channel widths, would be impossible without the superheterodyne. The signal strength amplitude of the radio signal from a receiver's antenna varies drastically, by orders of magnitude, depending on how far away the radio transmitter is, how powerful it is, and propagation conditions along the path of the radio waves.
In addition as the receiver is tuned between strong and weak stations, the volume of the sound from the speaker would vary drastically. Without an automatic system to handle it, in an AM receiver, constant adjustment of the volume control would be required. With other types of modulation like FM or FSK the amplitude of the modulation does not vary with the radio signal strength, but in all types the demodulator requires a certain range of signal amplitude to operate properly.
Therefore, almost all modern receivers include a feedback control system which monitors the average level of the radio signal at the detector, and adjusts the gain of the amplifiers to give the optimum signal level for demodulation.
Simple FM Transmitter
In radio communications , a radio receiver , also known as a receiver , a wireless or simply a radio , is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves electromagnetic waves and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation. Radio receivers are essential components of all systems that use radio. The information produced by the receiver may be in the form of sound, moving images television , or digital data.
It is surprisingly powerful despite its small component count and 3V operating voltage. The circuit we use is based on a proven Australian design. It may be tuned anywhere in the FM band. Or it may be tuned outside the commercial M band for greater privacy. However, some countries may ban ALL wireless transmissions without a license. It is the responsibility of the builder to check the legal requirements for the operation of this circuit and to obey them. The circuit is basically a radio frequency RF oscillator that operates around MHz.
Crystal Oscillator. We used a 24MHz packaged crystal oscillator to provide the local oscillator signal on the receiver side of the circuit. This provides a simple and.
rf transmitter and receiver circuit diagram pdf
Fm Receiver Project Then the Arduino would set the transmitters to the next 10 frequencies recorded by the FM receiver and repeat the message. You may built FM or Radio receivers by using radio tuner components and it requires lot of efforts to built accurate radio receiver. PNP Shortwave Receiver. Radio Tuners have a wealth of music, conversation and sport all available free of charge and in superb stereo sound quality quality, so it is not surprising that for many a radio tuner is an essential addition to their hi-fi. It's how some car radios can display the FM station and current song playing.
Introduction In the past decade, portable wireless communication systems have experienced tremendous growth. Top 10 Articles. RF Tuner Section. Hamster Wheel Sensor T.
The amplitude modulated wave received by the antenna is first passed to the tuner circuit through a transformer.
Step 1: Components Required
Может быть, хочешь воды. Она не нашлась что ответить. И проклинала. Как я могла не выключить монитор. Сьюзан понимала: как только Хейл заподозрит, что она искала что-то в его компьютере, то сразу же поймет, что подлинное лицо Северной Дакоты раскрыто. И пойдет на все, лишь бы эта информация не вышла из стен Третьего узла.
Хейл его отключил. И Сьюзан принялась объяснять, как Хейл отозвал Следопыта и как она обнаружила электронную почту Танкадо, отправленную на адрес Хейла. Снова воцарилось молчание. Стратмор покачал головой, отказываясь верить тому, что услышал. - Не может быть, чтобы Грег Хейл был гарантом затеи Танкадо. Это полный абсурд.
Вылил целую бутылку. Хейл включил свой компьютер.