Product general purpose radio stations and radios
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Two-Way Radios & Police Radios
In radio communications , a radio receiver , also known as a receiver , wireless or simply 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 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 : .
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 all 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 no 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. AGC can be compared to the dark adaptation mechanism in the human eye ; on entering a dark room the gain of the eye is increased by the iris opening.
In a superheterodyne receiver AGC is usually applied to the IF amplifier , and there may be a second AGC loop to control the gain of the RF amplifier to prevent it from overloading, too. In certain receiver designs such as modern digital receivers, a related problem is DC offset of the signal. This is corrected by a similar feedback system.
Radio waves were first identified in German physicist Heinrich Hertz 's series of experiments to prove James Clerk Maxwell's electromagnetic theory. Hertz used spark-excited dipole antennas to generate the waves and micrometer spark gaps attached to dipole and loop antennas to detect them.
The first radio transmitters , used during the initial three decades of radio from to , a period called the spark era , were spark gap transmitters which generated radio waves by discharging a capacitance through an electric spark. So spark transmitters could not transmit sound, and instead transmitted information by radiotelegraphy. The transmitter was switched on and off rapidly by the operator using a telegraph key , creating different length pulses of damped radio waves "dots" and "dashes" to spell out text messages in Morse code.
Therefore, the first radio receivers did not have to extract an audio signal from the radio wave like modern receivers, but just detected the presence of the radio signal, and produced a sound during the "dots" and "dashes".
Since there were no amplifying devices at this time, the sensitivity of the receiver mostly depended on the detector. Many different detector devices were tried. Radio receivers during the spark era consisted of these parts: . The signal from the spark gap transmitter consisted of damped waves repeated at an audio frequency rate, from to perhaps per second, so in the earphone the signal sounded like a musical tone or buzz, and the Morse code "dots" and "dashes" sounded like beeps.
The first person to use radio waves for communication was Guglielmo Marconi. Therefore, Marconi is usually given credit for building the first radio receivers. The first radio receivers invented by Marconi, Oliver Lodge and Alexander Popov in used a primitive radio wave detector called a coherer , invented in by Edouard Branly and improved by Lodge and Marconi.
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Best Rated in Portable Radios
Compare the most helpful customer reviews of the best rated products in our Portable Radios store. These products are shortlisted based on the overall star rating and the number of customer reviews received by each product in the store, and are refreshed regularly. Skip to main content Best Rated in Portable Radios. Best Rated by Department. Current Department. Portable Radios. Portable Headset Radios. Portable Shortwave Radios. Weather Radios.
TQ portable radio stations
We still have a lot of love for the original 'wireless' — the radio. Yes, we now have myriad options at our disposal for listening to music and accessing news, but there are times when sticking the radio on just can't be beaten — especially during the holiday season. With the advent of DAB radio, internet radio and Bluetooth streaming, the radio has come a long way since its basic bedside clock integration. You can now even get a digital upgrade for your car.
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Trio Licensed Radios
Guarantees of the values of user-friendliness, performance, safety and dependability, all products of the line have won an international reputation for themselves. The head office, located across from the Thau Sound on 60, m2 of land, an ultra modern building which is in harmony with the environment, assembles reception, offices, warehouse and after-sales service over an area of 12, m2. The image of a strong company is a reflection of management which is supported by an efficient team to meet the demands of a constantly evolving field. Locations, addresses, phone and fax numbers and e-mail contacts.SEE VIDEO BY TOPIC: Free Radio Jingles 2020
Radio is the technology of signaling and communicating using radio waves. They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by a radio receiver connected to another antenna. Radio is very widely used in modern technology, in radio communication, radar , radio navigation , remote control , remote sensing and other applications. In radio communication , used in radio and television broadcasting , cell phones , two-way radios , wireless networking and satellite communication among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal impressing an information signal on the radio wave by varying some aspect of the wave in the transmitter. In radar , used to locate and track objects like aircraft, ships, spacecraft and missiles, a beam of radio waves emitted by a radar transmitter reflects off the target object, and the reflected waves reveal the object's location. In radio navigation systems such as GPS and VOR , a mobile receiver receives radio signals from navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth.
GMRS or FRS Radio: How to Choose
The purpose of this awesomely-bad B-movie trailer is to get everyone thinking about a world without radio. As ridiculous as the premise seems, if some catastrophic event took out radio transmitters, what would people do? Well, they would use the digital options they already have. It turns out that no catastrophic event is even necessary to create a shift in listening behavior — because it is already happening. Broadcast radio has a big problem: A hardware problem. This is a topic that is pretty much never talked about at American radio conferences.
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Best Rated in Portable Radios & DAB
Whether it's our new compact Ray53, full-sized Ray63, or multifunction Ray73, you can depend on your Raymarine VHF Radio for years of trouble-free communication at sea. With an oversized LCD and simple controls, the RayMic is a compact all-in-one handset that fits easily on any secondary helm, tower or navigation station. The Ray90 is a black-box design with a transceiver that hides out of sight under your helm, in a locker, or just about anywhere.
Best DAB radios: portable, Bluetooth, in-car
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Radio technology has been around for more than a century, and traditional wheel-tuned radio products have been used for decades by countless listeners around the world. They provide a simple user interface based on a tuning wheel to dial the frequency and a moving needle with a frequency mark to show the tuned station. This article will discuss how to design a mid-level wheel-tuned radio with an LCD to display frequencies, and it will explore the practical considerations in selecting audio ICs and display drivers, as well as how to leverage these technologies to deliver the best end-user radio tuning experience. As a growing number of portable applications such as mobile phones and portable media players integrate the FM radio function, there's a misconception in the market that traditional radios are no longer needed. The reality is, wheel-tuned radios have remained immensely popular for a number of reasons.
L3Harris Falcon® Radios
In radio communications , a radio receiver , also known as a receiver , wireless or simply 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.
Two-way Radios from Hytera
Further information for aircraft holders can be obtained from Eurocontrol's website radio. This register is an information resource on 8,33 kHz radio equipment, mandates and funding opportunities for General Aviation operating in the European airspace. The ATR is a complete solution for radios in small aircraft with the new channel separation of 8.