receiverelectronics

• telecommunications systems telecommunications media

  The two most common kinds of optoelectronic receivers for optical links are the positive-intrinsic-negative (PIN) photodiode and the avalanche photodiode (APD). These optical receivers extract the baseband signal from a modulated optical carrier signal by converting incident optical power into electric current. The PIN photodiode has low gain but very fast response; the APD has high gain but...

• component of communication model communication

  ...the communication process extant nor is it universally accepted. As originally conceived, the model contained five elements—an information source, a transmitter, a channel of transmission, a receiver, and a destination—all arranged in linear order. Messages (electronic messages, initially) were supposed to travel along this path, to be changed into electric energy by the...

development of

• radar ( in radar: Receivers )

  Like most other receivers, the radar receiver is a classic superheterodyne. It has to filter the desired echo signals from clutter and receiver noise that interfere with detection. It also must amplify the weak received signals to a level where the receiver output is large enough to actuate a display or a computer. The technology of the radar receiver is well established and seldom sets a limit...

  in radar: Receiver noise )

  The sensitivity of a radar receiver is determined by the unavoidable noise that appears at its input. At microwave radar frequencies, the noise that limits detectability is usually generated by the receiver itself (i.e., by the random motion of electrons at the input of the receiver) rather than by external noise that enters the receiver via the antenna. A radar engineer often employs a...

• telecommunications

  • facsimile transmission ( in facsimile: Standard fax transmission. )

    Communication between a transmitting and a receiving fax machine opens with the dialing of the telephone number of the receiving machine. This begins a process known as the handshake, in which the two machines exchange signals that establish compatible features such as modem speed, source code, and printing resolution. The page information is then transmitted, followed by a signal that...

    in telephone and telephone system: Early telegraph facsimile )

    ...the transmitter cylinder, and then scanned by a...

• major reference television

  At the television receiver the sound and picture carrier waves are picked up by the receiving antenna, producing currents that are identical in form to those flowing in the transmitter antenna but much weaker. These currents are conducted from the antenna to the receiver by a lead-in transmission line, typically a 12-mm (one-half-inch) ribbon of plastic in which are embedded two parallel copper...

• resonance resonance

  ...in frequency-sensitive (alternating-current) circuits makes it possible for communication devices equipped with such circuits to accept signals of certain frequencies while rejecting others. In a television receiver, for example, resonance occurs when the frequency of one of the incoming signals reaching the circuit is near the natural frequency of the circuit, which then responds by...

• work of Du Mont Du Mont, Allen B.

  ...commercial television receivers, which were based upon his improved cathode-ray tube. His company also established experimental television transmission facilities and marketed the first postwar television receivers.

• military warning and detection systems warning system

  For atmospheric or space explosions, radio-pulse receivers and light flash and acoustic detectors are used, as well as devices to measure fallout. Aircraft and rockets can be used to collect radioactive debris, while high-altitude satellites carry detectors for gamma rays and other emissions.

• description ceilometer

  There are two basic types of ceilometers: the scanning receiver and the rotating transmitter. The scanning-receiver ceilometer has its separate light transmitter fixed to direct its beam vertically. The receiver is stationed a known distance away. The parabolic collector of the receiver continuously scans up and down the vertical beam, searching for the point where the light intersects a cloud...