Received Noise Power. The calculated or measured noise power, within the bandwidth being used, at the receive end of a circuit, channel, link, or system.
Receiver. [Detector]. Electronic Equipment that converts electromagnetic energy into a visible or an audible form. As in FM Receiver, AM Receiver or Radar Receiver. The electromagnetic component used in a telephone handset to convert electrical energy into sound energy.
Receiver Sensitivity. The degree to which a receiver can usefully detect a weak signal. The lower limit of useful signal input to the receiver.
Receiving Antenna. The device used to pick up the RF signal from space. Also refer to the dictionary of Antenna Terms. Related; Antenna Manufacturers.
Receptacle. A socket that accepts a plug or jack. An AC outlet.
Recovery Time. The time required for a device to return to its previous state after a change.
Rectangular Connector. A series of connector types that have a basic rectangular shape, but with a large number of pin arrangements, pin styles, and shell shapes. Refer to the graphic to the right.
Rectangular Waveform. A Periodic waveform, or squarewave having something other than a 50 percent duty cycle and only two distinct values. Also refer to a LM124 Rectangular Wave Generator.
Rectification. The conversion of AC into DC by means of a rectifier.
Rectifier. A device [diode] used to convert ac to pulsating dc. Also refer to Half-Wave Rectifier Circuit, or Full-Wave Rectifier Circuit. A two terminal semiconductor or electron tube that converts Alternating current into direct current. A device that only conducts in one direction. [Diode Manufacturers]
Rectifier Circuit. A circuit used to convert ac to pulsating dc; Half-wave [single diode], Full-wave Center Tapped Transformer [two diodes], Full-wave Bridge [four diodes], Dual Complementary Center Tapped Transformer [four diodes]
Redundant Array of Inexpensive Disks. An array of hard disks used to store or backup data. There are a number of different way the disks may be interconnected. RAID 0 is the 'Stripping' form of RAID, each disk of a two disk set gets half the data speeding the process of reading/writing to disk.
Reed Relay. A type of relay that uses a ferromagnetic material (reed) which is encapsulated in glass. A Reed Switch. Related Mechanical Reed Relay Manufacturers. A relay consisting of an energizing coil and a metallic reed switch mechanism. The reeds serve as both core and contacts, which are not hinged or pivoted and which move by flexure when acted upon by a magnetic field induced by energization of the coil. It may also include a biasing magnet. The biasing magnet, either aids or opposes the movement of the reeds and the opening or closing of the contacts.
Reed Switch. A switch actuated by an external magnetic field and having two or more contacts inclosed in a sealed capsule.
Reference Frequency. A standard fixed frequency from which operational frequencies may be derived or with which they may be compared.
Reference Line. The position of zero displacement in a wave.
Reference Plane. A layer on a Printed Wiring Board [PWB] used as a signal reference. Usually ground is used and preferred as the reference plane, but a voltage may also be used instead of ground. Also refer to the dictionary of Printed Circuit Board Terms.
Reference Point. A point in a circuit to which all other points in the circuit are compared. Normally the reference point in a circuit is grounded, so the reference would be ground [which does not have to be zero volts].
Reflected Wave. The wave that reflects back from a medium. The wave moving back to the source from the termination of a transmission line after reflection has occurred.
Reflection. The abrupt change in direction of a wave front at an interface between two dissimilar media so that the wave front returns into the medium from which it originated.
Reflection Waves. Waves that are neither transmitted nor absorbed, but are reflected from the surface of the medium they encounter.
Reflector. The parasitic element of an array that causes maximum energy radiation in a direction toward the driven element.
Reflex Klystron. A klystron with a reflector (repeller) electrode in the place of a second resonant cavity used to redirect the velocity-modulated electrons back through the cavity that produced the modulation. A microwave oscillator that is tuned by changing the repealer voltage.
Reflected Impedance. The apparent impedance of a transformer primary due to current flowing in the secondary winding.
Reflection. The changing of direction of a wave as it leaves one medium and enters another medium of a different density.
Reflection Coefficient. [RC] The ratio of the amplitude of the reflected wave and the amplitude of the incident wave.
Refractive Index. In a wave-transmission medium, the ratio between the phase velocity in free space and in the medium.
Regenerated Clock. A clock signal which has been generated or reconstructed from a digital data sequence.
Regeneration. In a regenerative repeater, the process by which digital signals are amplified, reshaped, retimed, and retransmitted.
Regenerative Detector. A detector circuit that produces its own oscillations, heterodynes them with an incoming signal, and deflects them.
Regenerative Feedback. Feedback in which the portion of the output signal that is returned to the input has a component that is in phase with the input signal. The process by which a portion of the output signal of an amplifying device is fed back in phase to reinforce the input. [Positive Feedback].
Register. A device, accessible to one or more input circuits, that accepts and stores data. A flip flop, latch or shift register.
Registered Jack. [RJ] Any of the series of jacks, described in the Code of Federal Regulations, Title 47, part 68, used to provide interface to the public telephone network. An RJ45 is shown below, also see Telecom Connector Manufacturers.
Regulator. [Voltage Regulator] The section in a power supply that maintains the output of the power supply at a constant level in spite of large changes in load current or input line voltage. There are two main styles; Switching Regulators and Linear Regulators. [Regulator Manufacturers]
Relative Transmission Level. The ratio of the signal power, at a given point in a transmission system, to a reference signal power.
Relaxation Oscillator. An oscillator that uses either an inductor or capacitor to produce a non-sinusoidal output by allowing the component to charge and then forcing it to quickly discharge once a voltage threshold is reached. A Neon Tube Relaxation oscillator shown to right, or a UJT Relaxation Oscillator.