Q-Factor: Quality factor. The amplification of an oscillating (tuned) circuit. The ratio of the voltage produced by the circuit divided by the voltage applied to it.
Quiescent Current: The standing current that flows in a circuit when the signal is not applied. The quiescent current is usually very low or lower than when processing a signal.
Random Access Memory (RAM): Memory that can be both read and changed during computer operation. Unlike other semi-conductor memories, RAM is volatile-if power to the RAM is disrupted or lost, all the data stored is lost.
Radio Frequency: RF for short. That part of the spectrum from approx 50kHz to gigahertz.
R-C: Resistance-Capacitance such as R-C coupling.
Read Only Memory (ROM): Memory that contains fixed data. The computer can read the data, but cannot change it in any way.
Real-time Sampling: A sampling mode in which the oscilloscope collects as many samples as it can as the signal occurs.
Receiver (Rx): A circuit in which electrical waves or currents are converted into audible signals.
Rectifier: A device that pases current in only the forward direction.
Record Length: The number of waveform points used to create a record of a signal.
Regenerative Receiver: An amplitude modulated (AM) radio receiver in which positive feedback is used in order to increase the sensitivity and selectivity of the receiver.
Register: A storage device with a specific capacity, such as a bit, byte or word.
Relay (Mechanical): An electromechanical device that completes or interrupts a circuit by physically moving electrical contacts into contact with each other.
Relay (Solid State): A solid state switching device which completes or interrupts a circuit electrically with no moving parts.
Resistance: The resistance to the flow of electric current measured in ohms (1/2) for a conductor. Resistance is function of diameter, resistivity (an intrinsic property of the material) and length.
Resonant Frequency: The frequency at which resonance occurs. In a parallel resonant circuit, the current in the circuit is a minimum and the voltage is a maximum.
Resistor: Passive component with a known resistance. The value of resistance is usually shown by a set of coloured bands on the body of the component.
Resolution: The smallest detectable increment of measurement. Resolution is usually limited by the number of bits used to quantize the input signal. For example, a 12-bit A/D can resolve to one part in 4096 (2 to the 12 power equals 4096).
Rheostat: A variable resistor.
Rise Time:The time taken for the leading edge of a pulse to rise from its minimum to its maximum values (typically measured from 10% to 90% of these values).
RMS:Root mean square.
Room Conditions: Ambient environmental conditions under which transducers must commonly operate.
Root Mean Square (RMS): Square root of the mean of the square of the signal taken during one full cycle.
RTD: Resistance temperature detector.