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Crystal and frequency control glossary

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r face

One of the three smaller faces which occur at the ends of the natural quartz crystal.

R face

One of the three larger faces which occur at the ends of the natural quartz crystal.

Radiation

The outward flow of energy from any source in the form of radio waves.

Radio

Telecommunication by modulation and radiation of electromagnetic waves. A transmitter, receiver, or transceiver used for communication via electromagnetic waves. A general term applied to the use of radio waves.

Radio control

The remote control of an apparatus by signals conveyed by electromagnetic waves.

Radio frequency (RF)

A term that refers to alternating current (AC) having characteristics such that, if the current is input to an antenna, an electromagnetic (EM) field is generated suitable for wireless broadcasting and/or communications.

Radio frequency interference (RFI)

Any electromagnetic disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics/electrical equipment.

Radio telephony

The use of radio to communicate sounds.

Radio wave

An electromagnetic wave of a frequency arbitrarily lower than 3000 GHz.

Radiocommunication

Telecommunication by means of radio waves.

Radiotelegraphy

The use of radio (instead of wire) to communicate a message(s) over a distance.

RbXO

Rubidium-crystal oscillator often used in satellite terminals and bistatic and multistatic radar.

Reactance

The opposition to an alternating current presented by inductance, capacitance, or a combination of the two. Reactance is measured in ohms and is represented by the letter X.

Read-only memory (ROM)

A memory in which data, under normal conditions, can only be read.

Recrystalling

The removal of one crystal and the replacement by a crystal of a different frequency and the realignment of the equipment.

Refarming

An FCC initiative to promote more efficient use of the frequency bands below 512 MHz allocated to private land mobile radio services.

Reference edge

The edge of a blank or wafer identified for use in orienting the blank or wafer on an x-ray chuck for making orientation measurements.

Reference flat

The flat edge on an otherwise circular blank for use as a reference edge. Called an X-flat when perpendicular to the X-axis.

Reference frequency

Frequency having a fixed and specified position with respect to the assigned frequency.

Relative Bechmann Angle (RBA)

Relative Bechmann Angle is the apparent angle of orientation of an AT crystal blank, which is derived from a plot of the temperature vs. frequency characteristic of a crystal resonator.

Repeater

Devices that receive a radio signal, amplify it and re-transmit it in a new direction. Used in wireless networks to extend the range of base station signals, thereby expanding coverage – within limits – more economically than by building additional base stations. They are typically used for buildings, tunnels or difficult terrain.

Resistance weld

Procedure involving pressure sealing with electricity and backfilling with nitrogen to force out oxygen and moisture. This results in superior aging characteristics.

Resistance

In a device, circuit, or component, the opposition to current flow. Resistance is identified by the letter R and is measured in ohms.

Resistor

An electrical component that limits or regulates the flow of electrical current in an electronic circuit. Resistors can also be used to provide a specific voltage for an active device such as a transistor. A component used to introduce resistance into a circuit.

Resonance

The creation of vibrations in a system by the application of a periodic force. The state that exists when the frequency of the applied force is equal to the natural frequency of the system.

Resonance resistance (Rr, R1)

The resistance of the crystal unit alone at the resonance frequency.

Resonant frequency

The natural frequency at which a circuit oscillates or a device vibrates. Abbreviated as Fr or fr.

Resonator

A body that is capable of being set into resonance by the application of a periodic force. See blank and plate.

Resonator plate

The quartz blank or resonator.

RFIC

Abbreviation for radio frequency integrated circuit.

Ripple

The difference between maximum and minimum attenuation in the passband.

RISC

Acronym for reduced instruction set chip, reduced instruction set computing.

Rise and fall times

Rise time is the amount of time, measured in nanoseconds that it takes to go from the logic "0" state to the logic "1" state. The fall time is the transition time from logic "1" state to logic "0" state. The time is measured at the 10% and the 90% points of the voltage transition.

Rise time

The rise time, measured in nanoseconds (nSec), is defined as the transition time from an output logic low to an output logic high. See fall time.

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