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Crystal and frequency control glossary

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Mask

In communications systems, to obscure, hide, or otherwise prevent information from being derived from a signal. Masking is usually the result of interaction with another signal, such as noise, static, jamming, or other forms of interference.

Master frequency generator

In frequency-division multiplexing (FDM), equipment used to provide system end-to-end carrier frequency synchronization and frequency accuracy of tones.

Maximum usable frequency (MUF)

In radio transmission using reflection from the regular ionized layers of the ionosphere, the upper frequency limit that can be used for transmission between two points at a specified time.

MCXO

Microcomputer compensated crystal oscillator often used in spread spectrum system clocks, MTI radars, wireless base stations, telecom timing modules, and precision test equipment.

MDS

Abbreviation for multipoint distribution systems.

Mechanical strip

See AT strip.

Medium frequency (MF)

Frequencies from 300 kHz to 3000 kHz.

Mega

A prefix, abbreviated "M", used to denote units of millions. One "Mega" is equal to one million. In our industry, one MegaHertz is a frequency of one million Hertz (cycles per second).

MegaHertz (MHz)

Used to describe the frequency of a crystal or oscillator in terms of millions of Hertz (cycles per second). A frequency specified as "10.0 MHz" would be understood as being a frequency of 10,000,000 Hertz (cycles per second).

Metal-oxide semiconductor field-effect transistor (MOSFET)

A special type of field-effect transistor (FET) that works by electronically varying the width of a channel along which charge carriers (electrons or holes) flow. The wider the channel, the better the device conducts.

Microbalance

An unsealed plated quartz crystal wafer used to measure very minute changes in its mass by monitoring its frequency.

Microprocessor crystal

Standard crystals for use in clock circuits of microprocessors.

Microwave

RF signals between 890 MHz and 20 GHz. Point-to-point microwave transmission is commonly used as a substitute for copper or fiber cable.

Microwave band

Those frequencies from about 1 GHz upward that use microwave frequencies for point-to-point and point-to-multipoint communications, including common carriers, cable TV operators, broadcasters and private operational fixed users.

Microwave radio

A radio frequency used extensively for long-distance telephone transmission. Digitally encoded messages are sent through microwave channels either between terrestrial antennae, via satellite, or through waveguides.

Military crystals

Quartz crystals that are designed to meet military specifications (Mil-Spec) and produced to Mil-Spec requirements (QPL).

Milli

A prefix, abbreviated "m", used to denote units of thousandths. One "milli" is equal to 1/1000th of a unit.

MMIC

Abbreviation for monolithic microwave integrated circuit.

Mobile earth station

An Earth station in the mobile-satellite service intended to be used while in motion or during halts at unspecified points.

Mobile service

A radiocommunication service between mobile and land stations, or between mobile stations.

Mobile station

A station in the mobile service intended to be used while in motion or during halts at unspecified points.

Mode of operation

The mode of operation of a quartz device is one of the factors that will determine the frequency of oscillation. For AT-cut quartz crystals, overtone modes are at odd frequency harmonics. A crystal may operate at its fundamental frequency of 10 MHz, or at odd harmonics of approximately 30MHz (Third Overtone), 50MHz (Fifth Overtone), and 70 MHz (Seventh Overtone).

Modulation

Impressment of information on a carrier signal by varying one or more of the signal's basic characteristics: frequency, amplitude and phase.

Monolithic crystal

A crystal with two or more electrodes where energy is coupled between the electrodes by way of the vibrating quartz structure.

Monolithic crystal filter (MCF)

Filter which is a crystal with two or more electrodes where energy is coupled between the electrodes by way of the vibrating quartz structure.

Motional capacitance

A parameter associated with a quartz crystal unit, used to illustrate the electronic equivalence of the mechanical elasticity of the unit. Motional capacitance may be abbreviated as "Cm" or "C1." The actual value of C1 has physical limitations when it is realized in a quartz crystal design. These constraints include the mode of operation, the quartz cut, the mechanical design, and the nominal frequency of the crystal.

Motional inductance

A parameter associated with a quartz crystal unit, used to illustrate the electronic equivalence of the mechanical mass of the unit. Motional inductance may be abbreviated as "Lm" or "L1."

Motional resistance

The energy lost within the vibrating area of the crystal resonator. Does not include any loss external to the vibrating crystal. It is represented in the electrical circuit as a resistor. See resistance.

MS/s

Abbreviation for million of samples per second.

Multichannel multipoint distribution service (MMDS)

A broadcasting and communications service that operates in the ultra-high-frequency (UHF) portion of the radio spectrum between 2.1 and 2.7 GHz. MMDS is also known as wireless cable.

Multi-element dipole antenna

An antenna consisting of an arrangement of multiple dipole antennas.

Multipoint distribution service (MDS)

Also known as "wireless" cable. This is a one-way, domestic public radio service broadcast on microwave frequencies from a fixed station that transmits (usually in an onmidirectional pattern) to multiple receiving facilities located at fixed points.

Multi-satellite link

A radio link between a transmitting Earth station and a receiving Earth station through two or more satellites, without any intermediate Earth station.

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