Nominal frequency: the nominal value of the center frequency or frequency of the oscillator output.

Frequency accuracy: deviation of oscillator output frequency from nominal frequency at room temperature (25 ℃± 2 ℃).

Adjust frequency difference: the maximum allowable frequency deviation of the oscillator output frequency relative to the measured value at 25 ℃ within the specified temperature range.

Load resonance frequency (FL): under specified conditions, the crystal is connected in series or in parallel with a load capacitor, and its combined impedance is one of the two frequencies when it is resistive (resonance is generated). When the load capacitor is connected in series, the load resonant frequency is the lower of the two frequencies, and when the load capacitor is connected in parallel, it is the higher of the two frequencies.

Static capacitance: the capacitance connected in parallel with the series arm in the equivalent circuit, also known as parallel capacitance, usually represented by C0.

Operating temperature range: the temperature range that can ensure that the output frequency and various characteristics of the oscillator meet the index.

Frequency temperature stability: the maximum allowable frequency deviation without implicit reference temperature or with implicit reference temperature operating within the specified temperature range under nominal power supply and load.

ft=±(fmax-fmin)/(fmax fmin)

ftref＝±MAX[｜(fmax-fref)/fref｜，｜(fmin-fref)/fref｜]

FT: frequency temperature stability (without implied reference)

Ftref: frequency temperature stability (with implied reference temperature)

Fmax: the highest frequency measured within the specified temperature range

Fmin: the lowest frequency measured within the specified temperature range

Fref: frequency measured at specified reference temperature

Note: the production difficulty of crystal oscillator with ftref index is higher than that of crystal oscillator with FT index, so the price of crystal oscillator with ftref index is higher.

Load capacitance: the effective external capacitance that determines the load resonant frequency FL together with the crystal, expressed in CL.

Load capacitance series: 8pf 12PF 15pF 20pF 30pf 50pF 100pF

Excitation level: the characteristic value of the power consumed by the crystal during operation. The optional values of excitation level are: 2MW, 1MW, 0.5MW, 0.2mw, 0.1MW and 50 μ W、20 μ W、10 μ W、1 μ W、0.1 μ W et al

Aging rate: the relative change of output frequency within a certain time.

Fundamental frequency: the lowest order vibration frequency in the vibration mode.

Overtone: mechanical harmonic of crystal vibration. The ratio of overtone frequency to fundamental frequency is close to an integer multiple, but not an integer multiple, which is the main difference between overtone frequency and electrical harmonic. Overtone vibration has 3 overtones, 5 overtones, 7 overtones, 9 overtones, etc.