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

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

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

Load resonance frequency (fL): Under specified conditions, a crystal is connected in series or in parallel with a load capacitor, and its combined impedance appears to be resistive (resonance). When load capacitors are connected in series, the load resonance frequency is the lower of the two frequencies, and when load capacitors are 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 called parallel capacitance, usually represented by C0.

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

Frequency and temperature stability: Under the nominal power supply and load, the maximum allowable frequency deviation without implicit reference temperature or with implicit reference temperature in the specified temperature range.

     ft=±(fmax-fmin)/(fmax+fmin)

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

     ft: Frequency temperature stability (without implicit reference degree)

     ftref: frequency temperature stability (with implicit reference temperature)

     fmax: the highest frequency measured within the specified temperature range

     fmin: the lowest frequency measured within the specified temperature range

     fref: Specifies the frequency measured by the reference temperature

Note: The production difficulty of crystal oscillators using ftref index is higher than that of crystal oscillators using ft index, so crystal oscillators with ftref index sell for higher prices.

Load capacitance: The effective external capacitance that determines the load resonance frequency FL together with the crystal, expressed by CL.

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

Excitation level: the characteristic value of the power consumed when the crystal is working. Optional values of excitation level are: 2mW, 1mW, 0.5mW, 0.2mW, 0.1mW, 50μW, 20μW, 10μW, 1μW, 0.1μW, etc.

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

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

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