Resonator refers to the resonant frequency of the electronic components, commonly used is divided into quartz crystal resonator and ceramic resonator.
　　① Nominal Frequency: The resonant center frequency specified by the resonator under the specified conditions.
　　② adjust the frequency difference: under the conditions specified, the reference temperature of the operating frequency relative to the maximum deviation of the nominal frequency.
　　③ temperature frequency difference: under the specified conditions, the entire operating temperature range, relative to the reference temperature when the operating frequency of the allowable deviation value.
　　(4) Reference temperature: When measuring quartz crystal resonator parameters, the specified ambient temperature. For the constant temperature quartz crystal resonator, the central point of the operating temperature range is generally; for non-constant quartz crystal resonator, 25 ℃ ± 2 ℃.