QP值和PK值的区别
1，峰值（PK），所表现的就是测量波形的瞬时最大值。对应的峰值检波器就要求电路的充电足够快，而放电足够慢。峰值的大小只取决于信号的幅度。
准峰值（QP），所表现的是测量信号能量的大小。由于准峰值检波器的充电时间要比放电时间快得多，因此信号的重复频率越高，得出的准峰值也就越高。（在GB9254-1998中提到过在测量接收机上所示的读数在限值附近波动时，则读数的观察时间应不少于15s，记录最高读数，而孤立的瞬间高值忽略不记。）准峰值检波器还能以线性方式对不同幅度的信号起响应。这样，准峰值既可以反映信号的幅度，也能反映出信号的时间分布。}
1）幅度大、重复频率低的信号与幅度小、重复频率高的信号可能会有相同的准峰值输出。
2）对于连续波信号，准峰值测量的结果与峰值测量的结果是一样的。
3）准峰值测量要比峰值测量慢2-3个数量级。
英文解释：
Quasi-peak Measurements Quasi-peak detection is a form of detection where a signal level is weighted bad on the repetition frequency of the spectral components making up the signal. That is to say; the result of a quasi-peak measurement depends on the repetition rate of the signal. Signals can be classified into two general categories bad upon their repetition rate: narrowband or broadband. A narrowband signal is a signal that can be resolved by the spectrum analyzer. An example of a narrowband signal is a continuous wave (CW) signal. A CW signal is one signal at a fixed frequency. A broadband signal is a signal that cannot be resolved by the spectrum analyzer. An example of a broadband signal is a pul signal. Peak, quasi-peak, and average detection will yield the same amplitude level for a narrowband signal. A broadband signal will yield a quasi-peak level lower than the peak level. The weighting (accounted for through specific charge and discharge time constants in the quasi-peak detector circuit), is a function of the repetition frequency of the signal being measured. The lower the repetition frequency, the lower the quasi-peak level. Many agencies governing the electromagnetic interference (EMI) from commercial products require quasi-peak detectio
n to be ud .Even if the emission from a device is over a test limit when measured with peak detection, the device will be considered to pass if the quasi-peak level is below the test limit. Becau of the charge and discharge time constants ud in the quasi-peak detector , the spectrum analyzer must sweep considerably slower when the quasi-peak detector is on. Since the quasi-peak level of a signal is always equal to or less than the peak level of that signal, quasi-peak detection need be employed only when a signal is clo to or over the test limit when measured with peak detection. For initial measurements, peak detection is ud since peak detection does not require the slower sweep times.
2，峰值（PK），所表现的就是测量波形的瞬时最大值。对应的峰值检波器就要求电路的充电足够快，而放电足够慢。峰值的大小只取决于信号的幅度。也正因为如此，在测量的时候用峰值检波扫描，只要所有信号的峰值都处在限值的下方，则EUT是合格的，无需进一步测量。
准峰值（QP），所表现的是测量信号能量的大小。由于准峰值检波器的充电时间要比放电
时间快得多，因此信号的重复频率越高，得出的准峰值也就越高。（在 GB9254-1998中提到过在测量接收机上所示的读数在限值附近波动时，则读数的观察时间应不少于15s，记录最高读数，而孤立的瞬间高值忽略不 记。）准峰值检波器还能以线性方式对不同幅度的信号起响应。这样，准峰值既可以反映信号的幅度，也能反映出信号的时间分布。
注意：
1）幅度大、重复频率低的信号与幅度小、重复频率高的信号可能会有相同的准峰值输出。
2）对于连续波信号，准峰值测量的结果与峰值测量的结果是一样的。
3）准峰值测量要比峰值测量慢2-3个数量级。
