Abstract
For the traditional numeral frequency meter the frequency measurement error mainly contains two itemsσ=σ1+σ2. σ1 is the relative error of strobe time which in value is equal to the accuracy of standard frequency signal, σ1=-ΔFs/Fs, Fs is the standard frequency of the standard signal; σ2 is the relative quantification error to the frequency measurement technology, σ2=±Tx/T, Tx is the period of the measured signal, T is the strobe time. σ1 is related with the uses the frequency stability of the quartz crystal. σ1 often can be reduced by using high stability quartz crystal oscillator; σ2 is a variable, the value of which the differs several magnitudes between the low frequency band and the high frequency band in the identical strobe, so the influence to the frequency measurement precision of σ2 is the most serious. In order to reduceσ2 the following method is often used: chang to cycle measure when the frequency is low; multi-cycles measure; Analog interpolation; ampify the frequency and so on. By using these methods the frequency measurement error can be reduced for a little, but the basic problem can not be solved, and also increased the software and hardware cost.
In this article, we introduced a cymometer with high accuracy which realizes by using the monolithic integrated circuit, its characteristics are:
High Measuring accuracy, and the precision of all of the measured frequency is equal in the identical strobe, when the strobe time is 10s, σ2≈10 -7;
(2) The strobe time can be random setting in the rang of 0.01s--10s;
(3) The frequency measurement scope is wide, Fx=0.1Hz --100M Hz;
(4) The operation rate is high. By using special given points operation to replace the floating number operation, 4 byte significant digit is retains in the operation;
(5) In the software for display 8-bit decimal bases significant digits are displayed through the fluctuation decimal point position;
(7) It has the continuously demonstration function.
Key words: Cymometer, Measurements with the same precision, Single-chip Machine