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Improved method and apparatus for measuring stability of frequency of time domain signal

A technology of frequency stability and time-domain signals, applied in frequency measurement devices, frequency-to-phase shift conversion, heterodyne/beat frequency comparison, etc., can solve problems such as different errors, counting errors, and inaccuracies

Inactive Publication Date: 2007-05-16
JIANGHAN UNIVERSITY
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Problems solved by technology

It can be seen from Figure 2 that there is a time difference Δt between the time points A and B of the enable counter and the arrival of the next edge pulse of the reference time base signal 1 , Δt 2 , the size of the specific difference depends on the phase difference between the measured signal and the reference time base signal at time A or B, and its size is not a constant fixed phase difference relationship, which will lead to There are different errors, which is also the reason for the counting error

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  • Improved method and apparatus for measuring stability of frequency of time domain signal
  • Improved method and apparatus for measuring stability of frequency of time domain signal
  • Improved method and apparatus for measuring stability of frequency of time domain signal

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[0037] 1. Reference frequency signal f 0 Processing: as shown in Figure 5

[0038] Reference frequency signal f 0 After passing through the isolation amplifier 1, it is sent to the external clock input terminal of DDS1 as an external reference clock for DDS1 work. At the same time, the external communication port of DDS1 is connected to the processor to receive control word commands and bidirectional data transmission from the processor. There are two 48-bit frequency control registers (F0, F1) inside the actually selected DDS1 chip. For the device reference frequency signal f 0 When the DDS1 internal PLL frequency multiplication function is not used, when the 48-bit frequency control register F0 is filled with 1, DDS1 will output a 10MHz frequency signal. Therefore, in order to obtain a standard periodic sampling time signal T (such as 1 second, 10 seconds), you need to set the corresponding frequency division value for the frequency control register F0 in DDS1, the specifi...

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Abstract

This invention discloses one method and device to improve time zone signals frequency stability measurement, which comprises the following steps: reference time signals are processed through DDS technique to get stable and accurate circle signals; expending measurement frequency signals range to get better reference signals and signals to be tested at fine time measurement; using DDS unit to process measurement frequency signals; when circle sample time singles come, according to fine time measurement module minimum resolution rate to test signals to be tested with reference time signals minimum phase difference to make the meter work to fulfill frequency signal measurement.

Description

technical field [0001] The invention belongs to the frequency stability measurement technology, and in particular relates to a method and a device for measuring the frequency stability of a time-domain signal. Background technique [0002] Frequency stability is an important index to measure the stability of the output frequency signal of a clock signal source. In the time domain, the frequency of the clock signal changes with time. The frequency can be regarded as a continuous function of time t, expressed by f(t) . f(t) also represents the instantaneous frequency at time t. In fact, due to the difficulty in measurement, the instantaneous frequency is only a theoretical concept, because all measurements and frequency stability involved require a certain sampling time, and the measurement result is the average frequency within the sampling time. Taking a certain time t0 as the starting point on the time axis, the measured signal is continuously sampled, each sampling count...

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Application Information

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IPC IPC(8): G01R23/02G01R23/14G01R23/12
Inventor 雷海东候群张霞操长茂钱同惠李建民李明涛叶锋漆为民王中明
Owner JIANGHAN UNIVERSITY
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