CN201540331U - Multi-passage high-precision synchronous frequency-measuring device - Google Patents

Abstract

The utility model discloses a multi-passage high-precision synchronous frequency-measuring device comprising an input part, a control part and an output part, wherein the main body of the control part consists of an FPGA and a measurement time-base circuit; the FPGA comprises an embedded DSP, an embedded MicroBlaze, a frequency synchronous collecting logic, a clock phase synchronous collecting control logic and a communication interface; the measurement time-base circuit consists of a GPS synchronous clock and a crystal oscillator; the crystal oscillator is connected with a power module by a memory module; the input part comprises a frequency signal and a temperature signal that are collected and input simultaneously; the frequency signal is directly connected with the embedded DSP; the temperature signal is connected with the FPGA of the control part by an AD converter; and the output part comprises a USB interface and a serial communication interface that are connected with the communication interface respectively. The multi-passage high-precision synchronous frequency-measuring device has the benefits that the long-term, synchronous and high-precision measurement on the frequency signals of multiple passages can be carried out, and the final user can directly select the testing passage, and the information such as records, sizes and the like of the measured frequency values.

Description

The synchronous frequency measuring device of multi-channel high-accuracy

Technical field

The utility model belongs to the electron and information technology field, relates to the synchronous frequency measuring device of a kind of multi-channel high-accuracy.

Background technology

High precision channelized frequencies metering system is widely used in numerous areas such as metering, scientific research, teaching, Aero-Space, Industry Control, military affairs.Frequency measurement mode in the past, the hardware simulation circuit that adopt more, obtain the frequency of measured signal by comparing measured signal and the mode of standard signal zero crossing mistiming, this mode depends on the realization precision of mimic channel, yet in the application process of reality because the interference of circuit itself and the various noises that come from the outside will have a strong impact on the precision of system frequency measurement, therefore in today that frequency-measurement accuracy is had relatively high expectations, this mode based on the simulation test circuit obviously can not satisfy application.Development along with digital circuit, the mode measured with the special ASIC chip has been proposed in the frequency measurement field, the ratio of precision of this method frequency measurement is higher, yet when carrying out the synchro measure of multiple signals, but be difficult to accomplish synchro measure because of its design factor, and the user can not directly control, and need add little process chip in addition and just can carry out.

Summary of the invention

The purpose of this utility model provides the synchronous frequency measuring device of a kind of multi-channel high-accuracy, solved in the prior art and when carrying out the synchro measure of multiple signals, but be difficult to accomplish synchro measure because of its design factor, and the user can not directly control, and need add the problem that little process chip just can be carried out in addition.

The technical scheme that the utility model adopted is, the synchronous frequency measuring device of a kind of multi-channel high-accuracy comprises importation, control section and output,

The main body of described control section is made of FPGA and measurement time base circuit, include embedded DSP among the FPGA, embedded MicroBlaze, Frequency Synchronization acquisition logic, clock phase synchronization acquisition controlling logic and communication interface connects to form, measure time base circuit and be made of GPS synchronous clock and crystal oscillator, crystal oscillator is connected with power module by memory module;

Described importation comprises frequency signal and the temperature signal of gathering input simultaneously, and frequency signal directly is connected with embedded DSP, and temperature signal is connected with the FPGA of control section by AD converter;

Described output comprises USB and the serial communication interface that is connected with communication interface respectively.

The synchronous frequency measuring device of multi-channel high-accuracy of the present utility model, its feature also is:

Described frequency signal, temperature signal and power module all adopt standard DB25 physical interface to insert or pick out.

The beneficial effects of the utility model are, can carry out the frequency signal of a plurality of passages for a long time, synchronously, high-acruracy survey (1 * 10 ^-9), and the final user can directly select the information such as record size of test channel, frequency measurement.

Description of drawings

Fig. 1 is the structural representation of the utility model frequency measuring device;

Fig. 2 is the gate synchro measure principle of work synoptic diagram of the utility model frequency measuring device.

Among the figure, 1.FPGA, 2.DSP, 3.MicroBlaze, 4. Frequency Synchronization acquisition logic, 5. clock phase synchronization acquisition controlling logic, 6. communication interface, 7.USB, 8. serial communication interface, 9.GPS synchronous clock, 10. crystal oscillator, 11. memory modules, 12. power module, 13. frequency signal, 14. temperature signals, 15.AD converter.

Embodiment

Below in conjunction with the drawings and specific embodiments the utility model is elaborated.

As Fig. 1, the structure of the utility model frequency measuring device is to comprise three parts: importation, control section and output.The main body of described control section is made of FPGA1 and measurement time base circuit, including embedded DSP2, embedded MicroBlaze3, Frequency Synchronization acquisition logic 4, clock phase synchronization acquisition controlling logic 5 and communication interface 6 among the FPGA1 connects to form, measure time base circuit and be made of GPS synchronous clock 9 and crystal oscillator 10, crystal oscillator 10 is connected with power module 12 by memory module 11; Described importation comprises frequency signal 13 and the temperature signal 14 of gathering input simultaneously, and frequency signal 13 directly is connected with embedded DSP2, and temperature signal 14 is connected with the FPGA1 of control section by AD converter 15; Described output comprises USB7 and the serial communication interface 8 that is connected with communication interface 6 respectively.

IO interface in the above-mentioned hardware circuit (the electric current input of the input of 9 road frequency signals 13,3 road temperature signals 14 and power module 12 of circuit supply) all adopts standard DB25 physical interface to insert or pick out circuit board.The antennal interface of USB interface and GPS synchronous clock 9 is drawn separately.

The utility model utilizes Xilinx FPGA technology, utilizes its embedded DSP2, embedded MicroBlaze3 processor, high-precision Frequency Synchronization acquisition logic 4 and clock phase-locking acquisition controlling logic 5 to finish the synchro measure of channelized frequencies signal.

The work that clock phase synchronization acquisition controlling logic 5 is responsible for FPGA1 provides the clock source of high precision low jitter.Frequency acquisition module carries out synchronous acquisition according to the configuration order of receiving to frequency signal from serial communication interface, and according to improved gate method for synchronously measuring survey frequency, then measured value is given the DSP module to carry out filtering, output to the outside by MicroBlaze at last.Measuring accuracy guarantees by modified gate synchro measure algorithm with based on the high accurate clock signal that GPS proofreaies and correct.

The logic control core of test macro is FPGA, wherein includes Embedded DSP, Embedded MicroBlaze nuclear, clock phase synchronization acquisition controlling logic and high-precision Frequency Synchronization acquisition logic.The temperature signal that the Embedded DSP module of FPGA inside will be mainly used in being got by temperature sensor measurement calculates, and makes demands thereby can reach in the charter fast and accurately.MicroBlaze is a embedded kernel that Xilinx company releases, and clock can reach 150MHz, takies resource less than 1000 Slice, and responsible with extraneous is mutual.The work that clock phase synchronization acquisition controlling logic is responsible for FPGA provides the clock source of high precision low jitter.

The utility model changes the mode of FPGA+CPU commonly used in the embedded system in the past in hardware configuration, directly remove to finish control algolithm and input/output function with single FPGA.

The wider range that the utility model is suitable for, the accuracy requirement height of frequency measurement, general measuring method can not meet design requirement, guarantee the satisfactory of frequency measurement, except aforementioned good measuring method and, also must have and can and have good long and the crystal oscillator of short-term stability provides base when measuring for system in the work of total temperature scope, this is that the utility model is finished the key point that high-quality is measured.

The serviceability of crystal oscillator 10 is limited by two Fundamentals.One is the influence of environment temperature, and it makes the output frequency of crystal oscillator accelerate with temperature or be slack-off that at this factor, the utility model has been chosen temperature compensating crystal oscillator, thereby satisfies technical requirement.Another is the crystal oscillator output influence of the characteristic of drift in time, and is just long steady.The utility model proposes the time base technology of utilizing GPS and provide real-time adjustment, make it can satisfy task the steady needs of system head to the output frequency and the output phase of local crystal oscillator.

As Fig. 2, the concrete grammar of the utility model measurement device is: the standard time clock number (N of known gate width and gate correspondence ₀), measure in gate by measured frequency upper and lower along number (Nx), gate opening to by the clock ratio (N on first effective edge of measured frequency _C1), closing gate is to by the clock ratio (N on last effective edge of measured frequency _C2), then be by measured frequency:

When using the utility model device to measure, characteristics have: 1), measure fully and gate synchronous; Adopt two opposite gates of sequential to measure jointly, when a gate was operated in the sampling time, another gate then was in computing time, and the benefit of doing like this is the operational use time that has increased gate, thereby has improved the approximation ratio of frequency measurement; 2), the open and close of gate fully and clock synchronization, the tight arrangement of the lag line by FPGA inside can be avoided the trigger error of counter; 3), measuring accuracy depends on the precision of standard time clock and the frequency of operation of counter, error equals 1/2 clock period, therefore very convenient control accuracy.

Existing FPGA can realize the counter works frequency about 60MHz, and the utility model device can be realized counter works frequency about 200MHz by sacrificing the FPGA resource, if adopt interpolation method also can realize the equivalent count device frequency of operation of 400MHz.Under the condition of not considering the standard signal frequency error $\mathrm{\τ}=\frac{1}{10000}S$ Condition under δ ≈ 2.1 * 10 ^-5, consider that other errors can accomplish δ≤1 * 10 ^-4δ ≈ 2.1 * 10 under the condition of τ=10S ^-10, consider that other errors can accomplish δ≤1 * 10 ^-9(not containing the standard signal frequency error).

Claims (2)

1. synchronous frequency measuring device of multi-channel high-accuracy is characterized in that: comprise importation, control section and output,

The main body of described control section is by FPGA (1) and measure the time base circuit formation, include embedded DSP (2) among the FPGA (1), embedded MicroBlaze (3), Frequency Synchronization acquisition logic (4), clock phase synchronization acquisition controlling logic (5) and communication interface (6) connects to form, measure time base circuit and be made of GPS synchronous clock (9) and crystal oscillator (10), crystal oscillator (10) is connected with power module (12) by memory module (11);

Described importation comprises frequency signal (13) and the temperature signal (14) of gathering input simultaneously, and frequency signal (13) directly is connected with embedded DSP (2), and temperature signal (14) is connected with the FPGA (1) of control section by AD converter (15);

Described output comprises USB (7) and the serial communication interface (8) that is connected with communication interface (6) respectively.

2. the synchronous frequency measuring device of multi-channel high-accuracy according to claim 1 is characterized in that: described frequency signal (13), temperature signal (14) and power module (12) all adopt standard DB25 physical interface to insert or pick out.

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