阅读说明：本技术 一种相位连续的任意波信号对数扫频信号的产生方法 (Method for generating logarithmic sweep frequency signal of continuous-phase arbitrary wave signal ) 是由 陈洪兴 赵爱君 王颖 金晶晶 于 2019-08-02 设计创作，主要内容包括：本发明公开了一种相位连续的任意波信号对数扫频信号的产生方法,该方法步骤为：将用户设置的扫描时间根据起始频率、结束频率转化为若干个时间段,在每个时间段内,根据波形数据的长度产生扫描进度,产生采样步长的时钟信号；当用户的扫描触发条件满足时,相位控制逻辑将采样步长时钟不断读取相位调理模块的步长控制字通过乘法器产生相应的信号相位调节字。本发明的有益效果为：本发明可以极大减少扫描信号产生的硬件需求,增加信号产生的可控性和精度。在整个的对数扫频信号的产生过程中,不需要上位机来控制,寻址地址可以在单周期内产生,因而频带可以较宽,而且稳定性、可靠性强。在信号源的设备升级中,该功能可以便捷地移植。(The invention discloses a method for generating a logarithmic sweep frequency signal of an arbitrary wave signal with continuous phase, which comprises the following steps: converting the scanning time set by a user into a plurality of time periods according to the starting frequency and the ending frequency, and generating a scanning progress and a clock signal of a sampling step length according to the length of waveform data in each time period; when the scanning trigger condition of the user is met, the phase control logic enables the sampling step length clock to continuously read the step length control word of the phase conditioning module and generates a corresponding signal phase adjusting word through the multiplier. The invention has the beneficial effects that: the invention can greatly reduce the hardware requirement for generating scanning signals and increase the controllability and precision of signal generation. In the whole generation process of the logarithmic sweep frequency signal, an upper computer is not needed for control, and an addressing address can be generated in a single period, so that the frequency band can be wider, and the stability and the reliability are strong. In the equipment upgrading of the signal source, the function can be conveniently transplanted.)

1. A method for generating a logarithmic sweep frequency signal of an arbitrary wave signal with continuous phase is characterized by comprising the following steps: the method comprises the following steps: converting the scanning time set by a user into a plurality of time periods according to the starting frequency and the ending frequency, and generating a scanning progress and a clock signal of a sampling step length according to the length of waveform data in each time period; when the scanning trigger condition of the user is met, the phase control logic enables the sampling step length clock to continuously read the step length control word of the phase conditioning module to generate a corresponding signal phase adjusting word through the multiplier, the signal phase adjusting word generates an addressing address of a signal in the accumulator, the waveform data in the waveform memory is read according to the addressing address, and the waveform signal generates a logarithmic sweep frequency signal according to the frequency of the scanning progress.

2. The method for generating a logarithmic sweep signal of an arbitrary wave signal with continuous phase according to claim 1, wherein: the waveform memory is used for storing monocycle waveform data of the scanning wave, and when the stored waveform is sine, a logarithmic sweep frequency signal of a sine signal is generated; when the stored waveform is an arbitrary waveform customized by a user, a logarithmic sweep signal of the arbitrary waveform is generated.

3. The method for generating a logarithmic sweep signal of an arbitrary wave signal with continuous phase according to claim 1, wherein: the addressed address is generated in a single cycle.

4. The method for generating a logarithmic sweep signal of an arbitrary wave signal with continuous phase according to claim 1, wherein: and the waveform signal is sent to a DAC analog-to-digital converter according to the frequency of the scanning progress, and the digital form of the waveform data is converted into an analog signal, so that a logarithmic frequency sweeping signal is generated.

5. The method for generating a logarithmic sweep signal of an arbitrary wave signal with continuous phase according to claim 1, wherein: the waveform signal is sent to a signal comparator according to the frequency of the scanning progress for generating a digital pulse signal.

6. The method for generating a logarithmic sweep signal of an arbitrary wave signal with continuous phase according to claim 1, wherein: the generation of signals needs to decompose commands of the upper computer according to setting commands of the upper computer, command interpretation logic decomposes the commands of the upper computer and sends the commands to each functional module, frequency division is accurately carried out according to scanning time and scanning frequency span in command parameters to obtain a reading frequency clock with step length, a current frequency step length parameter is read through the clock, an actual current frequency step length coefficient is obtained through multiplication of a multiplier and initialized multiplication factors, a decimal part compensation is carried out to obtain an accurate phase step length for generating signals, a reading address of a waveform data memory is obtained in an addressing address generation accumulator C according to an initial phase and the accurate phase step length, and required signals can be obtained after waveform data read according to the address passes through a DAC.

7. The method for generating a logarithmic sweep signal of an arbitrary wave signal with continuous phase according to claim 6, wherein: the current frequency of the current logarithmic scanning is given in real time through a transient frequency monitoring control module and is used for detecting the intermediate trigger frequency set by a user and judging the scanning end frequency; the compensation accumulator A compensates decimal frequency division information in the scanning process, the phase accumulator B generates the phase step length of a current frequency signal, the addressing address generation accumulator C accumulates an initial phase value and the current phase step length, and the result is accumulated with the current phase step length continuously, so that the addressing address of the waveform memory is generated continuously.

8. The method for generating a logarithmic sweep signal of an arbitrary wave signal with continuous phase according to claim 5 or 6, characterized in that: storing 10 octaves of phase step length information of logarithmic scanning by a scanning step length memory, and generating an accurate step length reading clock of a frequency sweeping signal by a high-frequency working clock according to scanning frequency span and scanning time set by a user by a sampling frequency generator; the scanning phase controller converts the step information into address addressing information and reads the waveform data of the waveform memory by using the addressing address generated by the scanning phase controller.

Technical Field

The invention relates to generation of logarithmic sweep frequency signals, can be used in the field of measuring instruments, is suitable for a signal generator of high-precision logarithmic sweep frequency signals, and mainly relates to a method for generating random wave signal logarithmic sweep frequency signals with continuous phases.

Background

In the current signal generation design, a fixed clock is generally utilized to continuously control a direct frequency synthesis chip (DDS) through an MCU (microprogrammed control Unit) to generate a logarithmic frequency sweeping signal, and the logarithmic frequency sweeping signal has a certain step length, discontinuous phase and poor precision. In addition, a large amount of data is generated through the operation of an upper computer, and the logarithmic scanning of the frequency is completed through a DAC (digital-to-analog converter), so that the very high frequency is difficult to achieve. With the increasing demand of users, it is difficult to generate a wide-band and high-precision logarithmic scan frequency signal by these methods alone. According to patent retrieval and published data, a convenient implementation method for realizing a high-precision frequency logarithmic sweep signal with continuous phases and settable parameters of a wide frequency band does not exist.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for generating a logarithmic sweep signal of an arbitrary wave signal with continuous phase, which can realize the logarithmic sweep signal of the continuous phase by a phase control method and by using less resources and can set parameters such as starting frequency, scanning time, ending frequency, scanning times, scanning trigger conditions and the like.

The object of the present invention is achieved by the following technical means. A method for generating a logarithmic sweep frequency signal of an arbitrary wave signal with continuous phase comprises the following steps: converting the scanning time set by a user into a plurality of time periods according to the starting frequency and the ending frequency, and generating a scanning progress and a clock signal of a sampling step length according to the length of waveform data in each time period; when the scanning trigger condition of the user is met, the phase control logic enables the sampling step length clock to continuously read the step length control word of the phase conditioning module to generate a corresponding signal phase adjusting word through the multiplier, the signal phase adjusting word generates an addressing address of a signal in the accumulator, the waveform data in the waveform memory is read according to the addressing address, and the waveform signal generates a logarithmic sweep frequency signal according to the frequency of the scanning progress.

Preferably, the waveform memory is used for storing monocycle waveform data of the scanning wave, and when the stored waveform is a sine, a frequency logarithmic sweep signal of the sine signal is generated; when the stored waveform is an arbitrary waveform customized by a user, a frequency logarithmic sweep signal of the arbitrary waveform is generated.

Preferably, the addressing address is generated in a single cycle.

Preferably, the waveform signal is sent to a DAC analog-to-digital converter according to the frequency of the scanning progress, and the digital form of the waveform data is converted into an analog signal, so as to generate a logarithmic sweep signal; or the waveform signal is sent to the signal comparator according to the frequency of the scanning progress for generating a digital pulse signal.

Furthermore, the generation of signals requires that according to a setting command of the upper computer, command interpretation logic decomposes the command of the upper computer and sends the command to each functional module, frequency division is accurately carried out according to the scanning time and the scanning frequency span in the command parameters to obtain a reading frequency clock with step length, the current frequency step length parameter is read through the clock, an actual current frequency step length coefficient is obtained through multiplication of a multiplier and an initialized multiplication factor, a precise phase step length for generating signals is obtained through compensation of a decimal part, a reading address of a waveform data memory is obtained according to an initial phase and the precise phase step length in an addressing address generation accumulator C, and the required signals can be obtained after waveform data read according to the address passes through a DAC analog-to-digital converter.

Furthermore, the current frequency of the current logarithmic scanning is given in real time through the transient frequency monitoring control module, and the current frequency is used for detecting the intermediate trigger frequency set by a user and judging the scanning ending frequency; the compensation accumulator A compensates decimal frequency division information in the scanning process, the phase accumulator B generates the phase step length of a current frequency signal, the addressing address generation accumulator C accumulates an initial phase value and the current phase step length, and the result is accumulated with the current phase step length continuously, so that the addressing address of the waveform memory is generated continuously.

Furthermore, the invention stores the phase step length information of a 10 octave of logarithmic scanning by the scanning step length memory, and generates the accurate step length reading clock of the frequency sweeping signal by the sampling frequency generator according to the scanning frequency span and the scanning time set by the user; the scanning phase controller converts the step information into address addressing information and reads the waveform data of the waveform memory by using the addressing address generated by the scanning phase controller.

The invention has the beneficial effects that: the invention can greatly reduce the hardware requirement for generating scanning signals and increase the controllability and precision of signal generation. In the whole generation process of the logarithmic sweep frequency signal, an upper computer is not needed for control, and an addressing address can be generated in a single period, so that the frequency band can be wider, and the stability and the reliability are strong. In the equipment upgrading of the signal source, the function can be conveniently transplanted. By the method, the logarithmic frequency sweep signal with the signal frequency of 1 uHz-50 MHz and the scanning time of 0.1 mS-40000 second which can be randomly set is successfully generated.

Drawings

Fig. 1 is a hardware block diagram of a frequency sweep signal implementation of the present invention.

Fig. 2 is a functional block diagram of a frequency sweep control method.

Fig. 3 is a functional block diagram of a scanning phase controller.

Detailed Description

The invention will be described in detail below with reference to the following drawings:

the resources required by the present invention are: the logarithmic sweep frequency signal can be realized by a peripheral waveform data memory, a DAC digital-to-analog converter, a phase conditioning module (realized in FPGA) and an adjustable frequency signal source. When the waveform stored in the waveform data memory unit is sine, the method generates a logarithmic sweep signal of a sine signal; when the waveform stored in the waveform memory unit is an arbitrary waveform customized by a user, a logarithmic sweep signal of the arbitrary waveform is generated.

The realization principle is as follows: the scanning time set by the user is converted into a plurality of equal-length time periods according to the starting frequency and the ending frequency by utilizing a received user instruction (such as the starting frequency, the scanning time, the ending frequency, the scanning times, the scanning triggering condition and the like), a scanning progress is generated according to the length of waveform data in each time period, a clock signal of a sampling step is generated, when the scanning triggering condition of the user is met, a phase control logic enables a sampling step clock to continuously read a step control word of a phase conditioning module, a corresponding signal phase adjusting word is generated through a multiplier, the phase adjusting word generates an addressing address of a signal in an accumulator, the waveform data in a waveform memory is read according to the addressing address, and the waveform signal is sent to a DAC analog-to-digital conversion circuit according to the frequency of the scanning progress to realize the generation of the sweep frequency signal.

Fig. 1 illustrates a block diagram of hardware in a frequency log swept signal implementation. The command of the upper computer can be accessed through any interface form. The reference clock is a base clock that generates the swept frequency signal. The waveform data memory is used for storing the monocycle waveform data of the scanning wave, and sine signals can be prestored or waveform data defined by a user can be loaded by the user. DAC adcs are high-speed DAC converters used to convert digital forms of waveform data into analog signals or employ signal comparators for generating digital pulse signals.

Fig. 2 illustrates a detailed block diagram of the generation of the swept frequency phase control method. The command interpretation logic transfers the command of the upper computer to the corresponding functional module. The scanning step memory is a ROM storage unit and stores phase step information of one 10 octave of logarithmic scanning. The sampling frequency generator generates a precise step length reading clock of the frequency sweeping signal according to the scanning frequency span and the scanning time set by a user by using the high-frequency working clock. The scanning phase controller is used for completing a control circuit which converts the step information into address addressing information and reading the waveform data of the waveform memory by using the addressing address generated by the scanning phase controller. The PLL circuit multiplies a low-frequency reference clock by the PLL circuit to generate a high-frequency operating clock.

Fig. 3 illustrates a block diagram of functional modules to be completed inside the scanning phase controller, taking 48BIT step as an example, wherein the transient frequency monitoring control module can give the current frequency of the current logarithmic scanning in real time, and can be used for detecting the intermediate trigger frequency set by the user and judging the scanning end frequency; compensation accumulator (a): the compensation for fractional division information in the scanning process can make the scanning frequency more accurate and make the starting frequency lower. Phase accumulator (B): a phase step for generating a current frequency signal; addressing address generation accumulator (C): and accumulating the initial phase value and the current phase step length, and accumulating the result with the current phase step length continuously so as to generate the addressing address of the waveform memory continuously.

1) Hardware requirements:

the hardware design shown in fig. 1 is required, and the method can be implemented by various FPGAs with sufficient capacity, in this example, EP2C5 from ALTERA corporation. Other devices having the same function may be selected.

2) Signal generation process

The signal generation needs to be based on the set command of the user (upper computer), the command interpretation logic can decompose the command of the upper computer and send to each functional module, fig. 2 is a block diagram of the log scan functional module, accurately dividing the reading frequency clock to obtain step size according to the scanning time and scanning frequency span in the command parameters, reading the current frequency step parameter by the clock, multiplying the initialized multiplication factor by the multiplier to obtain the actual current frequency step coefficient, compensating by the decimal part to obtain the accurate phase step of the generated signal, the read address of the waveform data memory can be obtained in the addressing address generating accumulator (C) according to the initial phase and the precise phase step, and the waveform data read according to the read address can obtain the required signal after passing through the DAC. In the whole process, since the step parameter is continuously changed along with the step of the logarithmic function, the phase step is also changed according to the logarithmic function, so that the frequency of the generated signal is also continuously changed according to the logarithmic function.

3) Step length of logarithmic sweep signal

According to the characteristics of logarithmic sweep frequency signals, the scanning time used by every 10 octaves is the same, so that the step length parameter only needs to be 10 multiplied frequencies of a fixed point numberStep size of the range (the parameter is LOG)₁₀X-form generation), other octave step size parameters may be multiplied by a multiple of 10 on this basis. In the method, 1024 scanning points are adopted every 10 octaves, and the step length parameter is specifically calculated as follows:

Log_tmp＝65536 (1)

For(i＝1；i<1025；i++)

the calculation results log _ dat are all converted into hexadecimal numbers, and these results are taken as initial values in a scan step memory (ROM).

4) Generation of step size parameter read frequency

When the starting triggering condition of the logarithmic sweep frequency signal is met, calculating the frequency of the reading step length parameter according to the scanning time and the span of frequency scanning, wherein the specific calculation method comprises the following steps:

D＝LOG(Fend/Fbeg)/LOG(10) (2)

Fs＝D*1024/Ts (3)

in the formula: d: is the number of 10 times of the frequency multiplication path between the starting frequency (Fbeg) and the ending frequency (Fend);

fs: a reading frequency which is a reading step length;

ts: time for one logarithmic scan;

therefore, the FPGA needs to generate an accurate step reading frequency Fs by dividing the working frequency of the high frequency. The generation process is as follows:

R＝Fs/Fw (4)

in the formula: fs is the reading frequency of the reading step;

fw: the working frequency of the FPGA;

r: a frequency division coefficient;

r is a decimal number, and in order to make the scanning time long enough and the frequency dividing precision high enough, the frequency dividing coefficient is expanded by M bits, taking 36 bits as an example, i.e. N-R2³⁶Then, N is accumulated by using a 36-bit accumulator according to each working clock, and when the accumulator has carry bit, the carry bit is carriedInformation represents the step parameter read frequency clock.

5) Scanning initialization:

when all the scanning parameters are received by the FPGA, the logarithmic scanning function module starts to initialize the function module, mainly finishing the multiplication factor of the initial scanning step length. The multiplication factor is used to multiply the step size parameter, which results in the true step size of the logarithmic scan.

An initialization process: the multiplication factor takes a 36Bit length hexadecimal number and the initial value takes 1. The module reads the step parameter by the working frequency, multiplies the read parameter by the multiplication factor, compares the result with the initial frequency of logarithmic sweep, judges whether the result reaches or just exceeds the frequency increment value of a sampling point of the initial frequency (namely 0.00225 times of the initial frequency), when the requirement can not be met, the module takes the next step parameter value, compares the step parameter value in the same way until 1024 points are read, if the requirement of the frequency increment value can not be met, the multiplication factor is amplified by 10 times, compares the step parameter value from the first value of the step parameter, and repeats the steps until the judgment condition is met. The multiplication factor and parameter address at this time are recorded. And converting the reading clock into a step parameter reading frequency clock.

6) Logarithmic scanning is realized:

after initialization of the functional module is finished, waiting for trigger information of scanning start, after the trigger information of scanning start is received, the functional module starts to generate an initial frequency signal, simultaneously, reading a frequency reading step parameter according to the previously generated step parameter, wherein the initial address of the reading step parameter is the address of the initialization end, the read result is multiplied by a multiplication factor after the initialization is finished, the lower 16 bits of the result are circularly accumulated in a compensation accumulator (A), and the accumulated carry bit is sent to a phase accumulator (B) for compensation; the upper 16 bits of the result are accumulated in a phase accumulator (B) with the integer part of the starting frequency, the accumulated result being the phase step of the current frequency. The initial value of the addressing address generation accumulator (C) is the signal initial phase set by the command, and is added with the current frequency phase step continuously according to the working frequency (200MHz), and the result is the addressing address of the waveform data memory. When the scanning step length memory finishes one reading, the address of the reading step length parameter is added with 1, when the address of the reading step length parameter is full 1024, the address is changed into 0, and at the moment, the multiplication factor is amplified by 10 times. And continuing to perform the steps, simultaneously monitoring the current signal output frequency in real time by the transient frequency monitoring control logic, finishing the logarithmic scanning when the current signal output frequency is monitored to reach the finishing frequency, and performing the next frequency scanning or waiting for the next trigger information according to the user setting.

7) Transient frequency monitoring control

The transient frequency monitoring control logic is composed of two adders, one adder completes the addition of the integer part of the starting frequency and the upper 16 bits of the current step value, the other adder completes the addition of the decimal part of the starting frequency and the middle 16 bits of the current step value, and the results of the two adders can be combined into the frequency value of the current signal.

It should be understood that equivalent substitutions and changes to the technical solution and the inventive concept of the present invention should be made by those skilled in the art to the protection scope of the appended claims.