CN103560785B - Method and device for generating phase-coherent signals - Google Patents

Abstract

The present invention provides a method and device for generating phase coherent signals, which consist of several radio frequency signal generation modules controlled by synchronous signals; the radio frequency signal generation modules are composed of a phase detector, a loop filter, a voltage controlled oscillator, and a fractional frequency division logic The unit and the phase setting module are connected to each other and communicate with each other; the synchronization signal is used to realize the synchronization work of the plurality of radio frequency signal generation modules; the phase detector is used to compare the frequency-divided signal with the clock reference The signal is compared to obtain a comparison result; the loop filter is used to filter the comparison result under a predetermined bandwidth condition and then send it to the voltage-controlled oscillator; the voltage-controlled oscillator is used to generate a radio frequency Signal. Adopting the above-mentioned solution has the flexibility of expansion and configuration, and the number of signal channels can be configured according to needs, further saving costs. Combined with the signal phase receiving and detection module, it can realize phase closed-loop control, which is convenient for monitoring and correction.

Description

A method and device for generating a phase coherent signal

technical field

The invention belongs to the field of electronic measuring instruments, and in particular relates to a method and a device for generating phase coherent signals.

Background technique

In the field of electronic testing technology, phase-coherent multi-channel RF signals are often required, these signals have the same frequency, and have a definite mutual phase relationship. As shown in Figure 1, the three signals have the same change period, but the initial phase (that is, the phase at zero time) is different (the initial phase is arbitrary, or the same, and does not affect the phase coherence characteristics). For example, phased array radar signal simulation and testing, differential amplifier differential mode/common mode performance testing, microwave nonlinear network parameter testing, etc., all involve the transmission and processing of radio frequency signals with the same frequency and a certain phase relationship between multiple channels. take over.

At present, the technical solutions for phase coherent signal generation mainly include phase shifter method, switch delay line method, and vector signal generator method.

According to the characteristics of phase coherence, the most intuitive method for generating such signals is to use a phase shifter to shift the signal by a certain angle (phase delay) and then output it to form a phase coherent relationship with the original signal. Phase shifter has analog phase shifter and digital phase shifter, the principle is the same, but the control method is different.

The switch delay line method allows the same signal to be output after passing through delay lines of different electrical lengths by means of multiple switches. Since the electrical lengths of different delay lines are different, the phase delay between the output signals after the same signal passes through each delay line is different. , thus realizing the generation of multi-channel phase coherent signals.

The solution based on the vector signal generator is actually a multi-machine system. The RF signal output of a general signal generator is sent to several other signal generators through a power divider (the number is determined by the number of signal channels required) as The local oscillator signal replaces the local oscillator signal in the machine, and uses the vector modulation control circuit in the machine to control the phase of the radio frequency, thereby realizing the generation of multi-channel phase coherent signals. In this solution, changing the signal phase is achieved by changing the control data of the dual arbitrary waveform generators used for vector modulation inside the signal source. The coherence of the baseband signal must be guaranteed, so another signal generator is required to provide Unified baseband processing clock.

In the switch delay line method, since the length of the delay line is fixed, the size of the phase delay is related to the signal frequency, and the number of delay lines of different lengths is also limited, so the working frequency band of the switch delay line method is generally narrow, and the phase coherent phase The adjustment range can only be limited, and the real-time calibration, correction and continuous and accurate adjustment of coherence cannot be realized. The application range is limited and the test accuracy is difficult to guarantee. Moreover, the continuous adjustment of the amplitude cannot be realized between the channels.

In the phase shifter method, the phase adjustment accuracy depends on the phase resolution of the digitally controlled phase shifter, and the operating frequency range is relatively limited. The phase shifter method is basically used in the construction of some special test systems, and it is difficult to achieve a wide range of universal .

The above two methods are only achievable technical approaches, and they must cooperate with existing signal generating devices to complete the control of the signal phase, which is very inflexible in practical applications. Due to the limitations of each method itself, its application range is greatly limited.

Another more general technical solution is based on the vector signal generator method, which is based on the general vector signal generator plus special test software and test accessories, and each signal requires an expensive general vector signal generator. Generator, the huge system composition is difficult to meet the needs of field testing, which is not conducive to large-scale promotion and application.

When the above several schemes are used in the field of electronic testing, a testing system must be formed, which is bulky and expensive, and it is difficult to complete the testing task in the form of a single measuring instrument.

Therefore, there are defects in the prior art and need to be improved.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method and device for generating phase coherent signals in view of the deficiencies in the prior art.

Technical scheme of the present invention is as follows:

A device for generating phase-coherent signals, wherein a plurality of radio frequency signal generation modules are controlled by synchronous signals; the radio frequency signal generation module is composed of a phase detector, a loop filter, a voltage controlled oscillator, a fractional frequency division logic unit and a phase The modules are connected to each other and communicate with each other; the synchronous signal is used to generate a synchronous control signal and sent to the plurality of radio frequency signal generating modules; the phase detector is used to divide the frequency of the fractional frequency logic unit The signal is compared with the clock reference signal to obtain a comparison result and sent to the loop filter; the loop filter is used to filter the comparison result under a predetermined bandwidth condition and then send it to the voltage control Oscillator; the voltage-controlled oscillator is used to generate a radio frequency signal; the fractional frequency division logic unit is used to perform fractional frequency division on the radio frequency signal; the phase setting module is used to adjust the fractional frequency division The initial phase offset when the logic unit generates fractional values.

The device for generating a phase coherent signal, wherein, the radio frequency signal generation module further includes a radio frequency phase receiving and detection module, which is used to compare the phase information with a preset phase value, and compare the phase difference formed after the comparison sent to the phase setting module, and the phase setting module monitors, corrects and calibrates the phase difference in real time.

The device for generating phase coherent signals, wherein the radio frequency phase receiving and detection module is composed of a directional coupler, a mixer and an intermediate frequency processing unit; the directional coupler is used to separate the radio frequency output signal and the feedback detection signal The mixer is used to convert the radio frequency signal to an intermediate frequency; the intermediate frequency processing unit is used to digitally process the intermediate frequency signal output by the mixer to obtain the phase information of the signal.

In the device for generating phase coherent signals, the radio frequency signal generation module further includes a frequency multiplier, and the frequency multiplier is used to extend the frequency range of the radio frequency signal.

In the device for generating phase-coherent signals, the method for calculating the phase offset when adjusting the fractional frequency division logic unit in the phase setting module to generate the fractional frequency division value is as follows: in the phase setting module, the bit width of the phase setting value is set to B bit, the phase setting value is set to b, then the influence of the phase setting value b on the phase of the output signal relative to the phase value 0 is p, then: Resolution f of phase control:

A method of generating a phase coherent signal, comprising the steps of:

Step 1: Set several RF signal generating modules to output frequency signals, and lock the frequency signals;

Step 2: setting the phase data required to be sent by the phase setting module in several radio frequency signal generating modules;

Step 3: Send a synchronization signal to several radio frequency signal generation modules, so that several radio frequency signal generation modules start to change the signal phase synchronously;

Step 4: After re-locking the frequency signals received by several radio frequency signal generating modules, send the frequency output signal.

The method for generating a phase-coherent signal, wherein, in the first step, the radio frequency signal generation module is composed of a phase detector, a loop filter, a voltage-controlled oscillator, a fractional frequency division logic unit, and a phase setting module that are connected to each other and communicate with each other .

The method for generating a phase coherent signal, wherein, in the step 2, sending phase data is used to adjust the phase offset that occurs when the fractional frequency division logic unit generates the fractional frequency division value, and the calculation method is: phase in the phase setting module If the bit width is set to B, and the phase setting value is set to b, then the influence of the phase setting value b relative to the phase value 0 on the output signal phase is p, then: Resolution f of phase control:

By adopting the above scheme, the shortcomings of the traditional scheme such as narrow frequency band, narrow phase adjustment range, low control precision, complex hardware scheme and high cost are overcome. In the vector modulation scheme, the design and production of the core component vector modulator is very difficult, and it is even more difficult to extend to the microwave and millimeter wave frequency bands. The problems brought about are high cost and poor control accuracy. However, the present invention does not need a vector modulator, and can be realized by adding some digital control modules on the basis of the traditional scheme. The scheme has low complexity and low hardware overhead, and can be conveniently realized in a single desktop instrument. At the same time, the solution of the present invention has the flexibility of expansion and configuration, and the number of signal channels can be configured according to needs, thereby further saving costs. Combined with the signal phase receiving and detection module, it can realize phase closed-loop control, which is convenient for monitoring and correction.

Description of drawings

FIG. 1 is a schematic diagram of phase coherent signals in the present invention.

Fig. 2 is a schematic structural diagram of the device according to the first embodiment of the present invention.

Fig. 3 is a schematic structural diagram of a device according to a second embodiment of the present invention.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment one

As shown in Figure 1, each sine wave represents a signal, and their amplitude, phase, and period are determined by their respective (x, y, z) expressions, the horizontal axis is the time axis t, and the vertical axis is the amplitude. The initial phase is the phase when t is 0. The initial phase of the x signal in the figure is 0, and the initial phase of the y signal is The initial phase of the z signal is

On the basis of Fig. 1, as shown in Fig. 2, the device of the present invention is composed of N identical radio frequency signal generating modules 1 on the hardware, and the specific value of N is determined according to the required number of channels, so that the device is very flexible in setting . The core of each radio frequency signal generating module 1 is a phase-locked loop for precise frequency control, and the function of the phase-locked loop is the same as that of the signal generator. In order to control the phase of the output radio frequency signal, the present invention adds a phase setting module 105 in the phase-locked loop, and the control program of the phase setting module 105 will compare the received phase information with the preset phase information, according to the comparison As a result, the preset phase is corrected. In order to achieve phase coherence, the phase-locked loops of each radio frequency signal generation module 1 must use the same clock reference signal 109, and each radio frequency signal generation module 1 uses a unified synchronization signal 106, and the signal generation link also samples the same system. The clock phase reference 109 is generally implemented by an oven-controlled crystal oscillator, which is characterized by high phase stability, and provides a phase-detection reference signal for the phase-locked loop. For the convenience of expression, Figure 2 only shows the part where the phase-locked loop is the center, and the existing technology can be used for the computer control circuit and the radio frequency multiplication circuit. As shown in FIG. 2 , the radio frequency output frequency range is determined by the operating frequency of the voltage-controlled oscillator 103 . In the actual scheme, the signal generated by the phase-locked loop can be properly divided and multiplied outside the phase-locked loop to meet the wide-band requirements of practical work, and the influence of frequency division and frequency multiplication on the phase control accuracy can be omitted. In order to improve the phase coherence performance of the signal generation scheme, the frequency of the clock reference signal and its phase noise index and temperature stability index can be increased. Increasing the clock reference frequency means increasing the phase detection frequency of the phase-locked loop, which can increase the phase noise of the output frequency of the phase-locked loop. Ensure that each phase-locked loop module has the same hardware system architecture and parameters, and is in the same temperature field when working, so that the phase drift of each module has similar characteristics, and the coherence can also be improved. These measures are suitable for implementing the inventive solution in a single instrument.

In order to illustrate the phase control principle of the present invention, as shown in Figure 2 and Figure 3, a typical structure of a phase-locked loop based on fractional frequency division includes a phase detector 101, a loop filter 102, and a voltage-controlled oscillator 103 and a fractional frequency division logic unit 104 . The phase detector 101 is used to compare the frequency-divided signal with the reference signal, and the comparison result is filtered by the loop filter 102 under a certain bandwidth condition to control the voltage-controlled oscillator 103 to generate a radio frequency signal. It means to determine according to the required phase noise index, the smaller the bandwidth, the better the phase noise, but the longer the phase locking time of the system, preferably, the bandwidth is the result of mutual check and balance between the phase noise and the phase locking time. The reference signal and the fractional frequency division value determine the output signal frequency of the phase-locked loop. The fractional frequency division logic unit 104 of the present invention is used for performing frequency division of high-precision fractional values on the radio frequency signal generated by the front end. The so-called fractional frequency division is relative to the integer frequency division technology. The phase control amount is added to the fractional frequency division logic unit 104. By setting different phase quantities, the working state offset of the fractional frequency division logic unit 104 can be adjusted. , which in turn affects the phase of the final output RF signal.

If the bit width of the phase setting is B bits, and the phase setting value is b, then the influence p (in degrees) of the phase value b relative to the phase value 0 on the output signal phase can be expressed as:

The resolution f of the phase control can be expressed as:

If B=32, that is, the bit width of the phase quantity is selected as 32 bits, then the theoretical precision of the phase control can be:

It can be seen from this that the theoretical phase accuracy value doubles after each frequency multiplication outside the phase-locked loop, and the theoretical accuracy value decreases by one time after each frequency division. Since this precision is much smaller than the phase jitter in actual hardware work, the phase control precision value obtained here is still sufficient to meet the actual work requirements after frequency division or frequency multiplication.

In conjunction with Fig. 2, the work control process of the present invention: first set the frequency of each radio frequency signal generation module 1, and then set the phase data of each radio frequency signal generation module 1 as required after each radio frequency signal generation module 1 is locked, and then use a unified synchronization The signal synchronizes the state of each RF signal generating module 1. This step will temporarily disturb the locking state of each RF signal generating module 1. After the loop in the RF signal generating module 1 is re-locked, the output signal of each RF signal generating module 1 That is, a set of phase coherent signals.

On the basis of the above content, as shown in FIG. 3 , the radio frequency signal generation module 1 includes two symmetrical phase-coherent signal channels, combined with the radio frequency phase receiving and detection module 107, can realize closed-loop control of the radio frequency signal phase. The RF phase receiving and detecting module 107 is composed of a directional coupler, a mixer, and an intermediate frequency processing unit. The phase information fed back is compared with the preset phase value, and the difference is sent to the phase setting module 105 again to adjust the output phase , so that the closed-loop control of the phase with the radio frequency signal is completed. This closed-loop mechanism can compensate for the phase drift error caused by hardware mismatch and temperature changes between modules, and monitor, correct and calibrate the phase error between channels caused by various reasons in real time. As shown in Figure 3, a frequency multiplier 108 is introduced outside the phase-locked loop, which can expand the frequency range of the output signal, and the number of frequency multiplications can be controlled according to needs, thereby covering a wider frequency band, and the influence on the phase control accuracy can be ignored.

Embodiment two

On the basis of the above embodiments, the number of radio frequency channels is further expanded to form an N-channel phase-correlation signal generating device. Wherein, it is composed of a plurality of radio frequency signal generation modules controlled by synchronous signals; the radio frequency signal generation modules are connected to each other by a phase detector 101, a loop filter 102, a voltage controlled oscillator 103, a fractional frequency division logic unit 104 and a phase setting module 105 and mutual communication; the synchronization signal 106 is used to generate a synchronization control signal and send it to the plurality of radio frequency signal generation modules; the phase detector 101 is used to divide the signal by the fractional frequency division logic unit 104 The comparison result obtained by comparing with the clock reference signal 109 is sent to the loop filter 102; the loop filter 102 is configured to filter the comparison result under a predetermined bandwidth condition and send it to the A voltage-controlled oscillator 103; the voltage-controlled oscillator 103 is used to generate a radio frequency signal; the fractional frequency division logic unit 104 is used to perform fractional frequency division of the radio frequency signal; the phase setting module uses It is used to adjust the initial phase offset when the fractional frequency division logic unit generates the fractional frequency division value.

Further, the radio frequency signal generating module also includes a radio frequency phase receiving and detecting module 107, which is used to compare the phase information with a preset phase value, and send the phase difference formed after the comparison to the phase setting module 105. The phase setting module 105 monitors, corrects and calibrates the phase difference in real time.

Further, the radio frequency phase receiving and detection module 107 is composed of a directional coupler, a mixer and an intermediate frequency processing unit; the directional coupler is used to separate the radio frequency output signal and the feedback detection signal; the mixer is used to The radio frequency signal is converted to an intermediate frequency; the intermediate frequency processing unit is used to digitally process the intermediate frequency signal output by the mixer to obtain the phase information of the signal.

Further, the radio frequency signal generating module further includes a frequency multiplier 108, and the frequency multiplier 108 is used to extend the frequency range of the radio frequency signal.

Further, in the phase setting module 105, the method for calculating the phase offset when the fractional frequency division logic unit 104 is adjusted to generate the fractional frequency division value is as follows: in the phase setting module 105, the phase setting amount bit width is set to B bits, and the phase setting value is set to b, then the influence of the phase setting value b relative to the phase value 0 on the output signal phase is p, then: Resolution f of phase control:

Embodiment three

On the basis of the above embodiments, a method for generating a phase coherent signal is further provided, which includes the following steps:

Step 1: Set several RF signal generating modules to output frequency signals, and lock the frequency signals;

Step 2: setting the phase data required to be sent by the phase setting module in several radio frequency signal generating modules;

Step 3: Send a synchronization signal to several radio frequency signal generation modules, so that several radio frequency signal generation modules start to change the signal phase synchronously;

Step 4: After re-locking the frequency signals received by several radio frequency signal generating modules, send the frequency output signal.

Furthermore, the radio frequency signal generating module in the first step is composed of a phase detector, a loop filter, a voltage controlled oscillator, a fractional frequency division logic unit and a phase setting module which are interconnected and communicate with each other.

Further, in the step 2, the sending phase data is used to adjust the phase offset that occurs when the fractional frequency division logic unit generates the fractional frequency division value, and its calculation method is: the phase setting quantity bit width in the phase setting module is set to B bit, the phase setting value is set to b, then the influence of the phase setting value b relative to the phase value 0 on the output signal phase is p, then: Resolution f of phase control:

By adopting the above scheme, the shortcomings of the traditional scheme such as narrow frequency band, narrow phase adjustment range, low control precision, complex hardware scheme and high cost are overcome. In the vector modulation scheme, the design and production of the core component vector modulator is very difficult, and it is even more difficult to extend to the microwave and millimeter wave frequency bands. The problems brought about are high cost and poor control accuracy. However, the present invention does not need a vector modulator, and can be realized by adding some digital control modules on the basis of the traditional scheme. The scheme has low complexity and low hardware overhead, and can be conveniently realized in a single desktop instrument. At the same time, the solution of the present invention has the flexibility of expansion and configuration, and the number of signal channels can be configured according to needs, thereby further saving costs. Combined with the signal phase receiving and detection module, it can realize phase closed-loop control, which is convenient for monitoring and correction.

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present invention.

Claims (2)

1. it is a kind of produce phase coherent signal device, it is characterised in that by synchronizing signal control some radiofrequency signals occur Module is constituted；There is module by phase discriminator, loop filter, voltage controlled oscillator, fractional frequency division logical block in the radiofrequency signal And phase place setup module is connected with each other and mutually communication is constituted；The synchronizing signal is used to send to some radiofrequency signals to be sent out The phase place setup module of raw module, makes some radiofrequency signals that module synchronization to occur and starts to change signal phase；The phase discriminator, uses Signal after the fractional frequency division logical block is divided carries out being sent to than mutually obtaining comparative result with clock reference signal The loop filter；The loop filter, for the comparative result to be carried out the filtering under the conditions of bandwidth after send out Give the voltage controlled oscillator；The voltage controlled oscillator, for producing radiofrequency signal；The fractional frequency division logical block, is used for The frequency dividing of fractional value is carried out to the radiofrequency signal；The phase place setup module, produces for adjusting fractional frequency division logical block Initial phase offset during fractional frequency division value；The radiofrequency signal occurs also to include that RF phse receives and detection mould in module Block, for phase information to be compared with default phase value, the phase difference value for being formed more afterwards is sent to the phase place Setup module, the phase place setup module carries out real-time monitoring, amendment to the phase difference value and calibrates；The RF phse connects Receipts are made up of with detection module directional coupler, frequency mixer and IF processing unit；The directional coupler is used for radio frequency is defeated Go out signal and feedback detection signal is separated；The frequency mixer is used to for radiofrequency signal to be transformed into intermediate frequency；The IF process Unit is used to that the intermediate-freuqncy signal that frequency mixer is exported to be digitized after process the phase information for obtaining signal；The radio frequency Also include doubler in signal generating module, the doubler is used to extend the frequency range of the radiofrequency signal；The phase place The computational methods of generation phase offset are when fractional frequency division logical block generation fractional frequency division value is adjusted in setup module：Phase place is arranged Phase place set amount bit wide is set to B positions in module, and phase settings are set to b, then the phase settings b is relative to phase value 0 is p for the impact of phase of output signal, then：Resolution f of phase controlling：

2. it is a kind of produce phase coherent signal method, it is characterised in that comprise the following steps：

Step one：Some radiofrequency signals are set module output frequency signal occurs, and frequency signal is locked；

Step 2：The phase data sent required for the phase place setup module that some radiofrequency signals occur in module is set；

Step 3：Send synchronizing signal and module occurs to some radiofrequency signals, make some radiofrequency signals that module synchronization to occur and start Change signal phase；

Step 4：After the frequency signal that some radiofrequency signals occur module reception is relocked, transmission frequency output signal；

In the step one there is module by phase discriminator, loop filter, voltage controlled oscillator, fractional frequency division logic list in radiofrequency signal Unit and phase place setup module are connected with each other and mutually communication is constituted；The phase discriminator, for by the fractional frequency division logical block Signal after frequency dividing carries out being sent to the loop filter than mutually obtaining comparative result with clock reference signal；The loop filter Ripple device, for the comparative result to be carried out the filtering under the conditions of bandwidth after be sent to the voltage controlled oscillator；The pressure Controlled oscillator, for producing radiofrequency signal；The fractional frequency division logical block, for carrying out fractional value to the radiofrequency signal Frequency dividing；The phase place setup module, for receive synchronizing signal and adjust fractional frequency division logical block produce fractional frequency division value when Initial phase offset；In the step 2, sending phase data is used to adjust fractional frequency division logical block generation fractional frequency division The phase offset occurred during value, its computational methods is：Phase place set amount bit wide is set to B positions in phase place setup module, and phase place sets Put value and be set to b, then the phase settings b relative to phase value 0 for phase of output signal impact be p, then：Resolution f of phase controlling：