CN114124248A - System for realizing precise control aiming at high peak-to-average ratio signal in vector signal generator - Google Patents
System for realizing precise control aiming at high peak-to-average ratio signal in vector signal generator Download PDFInfo
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- CN114124248A CN114124248A CN202111434466.9A CN202111434466A CN114124248A CN 114124248 A CN114124248 A CN 114124248A CN 202111434466 A CN202111434466 A CN 202111434466A CN 114124248 A CN114124248 A CN 114124248A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/0082—Monitoring; Testing using service channels; using auxiliary channels
- H04B17/0085—Monitoring; Testing using service channels; using auxiliary channels using test signal generators
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/0003—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain
- H04B1/0028—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at baseband stage
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/0082—Monitoring; Testing using service channels; using auxiliary channels
- H04B17/0087—Monitoring; Testing using service channels; using auxiliary channels using auxiliary channels or channel simulators
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Abstract
The invention relates to a system for realizing precise control aiming at a high peak-to-average ratio signal in a vector signal generator, which comprises a baseband generation module, an IQ modulation module, a frequency synthesis module and a radio frequency channel module, wherein the IQ modulation module is connected with the baseband generation module, the frequency synthesis module is connected with the IQ modulation module, the radio frequency channel module is connected with the IQ modulation module, the baseband generation module is used for selecting a baseband signal, measuring and calculating the RMS power of the baseband signal, extracting the pulse time sequence of the baseband signal and generating a time sequence power signal synchronous with the baseband signal, the IQ modulation module carries out frequency mixing on the baseband signal and a local oscillator signal from the frequency synthesis unit, and the radio frequency channel module carries out digital modulation on radio frequency. The system for realizing precise control aiming at the high peak-to-average ratio signal in the vector signal generator ensures the accuracy of the output power of different peak-to-average ratio signals and the stability of the output power of different peak-to-average ratio signals.
Description
Technical Field
The invention relates to the field of digital communication, in particular to the field of a vector signal generator, and specifically relates to a system for realizing precise control aiming at a high peak-to-average ratio signal in the vector signal generator.
Background
With the development of digital communication technology, various wireless communication standards typified by 4G/5G, WiFi, bluetooth, and the like are widely used. The vector signal generator is one of the basic universal test instruments widely used in modern digital communication technology, and is generally used for generating radio excitation signals with predictable frequency, power and standard, and measuring and evaluating the response of a tested object to judge whether the function and performance indexes meet the requirements. The method is widely applied to verification, research and development, production and maintenance of communication equipment, terminals, modules and chips.
A typical vector signal Generator principle is shown in fig. 1, and mainly includes baseband generation, IQ modulation, frequency synthesis, and radio frequency channel, etc., and its working principle is that a baseband generation unit (BBG) generates two paths of orthogonal digital I and Q signals according to signal system or type, and the generated path may be local generation, or may be a data stream or file from outside, and is converted into analog I and Q baseband signals by a digital-to-analog converter. Analog baseband signals enter an IQ Modulator (IQ Modulator) and are respectively mixed with Local Oscillator (LO) signals from a frequency synthesis unit, the two local oscillator signals have a 90-degree phase difference, and the outputs of the two mixers are summed and output after being combined to complete digital modulation on radio frequency. The frequency synthesis unit is generally formed by a phase-locked loop and generates signals within a certain frequency range. The IQ modulated signal enters a radio frequency channel, which mainly realizes the control of signal power, and the inside of the IQ modulated signal comprises an analog voltage controlled attenuator (VVA), an Amplifier (AMP), a Coupler (Coupler), a Digital Step Attenuator (DSA) and the like, so that the continuous adjustment of the radio frequency signal power can be realized. In addition, the analog voltage controlled attenuator, coupler and Detector (DET) form a closed loop Automatic Level Control (ALC) negative feedback to stabilize the power output of the signal and improve the power fluctuation caused by environmental changes and other factors.
The output signal power of the vector signal generator is one of the core indicators for measuring the performance of the instrument. In practical application, performance parameters such as distortion degree, sensitivity, dynamic range and the like of a tested piece all need to meet certain requirements on power accuracy and stability of an excitation signal. For continuous wave CW signals, the ALC loop in the above schematic block diagram can solve the power accuracy and stability problems well. However, for signals with a certain duty cycle, such as 5G or burst signals, the operation of the ALC loop can cause signal distortion. Thus, the ALC loop is typically closed for such signals. This can present two problems. Firstly, the negative feedback system of the ALC is closed, the power at this time depends on the presetting of the ALC loop, the gain of the channel is ensured to be constant, but the channel gain can generate large-range fluctuation along with the change of the environment temperature, and further the stability of the output power is influenced. Secondly, for 5G burst signals and the like, the signals have certain duty ratio and certain peak-to-average ratio, the precision of the peak-to-average ratio determines the precision of output power, and for digital or analog modulation signals input externally, how to ensure the power accuracy and stability of the modulation signals under the state of an internal ALC loop open loop is a problem existing in a vector signal generator.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a system which has high accuracy, high accuracy and good stability and can realize precise control on high peak-to-average ratio signals in a vector signal generator.
In order to achieve the above object, the system of the present invention for implementing fine control for a high peak-to-average ratio signal in a vector signal generator is as follows:
the system for realizing precise control aiming at the high peak-to-average ratio signal in the vector signal generator is mainly characterized by comprising a baseband generation module, an IQ modulation module, a frequency synthesis module and a radio frequency channel module, wherein the IQ modulation module is connected with the baseband generation module, the frequency synthesis module is connected with the IQ modulation module, the radio frequency channel module is connected with the IQ modulation module, the baseband generation module is used for selecting a baseband signal, measuring and calculating the RMS power of the baseband signal, extracting the pulse time sequence of the baseband signal and generating a time sequence power signal synchronous with the baseband signal, the IQ modulation module mixes the baseband signal with a local oscillator signal from a frequency synthesis unit, and the radio frequency channel module carries out digital modulation on radio frequency.
Preferably, the baseband generation module includes:
a multichannel data switch for selecting a baseband data source from the built-in baseband, the external digital baseband and the digitized analog IQ baseband signal;
the RMS detection circuit is connected with the multi-channel data switch and is used for measuring and calculating the RMS power of the baseband signal;
and the pulse extraction circuit is connected with the multi-channel data switch and used for extracting the pulse time sequence of the baseband signal, generating a time sequence power signal completely synchronous with the baseband signal and performing switch control.
Preferably, the RMS detection circuit includes an I-path multiplier, a first digital-to-analog unit, a Q-path multiplier, a Q-path power accumulator, and a total power accumulator, wherein an input end of the I-path power accumulator is connected to the I-path multiplier, an input end of the Q-path power accumulator is connected to the Q-path multiplier, and an input end of the total power accumulator is connected to the I-path power accumulator and the Q-path power accumulator, respectively.
Preferably, the RMS detection circuit further includes a first digital-to-analog unit and a second digital-to-analog unit, both the first digital-to-analog unit and the second digital-to-analog unit are connected to the multi-channel data switch, the input ends of the first digital-to-analog unit are further connected to the I-path multiplier, the input ends of the second digital-to-analog unit are further connected to the Q-path multiplier, both ends of the pulse extraction circuit are connected to both ends of the RMS detection circuit, and the multi-channel data switch of the first digital-to-analog unit is connected to each other.
Preferably, the baseband generation module performs signal processing on the baseband signal by the following method:
sending the baseband signal to a digital-to-analog converter for analog quantization output;
measuring and storing the RMS power of the baseband signal to realize accurate power control of the modulation signal;
and carrying out time domain monitoring on the IQ baseband signal, outputting a pulse signal synchronous with the baseband signal, and controlling the ALC loop.
Preferably, the RMS detection circuit calculates the RMS power of the baseband signal, specifically:
the RMS power of the baseband signal is calculated according to the following formula:
Prms＝I2+Q2；
wherein, PrmsThe RMS power of the baseband signal is shown as I, and Q is Q.
Preferably, the signal source of the baseband generation module is a built-in baseband signal generator, an external digital IQ signal, or an external analog IQ baseband signal.
The system for realizing precise control aiming at the high peak-to-average ratio signal in the vector signal generator is adopted to carry out precise power control on the output power of the vector-modulated signal, thereby ensuring the accuracy of the output power of different peak-to-average ratio signals; for the vector modulation signal of the burst signal, the intra-pulse stability can be realized, thereby ensuring the stability of the output power of signals with different peak-to-average ratios. The invention not only supports the internal baseband, but also supports the power control of the external baseband input, thereby ensuring the accuracy and stability of the output power of the signal generator during the external IQ modulation.
Drawings
Fig. 1 is a schematic circuit diagram of a prior art.
Fig. 2 is a schematic circuit diagram of a system for implementing precise control for high peak-to-average ratio signals in a vector signal generator according to the present invention.
Detailed Description
In order to more clearly describe the technical contents of the present invention, the following further description is given in conjunction with specific embodiments.
The system for realizing precise control aiming at the high peak-to-average ratio signal in the vector signal generator comprises a baseband generation module, an IQ modulation module, a frequency synthesis module and a radio frequency channel module, wherein the IQ modulation module is connected with the baseband generation module, the frequency synthesis module is connected with the IQ modulation module, the radio frequency channel module is connected with the IQ modulation module, the baseband generation module is used for selecting a baseband signal, measuring and calculating the RMS power of the baseband signal, extracting the pulse time sequence of the baseband signal and generating a time sequence power signal synchronous with the baseband signal, the IQ modulation module mixes the baseband signal with a local oscillator signal from the frequency synthesis unit, and the radio frequency channel module carries out digital modulation on radio frequency.
As a preferred embodiment of the present invention, the baseband generation module includes:
a multichannel data switch for selecting a baseband data source from the built-in baseband, the external digital baseband and the digitized analog IQ baseband signal;
the RMS detection circuit is connected with the multi-channel data switch and is used for measuring and calculating the RMS power of the baseband signal;
and the pulse extraction circuit is connected with the multi-channel data switch and used for extracting the pulse time sequence of the baseband signal, generating a time sequence power signal completely synchronous with the baseband signal and performing switch control.
As a preferred embodiment of the present invention, the RMS detection circuit includes an I-way multiplier, a first digital-to-analog unit, a Q-way multiplier, a Q-way power accumulator, and a total power accumulator, wherein an input end of the I-way power accumulator is connected to the I-way multiplier, an input end of the Q-way power accumulator is connected to the Q-way multiplier, and an input end of the total power accumulator is connected to the I-way power accumulator and the Q-way power accumulator, respectively.
As a preferred embodiment of the present invention, the RMS detection circuit further includes a first digital-to-analog unit and a second digital-to-analog unit, the first digital-to-analog unit and the second digital-to-analog unit are both connected to the multichannel data switch, the input end of the first digital-to-analog unit is also connected to the I-way multiplier, the input end of the second digital-to-analog unit is also connected to the Q-way multiplier, the two ends of the pulse extraction circuit are connected to the two ends of the RMS detection circuit, respectively, and the multichannel data switch of the first digital-to-analog unit is connected to the digital-to-analog unit.
As a preferred embodiment of the present invention, the baseband generation module performs signal processing on the baseband signal by:
sending the baseband signal to a digital-to-analog converter for analog quantization output;
measuring and storing the RMS power of the baseband signal to realize accurate power control of the modulation signal;
and carrying out time domain monitoring on the IQ baseband signal, outputting a pulse signal synchronous with the baseband signal, and controlling the ALC loop.
As a preferred embodiment of the present invention, the RMS detection circuit calculates the RMS power of the baseband signal, specifically:
the RMS power of the baseband signal is calculated according to the following formula:
Prms＝I2+Q2；
wherein, PrmsThe RMS power of the baseband signal is shown as I, and Q is Q.
In a preferred embodiment of the present invention, the signal source of the baseband generation module is a built-in baseband signal generator, an external digital IQ signal, or an external analog IQ baseband signal.
In the embodiment of the invention, the power of the baseband signal and the output power are in a linear relation for the vector signal generator. Based on the linear relation, the peak-to-average ratio of the final radio frequency output signal can be accurately obtained through measuring the peak-to-average ratio of the baseband signal, so that the accuracy of the power of the IQ signal is realized.
For burst signals, there can be a time division into a waveform output time and a non-waveform output time. The signal output power at the time of waveform output is expected to be stable, and an ALC loop can work; and at the moment of no waveform output, the ALC automatic gain control can be closed, so that the stability of the peak output power can be ensured, and meanwhile, the whole signal is ensured not to be distorted due to the adjusting action of the ALC loop.
The baseband unit of the signal generator has the following 3 sources: the first is a device built-in baseband signal generator; second, an external digital IQ signal; and the third is an external analog IQ baseband signal input. For external IQ baseband signals, especially analog IQ input signals, digital processing is required to achieve the above-mentioned precise power control and extraction of time domain information.
The general principle is as follows: the signal processing of three processes is simultaneously performed on the IQ baseband signal from the inside or the outside. Firstly, sending a baseband signal to a DAC for analog quantization output; secondly, simultaneously, the RMS power of the baseband signal is measured and stored, and the accurate power control of the modulation signal can be realized through the measurement of the RMS power; thirdly, the IQ baseband signal is monitored in the time domain, a pulse signal synchronous with the baseband signal is output, and an ALC loop is controlled.
As shown in fig. 2, compared with the prior art, the following key circuits are added in the circuit:
multi-channel data switch (MCD): for selecting different baseband data sources, including an internal baseband (Int BBG), an external digital baseband (Ext BBG), a digitized analog IQ baseband signal. Selecting one path of signal to enter subsequent processing;
RMS detection circuit (RMS): the system comprises 1I path multiplier, an I path power accumulator, a Q path multiplier, a Q path power accumulator and a total power accumulator. Calculating the RMS power of the baseband signal by the IQ digital baseband signal according to the following formula;
Prms＝I2+Q2；
pulse extraction circuit (PDT): the pulse timing sequence of the baseband signal is accurately extracted to generate a timing sequence power signal which is completely synchronous with the baseband signal so as to realize the on-off control of an ALC loop;
the pulse timing signal generated by the PDT controls the integration circuit of the ALC loop. At the moment when the baseband signal has waveform output, an ALC loop is started; at the time of no waveform output, the ALC loop is opened and the control voltage remains in the previous state.
The system for realizing precise control aiming at the high peak-to-average ratio signal in the vector signal generator is adopted to carry out precise power control on the output power of the vector-modulated signal, thereby ensuring the accuracy of the output power of different peak-to-average ratio signals; for the vector modulation signal of the burst signal, the intra-pulse stability can be realized, thereby ensuring the stability of the output power of signals with different peak-to-average ratios. The invention not only supports the internal baseband, but also supports the power control of the external baseband input, thereby ensuring the accuracy and stability of the output power of the signal generator during the external IQ modulation.
In this specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.
Claims (7)
1. A system for realizing precise control aiming at a high peak-to-average ratio signal in a vector signal generator is characterized by comprising a baseband generation module, an IQ modulation module, a frequency synthesis module and a radio frequency channel module, wherein the IQ modulation module is connected with the baseband generation module, the frequency synthesis module is connected with the IQ modulation module, the radio frequency channel module is connected with the IQ modulation module, the baseband generation module is used for selecting a baseband signal, measuring and calculating the RMS power of the baseband signal, extracting the pulse time sequence of the baseband signal and generating a time sequence power signal synchronous with the baseband signal, the IQ modulation module mixes the baseband signal with a local oscillation signal from a frequency synthesis unit, and the radio frequency channel module carries out digital modulation on radio frequency.
2. The system of claim 1, wherein the baseband generation module comprises:
a multichannel data switch for selecting a baseband data source from the built-in baseband, the external digital baseband and the digitized analog IQ baseband signal;
the RMS detection circuit is connected with the multi-channel data switch and is used for measuring and calculating the RMS power of the baseband signal;
and the pulse extraction circuit is connected with the multi-channel data switch and used for extracting the pulse time sequence of the baseband signal, generating a time sequence power signal completely synchronous with the baseband signal and performing switch control.
3. The system of claim 1 for implementing fine control of papr signals in vector signal generator, wherein the RMS detection circuit comprises an I-path multiplier, a first digital-to-analog unit, a Q-path multiplier, a Q-path power accumulator, and a total power accumulator, wherein an input terminal of the I-path power accumulator is connected to the I-path multiplier, an input terminal of the Q-path power accumulator is connected to the Q-path multiplier, and an input terminal of the total power accumulator is connected to the I-path power accumulator and the Q-path power accumulator, respectively.
4. The method of claim 3, wherein the RMS detection circuit further includes a first digital-to-analog unit and a second digital-to-analog unit, the first digital-to-analog unit and the second digital-to-analog unit are both connected to a multi-channel data switch, the input terminals of the first digital-to-analog unit are also connected to the I-channel multiplier, the input terminals of the second digital-to-analog unit are also connected to the Q-channel multiplier, the two ends of the pulse extraction circuit are connected to the two ends of the RMS detection circuit, and the multi-channel data switch of the first digital-to-analog unit is connected to the first digital-to-analog unit.
5. The system of claim 1, wherein the baseband generation module processes the baseband signal by:
sending the baseband signal to a digital-to-analog converter for analog quantization output;
measuring and storing the RMS power of the baseband signal to realize accurate power control of the modulation signal;
and carrying out time domain monitoring on the IQ baseband signal, outputting a pulse signal synchronous with the baseband signal, and controlling the ALC loop.
6. The system of claim 2, wherein the RMS detection circuit calculates the RMS power of the baseband signal, specifically:
the RMS power of the baseband signal is calculated according to the following formula:
Prms＝I2+Q2；
wherein, PrmsThe RMS power of the baseband signal is shown as I, and Q is Q.
7. The system of claim 1, wherein the signal source of the baseband generation module is an in-device baseband signal generator, an external digital IQ signal, or an external analog IQ baseband signal.
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