An integrated signal generation and acquisition device and method based on RFSOC for detecting interference.

Abstract

This invention discloses an integrated radar detection and jamming signal generation and acquisition device and method based on RFSOC, belonging to the field of radar detection and jamming integration technology. This invention can flexibly control the sampling rate and mixing frequency to intercept the opponent's linear frequency modulated signal and transmit and acquire our integrated radar detection waveform signal. By estimating the parameters of the intercepted pulse, and generating and modulating the linear frequency modulated signal accordingly, a waveform signal with dual functions of detection and jamming is produced. A connection to a host computer is achieved via the UDP protocol, allowing users to issue configuration commands in real time and save radar echo data for real-time signal processing and subsequent analysis. By intercepting the opponent's signal and generating, transmitting, and acquiring the integrated radar detection waveform signal, the device possesses the dual functions of a radar detector and jammer, offering advantages such as high processing speed, high reliability, and high portability.

Description

Technical Field

[0001] This invention relates to the field of radar detection and jamming integration technology, and in particular to a radar detection and jamming integrated signal generation and acquisition device and method based on RFSOC. Background Technology

[0002] Both radar and jammers are essentially based on the utilization of the electromagnetic spectrum. By transmitting a signal that simultaneously possesses radar detection and jamming capabilities, they can detect and track enemy targets while effectively interfering with the radar systems of enemy platforms. This technology not only significantly improves jamming efficiency and radar combat capabilities but also enhances the efficiency of equipment resource utilization.

[0003] With the development of field-programmable gate array (FPGA) technology, the new generation of RFSOC chips integrates radio frequency transmission and acquisition links into the chip, thereby enabling the chip to transmit and receive radio signals and process signals. This not only reduces system power consumption but also shrinks the system size and improves the overall integration and performance of the device.

[0004] Existing integrated signal generation and acquisition devices mostly rely on analog-to-digital converter chips and field-programmable gate array technology. These devices suffer from significant delays between signal sampling and processing, large device size, and lack of flexibility and portability in combat environments. Upgrading and expanding the system is also quite difficult. Summary of the Invention

[0005] The purpose of this invention is to propose an integrated signal generation and acquisition device and method based on RFSOC, which intercepts the opponent's signal and generates an integrated waveform signal with dual functions of detection and jamming. This enables the device to function as both a radar detector and a jammer, effectively overcoming the problems of insufficient mobility and low resource utilization caused by the traditional method of requiring two separate devices to perform detection and jamming functions.

[0006] The technical solution for achieving the objective of this invention is: an integrated signal generation and acquisition device based on RFSOC, comprising:

[0007] The radio frequency data conversion module is used to realize bidirectional conversion between digital baseband signals and analog radio frequency signals. This module realizes the sampling of radio frequency analog signals through downconversion and decimation processing. At the same time, this module upconverts the generated integrated probe waveform signal to a specified frequency point.

[0008] The DMA transfer module is used to realize communication between the PL and PS terminals within the RFSOC chip. This module is used to forward control commands from the host computer, transmit the signals collected by the RF data conversion module to the PS terminal, and save them to its memory.

[0009] The pulse parameter estimation module is used to extract the necessary pulse parameters from the intercepted enemy radar signal, providing input basis for generating the integrated detection and interference waveform;

[0010] The integrated waveform generation module for probe is used to generate LFM pulse signals and generate integrated waveform signals for probe through a phase-encoded cutting and smart modulation method.

[0011] The UDP transport module is used to enable data communication between the RFSOC and the host computer.

[0012] A method for generating integrated detection and jamming signals based on RFSOC, using the aforementioned integrated detection and jamming signal generation and acquisition device, generates an integrated waveform signal with dual detection and jamming functions by intercepting the opponent's signal, enabling the device to simultaneously function as a radar detector and jammer. The method includes the following steps:

[0013] Step 1: Device initialization and parameter distribution; After the equipment is powered on, the PS terminal establishes a UDP network port initialization connection with the host computer and configures the clock chip via the SPI serial port to provide the required clock input for the RFSOC chip and the RF data conversion module; After the host computer connects via the network port, it sends the number of encoded symbols, the number of accumulated probe pulses, and the signal frequency band information to the device via the UDP protocol. The PS terminal sends the received parameters to the PL terminal via the DMA transfer module and configures the sub-band mixing frequency of the RF data conversion module via the AXI protocol.

[0014] Step 2: The radio frequency data conversion module sequentially intercepts the signal in each sub-band, and obtains the digital baseband signal through radio frequency sampling and down-conversion processing for subsequent pulse parameter estimation;

[0015] Step 3: Perform pulse detection and parameter estimation on the digital baseband signal; once it is determined that the other party's pulse signal has been intercepted, obtain the pulse width and pulse repetition interval of the intercepted signal by calculating the energy, and obtain the carrier frequency and bandwidth of the intercepted signal by FFT.

[0016] Step 4: Generate a linear frequency modulated pulse signal with the same parameters as the intercepted signal, and make it have both detection and interference functions by phase coding and cutting smart modulation. Buffer the generated integrated detection and interference signal into RAM for subsequent transmission.

[0017] Step 5: Implement the transmission and reception of the integrated probe waveform signal; the RF data conversion module reads the integrated probe waveform signal cached in RAM and upconverts it to the frequency of the other party's signal, and transmits it by controlling the microwave front-end and TR antenna through RFSOC; after each transmission, the RF data conversion module collects the probe echo signal of its own side, and uploads it to the PS end cache through DMA after downconversion and decimation processing; repeat the above pulse transmission and reception process according to the set number of pulse accumulations.

[0018] Step 6: After a radar CPI cycle ends, the PS terminal uploads the accumulated echo data to the host computer via UDP protocol for storage and processing.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) This invention generates and acquires integrated radar detection waveforms, enabling a single antenna device to simultaneously possess the dual functions of radar detection and enemy jamming. While achieving high functional integration and high data utilization, it eliminates the dependence on multiple antennas for simultaneous use of different functional devices, thereby improving the portability of combat equipment.

[0021] (2) This invention relies on the direct input and output function of the RFSOC chip, reducing the dependence of existing technologies on external analog circuits. While eliminating the influence of uncontrollable factors that may be introduced by conventional external analog circuits, it also solves the disadvantages of conventional analog-to-digital converter chips and digital-to-analog converter chips, such as complex wiring and large size. This makes the invention have the advantages of stable operation, small size and low power consumption.

[0022] (3) This invention allows for flexible setting of the sampling rate within the RFSOC and flexible configuration of the mixing frequency via the AXI bus, solving the problems of fixed sampling rates and poor flexibility in traditional chips. Compared to traditional 204B interface or SPI serial port configuration methods, this invention significantly reduces configuration latency, enabling efficient adjustment of operating parameters in different usage scenarios and rapid response to complex battlefield demands.

[0023] (4) This invention uses on-chip DMA transmission and inter-device UDP network transmission to save the detected echo data to the host computer for processing, thus solving the problems of complex radar target detection code porting and difficult debugging in the prior art. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the hardware connections used in the experiment.

[0025] Figure 2 This is an internal flowchart of the present invention.

[0026] Figure 3 This is a schematic diagram of the experimental test scenario setup for this invention.

[0027] Figure 4 This is a diagram showing the detection capability test results in the detection experiment of this invention.

[0028] Figure 5 This is a diagram showing the radar detection effect of the target when the equipment interference was not enabled in the experiment of this invention.

[0029] Figure 6 This is a diagram showing the radar detection effect after the device interference was activated in the experiment of this invention. Detailed Implementation

[0030] This invention proposes an integrated signal generation and acquisition device for signal detection based on a Radio Frequency System on Chip (RFSOC), comprising: a radio frequency data conversion module, a Direct Memory Access (DMA) transmission module, a pulse parameter estimation module, an integrated waveform generation module for signal detection, and a User Datagram Protocol (UDP) transmission module, wherein:

[0031] The aforementioned radio frequency data conversion module is used to realize bidirectional conversion between digital baseband signals and analog radio frequency signals. This module acquires the counterpart signal and our own detection echo signal within the radio frequency band through down-conversion and decimation processing. Simultaneously, this module can up-convert the generated integrated detection waveform signal to a specified frequency point, directly connecting it to the power amplifier circuit and antenna array via the radio frequency interface to complete the transmission of the integrated detection waveform signal.

[0032] The DMA transfer module is used to enable communication between the programmable logic (PL) and the processing system (PS) on the chip. This module is responsible for forwarding control commands from the host computer and transmitting signals acquired by the RF data conversion module to the PS and storing them in its memory.

[0033] The pulse parameter estimation module is used to extract necessary pulse parameters from the intercepted radar signal, providing input for generating the integrated detection and interference waveform. This module consists of three parts: pulse determination, time-domain parameter calculation, and frequency-domain parameter calculation. It calculates the modulus and power of the acquired signal; when the power exceeds a set threshold, a pulse signal is determined to exist. The start and end times of the pulses are recorded, and the pulse midpoint and repetition period are calculated. Pulse width measurement is based on power analysis, recording the maximum power point and the end point where the maximum power value drops by 3dB. The effective pulse width is twice the difference between the pulse end point and the pulse midpoint. Frequency-domain parameter calculation uses Fast Fourier Transform (FFT) for spectral estimation. The real and imaginary parts of the FFT output are squared and added to form the power spectrum. The spectral line with the largest amplitude in the power spectrum is searched, and the starting and ending spectral lines where the power value drops by 3dB at that point are further calculated and searched. The signal carrier frequency is the median of these two lines, and the frequency bandwidth is the difference between them.

[0034] In this module, the search process for maximum power involves averaging a range of sampling points using a sliding window to reduce random errors.

[0035] In this module, the basic unit for calculating pulse width is the clock cycle count of the system clock, and the count values ​​are all relative to the start of sampling. The basic unit for calculating carrier frequency and bandwidth is the minimum frequency resolution of the FFT.

[0036] In this module, FFT is implemented using the FFTip core.

[0037] The integrated waveform generation module for probes is used to generate linear frequency modulation (LMF) pulse signals and to generate integrated probe waveforms through phase-encoded cutting and smart modulation. Its functions include: generating LMF signals and phase encoding, implementing smart modulation cutting, and buffering the signal waveform. First, based on the captured LMF pulse signal parameters, a direct digital synthesizer (DDS) is used with a counter to perform frequency stepping to generate the LMF signal. Then, based on the number of symbols sent by the host computer, a shift register is used to perform low-bit to high-bit shifting and XOR operations to generate the required binary code. After spreading the binary code, the phase-encoded cutting and smart modulation of the LMF pulse signal is achieved. Finally, the generated integrated probe waveform signal is buffered in random access memory (RAM).

[0038] The phase-coded segmentation smart modulation in this module involves segmenting the linear frequency modulated (LFM) signal in the time domain and then modulating it using a phase-coded sequence. This achieves both high coherence with the opponent's radar signal and strong random transitions. When our radar is conducting detection and jamming, it can effectively distinguish our signal from the opponent's LFM signal, while simultaneously increasing the difficulty for the opponent to identify our complex signal and remove our jamming signal.

[0039] The UDP transmission module is used to realize data communication between the RFSOC and the host computer. After completing the network port initialization process, this module can establish a network connection between the present invention and the host computer, and realize the transmission of parameters from the host computer to the RFSOC and the transmission of real-time echo data from the RFSOC to the host computer through the UDP protocol.

[0040] The implementation steps of the integrated signal generation and acquisition of the present invention include:

[0041] Step 1: Device Initialization and Parameter Distribution. After the equipment is powered on, the PS terminal establishes a UDP network connection with the host computer and configures the clock chip via the Serial Peripheral Interface (SPI) serial port to provide the necessary clock input for the RFSOC chip and RF data conversion module. After the host computer connects via the network port, it sends the number of encoded symbols, the number of accumulated probe pulses, and the signal frequency band information to the device via the UDP protocol. The PS terminal sends the received parameters to the PL terminal via the DMA transfer module and configures the sub-band mixing frequency of the RF data conversion module via the Advanced eXtensible Interface (AXI) protocol.

[0042] Step 2: The radio frequency data conversion module sequentially intercepts the signal in each sub-band, and obtains the digital baseband signal through radio frequency sampling and down-conversion processing for subsequent pulse parameter estimation.

[0043] Step 3: Perform pulse detection and parameter estimation on the digital baseband signal. Once it is determined that the other party's pulse signal has been intercepted, the pulse width and pulse repetition interval of the intercepted signal are obtained by calculating the energy, and the carrier frequency and bandwidth of the intercepted signal are obtained by FFT.

[0044] Step 4: Generate a linear frequency modulated pulse signal with the same parameters as the intercepted signal, and make it have both detection and interference functions by phase coding and cutting smart modulation. Buffer the generated integrated detection and interference signal into RAM for subsequent transmission.

[0045] Step 5: Implement the integrated transmission and reception of waveform signals from the probe. The RF data conversion module reads the waveform signal buffered in RAM and upconverts it to the frequency of the counterparty signal. Transmission is achieved by controlling the power amplifier and antenna transmission components via the RFSOC. After each transmission, the RF data conversion module acquires the probe echo signal, downconverts and decimates it, and then uploads it to the PS buffer via DMA. The above pulse transmission and reception process is repeated according to the set pulse accumulation count.

[0046] Step 6: After one radar coherent processing interval ends, the PS terminal uploads the accumulated echo data to the host computer via UDP protocol for storage and processing.

[0047] Furthermore, the configuration clock via serial port on the PS side in step 1 refers to writing the value to the register of the LMK clock management chip via SPI serial port. The specific value written to the register can be calculated and generated using TICS software according to the reference clock requirements of the RF data conversion module.

[0048] Furthermore, the configuration of the RF data conversion module via the AXI bus at the PS end in step 1 refers to the mixing control. By configuring the mixing frequency of the RF data conversion module at the PS end, flexible control of the RF transceiver signal frequency can be achieved.

[0049] Furthermore, the sub-band mixing frequency points mentioned in step 1 are obtained by dividing the frequency band of interest under the condition that the bandwidth of each sub-band does not exceed the sampling bandwidth limit of the RF data conversion module, and the frequency band is covered by sampling several sub-bands.

[0050] Furthermore, the radio frequency data conversion module described in step 2 can be used to collect the other party's signal and our side's detection echo signal within the radio frequency band by setting the AD sampling rate, down-mixing frequency point, and decimation factor; this module can be used to up-convert the generated integrated detection waveform signal to a specified frequency point for transmission by setting the DA sampling rate, up-mixing frequency point, and interpolation factor.

[0051] Furthermore, the pulse parameter estimation module in step 3 estimates the time-domain parameters of the intercepted signal using the power threshold method and uses the FFTip kernel to estimate the frequency-domain parameters of the intercepted signal.

[0052] Furthermore, the phase-coded segmentation and smart modulation described in step 4 involves segmenting the linear frequency modulated signal in the time domain and then performing phase modulation through a phase-coded sequence; this enables the linear frequency modulated signal to acquire both detection and jamming capabilities, achieving both high coherence with the opponent's radar signal and strong random jump characteristics.

[0053] To further illustrate the technical solutions and effects adopted by the present invention to achieve the intended purpose, the present invention will be further described in detail below with reference to the accompanying drawings and specific experimental examples.

[0054] Example

[0055] The effectiveness of this invention can be further demonstrated through the following experiments.

[0056] Hardware connection diagram for the experiment (see reference) Figure 1 The experimental hardware consists of this invention, a microwave front-end TR antenna, and a host computer.

[0057] This invention integrates waveform generation, acquisition, data transmission, and control into a single process. The microwave front-end TR antenna amplifies the signal power and performs antenna transmission and reception. The host computer sends parameters and receives echo signal data via a UDP network port for signal processing and data analysis.

[0058] Internal flowchart of the present invention (see reference) Figure 2 The present invention provides an integrated signal generation and acquisition device and method based on RFSOC, comprising a parameter initialization module, a radio frequency data conversion module, a DMA transmission module, a pulse parameter estimation module, an integrated waveform generation module, and a UDP transmission module.

[0059] Experimental scenario setup diagram reference Figure 3 The experimental equipment included: one of the present inventions, one Universal Software Radio Peripheral (USRP), two microwave systems, and two metal corner reflectors. Corner reflector target 1 was the target we needed to protect and also the target the enemy needed to detect. Corner reflector target 2 was the target we needed to detect. Corner reflector targets 1 and 2 had the same radar cross-section. During the experiment, corner reflector targets 1 and 2 were lifted by the participants and moved relative to the radar at a certain radial velocity. The USRP, simulating the enemy radar, was placed on the left side of the scene and emitted an LFM signal to detect corner reflector target 1. The present invention was placed on the right side of the scene, emitting an integrated detection and interference signal to detect corner reflector target 2 while simultaneously interfering with the enemy radar's detection of corner reflector target 1.

[0060] Step 1: Turn on the USRP device to simulate the enemy radar detecting diagonally opposite target 1. The host computer processes the enemy radar echo that is not interfered with by this invention and records the detection effect of the enemy radar.

[0061] Step 2: Activate the present invention, intercept the opponent's LFM signal and generate an integrated detection and interference waveform, and transmit the integrated detection and interference signal to detect the diagonal anti-target 2 while interfering with the opponent's radar detection of the diagonal anti-target 1.

[0062] Step 3: Process the integrated detection waveform signal echo acquired and transmitted by the present invention through the host computer, and analyze the detection effect of the present invention.

[0063] Step 4: Process the detection echo data of the enemy radar simulated by the USRP device under the interference of the present invention through the host computer, and analyze the interference effect of the present invention on the enemy radar detection target.

[0064] The following is combined Figure 4 , Figure 5 and Figure 6 The images further illustrate the effects of the present invention.

[0065] Figure 4 This is a top-down view of the target range in a Doppler plane, obtained by the host computer after processing the radar signal echo data collected and transmitted by the integrated radar detection waveform signal of this invention. The figure shows a target distance of approximately 19 meters and a speed of approximately 4 meters per second, which is consistent with the actual test target parameters. This indicates that the invention has successfully detected an angularly opposed target, verifying that the generated integrated radar detection waveform signal has effective target detection capability.

[0066] Figure 5 This is the detection result of the enemy radar on our target when the invention is not activated. Our target can be clearly seen on the range-Doppler plane, indicating that the enemy radar can effectively detect our target under interference-free conditions. Figure 6 This is the detection result of the enemy radar on our target after the invention was activated. The target could no longer be seen on the range-Doppler plane, proving that the integrated detection and interference waveform signal generated by the invention has an interference effect on the enemy radar, successfully protecting our target.

[0067] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention, but it should not be construed as limiting the specific implementation of the invention to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A signal generation and acquisition device based on RFSOC, characterized in that, include: The radio frequency data conversion module is used to realize bidirectional conversion between digital baseband signals and analog radio frequency signals; This module achieves sampling of radio frequency analog signals through downconversion and decimation processing. At the same time, this module upconverts the generated integrated detection waveform signal to a specified frequency point. The DMA transfer module is used to enable communication between the PL and PS terminals within the RFSOC chip. This module is used to forward control commands from the host computer, transmit the signals collected by the RF data conversion module to the PS terminal and save them to its memory; The pulse parameter estimation module is used to extract pulse parameters from the intercepted radar signal of the other party, providing input basis for generating the integrated detection and interference waveform. The pulse parameter estimation module consists of three parts: pulse determination, time domain parameter calculation, and frequency domain parameter calculation. It calculates the modulus and power of the acquired signal. When the power is greater than a set threshold, it determines that there is a pulse signal. It counts and records the pulse start time and pulse end time, and calculates the pulse midpoint and pulse repetition period. The pulse width is measured based on power analysis. The maximum power point of the pulse and the end point where the maximum power value drops by 3dB are recorded. The effective pulse width is twice the difference between the pulse end point and the pulse midpoint. Frequency domain parameter calculation is performed by spectral estimation using Fast Fourier Transform (FFT). The real and imaginary parts of the FFT output are squared and added together to form the power spectrum. The spectral line with the largest amplitude in the power spectrum is searched, and the starting and ending spectral lines at which the power value drops by 3dB are calculated and searched. The signal carrier frequency is the median of the two, and the frequency domain bandwidth is the difference between the two. The integrated waveform generation module for detecting linear frequency modulation (LFM) pulse signals is used to generate LFM pulse signals and generate integrated waveform signals for detecting LFM pulse signals through phase encoding and cutting smart modulation. Specifically, the integrated waveform generation module for detecting LFM pulse signals is implemented as follows: based on the parameters of the intercepted LFM pulse signal, a counter is used to perform frequency stepping on a direct digital frequency synthesizer to generate a LFM signal; based on the number of symbols sent by the host computer, a shift register is used to perform low-bit to high-bit shifting and XOR operations to generate the required binary code; after spreading the binary code, the phase encoding and cutting smart modulation of the LFM pulse signal is achieved; the generated integrated waveform signal for detecting LFM pulse signals is cached in random access memory. The UDP transport module is used to enable data communication between the RFSOC and the host computer.

2. The integrated signal generation and acquisition device based on RFSOC as described in claim 1, characterized in that, The search for the maximum power involves averaging a range of sampling points using a sliding window.

3. The integrated signal generation and acquisition device based on RFSOC as described in claim 1, characterized in that, After completing the network port initialization process, the UDP transmission module establishes a network connection between the device and the host computer, and uses the UDP protocol to enable the host computer to send parameters to the RFSOC and the RFSOC to transmit real-time echo data to the host computer.

4. An integrated signal generation method based on the device of claim 1, characterized in that, By intercepting the opponent's signal, an integrated waveform signal with both detection and jamming functions is generated, enabling the device to function as both a radar detector and a jammer. This method includes the following steps: Step 1: Device initialization and parameter distribution; After the equipment is powered on, the PS terminal establishes a UDP network port initialization connection with the host computer and configures the clock chip via the SPI serial port to provide the required clock input for the RFSOC chip and the RF data conversion module; After the host computer connects via the network port, it sends the number of encoded symbols, the number of accumulated probe pulses, and the signal frequency band information to the device via the UDP protocol. The PS terminal sends the received parameters to the PL terminal via the DMA transfer module and configures the sub-band mixing frequency of the RF data conversion module via the AXI protocol. Step 2: The radio frequency data conversion module sequentially intercepts the signal in each sub-band, and obtains the digital baseband signal through radio frequency sampling and down-conversion processing for subsequent pulse parameter estimation; Step 3: Perform pulse detection and parameter estimation on the digital baseband signal; once it is determined that the other party's pulse signal has been intercepted, obtain the pulse width and pulse repetition interval of the intercepted signal by calculating the energy, and obtain the carrier frequency and bandwidth of the intercepted signal by FFT. Step 4: Generate a linear frequency modulated pulse signal with the same parameters as the intercepted signal, and make it have both detection and interference functions by phase coding and cutting smart modulation. Buffer the generated integrated detection and interference signal into RAM for subsequent transmission. Step 5: Implement the transmission and reception of the integrated probe waveform signal; the RF data conversion module reads the integrated probe waveform signal cached in RAM and upconverts it to the frequency of the other party's signal, and transmits it by controlling the microwave front-end and TR antenna through RFSOC; after each transmission, the RF data conversion module collects the probe echo signal of its own side, and uploads it to the PS end cache through DMA after downconversion and decimation processing; repeat the above pulse transmission and reception process according to the set number of pulse accumulations. Step 6: After a radar CPI cycle ends, the PS terminal uploads the accumulated echo data to the host computer via UDP protocol for storage and processing.

5. The method according to claim 4, characterized in that, The sub-band mixing frequency points mentioned in step 1 are obtained by dividing the frequency band of interest under the condition that the bandwidth of each sub-band does not exceed the sampling bandwidth limit of the RF data conversion module. The frequency band coverage is achieved by sampling several sub-bands.

6. The method according to claim 4, characterized in that, The radio frequency data conversion module described in step 2 is used to collect the other party's signal and our side's detection echo signal in the radio frequency band by setting the AD sampling rate, down-mixing frequency, and decimation factor; the module is used to up-convert the generated integrated detection waveform signal to the specified frequency for transmission by setting the DA sampling rate, up-mixing frequency, and interpolation factor.

7. The method according to claim 4, characterized in that, In step 3, the pulse parameter estimation module estimates the time-domain parameters of the intercepted signal using the power threshold method and uses the FFTip kernel to estimate the frequency-domain parameters of the intercepted signal.

8. The method according to claim 4, characterized in that, The phase-coded cutting and smart modulation described in step 4 involves cutting the linear frequency modulated signal in the time domain and then performing phase modulation through a phase-coded sequence, so that the linear frequency modulated signal can acquire both detection and interference capabilities.

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