CN100416280C - Cognitive radio front-end RF signal detection equipment - Google Patents

Abstract

Cognitive radio front-end RF signal detection equipment is used to solve the problem of detecting RF events in the surrounding environment when using cognitive radio (CR: Cognitive Radio) technology, that is, when users apply cognitive radio technology, they must monitor the surrounding environment detection, so as to adjust the corresponding parameters and make better use of the existing frequency spectrum. The RSSI module (1), ADC module (2), control module (3), communication module (4), power supply module (5) of the detection equipment ) are sequentially connected in series, the input end of the RSSI module (1) is the input end of the detection device, the input end of the RSSI module (1) receives the signal of the RF signal source through the antenna, and the output end of the communication module (4) is the detection device The output end of the communication module (4) outputs the detected and processed signal to the computer.

Description

Cognitive radio front-end RF signal detection equipment

technical field

The present invention is used to solve the problem of detecting RF events in the surrounding environment when using the cognitive radio (CR: Cognitive Radio) technology, that is, when the user uses the cognitive radio technology, the surrounding environment must be detected, so as to adjust the corresponding The parameters of the situation, better use of the existing frequency spectrum, belong to the field of electronic technology.

Background technique

Cognitive radio (CR, cognitive radio) is a very novel concept, and designers have implemented many cognitive radio technologies, some of which are quite complex. Because these techniques can be extended in an incremental fashion until the full performance promised by CR is achieved, they point the way for future wireless communications.

The basic logic of CR is to allow the radio to make better use of the available spectrum by detecting the surrounding environment and making adjustments accordingly.

Cognitive radio needs to detect a wide variety of radio environment characteristics, including traffic statistics and other identifiable RF events (such as radar, Bluetooth, microprocessor noise or microwave oven noise). Also included are side effects such as collisions, failed packets, adjacent channel interference, covert stations, and unidentified noise sources. By recording RF events, identifying them where possible, and responding accordingly, cognitive radio technology improves the ability to optimize throughput. Considering the presence of substantial radio interference in unlicensed radio bands, cognitive radio functionality is essential to achieve the robust performance expected by users.

The detection module of the cognitive radio captures several characteristics of each RF event: signal strength, length, time of occurrence, and spectral content, among others. This last piece of information is captured because the detection logic has access to the fast Fourier transform block used to detect wireless signals.

Unless the RF event is too weak to represent a meaningful signal or cause interference, the event and its characteristics are passed to the software. Threshold programmable hardware filters out these inconspicuous events before overloading the software. This screening mechanism is important because the cognitive radio detection module is sensitive enough to capture a large number of RF events. Designers must carefully manage detection sensitivity to avoid flooding adaptive software with false intelligence.

When using cognitive radio technology, it is important to detect the characteristic value of RF events in the surrounding environment, so we developed this device to detect radio frequency (RF) signals in the environment.

Contents of the invention

Technical problem: The purpose of the present invention is to provide a sensory radio front-end radio frequency signal detection device and detection method, which can be used for signal detection when using sensory radio technology. It is easy to use, and after the user powers on the device, the device can automatically detect RF signals in the surrounding environment.

Technical solution: The present invention (radio frequency signal detection equipment based on the background of cognitive radio technology) organically combines signal detection technology with a widely used single-chip computer system, thereby providing an important function of detecting ambient RF signals for the use of cognitive radio technology At the same time, the detected signal characteristic value is transmitted to the PC for display, so that the user can understand the RF signal situation in the current environment in real time and intuitively, and lays the foundation for the user's subsequent operation. More specifically, the present invention detects signal strength conditions in RF event signatures. The main content lies in the actual circuit, in which the RSSI (signal strength indication) module receives the RF signal source in the surrounding environment and converts it into an analog voltage value for output. When the ambient RF signal strength is high, the output analog voltage value is large; when the ambient RF signal strength is low, the output analog voltage value is small. According to the difference of the analog voltage value, the RF signal strength in the current environment can be intuitively judged.

The function of the ADC module is to convert the analog voltage value output by the RSSI module into a digital quantity for subsequent data interaction with the PC.

The control module uses a single-chip microcomputer to control the operation of the entire device. It includes controlling the AD conversion of the ADC module, reading the converted data, and comparing it with the system preset threshold to determine whether to output the signal strength value to the PC for display through the communication module.

The function of the communication module is to control the data exchange between the equipment and the RS-232 port on the PC.

The power module provides stable power for the entire device.

Its specific working principle is: convert the analog value of the RF signal strength of the surrounding environment converted by the RSSI module into a digital quantity, and the communication module serves as the interface between the device and the PC, and sends the qualified strength data to the PC for display. At the same time, the control module uses the single-chip microcomputer to coordinate the division of labor and cooperation of the various modules of the entire device to complete the corresponding functions.

The present invention completes the detection of radio frequency (RF: Radio Frequency) events in the surrounding environment. There are many characteristics of RF events, including signal strength, length, time of occurrence, and frequency spectrum. More specifically, the present invention detects the signal strength of RF events , until the corresponding position of the target can be given according to the signal strength, and centimeter-level indoor precise positioning can be performed.

The specific detection method is: the device is placed in the required environment, after the user powers on the device, the initialization program enters the automatic query state, the user can simply test whether the device is normal, and manually generate a certain intensity of RF signal near the device, such as dialing Mobile phone, walkie-talkie, etc., the indicator light on the device has a strong signal display, indicating that the device is functioning normally, and the device can automatically detect the strength of the RF signal in the surrounding environment. Under normal circumstances, the RSSI module automatically senses the signal strength through the broadband antenna, and the signal strength Indicated by analog voltage, the high-speed parallel AD converts the analog voltage into a digital quantity, and displays the real-time segmentation threshold value on this machine, and can also transmit it to the PC through the RS-232 port so that the user can directly understand the environment. Further analysis and calculation of the RF signal, based on this characteristic value, the user can make corresponding changes to the cognitive radio device to better adapt to the surrounding environment. The eigenvalues below a certain threshold will not be transmitted to the PC, which can not only filter the interference signal, but also reduce the burden of the user, so that it does not need to re-discriminate the information on the PC. The device is designed with three buttons corresponding to three different thresholds, which makes the device more applicable and can be applied in different environments.

Beneficial effect: the present invention has the following advantages:

1. Easy to use. After the device is powered on, it can automatically detect the RF signal in the surrounding environment and output its signal strength without complicated settings.

2. The response range is large, and the detectable wireless signal frequency starts from LF (low frequency) up to 2.7GHz, which meets the needs of most situations.

3. The device is designed with multiple LED lights to indicate the status of the device, and the user can clearly understand the current work of the device when using it.

4. Thresholds are set in the system, which can filter out interference signals and reduce the burden on users, and there are three buttons on the device, corresponding to different thresholds, which can make the device adapt to the needs of different environments.

5. Highly reliable and low-cost MCU platform design, using a single-chip microcomputer to control the operation of the entire device, while providing data processing functions for the device, the user can process the signal strength data of the RF signal or output it directly.

6. Provide the ability of data interaction with the PC, so that the detection information can be displayed intuitively, which not only facilitates the user's viewing, but also lays a foundation for using the PC to process the detection data.

Description of drawings:

Figure 1 is a block diagram of a radio frequency signal detection device. It includes RSSI module 1, ADC module 2, control module 3, communication module 4 and power module 5.

Figure 2 and Figure 3 are schematic diagrams of the circuit of the radio frequency signal strength detection equipment.

Detailed ways

The RSSI module is used to receive the RF signal of the surrounding environment and convert it into an analog voltage value output; the ADC module converts the analog voltage value into a digital value; the control module uses a single-chip microcomputer to control the operation of the entire device; the communication module is responsible for data interaction with the PC; the power module Powers the entire device.

1. RSSI module

The module uses the AD8302 chip of ANALOG DEVICES to complete the detection of RF signals. The chip has complete RF signal detection and control functions. It has two signal inputs that can be used to measure the gain and phase of RF signals, and the frequency response ranges from LF (low frequency) to 2.7GHz. With excellent temperature stability, the operable temperature is from -40°C to +85°C. The supply range is from 2.7V to 5.5V. The chip essentially measures the amplitude ratio and phase difference of two input signals, and outputs a corresponding voltage value according to the ratio and difference. The larger the ratio, the larger the difference, and the larger the output voltage value. When a calibrated AC reference voltage is input to one of the input terminals, the intensity of the input unknown signal can be calculated according to the value of the output voltage and the output function of the chip, and the detection of the RF signal is completed. Of course, for the sake of convenience, the magnitude of the chip output signal can also be directly used to represent the strength of the unknown signal. It can be seen that AD8302 is very suitable as a signal strength indicator (RSSI) for wireless terminal equipment.

2. ADC module

The module selects the AD7821 chip of ANALOG DEVICES company. AD7821 is a high-speed 8-bit parallel AD conversion chip. Its sampling frequency reaches 1MHz, and the conversion time can reach up to 660ns, which can improve the operating speed of the entire device. AD7821 is designed with standard microprocessor control signals, latches and three-state data output terminals, and can be connected to high-speed data buses. These characteristics make it very suitable for single-chip control.

3. Control module

This module selects the microprocessor AT89C51 of ATMEL Company for use.

4. Communication module

The module uses MAX3232 from MAXIM Company. MAX3232 is a low-power, high-speed serial port transmission level conversion chip. It contains two receivers and two drivers, and the data transmission rate can reach 1Mbps. It can enable high-speed data interaction between the device and the PC.

5. Power module

The module uses MC7805 chip to provide a stable 5V voltage.

Claims (1)

1. detection device for sensing radio front-end radiofrequency signal, the RSSI module (1) that it is characterized in that this checkout equipment, ADC module (2), control module (3), communication module (4), be connected in series successively, power module (5) is above-mentioned 4 module for power supply, the input end of RSSI module (1) is the input end of this checkout equipment, the input end of RSSI module (1) receives the signal of RF signal source by antenna, the output terminal of communication module (4) is the output terminal of this checkout equipment, communication module (4) will output to computing machine through the signal that detects and handle, the input end of RSSI module (1) is the signal of the input end " INPA " of RF signal deteching circuit " U2 " by antenna reception RF signal source, and the output terminal of RSSI module (1) is that the output terminal " VMAG " of RF signal deteching circuit " U2 " connects " VMAG " end that ADC module (2) is an adc circuit " U3 "; " D0～D7 " end and the control module (3) of adc circuit " U3 " is that " D0～D7 " end of microprocessor " U5 " joins; " RXD1, the IXD1 " end and the communication module (4) of microprocessor " U5 " is that " RXD1, IXD1 " end of telecommunication circuit " U4 " joins.

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