CN202750081U - Software defined radio receiver comprising multi-level automatic gain control modules - Google Patents

Abstract

The utility model is a software radio receiver comprising a multi-stage automatic gain control module, including sequentially connected antennas, low-noise amplifiers, radio frequency filters, mixers, filters, analog-to-digital converters and FPGA modules, and direct digital frequency synthesis The filter is connected to the mixer, and a radio frequency automatic gain control module is connected to the radio frequency filter and the mixer. The low noise amplifier and/or the radio frequency filter are respectively connected with the first and second analog automatic gain control modules. The radio frequency automatic gain control module includes a digital automatic gain control sub-module inside the FPGA module, a digital-to-analog converter and a gain controller. The two analog automatic gain control modules have the same structure, including variable gain amplifier/attenuator, amplifier, automatic gain control detector, DC amplifier and low-pass filter. The receiver has a multi-stage analog and digital automatic gain control module, which has high power control precision and a large control dynamic range; the structure of the whole machine is relatively simple, high performance and low cost.

Description

Software Radio Receiver Containing Multi-Stage Automatic Gain Control Block

technical field

The utility model relates to the technical field of software radio, in particular to a software radio receiver including a multi-stage automatic gain control module. the

Background technique

The receiver is an important part of the wireless communication system. In order to overcome the technical limitations of traditional radio receivers such as single function and poor function scalability, Software Defined Radio (SDR) technology has emerged. The hardware structure is a communication platform, making full use of digital signal processing technology, and realizing different communication functions by running different software algorithms on the same hardware platform. The receiver using software radio technology is an advanced design concept. Its key technology is to process the radio frequency signal as close as possible to the antenna, so it is necessary to sample the radio frequency signal, so it is necessary to process the analog/digital signal before sampling. The power control of the radio frequency signal ensures the dynamic range performance of the receiver. the

The best solution to ensure the dynamic range of the receiver is the automatic gain control (Auto Gain Control, AGC). In traditional receivers, the analog automatic gain control circuit is used to directly detect the power of the analog radio frequency signal, and then control the variable gain amplifier or attenuator. This method is difficult to achieve high precision control and large dynamic range. With the advancement of technology, an all-digital automatic gain control scheme has emerged, which can improve the shortcomings of traditional automatic gain control circuits, but there are problems with complex structures. In addition, there is still room for technical improvement in the dynamic range of receivers. the

Utility model content

The purpose of this utility model is to provide a software radio receiver including a multi-stage automatic gain control module. The receiver includes an analog automatic gain control module and a digital automatic gain control module, which improves the gain control accuracy and increases the dynamic range of the receiver. the

The software radio receiver including the multi-stage automatic gain control module designed by the utility model includes sequentially connected antennas, low-noise amplifiers, radio frequency filters, mixers, filters, analog-to-digital converters and field programmable logic gate arrays module, the direct digital frequency synthesizer is connected to the mixer, and the radio frequency automatic gain control module is connected to the radio frequency filter and the mixer. the

The radio frequency automatic gain control module includes a digital automatic gain control submodule, a digital-to-analog converter and a gain controller (Gain Ctrl) inside the field programmable logic gate array module, and the digital automatic gain control submodule of the field programmable logic gate array module The module is connected to the gain controller through the digital-to-analog converter, and the gain controller is connected between the radio frequency filter and the mixer. the

The field programmable logic gate array module in the receiver controls the whole machine, detects the power of the digital baseband signal and decodes it; the mixer and the direct frequency synthesizer complete the down-conversion of the radio frequency analog signal. the

The output of the low-noise amplifier of the receiver is connected to the first-stage analog automatic gain control module, and the output of the latter is connected to the input of the low-noise amplifier; and/or the output of the radio-frequency filter of the receiver is connected to the second stage An analog automatic gain control block whose output is connected to the input of the RF filter. the

The first-stage analog automatic gain control module and the second-stage analog automatic gain control module have the same structure, and both include a variable gain amplifier/attenuator, an amplifier, an automatic gain control detector, a DC amplifier and a low-pass filter. The input signal is connected to a variable gain amplifier/attenuator, and the signal is output after the amplifier. The output of the amplifier is also connected to an automatic gain control detector, a DC amplifier and a low-pass filter, and the output of the low-pass filter is connected to a variable gain amplifier/attenuator. the

The advantages of the software radio receiver comprising the multi-stage automatic gain control module of the utility model are: 1. The multi-stage automatic gain control module fully combines the characteristics of the analog automatic gain control module and the digital automatic gain control module to realize high-precision power control , and the dynamic range controlled by the receiver is relatively large; 2. The hardware structure of the whole machine is relatively simple, high performance, low cost, and suitable for popularization and application. the

Description of drawings

Fig. 1 is the structural block diagram of the software radio receiver embodiment that comprises multistage automatic gain control module;

FIG. 2 is a structural block diagram of the first-stage or second-stage analog automatic gain control module in FIG. 1 . the

Detailed ways

The structure of the embodiment of the software radio receiver comprising the multi-stage automatic gain control module is shown in Figure 1, including an antenna connected in sequence, a low noise amplifier LNA, a radio frequency filter RF Filter, a radio frequency automatic gain control module RFAGC, a mixer, The filter, the analog-to-digital converter ADC and the field programmable logic gate array FPGA module, and the direct digital frequency synthesizer are connected to the mixer. the

The radio frequency automatic gain control module comprises a digital automatic gain control submodule, a digital-to-analog converter DAC and a gain controller Gain Ctrl inside the field programmable logic gate array module, and the digital automatic gain control submodule of the field programmable logic gate array module The module is connected to the gain controller Gain Ctrl through the digital-to-analog converter, and the gain controller Gain Ctrl is connected between the RF Filter and the mixer. the

The output of the low-noise amplifier of the receiver is connected to the first-stage analog automatic gain control module, and the output of the latter is connected to the input of the low-noise amplifier; the output of the radio-frequency filter of the receiver is connected to the second-stage analog automatic gain A control module whose output is connected to the input of the radio frequency filter. the

The first-stage analog automatic gain control module and the second-stage analog automatic gain control module have the same structure, as shown in Figure 2, both include a variable gain amplifier/attenuator, amplifier A, and an analog automatic gain control (AGC) detector , DC amplifier DA and low-pass filter LPF. The input signal is connected to the variable gain amplifier/attenuator, and the signal is output after passing through the amplifier A. The output of the amplifier A is also connected to the automatic gain control (AGC) detector, DC amplifier DA and low-pass filter LPF, low-pass filter The output of the LPF is connected to a variable gain amplifier/attenuator. the

In this example, the Field Programmable Logic Gate Array module FPGA is Altera's Clone III series chip, which makes full use of the Nios II embedded soft-core processor built into the FPGA to complete the control function of the receiver. the

In this embodiment, the frequency band of the antenna receiving signal f1 can be 300MHz to 800MHz. In this example, f1 is an orthogonal frequency division multiplexing signal (OFDM signal, OFDM is the abbreviation of Orthogonal Frequency Division Multiplexing) with a frequency point of 480MHz and a bandwidth of 2MHz. The amplification factor of the LNA is 10dB. The signal f1 received by the antenna is first sent to the low-noise amplifier LNA for amplification. When the useful signal is amplified, the noise signal is also amplified at the same time, which is beneficial to the RF filter of the subsequent stage. Filter out noisy signals. The bandwidth of the RF Filter in this example is 2MHz. When the received signal f1 passes through the low-noise amplifier LNA and the radio frequency filter RF Filter, it is controlled by the first-stage and second-stage analog automatic gain control modules (AGC1 and AGC2) respectively, and the power is input according to the strength of the input signal Rough tuning. In the first-stage and second-stage analog automatic gain control modules, the AGC detector is composed of a triode circuit, which generates a control voltage that passes through a DC amplifier and a low-pass filter, and acts on a variable gain amplifier/attenuator to control the input analog signal. power to increase the dynamic range of the receiver. The signal after the RF Filter is sent to the mixer for analog down-conversion, where the local oscillator signal f2 required by the mixer is provided by the direct frequency synthesizer, and the local oscillator frequency provided by the direct digital frequency synthesizer in this example f2 is configured as 481MHz by the program, and the signal f3 is obtained by mixing with a mixer. In this example, the frequency spectrum of f3 includes frequency components of 1MHz, 480MHz, 481MHz and 961MHz. The unnecessary high-frequency components are filtered out by the filter, and the reserved frequency is 1MHz. The analog low-intermediate frequency signal is converted into a digital signal by the analog-to-digital converter A/D and input to the field programmable logic gate array module FPGA, and digital down-conversion is first performed in the field programmable logic gate array module FPGA The baseband signal is obtained by the DDC, and the power calculation of the digital baseband signal is performed by the digital automatic gain control sub-module of the field programmable logic gate array module FPGA, and compared with the reference value, and the power control word of the digital automatic gain control obtained is passed through a single channel The 8-bit digital-to-analog converter D/A converts it into an analog control value, and sends it to the RF automatic gain control module RFAGC to complete the third-level automatic gain control in this example, that is, the power control of the RF automatic gain control RFAGC, to realize the control of the input signal power For further precise control, the voltage control range of the RF automatic gain control in this example is 0-4V. Finally, the decoding process of the OFDM baseband signal is completed in the field programmable logic gate array module FPGA. the

The direct digital frequency synthesizer in this example is a phase-locked loop PLL frequency synthesizer with a built-in voltage-controlled oscillator VCO, combined with an external loop filter circuit and an external reference clock to generate the local oscillator signal required by the mixer. In this example, the external reference frequency of the direct digital frequency synthesizer is provided by an external crystal oscillator of 20MHz as the reference clock, and the external loop filter circuit is composed of RC passive components. the

The above-mentioned embodiments are only specific examples for further specifying the purpose, technical solutions and beneficial effects of the utility model, and the utility model is not limited thereto. All modifications, equivalent replacements, improvements, etc. made within the disclosed scope of the present utility model are included in the protection scope of the present utility model. the

Claims (4)

1. the software radio receiver that comprises the multi-stage automatic gain control module, comprise the antenna, low noise amplifier, radio-frequency filter, frequency mixer, filter, analog to digital converter and the field programmable gate array module that are linked in sequence, Direct Digital Frequency Synthesizers access frequency mixer is characterized in that:

Described radio-frequency filter and frequency mixer are connected to radio frequency automatic gain control module.

2. the software radio receiver that comprises the multi-stage automatic gain control module according to claim 1 is characterized in that:

Described radio frequency automatic gain control module comprises digital Auto Gain control submodule, digital to analog converter and the gain controller of field programmable gate array inside modules, the digital Auto Gain control submodule of field programmable gate array module is through digital to analog converter insertion gain controller, and gain controller is connected between radio-frequency filter and the frequency mixer.

3. the software radio receiver that comprises the multi-stage automatic gain control module according to claim 1 and 2 is characterized in that:

The output of described low noise amplifier connects first order simulation automatic gain control module, the input of the latter's output access low noise amplifier; And/or the output of the radio-frequency filter of this receiver connects second level simulation automatic gain control module, the input of the latter's output access radio-frequency filter.

4. the software radio receiver that comprises the multi-stage automatic gain control module according to claim 3 is characterized in that:

Described first order simulation automatic gain control module is identical with second level simulation automatic gain control module structure, includes variable gain amplification/attenuation device, amplifier, simulation after detector, direct current amplifier and low pass filter; The signal access variable gain amplification/attenuation device of input, output signal behind amplifier, the output of amplifier is connecting analog after detector, direct current amplifier and low pass filter also, the output access variable gain amplification/attenuation device of low pass filter.

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