CN101178433B - An ultra-wideband fast-agile frequency source - Google Patents

Abstract

The invention discloses a super broad band rapid frequency conversion, which comprises a control unit, a DDS unit, a cent unit, a double frequency unit A, a double frequency unit B and a frequency choosing unit. When in reference, the 1GHz DDS time signal is obtained through a PLL lock phase; the DDS unit is driven to produce a 0 to 400MHz signal to be divided into three ways to send to the double frequency unit A, the double frequency unit B and the frequency choosing unit. An output signal of the double frequency unit A and the double frequency unit B are also sent to the frequency choosing unit and finally the frequency choosing unit outputs a final frequency signal. The invention doubles frequency of the signal output by the DDS, and conducts choosing output, which realizes super broad band rapid frequency, with short frequency conversion response time(less than 200ns). The frequency speed reaches nanosecond grade, the output frequency range to more than 1 GHz and the frequency differentiate rate less than 0.01Hz. Under the worst condition, the scattering and harmonic wave is less than -55dBc, noise less than -95dBc/Hz at 1KHz, -105dBc/Hz at 10KHz, with simple periphery control joint and convenient utilization.

Description

An ultra-wideband fast-agile frequency source

technical field

The invention relates to a signal source suitable for various wide-band radars such as frequency-agile system radar, RCS test and imaging radar, and specifically refers to an ultra-wideband fast-change frequency source.

Background technique

In recent years, more and more attention has been paid to various broadband radars such as frequency-agile system radars, RCS test and imaging radars. It has been widely used in military and civilian fields such as remote sensing and obstacle avoidance. Radars of various systems have also been put into use. For example, the commonly used frequency agility system has been applied in various types of missiles as a missile terminal guidance and anti-jamming technology, and RCS test radar has been applied many years ago. It has made great contributions to the stealth design of weapons in our country.

Frequency-agile radars and RCS test and imaging radars are all broadband radars, and the signal bandwidth and jump time have a great impact on their performance: for frequency-agile radars, the signal bandwidth and jump time directly affect the performance of frequency-agile radars. Probability of being intercepted; for RCS testing and imaging radar, the signal bandwidth determines its imaging resolution, while the jump time determines its test time and test distance.

The basic structure of broadband radar is to up-convert the lower-frequency signal of the broadband to the transmission frequency, so the lower-frequency broadband frequency conversion source is very important.

Broadband frequency synthesis technology mainly includes direct frequency synthesis, phase-locked frequency synthesis and direct digital synthesis (DDS) in three ways. These three methods have their own advantages and disadvantages. The frequency conversion time of direct frequency synthesis technology is short, but the structure is complex, and the output frequency range is limited, and the number of discrete frequencies cannot be too many; the phase-locked frequency synthesis technology has high output spectrum purity, but its frequency conversion time Longer, frequency resolution is also limited; DDS technology has the advantages of high frequency resolution, fast frequency switching, low phase noise, high frequency stability, etc., but the output signal bandwidth is limited. This article adopts the technology of direct digital synthesis (DDS) and direct frequency synthesis.

Contents of the invention

The object of the present invention is to provide an ultra-wideband fast-agile frequency source. The frequency conversion source can generate frequency conversion response time <200ns, bandwidth above 1GHz, frequency resolution less than 0.01Hz low spurious, low phase noise agile frequency signal, which can be used as the basic functional unit of various broadband radars.

The frequency conversion source of the present invention includes a control unit, a DDS unit, a power division unit, a frequency multiplication unit A, a frequency multiplication unit B, and a frequency selection unit.

The working principle of the frequency conversion source of the present invention: the technology of combining direct digital synthesis (DDS) and direct frequency synthesis is adopted, the reference clock is locked by the PLL to obtain a 1GHz DDS clock signal, and the DDS unit is driven to generate a 0-400MHz signal, which is passed through the power division unit It is divided into 3 channels, which are respectively sent to frequency multiplication unit A, frequency multiplication unit B and frequency selection unit. The output signals of frequency multiplication unit A and frequency multiplication unit B are also sent to frequency selection unit, and finally the frequency selection unit outputs the final shortcut frequency conversion signal.

Among them, in the control unit, the precise control of the DDS unit and the frequency selection unit is realized through high-speed logic devices, so that the DDS unit and the frequency selection unit can work closely together, thereby achieving an extremely short frequency conversion response time; In the above frequency multiplication unit A and frequency multiplication unit B, an ideal low spurious frequency multiplication signal is obtained by selecting an appropriate filter bandwidth.

Advantages of the present invention: (1) Excellent performance, frequency conversion response time<200ns, output frequency range>1GHz, frequency resolution<0.01Hz, in the worst case, spurious and contemporaneous waves are lower than -55dBc, and phase noise is lower than -95dBc/Hz@1KHz , -105dBc/Hz@10KHz ; (2) The control interface is simple and easy to use; (3) The work is stable and reliable.

Description of drawings

Fig. 1 is a functional block diagram of the frequency conversion source of the present invention.

Fig. 2 is a functional block diagram of the control unit of the frequency conversion source of the present invention.

Fig. 3 is a functional block diagram of the DDS unit of the frequency conversion source of the present invention.

Fig. 4 is a functional block diagram of the frequency multiplication unit A of the frequency conversion source of the present invention.

Fig. 5 is a functional block diagram of the frequency multiplication unit B of the frequency conversion source of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

The present invention is an ultra-broadband fast and agile frequency source, including a control unit 1, a DDS unit 2, a power division unit 3, a frequency multiplication unit A4, a frequency multiplication unit B5, and a frequency selection unit 6.

Described control unit 1 is by comprising field programmable gate array FPGA10, single-chip microcomputer MCU11, liquid crystal display module 12, keyboard 13; Described DDS unit 2 comprises constant temperature crystal oscillator 20, clock distributor 21, phase-locked loop PLL22, direct digital frequency synthesizer DDS23; described frequency multiplication unit A 4 comprises filter A410, amplifier A420, filter B411, frequency multiplier A430, filter C412, amplifier B421, amplifier C422, filter D413, filter E414, frequency multiplier B431, filter F415, amplifier E423, filter G416; the frequency multiplication unit B5 includes filter H510, amplifier F520, filter I511, frequency multiplier C530, filter J512, amplifier G521, amplifier H522, filter K513, filter L514 , Frequency multiplier D531, filter M515, amplifier I523, filter N516.

The control unit 1 sets the reference time base (internal time base/external time base), working mode (point frequency/frequency step/control code control), frequency sweep start and stop frequency and Step frequency, etc., and control the DDS unit 2 and the frequency selection unit 6 according to the preset parameters or the current control code 11 according to the set working state, so that they can work together to generate the required frequency-agile signal 9 .

The DDS unit 2, the clock distributor 21 selects the output of the constant temperature crystal oscillator 20 or the external reference time base 7 as the reference time base input of the phase-locked loop 22 according to the control of the control unit 1, and the phase-locked loop 22 is phase-locked and multiplied to 1 GHz The signal is used as the clock of the direct digital frequency synthesizer 23 , and the direct digital frequency synthesizer 23 outputs the DDS output signal 12 of 0-400MHz under the control of the control unit 1 .

The frequency multiplication unit A 4 and the frequency multiplication unit B 5 respectively amplify, filter, and frequency multiply the 0-400MHz signal obtained by the power division unit 3 and filter part of the bandwidth to obtain double and quadruple frequency signals respectively.

The frequency selection unit 6 adopts a PIN tube switch under the control of the control unit 1, and the DDS output signal 17 after power division, the double frequency signal 13 output by the frequency multiplication unit A, the quadruple frequency signal 14 and the frequency multiplier The double frequency signal 15 and the quadruple frequency signal 16 output by unit B are selectively output to obtain the desired frequency-agile signal 9 .

Claims (4)

1. An ultra-broadband fast-agile frequency source, characterized in that: The frequency conversion source includes a control unit (1), a DDS unit (2), a power division unit (3), a frequency multiplication unit A (4), a frequency multiplication unit B (5), and a frequency selection unit (6); wherein The reference clock (7 or 8) is locked by the PLL in the DDS unit (2) to obtain a 1GHz DDS clock signal, and drives the direct digital frequency synthesizer (23) in the DDS unit (2) to generate a 0-400MHz signal (12) , divided into 3 paths by the power division unit (3), respectively sent to frequency multiplication unit A (4), frequency multiplication unit B (5) and frequency selection unit (6), frequency multiplication unit A (4) and frequency multiplication unit The output signal of B (5) is also sent to the frequency selection unit (6), and finally the frequency selection unit (6) outputs the final frequency-agile signal (9). 2. A kind of ultra-broadband fast-agile frequency source according to claim 1, characterized in that: in the control unit (1), the DDS unit (2) and the frequency selection unit (6) are realized by a high-speed logic device The precise control enables the DDS unit (2) and the frequency selection unit (6) to work closely together, thereby achieving an extremely short frequency conversion response time. 3. a kind of ultra-broadband fast-agile frequency source according to claim 1, is characterized in that: in described frequency multiplication unit A (4) and frequency multiplication unit B (5), obtain by selecting appropriate filter bandwidth Ideal for low spurious multiplier signals. 4. An ultra-wideband fast-agile frequency source according to claim 1, characterized in that: in the frequency selection unit (6), a PIN switch is used for signal selection.

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