CN112019214A - Signal source system suitable for millimeter wave security inspection - Google Patents
Signal source system suitable for millimeter wave security inspection Download PDFInfo
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- CN112019214A CN112019214A CN202010649361.4A CN202010649361A CN112019214A CN 112019214 A CN112019214 A CN 112019214A CN 202010649361 A CN202010649361 A CN 202010649361A CN 112019214 A CN112019214 A CN 112019214A
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- 238000007689 inspection Methods 0.000 title claims abstract description 20
- 239000013078 crystal Substances 0.000 claims abstract description 13
- 230000002093 peripheral effect Effects 0.000 claims abstract description 8
- 230000010355 oscillation Effects 0.000 claims description 18
- 230000005540 biological transmission Effects 0.000 claims description 16
- 101100296075 Arabidopsis thaliana PLL4 gene Proteins 0.000 description 5
- 238000003384 imaging method Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 101100350613 Arabidopsis thaliana PLL1 gene Proteins 0.000 description 4
- 101100082028 Arabidopsis thaliana PLL2 gene Proteins 0.000 description 4
- 101100350628 Arabidopsis thaliana PLL3 gene Proteins 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/16—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop
- H03L7/18—Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop using a frequency divider or counter in the loop
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V8/00—Prospecting or detecting by optical means
- G01V8/005—Prospecting or detecting by optical means operating with millimetre waves, e.g. measuring the black losey radiation
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Abstract
The invention discloses a signal source system suitable for millimeter wave security inspection, which comprises a signal source and a peripheral circuit, wherein the signal source comprises a crystal oscillator, a plurality of local oscillator signal source circuits, an intermediate frequency signal source circuit, a plurality of mixers, a plurality of output branch circuits, a power amplifier, a local oscillator selection switch, an intermediate frequency selection switch and a mixing selection switch, and the peripheral circuit comprises a transmitting source circuit and a receiving source circuit. The invention can realize agility and reliable signal source system suitable for millimeter wave security inspection.
Description
Technical Field
The invention relates to a signal source system suitable for millimeter wave security inspection.
Background
The quality and speed of millimeter wave all-electronic imaging depends largely on the performance of the frequency synthesizer. For example, the operating frequency of the frequency source determines the directional resolution of millimeter wave imaging, the operating bandwidth determines the range resolution, the frequency hopping speed affects the imaging time of the final imaging system, and the transmitting power of the source determines the imaging range to some extent. The existing signal source is difficult to realize the system index of remote real-time high resolution and cannot carry out frequency shear relatively quickly.
Disclosure of Invention
A signal source system suitable for millimeter wave safety inspection comprises: signal source and peripheral circuit, wherein the signal source includes: a crystal oscillator for generating an oscillation frequency; the local oscillator signal source circuits can generate local oscillator signals for frequency mixing; an intermediate frequency signal source circuit capable of generating an intermediate frequency signal for frequency mixing; the frequency mixers are used for realizing frequency mixing of the local oscillation signals and the intermediate frequency signals; a plurality of output branch circuits for receiving and outputting the signals mixed by the mixer; a power amplifier for amplifying the signal output by the output branch circuit; the local oscillator selection switch is used for connecting one phase-locked loop in the local oscillator signal source circuit to one frequency mixer in a time-sharing manner; an intermediate frequency selection switch for connecting one of the mixers to the intermediate frequency signal source circuit in a time division manner; a mixing selection switch for connecting one of the output branch circuits to the mixer in time division; wherein, local oscillator signal source circuit includes: two or more phase-locked loops; the intermediate frequency signal source circuit comprises a direct digital frequency synthesizer; a mixing selection switch for connecting one of the output branch circuits to the mixer in time division; the crystal oscillator is electrically connected with the local oscillator signal source circuit and the intermediate frequency signal source circuit respectively; the peripheral circuit includes: the device comprises an emission source circuit and a receiving source circuit, wherein the emission source circuit and the receiving source circuit are both connected to a signal source; the emission source circuit includes: the device comprises a transmission source, a plurality of transmission shunts and a plurality of transmission frequency multipliers; wherein, a plurality of emission shunts are connected to the emission source, and a plurality of emission frequency multipliers are respectively connected to the emission shunts; the receiving source circuit includes: the system comprises a receiving source, a plurality of receiving shunts and a plurality of receiving frequency multipliers; wherein, a plurality of receiving shunts are connected to the receiving source, and a plurality of receiving frequency multipliers are respectively connected to the receiving shunts.
Further, the phase locked loop includes: the phase discriminator, the loop filter and the voltage-controlled oscillator are in a locked state when the local oscillation selection switch disconnects the phase-locked loop from the frequency mixer.
Further, the phase locked loop includes: and when the local oscillation selection switch is connected with the phase-locked loop and the frequency mixer, the voltage-controlled oscillator is in an output state.
Further, the crystal oscillator is an oven controlled crystal oscillator.
Furthermore, the number of phase-locked loops in one local oscillator signal source circuit is even.
Further, the number of phase-locked loops in one local oscillator signal source circuit is 2.
Further, the number of the local oscillation signal source circuits is even.
Further, the number of the local oscillation signal source circuits is 2.
Furthermore, the number of the local oscillator signal source circuit corresponds to the number of the frequency mixers.
Further, the number of output branch circuits corresponding to one mixing selection switch is even.
The invention has the advantages that:
a signal source system capable of agility and reliable suitable for millimeter wave security inspection is provided.
Drawings
FIG. 1 is a schematic diagram of a preferred embodiment of a signal source circuit suitable for millimeter wave security inspection according to the present invention
FIG. 2 is a schematic block diagram of a signal source system formed from the signal source circuitry of FIG. 1;
fig. 3 shows simulation results of phase noise when the local oscillator signal output is 3604.5 MHz.
Detailed Description
As shown in fig. 1 to 3, a signal source system suitable for millimeter wave security inspection includes: signal source and peripheral circuit, wherein the signal source includes: a crystal oscillator for generating an oscillation frequency; the local oscillator signal source circuits can generate local oscillator signals for frequency mixing; an intermediate frequency signal source circuit capable of generating an intermediate frequency signal for frequency mixing; the frequency mixers are used for realizing frequency mixing of the local oscillation signals and the intermediate frequency signals; a plurality of output branch circuits for receiving and outputting the signals mixed by the mixer; a power amplifier for amplifying the signal output by the output branch circuit; the local oscillator selection switch is used for connecting one phase-locked loop in the local oscillator signal source circuit to one frequency mixer in a time-sharing manner; an intermediate frequency selection switch for connecting one of the mixers to the intermediate frequency signal source circuit in a time division manner; a mixing selection switch for connecting one of the output branch circuits to the mixer in time division; wherein, local oscillator signal source circuit includes: two or more phase-locked loops; the intermediate frequency signal source circuit comprises a direct digital frequency synthesizer; a mixing selection switch for connecting one of the output branch circuits to the mixer in time division; the crystal oscillator is electrically connected with the local oscillator signal source circuit and the intermediate frequency signal source circuit respectively; the peripheral circuit includes: the device comprises an emission source circuit and a receiving source circuit, wherein the emission source circuit and the receiving source circuit are both connected to a signal source; the emission source circuit includes: the device comprises a transmission source, a plurality of transmission shunts and a plurality of transmission frequency multipliers; wherein, a plurality of emission shunts are connected to the emission source, and a plurality of emission frequency multipliers are respectively connected to the emission shunts; the receiving source circuit includes: the system comprises a receiving source, a plurality of receiving shunts and a plurality of receiving frequency multipliers; wherein, a plurality of receiving shunts are connected to the receiving source, and a plurality of receiving frequency multipliers are respectively connected to the receiving shunts.
Specifically, the phase-locked loop includes: the phase discriminator, the loop filter and the voltage-controlled oscillator are in a locked state when the local oscillation selection switch disconnects the phase-locked loop from the frequency mixer.
Specifically, the phase-locked loop includes: and when the local oscillation selection switch is connected with the phase-locked loop and the frequency mixer, the voltage-controlled oscillator is in an output state.
In particular, the crystal oscillator is an oven controlled crystal oscillator.
Specifically, the number of phase-locked loops in one local oscillator signal source circuit is even.
Specifically, the number of phase-locked loops in one local oscillator signal source circuit is 2.
Specifically, the number of local oscillation signal source circuits is an even number.
Specifically, the number of local oscillation signal source circuits is 2.
Specifically, the number of local oscillator signal source circuits and mixers corresponds.
Specifically, the number of output branch circuits corresponding to one mixing selection switch is even.
As a specific scheme, as shown in fig. 1 to 3, and as shown in fig. 2, the transmitter includes 20 transmit channels and 20 receive channels. Transmission and reception share a frequency source, respectively. And dividing the frequency source of each S waveband into 20 paths, and performing 8-time frequency multiplication on each path to obtain a Ka waveband frequency source. The frequency sources of each channel used for transmission and reception are implemented in a consistent manner.
As shown in fig. 1, 4 fixed local oscillator signals (LO) generated by a 4-way PLL are respectively mixed with an intermediate frequency signal (IF) generated by a DDS, a radio frequency signal (RF) is filtered and amplified to obtain an S-band agile frequency source, and then a Ka-band broadband agile frequency source is obtained by 8-way frequency multiplication.
The frequency of the final output can be expressed as:
fO=M2×(FN+M1×fDDS) (1)
wherein M1 is the frequency multiplication times of the intermediate frequency DDS, M2 is the frequency multiplication times of the S-band frequency source output, FN is F1, F2 respectively,
f3 or F4. The same resolution is
Wherein f isDDSresIs the resolution of the DDS. In this design, M1 is 2, M2 is 8, and the specific values of the frequencies of the local oscillator signal, the intermediate frequency signal and the rf signal are shown in table 1.
TABLE 1 specific values of local oscillator, IF, RF and final output frequencies
LO(MHz) | IF(MHz) | RF(MHz) | Fo(MHz) |
F1=3135 | 240-396.375 | f1(3375-3531.375) | 27-28.251 |
F3=3291.5 | 240-396.375 | f3(3531.5-3687.875) | 28.252-29.503 |
F2=3448 | 240-396.375 | f2(3688-3844.375) | 29.504-30.755 |
F4=3604.5 | 240-396.375 | f4(3844.5-4000.875) | 30.756-32.007 |
According to the scheme, the frequency mixing mode of the PLL switching and the DDS is adopted, so that the waiting time caused by the locking of the phase-locked loop in the local oscillator switching process is avoided, and the rapid frequency hopping among different frequency bands is realized. In the same frequency band, the switching time of the frequency point only depends on the frequency point switching time of the DDS, the switching time of the switch and the response time of the filter, so that the frequency agility can be realized. And the plurality of local oscillators are respectively mixed with the intermediate frequency signals generated by the DDS so as to expand the frequency band.
In the traditional mixed frequency synthesizer, the hopping time of a frequency point is limited because the locking time of a phase-locked loop is longer. In addition, the
In this architecture shown in fig. 2, all the phase locked loops (PLL0 through PLL4) are locked when the circuit is initialized (state 0). In swept mode, once PLL1 is mixed with the signal from the DDS, the outputs of PLL2 and PLL4 are disabled, but they are still locked just turning off the output of the VCO, while the output of PLL3 is enabled, ready to be mixed with the signal from the DDS (state 1). After the PLL1 and DDS signals are mixed, the SPDT3 (single-pole double-throw switch) is switched to the Mixer2, and the SPDT2 is switched to the PLL3, so that the PLL3 and DDS signals are mixed. At the same time, the outputs of PLL1 and PLL4 are disabled, PLL2 is enabled and ready to be mixed with the intermediate frequency signal output by the DDS (state 2). The operating principle of the PLL2 and the PLL4 is shown in table 2 as state3 and state4, and table 2 shows the detailed operating state of a plurality of phase-locked loops in one cycle. The working state of the frequency synthesizer in the frequency sweeping mode is switched among five states in sequence.
The method can avoid overlong locking time of the phase-locked loop, and reduces interference and power consumption between different local oscillator signals compared with the method of simultaneously starting 4 local oscillator signals. In this case, the hopping time is determined entirely by the switching time of the DDS and the switch and the response time of the filter, the sum of which reaches approximately the order of nanoseconds. Therefore, the method can realize frequency agility.
TABLE 2 detailed operating conditions of 4 phase locked loops (PLL1-PLL4) corresponding to different frequency ranges
states | Frequency range(MHz) | PLL1 | PLL2 | PLL3 | PLL4 |
State0 | Initialization | locked | locked | locked | locked |
State1 | f1 | enabled | disabled | enabled | disabled |
State2 | f3 | disabled | enabled | enabled | disabled |
State3 | f2 | disabled | enabled | disabled | enabled |
State4 | f4 | enabled | disabled | disabled | enabled |
The circuit of the frequency mixing part consists of four phase-locked loops for generating 4 local oscillation signals, a DDS for generating intermediate frequency signals, three SPDT switches and two frequency mixers. In consideration of the limitation of low DDS output frequency, the synthesizer adopts four local oscillation signals to expand the frequency width. In order to eliminate the time waiting for the phase locked loops to lock when switching between different frequency ranges, and at the same time avoid interference between different local oscillator signals, the method uses 4 phase locked loops instead of 2 phase locked loops to generate 4 local oscillator signals. In addition, the 4 phase-locked loops are divided into two groups, so that the minimum value of the DDS output frequency is reduced and the performance requirement on the DDS device is lowered on the premise of ensuring that the local oscillator leakage is not overlapped with the output useful signal. Each local oscillator signal is generated by a low phase noise fractional divider phase locked loop integrated with a Voltage Controlled Oscillator (VCO). The intermediate frequency signal is generated by frequency multiplication of the output signal 2 of the DDS.
Since the phase noise of the intermediate frequency signal output by the DDS is much lower than the phase noise of the local oscillator signal output by the PLL in this architecture, the phase noise of the mixing output signal is mainly determined by the phase-locked loop. The in-band phase noise of the local oscillator signal produced by the phase locked loop may be estimated by:
PN(f)=PN1Hz+10log fpfd+20log n
wherein, PN1HzIs 1Hz normalized phase noise, f, of the phase discriminatorpfdThe phase detection frequency is n, and the frequency division ratio is n. As can be seen from the data sheet of HMC829, when the output frequency is highThe rate is 3605MHz, the loop bandwidth is 250khz, and when the phase discrimination frequency is 50MHz, the closed loop phase noise is-110 dBc/Hz. In the worst case, when the LO signal is switched to 3604.5MHz at the highest frequency, the loop bandwidth is 200kHz, and the phase discrimination frequency is 100MHz, the phase noise is estimated from the above equation
The phase noise simulation results are shown in fig. 3. As can be seen from fig. 3, the loop filter is low-pass for the reference phase noise and high-pass for the VCO phase noise. Therefore, the loop bandwidth of each phase locked loop (PLL1-PLL4) is optimized to 200kHz for the tradeoff of noise rejection between the reference signal and the VCO.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.
Claims (10)
1. The utility model provides a signal source system suitable for millimeter wave safety inspection which characterized in that:
the signal source system suitable for millimeter wave security inspection comprises:
a signal source and a peripheral circuit, wherein,
wherein the signal source comprises:
a crystal oscillator for generating an oscillation frequency;
the local oscillator signal source circuits can generate local oscillator signals for frequency mixing;
an intermediate frequency signal source circuit capable of generating an intermediate frequency signal for frequency mixing;
the mixers are used for realizing frequency mixing of the local oscillator signals and the intermediate frequency signals;
a plurality of output branch circuits for receiving the signals mixed by the mixer and outputting the signals;
a power amplifier for amplifying the signal output from the output branch circuit;
the local oscillator selection switch is used for connecting one phase-locked loop in the local oscillator signal source circuit to one frequency mixer in a time-sharing manner;
an intermediate frequency selection switch for time-division connecting one of the mixers to the intermediate frequency signal source circuit;
a mixer selection switch for time-divisionally connecting one of the output branch circuits to the mixer;
wherein, local oscillator signal source circuit includes: two or more phase-locked loops; the intermediate frequency signal source circuit comprises a direct digital frequency synthesizer or a direct digital frequency synthesizer and a frequency multiplier;
a mixer selection switch for time-divisionally connecting one of the output branch circuits to the mixer; the crystal oscillator is electrically connected with the local oscillation signal source circuit and the intermediate frequency signal source circuit respectively;
the peripheral circuit includes:
a transmission source circuit and a reception source circuit, both connected to the signal source;
the emission source circuit includes:
the device comprises a transmission source, a plurality of transmission shunts and a plurality of transmission frequency multipliers;
the transmission splitters are connected to the transmission sources, and the transmission frequency multipliers are respectively connected to the transmission splitters;
the receiving source circuit includes:
the system comprises a receiving source, a plurality of receiving shunts and a plurality of receiving frequency multipliers;
the receiving splitters are connected to the receiving source, and the receiving frequency multipliers are connected to the receiving splitters respectively.
2. The signal source system suitable for millimeter wave security inspection according to claim 1, wherein:
the phase-locked loop includes: the phase detector, the loop filter and the voltage-controlled oscillator, wherein when the local oscillation selection switch disconnects the phase-locked loop from the frequency mixer, the voltage-controlled oscillator is in a locked state.
3. The signal source system suitable for millimeter wave security inspection according to claim 1, wherein:
the phase-locked loop includes: the phase detector, the loop filter and the voltage-controlled oscillator, wherein when the local oscillator selection switch is connected with the phase-locked loop and the mixer, the voltage-controlled oscillator is in an output state.
4. The signal source system path suitable for millimeter wave security inspection of claim 1, wherein:
the crystal oscillator is an oven-controlled crystal oscillator.
5. The signal source system suitable for millimeter wave security inspection according to claim 1, wherein:
the number of phase-locked loops in one local oscillator signal source circuit is even.
6. The signal source system suitable for millimeter wave security inspection of claim 5, wherein:
the number of phase-locked loops in one local oscillator signal source circuit is 2.
7. The signal source system suitable for millimeter wave security inspection according to claim 1, wherein:
the number of the local oscillator signal source circuits is even.
8. The signal source system suitable for millimeter wave security inspection of claim 7, wherein:
the number of the local oscillation signal source circuits is 2.
9. The signal source system suitable for millimeter wave security inspection according to claim 1, wherein:
the number of the local oscillator signal source circuit corresponds to that of the frequency mixer.
10. The signal source system suitable for millimeter wave security inspection according to claim 1, wherein:
the number of the output branch circuits corresponding to one mixing selection switch is even.
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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CN116667796A (en) * | 2023-07-28 | 2023-08-29 | 成都世源频控技术股份有限公司 | Power division amplifying circuit and method for improving anti-interference of reference clock signal |
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CN101060343A (en) * | 2006-04-21 | 2007-10-24 | 株式会社瑞萨科技 | IC for frequency hopping communication |
CN105119599A (en) * | 2015-09-01 | 2015-12-02 | 安徽四创电子股份有限公司 | Broadband low-stepping high-speed frequency synthesizer based on DDS (Direct Digital Synthesizer) and PLL (Phase Locked Loop) |
CN205377852U (en) * | 2015-12-30 | 2016-07-06 | 南京誉葆科技有限公司 | Frequently, subassembly is combined and received |
CN106533437A (en) * | 2016-09-27 | 2017-03-22 | 西安空间无线电技术研究所 | Broadband and small-step frequency source circuit |
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- 2020-07-07 CN CN202010649361.4A patent/CN112019214A/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2004356927A (en) * | 2003-05-29 | 2004-12-16 | Casio Comput Co Ltd | Radio communication apparatus |
CN101060343A (en) * | 2006-04-21 | 2007-10-24 | 株式会社瑞萨科技 | IC for frequency hopping communication |
CN105119599A (en) * | 2015-09-01 | 2015-12-02 | 安徽四创电子股份有限公司 | Broadband low-stepping high-speed frequency synthesizer based on DDS (Direct Digital Synthesizer) and PLL (Phase Locked Loop) |
CN205377852U (en) * | 2015-12-30 | 2016-07-06 | 南京誉葆科技有限公司 | Frequently, subassembly is combined and received |
CN106533437A (en) * | 2016-09-27 | 2017-03-22 | 西安空间无线电技术研究所 | Broadband and small-step frequency source circuit |
Cited By (2)
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CN116667796A (en) * | 2023-07-28 | 2023-08-29 | 成都世源频控技术股份有限公司 | Power division amplifying circuit and method for improving anti-interference of reference clock signal |
CN116667796B (en) * | 2023-07-28 | 2023-10-13 | 成都世源频控技术股份有限公司 | Power division amplifying circuit and method for improving anti-interference of reference clock signal |
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