CN102062859A - Novel TCAS (Traffic Collision Avoidance System) local oscillator design method - Google Patents
Novel TCAS (Traffic Collision Avoidance System) local oscillator design method Download PDFInfo
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- CN102062859A CN102062859A CN2009102189746A CN200910218974A CN102062859A CN 102062859 A CN102062859 A CN 102062859A CN 2009102189746 A CN2009102189746 A CN 2009102189746A CN 200910218974 A CN200910218974 A CN 200910218974A CN 102062859 A CN102062859 A CN 102062859A
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Abstract
The invention relates to a novel TCAS (Traffic Collision Avoidance System) local oscillator design method which makes an improvement on the existing condition that two local oscillators are used in the traditional system and designs a novel TCAS local oscillator based on the multi-loop and frequency-mixing phase lock technology. The local oscillator comprises four parts: a large step frequency generation unit, a small step frequency generation unit, a frequency-mixing phase lock loop and a control circuit, wherein the large step frequency unit generates local oscillation signals of the frequency-mixing phase lock loop; the small step frequency unit generates reference signals of the frequency-mixing phase lock loop; an error lock prevention circuit is arranged in the frequency-mixing phase lock loop; and a controller generates signals of 1030 and 1090 MHz by controlling the frequency dividing ratio of a phase lock loop frequency divider and can fast switch between the two signals. The local oscillator provided by the invention has the advantages of low cost, simple structure, high stability and the like.
Description
Affiliated technical field
The present invention relates to a kind of small-sized airborne collision avoidance system, belong to air traffic control and air traffic security fields.
Background technology
Collision avoidance system on the aircraft, the US Airways system is called air traffic early warning and collision avoidance system (hereinafter to be referred as TCAS), aviation system in Europe is called airborne collision avoidance system, both implications, function are consistent, and composition is also similar substantially, so the present patent application instructions is that technical background is described with TCAS.
Through years of development, the TCAS system has developed and multiple model, as: TCAS I, TCAS II, TCAS III, TCAS IV.Wherein TCAS II is most widely used at present, and it can provide with different colours and shape to the aviator and show the traffic prompting (TA) of the relative height of closing on aircraft, distance, orientation, rising/information such as decline state and show pitch channel change, attitude maintenance, the settling mode (RA) of information such as maintenance highly.Other more highest version model architecture based on TCAS II, difference slightly on function just.
In existing TCAS system, the TCAS transceiver separates with S pattern answering machine, and therefore, they have local vibration source separately.The local vibration source of TCAS transceiver is 1030MHZ, and the local vibration source of S pattern answering machine is 1090MHZ.For the microwave generating source of very high frequency(VHF) in this, existing TCAS adopts surface acoustic wave oscillator directly to produce.With S pattern answering machine is example, and surface acoustic wave oscillator (SAW) produces the signal of 1090 ± 0.2MHZ, and the power level of this signal is about 10 dbms.The output of oscillator is added to two buffer amplifiers to produce the persistent wave output of 100 milliwatts (20 dbm).This 20 dbm signal branch is made two-way: the one tunnel through behind local oscillator filtering and 4 db-losses as local oscillation signal and received signal mixing; Another road signal carries out pulsed modulation with the pulse input after multistage amplification, send after amplifying again.The local oscillator of TCAS transceiver is consistent with the local oscillator principle of work of S pattern answering machine.Different is that the peak value that transmitter provides benchmark is the signal amplification of 61dBm, is used to pulse amplitude modulation (PAM) after three amplifications.
After the transmitting-receiving principle and process analysis procedure analysis to the TCAS system, TCAS transceiver and S pattern answering machine promptly can not used local vibration source simultaneously not in synchronization work as can be known; It is therefore, this that to cause the two local vibration sources design of problems such as equipment cost raising, volume increase be reducible.
Summary of the invention
In order to overcome existing two local vibration source design cost height, bulky shortcoming, the present invention utilizes many rings and the design of mixing phaselock technique and a kind of novel TCAS local vibration source of frequency conversion fast of alternative former pair of local vibration source is provided;
The present invention solves the technical scheme that its technical matters takes: adopt many rings and the phase-locked method of mixing to realize the TCAS local vibration source.This scheme is mainly by big step frequency generation unit, little step frequency generation unit, and four parts of mixing phaselocked loop and control circuit are formed; It is 904～1204MHz that big step frequency generation unit produces frequency range by single loop phase locked loop, and stepping is the signal of 2MHz, and this signal is as the local oscillation signal of mixing phaselocked loop; It is 46～48MHz that the output signal that little step frequency generation unit advances phaselocked loop by small step produces frequency range after by frequency division, and stepping is the signal of 2.5KHz, and this signal is as the reference signal of mixing phaselocked loop; In the mixing phaselocked loop, for error lock prevention has adopted simple and reliable error lock prevention circuit, this circuit mainly is made up of active loop wave filter and totalizer; Simultaneously, the divider ratios of controlling the phaselocked loop frequency divider by controller makes stable output 1030M hertz of frequency synthesizer and 1090M hertz signal, and between switches fast.
The invention has the beneficial effects as follows,, can produce the frequency of the interior any stepping of 950～1250MHz scope greater than 10kHz by using above-mentioned many rings and mixing phaselock technique.Therefore, only different frequency dividing ratios need be set, will be with the frequency that realizes wanting.This programme only uses a phaselocked loop that the local vibration source of alternation on request in the high stability of 1030M hertz and 1090M hertz frequency just can be provided, and compares with former pair of local vibration source, and it is low that it has a cost, designs simplification, degree of stability advantages of higher.
Description of drawings
The present invention is further described below in conjunction with drawings and Examples.
Fig. 1 is an implementation of the present invention.
Fig. 2 is that little step frequency generation unit constitutes.
Fig. 3 is mixing principle of phase lock loop figure.
Embodiment
The present invention adopts many rings and the phase-locked method of mixing to realize the TCAS local vibration source.This scheme is mainly by big step frequency generation unit, little step frequency generation unit, and four parts of mixing phaselocked loop and control circuit are formed, and the total system scheme is as shown in Figure 1.
It is 904～1204MHz that big step frequency generation unit produces frequency range by single loop phase locked loop, and stepping is the signal of 2MHz, and this signal is as the local oscillation signal of mixing phaselocked loop; It is 46～48MHz that the output signal that little step frequency generation unit advances phaselocked loop by small step produces frequency range after by frequency division, and stepping is the signal of 2.5KHz, and this signal is as the reference signal of mixing phaselocked loop; In the mixing phaselocked loop, for error lock prevention has adopted simple and reliable error lock prevention circuit, this circuit mainly is made up of active loop wave filter and totalizer.
In order to realize the output of all Frequency points, at first the phase-locked loop circuit reference frequency output by little step frequency generation unit is 736～768MHz, and stepping is the signal of 40kHz, through obtaining frequency f behind 16 frequency divisions
1(frequency range is 46～48MHz, and stepping is 2.5kHz), the phase-locked loop circuit by big step frequency generation unit produces frequency f then
2(frequency range is 904～1204MHz, and stepping is 2MHz) is at last by mixing phase-lock-ring output frequency f
3(f
3=f
1+ f
2), having realized that reference frequency output is 950～1450MHz, stepping is 2.5KHz.
1, little step frequency generation unit design
The structure of little step frequency generation unit as shown in Figure 2.The frequency that little step frequency generation unit circuit need produce is 46～48MHz, and stepping is 2.5kHz.The frequency Direct Digital Frequency Synthesizers (DDS) of little stepping produces, and adopts DDS can realize little frequency step and low phase noise DDS, such as the chip AD9956 of AD company.But adopt the DDS chip that the reference signal of a hundreds of megahertz need be provided, and the reference signal that is provided among the design is 10MHz, Here it is need realize frequency multiplication by phase-locked loop circuit, and DDS output also needs external filters, has so just increased design cost.
Under the prerequisite that can satisfy the system index requirement, select for use little frequency to combine MPLL766B output 736～768MHz from design cost and actual cavity size, stepping is the signal of 40kHz, four-divider HMC426MS8 by 2 Hittite companies realizes 16 frequency divisions again, produced next life 46～48MHz, stepping is the signal of 2.5kHz.Phase detector adopts the ADF4113 of AD company, and its phase demodulation frequency reaches as high as 55MHz, can satisfy the needs of design.
2, big step frequency generation unit design
Big step frequency generation unit will be realized the frequency output of 904MHz-1204MHz scope, and stepping is 2MHz.Its implementation procedure and little stepping unit basically identical are the device property difference that each module is selected for use, no longer describe in detail here.
3, mixing phaselocked loop
The theory diagram of mixing phaselocked loop is as shown in Figure 3:
VT1 is the tuning voltage of hybrid path filter output, and VT2 is the tuning voltage of VCO2 in the big stepping phaselocked loop, and VT3 is the tuning voltage of VCO3.
The mixing phase detector has adopted the ADF4113 chip of AD company equally.The reference frequency that the ring generation is advanced in small step is 46～48MHz, the highest phase demodulation frequency 55MHz less than ADF4113, R can be taken as 1 with reference to frequency dividing ratio, and the frequency dividing ratio of phase detector should be set to 1, and then last output frequency is that reference frequency and big stepping ring produce the frequency sum.Used identical VCO in hybrid and the big stepping ring, i.e. the HE484 of 13 of electronics.Frequency mixer has adopted the passive frequency mixer RMS-25MHW of Mini company, and the local oscillator incoming frequency is 5～2500MHz, power input+13dBm, and conversion loss is 7dB, local oscillator and radio frequency isolation representative value are 32dBc.In order to strengthen local oscillator, isolation between radio frequency and the intermediate-freuqncy signal, signal input and output port at frequency mixer has all adopted some quarantine measures, promptly before the signal input, pass through decay earlier, amplify, enter frequency mixer again after the decay again, intermediate-freuqncy signal output is then sent into phase detector through filtering, decay, amplification with after decaying again.
The mixing phaselocked loop is wanted can operate as normal, must will satisfy f
2-N
3f
1＜f
3＜+∞.And in side circuit if f
3-f
2〉=N
3f
1At the stopband of LPF, make f
3-f
2Can not trigger frequency divider to such an extent as to signal is too weak, or (f
3-f
2)/N
3The maximum operation frequency f that surpasses phase detector
PDmaxThe time, phase detector can make f
3Further increase, thereby hybrid can't be locked.
Therefore, in order to guarantee the hybrid operate as normal, must satisfy following condition:
f
2-N
3f
1＜f
3＜+∞
(f
3-f
2)/N
3＜f
PDmax
f
3-f
2In the passband of LPF
The error lock prevention circuit mainly is made up of totalizer and active filter LF3 among the design, the key of its technology is that the VCO2 of big stepping ring will use identical VCO with VCO3 in the hybrid, promptly have identical voltage-controlled characteristic, and the output voltage V T1 of active filter LF3 to limit within the specific limits.For the scope of VT1, decided by two conditions: the VCO3 output frequency must be gone within the frequency band of lock at hybrid before the loop-locking; The output voltage range of VT1 will make hybrid can lock onto on the output frequency of requirement.
Claims (5)
1. novel TCAS local vibration source design, it is characterized in that: adopt many rings and mixing phaselock technique, realization is the novel local vibration source of frequency conversion fast.New local vibration source can produce in 950～1250MHz scope any stepping greater than the frequency of 10kHz, like this, just can timesharing generation 1030MHz and the frequency of 1090MHz, be respectively applied for TCAS transceiver and S pattern answering machine;
2. novel TCAS local vibration source design is characterized in that: novel local vibration source is by big step frequency generation unit, little step frequency generation unit, and four parts of mixing phaselocked loop and control circuit are formed;
3. novel TCAS local vibration source design, it is characterized in that: big step frequency generation unit produces the local oscillation signal of mixing phaselocked loop.Little step frequency generation unit produces the reference signal of mixing phaselocked loop;
4. novel TCAS local vibration source design is characterized in that: in the mixing phaselocked loop, use active loop wave filter and totalizer to realize simple and reliable error lock prevention circuit;
5. novel TCAS local vibration source design is characterized in that: the divider ratios by controller control phaselocked loop frequency divider realizes 1030 and the signal of 1090MHz and realize switching fast.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102420606A (en) * | 2011-11-18 | 2012-04-18 | 北京航天测控技术有限公司 | Low phase-noise and small step-frequency synthesized realizing method |
| CN113419111A (en) * | 2021-08-24 | 2021-09-21 | 深圳市鼎阳科技股份有限公司 | Spectrum analyzer and signal scanning method for same |
| CN113541678A (en) * | 2020-04-16 | 2021-10-22 | 颜佳 | Double-loop mixing phase-locking circuit, device and phase-locking method |
| CN115842549A (en) * | 2023-02-15 | 2023-03-24 | 成都天锐星通科技有限公司 | Frequency synthesizer |
-
2009
- 2009-11-16 CN CN2009102189746A patent/CN102062859A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102420606A (en) * | 2011-11-18 | 2012-04-18 | 北京航天测控技术有限公司 | Low phase-noise and small step-frequency synthesized realizing method |
| CN102420606B (en) * | 2011-11-18 | 2013-11-06 | 北京航天测控技术有限公司 | Low phase-noise and small step-frequency synthesized realizing method |
| CN113541678A (en) * | 2020-04-16 | 2021-10-22 | 颜佳 | Double-loop mixing phase-locking circuit, device and phase-locking method |
| CN113419111A (en) * | 2021-08-24 | 2021-09-21 | 深圳市鼎阳科技股份有限公司 | Spectrum analyzer and signal scanning method for same |
| CN113419111B (en) * | 2021-08-24 | 2021-11-02 | 深圳市鼎阳科技股份有限公司 | Spectrum analyzer and signal scanning method for same |
| CN115842549A (en) * | 2023-02-15 | 2023-03-24 | 成都天锐星通科技有限公司 | Frequency synthesizer |
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Application publication date: 20110518 |