CN202395754U - Accurate synthesis device for a plurality of frequency sources of BeiDou terminal module - Google Patents
Accurate synthesis device for a plurality of frequency sources of BeiDou terminal module Download PDFInfo
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- CN202395754U CN202395754U CN2011205273929U CN201120527392U CN202395754U CN 202395754 U CN202395754 U CN 202395754U CN 2011205273929 U CN2011205273929 U CN 2011205273929U CN 201120527392 U CN201120527392 U CN 201120527392U CN 202395754 U CN202395754 U CN 202395754U
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- big dipper
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Abstract
The utility model discloses an accurate synthesis device for a plurality of frequency sources of a BeiDou terminal module, belonging to the technical field of frequency synthesis in a BeiDou positioning system. The accurate synthesis device of the utility model uses a 22MHz temperature-compensation highly-stable electrically tunable crystal oscillator (TCVCXO) to accurately synthesize two local frequencies (1615.68MHz and 863.83MHz) of a radio-frequency transmitter and a radio-frequency receiver in a BeiDou terminal, thereby obtaining a good phase noise; and then the accurate synthesis device uses a digital frequency synthesis chip which is packaged into an ultra-small size to synthesize a reference frequency source (48.96 MHz) used for base band sampling.
Description
Technical field
The utility model belongs to the frequency synthesis technique field in the Big Dipper navigation system, is specifically related to the generating technique of the frequency source at Big Dipper terminal.
Background technology
In the terminal of existing Big Dipper navigation system; Use the reference clock of 16.32MHz mostly; Synthesize the frequency source in the terminal system, if, when synthesizing 863.83MHz, will bring a problem with accurately synthetic required local frequency 1615.68MHz and the 863.83MHz of 16.32MHz; Exactly this moment the phase demodulation frequency the highest very low 10KHz that has only, and so low phase demodulation frequency makes that the phase noise in the 863.83MHz local frequency source that synthesizes is very poor.Have a strong impact on the signal quality of system.
Method is exactly synthetic 863.84MHz frequency source in addition; Promptly departed from theoretical value 10KHz; Because the synthetic frequency source that produces of this method is accurate inadequately; With theoretical value certain deviation is arranged, the problem that the method is brought is the processing complexity that increases baseband system, requires base band must handle the frequency departure of 10KHz.
The utility model content
The utility model is very low or frequency source is accurate inadequately to the existing phase demodulation frequency of frequency source synthetic in the terminal of existing Big Dipper navigation system; Problems such as certain deviation are arranged with theoretical value, and a kind of accurate synthesizer that can a plurality of frequency sources of a kind of Big Dipper terminal module is provided.The utility model can be realized radio frequency sending set and two local frequencies of receiver (1615.68MHz and 863.83MHz) in the accurately synthetic Big Dipper terminal, obtains good phase noise; Re-use the reference frequency source (48.96MHz) of the synthetic baseband sampling use of numerical frequency synthesis chip of extra small encapsulation.
In order to achieve the above object, the utility model adopts following technical scheme:
The accurate synthesizer of a plurality of frequency sources of a kind of Big Dipper terminal module; This device comprises the local frequency synthesis unit and the base band reference clock synthesis unit of the local frequency of radio frequency sending set and receiver use in the synthetic Big Dipper terminal; Said device also comprises the temperature compensation high stable electricity accent crystal oscillator of 22MHz; The temperature compensation high stable of said 22MHz electricity transfers crystal oscillator to be electrically connected with local frequency synthesis unit and base band reference clock synthesis unit respectively, and the reference clock when synthesizing as local frequency synthesis unit and base band reference clock synthesis unit.
In the preferred version of such scheme, said local frequency synthesis unit is made up of microminiature packaged chip Si4133.
Further, said base band reference clock synthesis unit is made up of extra small packaged chip CY22U1.
The utility model uses 22MHz high stable temperature compensation electricity to transfer the reference clock of crystal oscillator (TCVCXO) as frequency synthesizer, can realize:
1. can zero deflection accurately synthetic F1 (1615.68MHz) and F2 (863.83MHz), the phase demodulation frequency that uses 880KHz (or 440KHz, or 220KHz or 110KHz) to synthesize as second local oscillator respectively as the synthetic phase demodulation frequency of first local oscillator and 110KHz.
2. because phase demodulation frequency than higher, therefore can obtain good phase noise, the process actual measurement reaches or is superior to:
-80dBc/Hz1KHz?offset；
-90dBc/Hz10KHz?offset；
-100dBc/Hz100KHz?offset。
3. can use microminiature encapsulation such as similar Si4133 like this, cheap synthesizer chip is dwindled the space thereby reach, cost-effective purpose.
4. can use extra small encapsulation such as similar CY22U1 like this, cheap digital frequency synthesizer can zero deflection accurately synthesize the reference clock F4 (48.96MHz) that Base-Band Processing is used, thereby help to dwindle the space, saves cost.
Thereby help to realize the terminal equipment miniaturization of Big Dipper navigation system, cost reduces, and signal quality improves, and Base-Band Processing can be oversimplified, and has also saved power consumption simultaneously.
Description of drawings
Further specify the utility model below in conjunction with accompanying drawing and embodiment.
Fig. 1 is the sketch map of the utility model scheme.
Fig. 2 is the basic functional principle figure of Transceiver Module that utilizes the Big Dipper positioning system terminal radio frequency of the utility model.
Embodiment
For technological means, creation characteristic that the utility model is realized, reach purpose and be easy to understand understanding with effect, below in conjunction with concrete diagram, further set forth the utility model.
Referring to Fig. 1, to the reception of Big Dipper RF transceiver with launch a shared local frequency RF_LOF1 (1615.68MHz), the second local frequency IF_LO of receiver uses the frequency scheme of F2 (863.83MHz); Or the receiver received of Big Dipper list uses RF_LO 1615.68MHz and the IF_LO 863.83MHz scheme as first and second local frequencies.The accurate synthesizer of a plurality of frequency sources of a kind of Big Dipper terminal module that the utility model provides mainly comprises the electric accent of the temperature compensation high stable crystal oscillator 14 of local frequency synthesis unit 12, base band reference clock synthesis unit 13 and the 22MHz of the local frequency that radio frequency sending set and receiver use in the synthetic Big Dipper terminal.
Wherein the temperature compensation high stable of 22MHz electricity transfers crystal oscillator 14 to be electrically connected with local frequency synthesis unit 12 and base band reference clock synthesis unit 13 respectively, and the reference clock when synthesizing with base band reference clock synthesis unit 13 as local frequency synthesis unit 12.
Based on this scheme; The utility model can zero deflection accurately synthesize F1 (1615.68MHz) and F2 (863.83MHz); And use 880KHz (or 440KHz respectively; Or 220KHz or 110KHz) as the synthetic phase demodulation frequency of first local oscillator and 110KHz as the synthetic phase demodulation frequency of second local oscillator, its phase demodulation frequency is very high.
For frequency synthesizer, phase noise and frequency accuracy are unusual important parameters.The height of phase demodulation frequency can influence phase noise greatly when selecting the frequency synthesis scheme, and the frequency translation principle of phase-locked loop is:
The Fout/N=Fref/R=phase demodulation frequency.
Wherein, Fout is an output frequency, and Fref is the reference frequency of input, and N is the divide ratio of output frequency, and R is the divide ratio of input reference frequency.
By finding out in the equality that phase demodulation frequency is the critical frequencies of frequency synthesis.When following formula is met, just can accurately synthesize the output frequency wanted in theory.
For the scheme in the utility model; Fout1=1615.68Mhz, Fref=22Mhz can select 880K, 440K, 220K, 110KHz as phase demodulation frequency; The N of this moment corresponds to 1836,3672,7344,14688, and R corresponds to 25,50,100,200.Fout2=863.83Mhz, Fref=22Mhz can select 110KHz, 55KHz as phase demodulation frequency, and the N of this moment is corresponding available 7853,15706, and R corresponds to 200,400.
Because as a reference during frequency, the residing scope of Frequency Dividing Factor of operable phase demodulation frequency and division frequency divider is more moderate with the high stable temperature compensation of 22MHz electricity accent crystal oscillator.The utility model can use and adopt microminiature packaged chip Si4133 to form local frequency synthesis unit 12.
Si4133 is the current phase-locked loop chip of the built-in VCO of double frequency of minimum encapsulation in the industry; The phase demodulation frequency scope is 10KHz～1MHz; The Frequency Dividing Factor N maximum of the division frequency divider (18bit) of RF can 262144, and the Frequency Dividing Factor N maximum of the division frequency divider (16bit) of IF can 65536.The Frequency Dividing Factor R maximum of the division frequency divider (13bit) of Fref can 8192.
The frequency of using 16.32MHz mostly corresponding to existing Big Dipper frequency synthesis scheme is frequency as a reference, can accurately synthesize 1615.68Mhz.But when synthetic 863.83MHz, if accurately synthetic, institute can with maximum phase demodulation frequency have only 10KHz, N=863.83/0.01=86383 at this moment, R=16.32/0.01=1632.Though can see N and R thus all within the parameter area of Si4133, phase demodulation frequency 10KHz has been the edge of the workable parameter of chip.More importantly be that phase noise is the important parameter of frequency synthesizer.According to the formula of theory, phase demodulation frequency is 20*logN to the factor of phase noise influence, and wherein N is the ratio of output frequency and phase demodulation frequency, and N is bigger, and the deterioration of phase noise is bigger, otherwise phase noise is good more.Compare the scheme of doing reference frequency of 22MHz, N has increased to 11 times during with 16.32Mhz, 110KHz/10KHz=11.Phase noise will worsen 20.8dB (20*log11) so.
The deterioration of 20dB is very considerable.It is exactly the signal to noise ratio of system and the variation of the error rate that this deterioration brings the result.So the frequency of the use 16.32MHz scheme of frequency as a reference will seek out phase noise preferably, is to have no idea to use the Si4133 chip.
During for the base band reference clock, the frequency of using 16.32MHz in prior art frequency as a reference synthesize 48.96MHz base band reference clock, generally is to use after the 3 frequency multiplication filtering of 16.32MHz the method for amplification again.Frequency multiplication, filtering, amplification, what brought is circuit complicated, increases the requirement in space.
And in the utility model, adopting extra small packaged chip CY22U1 to form base band reference clock synthesis unit 13, CY22U1 series is high-precision numerical frequency synthesis chip.And use the reference clock of 22MHz, the CY22U1 chip can accurately synthesize 48.96MHz base band reference clock.
Thus, use numerical frequency synthesis chip CY22U1 can save frequency multiplication with respect to prior art based on the frequency of 22MHz, the space of circuit such as amplification, CY22U1 only needs the space of 1.7mm*1.7mm.
On the basis of such scheme, the method for the accurately synthetic a plurality of frequency sources of Big Dipper terminal module that the utility model provides, this method are the reference clock when utilizing 22MHz high stable temperature compensation electricity to transfer crystal oscillator to synthesize for Big Dipper terminal module frequency source.
The practical implementation of the utility model that obtains according to such scheme is following:
Referring to Fig. 2, receiving unit
The satellite-signal F1 of Big Dipper navigation system is (after 2491.75MHz ± 4.08MHz) delivers to high-gain low-noise amplifier 1 and amplify via antenna 10; Send into first order converter unit 2 again and carry out frequency translation; Its local frequency is F4 (1615.68MHz); Exporting first intermediate frequency is F2 (876.07MHz), and first intermediate frequency is output intermediate frequency F3 (12.24MHz ± 4.08MHz) after second level converter unit 3 neutralization second local frequency F5 (863.83MHz) mixing.Intermediate frequency F3 give baseband processing module.
Radiating portion
Send into modulator 8 from the baseband signal that baseband processing module comes through after the shaping; In modulator, use local frequency F4 (1615.68MHz) directly to be modulated to transmit frequency band, amplify signal through power amplification unit 9 again; Launch via antenna 11, receive by satellite.
Baseband module needs end-fire Transceiver Module frequently that reference clock frequency F7 (48.96MHz) is provided the frequency as sampling.
Wherein, The first local frequency F4 and the second local frequency F5 are produced by the first local frequency synthesis unit 4 and the first local frequency synthesis unit 5 that the serial bifrequency synthesizer of the Si4133 of Silicon Lab company forms, and the reference clock F6 that is adopted is 22MHz.Use the temperature compensation high stable electricity of 22MHz to transfer crystal oscillator (TCVCXO) 7 can synthesize 1615.68MHz and 863.83MHz accurately as a reference.
When synthesizing 1615.68MHz, the parametric frequency dividers in the frequency synthesizer 4 can use 25,50,100; Frequency dividing ratios such as 200 can obtain to be respectively 880KHz than higher phase demodulation frequency 440KHz, 220KHz like this; 110KHz etc., corresponding radio frequency frequency dividing ratio is 1836,3672; 7344,14688 etc., thus the good local frequency output of phase noise can be obtained.
Equally for the second local frequency F5 (863.83MHz); Parametric frequency dividers in the frequency synthesizer 5 can use frequency dividing ratios such as 200,400, can obtain like this to be respectively 110KHz than higher phase demodulation frequency; 55KHz etc.; Corresponding radio frequency frequency dividing ratio is 7853,15706 etc., thereby can obtain the good local frequency output of phase noise.According to measured result, more than the phase noise in two local frequency sources all reach or be superior to:
-80dBc/Hz1KHz?offset
-90dBc/Hz10KHz?offset
-100dBc/Hz100KHz?offset
And this index has far exceeded the requirement of Big Dipper navigation system to the phase noise in local frequency source, reduces the debugging work to the local frequency source in producing in batches greatly.
The reference clock F7 (48.96MHz) that uses for baseband sampling has used the digital frequency synthesizer of extra small encapsulation of the CY22U1 series of Cypress company, and forms base band reference clock synthesis unit 6 by it.Because the greatest common divisor of 22MHz and 48.96MHz is 80KHz, the frequency dividing ratio of divider is respectively 275 and 612, can use similar CY22U1 frequency dividing ratio very high, and the digital frequency synthesizer of extra small encapsulation.
More than show and described the advantage of basic principle, principal character and the utility model of the utility model.The technical staff of the industry should understand; The utility model is not restricted to the described embodiments; The principle of describing in the foregoing description and the specification that the utility model just is described; Under the prerequisite that does not break away from the utility model spirit and scope, the utility model also has various changes and modifications, and these variations and improvement all fall in the utility model scope that requires protection.The utility model requires protection range to be defined by appending claims and equivalent thereof.
Claims (3)
1. the accurate synthesizer of a plurality of frequency sources of Big Dipper terminal module; This device comprises the local frequency synthesis unit and the base band reference clock synthesis unit of the local frequency of radio frequency sending set and receiver use in the synthetic Big Dipper terminal; It is characterized in that; Said device also comprises the temperature compensation high stable electricity accent crystal oscillator of 22MHz; The temperature compensation high stable of said 22MHz electricity transfers crystal oscillator to be electrically connected with local frequency synthesis unit and base band reference clock synthesis unit respectively, and the reference clock when synthesizing as local frequency synthesis unit and base band reference clock synthesis unit.
2. the accurate synthesizer of a plurality of frequency sources of a kind of Big Dipper terminal module according to claim 1 is characterized in that said local frequency synthesis unit is made up of microminiature packaged chip Si4133.
3. the accurate synthesizer of a plurality of frequency sources of a kind of Big Dipper terminal module according to claim 1 is characterized in that said base band reference clock synthesis unit is made up of extra small packaged chip CY22U1.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011205273929U CN202395754U (en) | 2011-12-15 | 2011-12-15 | Accurate synthesis device for a plurality of frequency sources of BeiDou terminal module |
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| CN2011205273929U CN202395754U (en) | 2011-12-15 | 2011-12-15 | Accurate synthesis device for a plurality of frequency sources of BeiDou terminal module |
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| CN202395754U true CN202395754U (en) | 2012-08-22 |
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| CN2011205273929U Withdrawn - After Issue CN202395754U (en) | 2011-12-15 | 2011-12-15 | Accurate synthesis device for a plurality of frequency sources of BeiDou terminal module |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102427366A (en) * | 2011-12-15 | 2012-04-25 | 上海唯星通信技术有限公司 | Device and method for precisely combining multiple frequency sources of beidou terminal module |
| CN105892606A (en) * | 2014-12-08 | 2016-08-24 | 飞思卡尔半导体公司 | Electric power management system for integrated circuit |
-
2011
- 2011-12-15 CN CN2011205273929U patent/CN202395754U/en not_active Withdrawn - After Issue
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102427366A (en) * | 2011-12-15 | 2012-04-25 | 上海唯星通信技术有限公司 | Device and method for precisely combining multiple frequency sources of beidou terminal module |
| CN102427366B (en) * | 2011-12-15 | 2013-09-18 | 上海唯星通信技术有限公司 | Device and method for precisely combining multiple frequency sources of beidou terminal module |
| CN105892606A (en) * | 2014-12-08 | 2016-08-24 | 飞思卡尔半导体公司 | Electric power management system for integrated circuit |
| CN105892606B (en) * | 2014-12-08 | 2020-04-10 | 恩智浦美国有限公司 | Power management system for integrated circuits |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20120822 Effective date of abandoning: 20130918 |
|
| RGAV | Abandon patent right to avoid regrant |