CN1006949B - Frequency modulation one-way single-carr generator - Google Patents
Frequency modulation one-way single-carr generatorInfo
- Publication number
- CN1006949B CN1006949B CN 87105936 CN87105936A CN1006949B CN 1006949 B CN1006949 B CN 1006949B CN 87105936 CN87105936 CN 87105936 CN 87105936 A CN87105936 A CN 87105936A CN 1006949 B CN1006949 B CN 1006949B
- Authority
- CN
- China
- Prior art keywords
- frequency
- adder
- generator
- variable capacitance
- vco
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
Abstract
The present invention relates to a frequency modulation single-channel single-carrier generator (an FM-SCPC generator for short) which belongs to a microwave communication device. The present invention uses a phase locking loop to realizes two functions of frequency modulation and frequency synthesis to directly generate FM-SCPC signals without the need of frequency mixing. The present invention has the advantages of simple circuit structure, convenient debugging, low cost, etc., solves the difficulty in selecting frequency of frequency mixing when local frequency is changed in a large range, and enlarges the application range; the work frequency can be controlled by a frequency selecting witch or a microcomputer.
Description
The present invention relates to satellite communication and microwave telecommunication devices, is a kind of frequency modulation one-way single-carr generator (being called for short the FM-SCPC generator).
In the communication equipment of satellite communication earth station, the frequency modulation one-way single-carr signal generator (FM-SCPC generator) that sends part is made up of crystal oscillator (CO), frequency modulator (FMO), frequency mixer (MIX), frequency synthesizer (FS) and band pass filter (BPF) usually, as shown in Figure 1.Crystal oscillator produces stable frequency f
1The incoming frequency modulator, by baseband signal to f
1Carry out frequency modulation, the generation centre frequency is f
1FM signal (FM signal); Frequency synthesizer output can be preset or program control frequency is f
2Signal; Centre frequency is f
1FM signal and can preset or program control frequency is f
2Signal respectively the signal input part and the local oscillator input of input mixer carry out mixing, mixed frequency signal takes out f through band pass filter
1With f
2With frequently or difference frequency signal f
0, promptly obtain centre frequency f
0Can preset or program control frequency modulation one-way single-carr signal (FM-SCPC signal).This scheme circuit structure complexity, debugging operational difficulties.And, because frequency mixer is non-linear, in its output signal, contain many interference frequency component, and single channel per carrier system (SCPC system) requires f
0Excursion (being 3 decibels of bandwidth of band pass filter) often very wide, in order to take out useful FM-SCPC signal, and the mixing that does not allow lower-order is disturbed and is fallen in 3 decibels of bandwidth of band pass filter, this has just caused f
1, f
2With f
0Harsh restriction condition between three frequencies makes the selected frequency difficulty, thereby has often limited applying of this scheme.
Existing phase-locked loop (PLL) is though FM circuit is fairly simple, the centre frequency f of the FM signal (FM signal) that produces
0Immobilize.And single channel per carrier system (SCPC system) requires f
0Can preset on demand or program control change in very wide scope, promptly produce a kind of FM-SCPC signal.
The objective of the invention is to shortcoming at prior art, develop a kind of circuit structure simple, debug frequency modulation one-way single-carr signal generator easily, it can solve the above-mentioned centre frequency f that changes on a large scale
0Difficulty, without frequency mixer and band pass filter, directly produce the FM-SCPC signal, so that can apply in practice.
The present invention adopts a phase-locked loop to realize frequency modulation(FM) and changes centre frequency, does not need mixing and directly produces the FM-SCPC signal.As shown in Figure 2, it is made up of mark frequency generator (1), phase discriminator (2), loop filter (3), adder (4), voltage controlled oscillator (being called for short VCO) (5), program divider (6) and D/A converter (7) etc.The stabilized frequency f of mark generator (1) generation frequently
rInput phase discriminator (2) is as the reference frequency of phase-locked loop.VCO(5) operating frequency f
0Carry out importing phase discriminator (2) behind N frequency division through the program divider (6) by microcomputer (or switch) control, the size of N is by microcomputer (or switch) control, and phase-locked loop locks back f
0/ N=f
rSo, operating frequency f
0=Nf
rBy program control (or manual) with f
rIntegral multiple change.The signal of phase discriminator (2) output is through loop filter (3) output control voltage, and gives VCO(5 after the coarse tuning voltage that D/A converter (7) produces is imported adder (4) addition) D
3And D
4, make f
0Follow the tracks of f
r(be f
0=Nf
r).Baseband signal is added to VCO(5) D
1And D
2On, to f
0Carry out frequency modulation.Like this, at VCO(5) output just obtained centre frequency f
0Can preset the FM signal that changes with program control (or manual), be called frequency modulation one-way single-carr signal (being called for short the FM-SCPC signal).
The present invention is different with general PLL FM circuit, and the frequency divider of employing is a program divider.And because VCO operating frequency f
0Excursion often require very wide, the pull-in range of general phase-locked loop and synchronously the scope of band do not reach desired bandwidth, perhaps promptly allow to catch, the time of seizure is also very long.In order to address this problem, the present invention sets up a D/A (D/A) converter (7), adder (4) is received in its output, supply with program divider (6) and D/A converter (7) respectively with corresponding code character by microcomputer (or switch), when program divider (6) changes N, coarse tuning voltage of D/A converter (7) output is to adder (4), after the fine tuning voltage addition of loop filter (3) output, input VCO(5) oscillation circuit is as control voltage.
Common PLL frequency modulator only adopts one group of (one or a pair of) variable capacitance diode, thereby the frequency modulation sensitivity of signal promptly equals loop control sensitivity.And, the index request of two kinds of sensitivity is often differed tens times in practical application, even hundred times, thereby common PLL FM circuit does not reach requirement.The present invention takes at VCO(5) oscillation circuit in two groups of variable capacitance diode (see figure 2)s, i.e. D in parallel
1With D
2Be one group (also available one), D
3With D
4Be another group (also available one).The control voltage of adder (4) output is added to D
3With D
4On, be used for controlling VCO(5) frequency of oscillation f
0, make f
0Follow the tracks of f
r(be f
0=Nf
r); Baseband signal can directly be added to D
1With D
2On, be used for to f
0Carry out frequency modulation.In order to make frequency modulation sensitivity at f
0Excursion in keep evenly, the present invention is at the same D of base band sources
1With D
2Between set up an adder (8), receive D after the addition of the output voltage of D/A converter (7) and baseband signal input adder (8)
1With D
2On, be used for to f
0Carry out frequency modulation.Suitably select D
1, D
2And D
3, D
4Two groups of variable capacitance diodes can reach the different requirements of frequency modulation sensitivity and control sensitivity.Sometimes in order to reduce frequency modulation sensitivity or to improve fm linearity, at D
1With D
2On the fixed capacity of can connecting, fixed capacity perhaps in parallel also can be connected and fixed capacity in parallel simultaneously.
The present invention compared with prior art has the following advantages:
1. compared to Figure 1, the present invention can finish frequency modulation(FM) and change centre frequency with a phase-locked loop, so simplified circuit structure and debugging step.
2. compared to Figure 1, owing on circuit structure, saved frequency synthesizer, frequency mixer and band pass filter etc., so reduced cost.
3. owing to do not adopt the mixing scheme of Fig. 1, thereby solved and changed centre frequency f on a large scale
0The time select the difficulty of mixing frequency, enlarged range of application.
4. compare with general PLL FM circuit, the present invention adopts micro-processor controlled program divider (6) and D/A converter (7), and centre frequency f can preset and automatically switch
0
5. the coarse tuning voltage owing to D/A converter (7) output can preset the working point of variable capacitance diode, thereby has enlarged centre frequency f
0Working range, and shortened the pull-in time of phase-locked loop, also promptly having shortened single channel per carrier signal carrier frequency (is f
0) switching time.
6. adopt two groups of variable capacitance diode schemes, can satisfy the different index requests of frequency modulation sensitivity and loop control sensitivity respectively, and can reach the index of frequency modulation sensitivity and fm linearity.
Fig. 1 is conventional FM-SCPC generator block diagram.
Fig. 2 is novel FM-SCPC generator block diagram.
Fig. 3 sends out the embodiment circuit diagram that produces device for FM-SCPC among Fig. 2.
The present invention can adopt following scheme implementation (with reference to Fig. 3):
Because operating frequency f VCO(5 in the practical application)
0Often higher, thereby increase a double modulus prescalar (9) before at variable program divider (6), it and program divider (6) are formed pulse swallow divider program.For the purpose of isolating, between adder (4) and adder (8), increase a follower (10), it is by operational amplifier A
2Constitute.The coarse tuning voltage of D/A converter (7) output is delivered to adder (4), and through R
7And follower (10) is delivered to adder (8).VCO(5) by integrated circuit E1648 and shunt capacitance C
3, C
4Reach oscillation circuit and form, oscillation circuit is by two groups of variable capacitance diode D
1, D
2And D
3, D
4After being in parallel again with the inductance L formation that is in parallel, variable capacitance diode D
1With D
2Between serial connection fixed capacity C
S, so that reduce frequency modulation sensitivity and improve fm linearity.Fine tuning voltage by loop filter (3) output is given adder (4), and output control voltage is through R
11, C
5, L
3Be added to VCO(5) tracking group variable capacitance diode D
3With D
4On, make f
0Follow the tracks of f
r(be f
0=Nf
r).Baseband signal is through C
1Be input to adder (8), it and process R
7And after follower (10) is input to the coarse tuning voltage addition of adder (8), again through R
4, C
2, L
2With L
1Be added to VCO(5) modulation group variable capacitance diode D
1With D
2On, baseband signal is to VCO(5) operating frequency f
0Carry out frequency modulation, coarse tuning voltage can make D
1With D
2The working point along with D
3With D
4The change of working point and changing synchronously.Adder (8) and (4) are respectively by operational amplifier A
1And A
3And resistance is formed potentiometer W
1And W
2Be used for adjusting A respectively
1And A
3The initial level of output.VCO(5) output increases a follower (11), and it is made of the two-stage emitter follower, is used for adjusting output level and realizes impedance matching.Mark generator (1) frequently is made up of 1MHz temperature compensating crystal oscillator ZWB-1, integrated circuit chip CC4049, LS74, LS90 etc., output f
rBe the 50KHz square wave.Phase discriminator (2) adopts integrated circuit T4044(or ST002 with loop filter (3)).Operational amplifier A in adder (4) and (8) and the follower (10)
3, A
1And A
2Can adopt a slice LM324 or two LM358 integrated circuits.Program divider (6) adopts 4 LS162A respectively as kilobit, hundred, ten and (individual position) counter of eating, adopt two LS10 as logic control circuit, and with integrated circuit E12012 as double modulus prescalar (9), thereby formed pulse swallow divider program.For 4 LS162A are preset with program control, adopt two integrated circuit LS273 as latch (12).D/A converter (7) adopts inner integrated circuit DAC0832 and operational amplifier that contains latch to form.The code character that microcomputer is sent here is divided into three group octet numeric data codes, the address code of being sent here according to microcomputer by decoder (13) is controlled latch and the latch (12) in the D/A converter (7) respectively, and three groups of numeric data codes are latched in the corresponding integrated circuit chip as coarse adjustment sign indicating number, hundred preset codes of kilobit and ten position preset codes respectively.Decoder (13) adopts the LS138 integrated circuit to constitute.
Each element circuit of FM-SCPC generator in the practical application also can be made up of the homogeneous circuit of other model.VCO(5) can adopt the circuit of discrete component, as operating frequency f
0Also can adopt microstrip circuit when higher.Phase discriminator (2), program divider (6), latch (12) etc. can adopt a slice large scale integrated circuit to realize, for example the phase-locked loop large scale integrated circuit of series such as MC145146 and MC145152.
Claims (7)
1, a kind of frequency modulation one-way single-carr generator, frequently generator (1), phase discriminator (2), loop filter (3), adder (4), voltage controlled oscillator (VCO) (5), program divider (6) and D/A converter (7) etc. are formed by mark, it is characterized in that adopting a phase-locked loop to realize frequency modulation(FM) and change centre frequency, in PLL, adopt the program divider (6) and the D/A converter (7) of microcomputer (or switch) control, in the oscillation circuit of VCO (5), adopt two groups of variable capacitance diode D in parallel
1, D
2And D
3, D
4Phase discriminator (2) is by loop filter (3) output fine tuning voltage, and after the addition, output control voltage is added to D to the coarse tuning voltage that it and D/A converter (7) are exported in adder (4)
3With D
4On, the change of the frequency f o of control centre.Baseband signal is added to D
1With D
2On, fo is carried out frequency modulation(FM).
2, generator according to claim 1 is characterized in that VCO(5) two groups of variable capacitance diodes of oscillation circuit, every group can also can constitute with a variable capacitance diode with a pair of.Modulation group variable capacitance diode D
1With D
2Between can be connected in series fixed capacity C
S, or at D
1With D
2Go up fixed capacity in parallel, also can connect simultaneously and fixed capacity in parallel.
3, generator according to claim 1 is characterized in that baseband signal can directly be added to variable capacitance diode D
1With D
2On, perhaps in base band sources with variable capacitance diode D
1With D
2Between an adder (8) is arranged, receive variable capacitance diode D after the addition of the output voltage of baseband signal and D/A converter (7) input adder (8)
1With D
2On.
4, generator according to claim 1 is characterized in that program divider (6) has a double modulus prescalar (9) before, and both form pulse swallow divider program.
5, according to the generator described in the claim 3, it is characterized in that between adder (4) and the adder (8) follower (10) being arranged, it is by operational amplifier A
2Constitute.
6, generator according to claim 1 is characterized in that VCO(5) output a follower (11) is arranged, it is made of the two-stage emitter follower.
7, generator according to claim 4 is characterized in that phase discriminator (2), program divider (6), latch (12) etc. constitute with a slice large scale integrated circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 87105936 CN1006949B (en) | 1987-12-12 | 1987-12-12 | Frequency modulation one-way single-carr generator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 87105936 CN1006949B (en) | 1987-12-12 | 1987-12-12 | Frequency modulation one-way single-carr generator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN87105936A CN87105936A (en) | 1988-06-08 |
| CN1006949B true CN1006949B (en) | 1990-02-21 |
Family
ID=4815516
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 87105936 Expired CN1006949B (en) | 1987-12-12 | 1987-12-12 | Frequency modulation one-way single-carr generator |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1006949B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1049779C (en) * | 1991-09-19 | 2000-02-23 | 李基生 | Subminiature microwave information transmitting system |
| CN101304235B (en) * | 2008-06-30 | 2010-06-02 | 深圳和而泰智能控制股份有限公司 | High-frequency carrier generator |
| CN105429597A (en) * | 2015-11-26 | 2016-03-23 | 青岛盛嘉信息科技有限公司 | Frequency signal generation circuit |
| CN105515573A (en) * | 2015-12-02 | 2016-04-20 | 青岛盛嘉信息科技有限公司 | Frequency signal source |
| CN109831401B (en) * | 2019-03-19 | 2021-04-13 | 西安电子科技大学 | Modulator and method based on common reference in MIMO system |
| CN112152662B (en) * | 2020-08-26 | 2021-06-25 | 南京云天致信信息科技有限公司 | Frequency hopping communication system and communication method for multi-frequency transmission |
-
1987
- 1987-12-12 CN CN 87105936 patent/CN1006949B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CN87105936A (en) | 1988-06-08 |
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