CN101587181A - Wideband digital telemetered signal isolating and matching method - Google Patents
Wideband digital telemetered signal isolating and matching method Download PDFInfo
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Abstract
A wideband digital telemetered signal isolating and matching method, includes the following steps : (1)the receiving, the impedance match and the anti-aliasing filter of the input signal are finished via a receiving and matching circuit; (2) the analog signals after passing through the receiving and matching circuit is in the sampling digitalization by an analog-to-digital conversion chip, the digit signals after the analog-to-digital conversion is in the isolation coupling by a digital coupled device; (3) the digit signal after the isolation coupling enters a signal processing unit, and the gain calibration, gain setting and choosing band-pass filtering for the signal are finished; (4) the signal processing unit is controlled by a human-computer interface and can be in the long-range control; (5) digit signal after passing through the signal processing unit is in the isolation coupling by the digital isolation coupled device, then is resumed to the analog signal through a digital -to- analog conversion chip; (6) the analog signal after the digital -to- analog conversion is output by the drive; (7) a power-supply module is isolated so that the isolation among an input unit, a signal processing unit and a output unit is conducted.
Description
One, technical field
The present invention surveys down provides a kind of wideband digital telemetered signal isolating and matching method, is specifically related to a kind of digitizing isolation coupling scheme of utilizing and realizes isolation, coupling and the signal replication of distant capable phase-shift keying (PSK) (PSK) signal are belonged to the satellite ground field tests.
Two, background technology
The isolation coupling of telesignalisation is applied in the satellite ground testing apparatus, finishes the isolation of descending psk signal of remote measurement and uphole equipment, and finishes the impedance matching of the descending psk signal of remote measurement.The descending psk signal frequency range of remote measurement is at (1 500) KHz, and the descending psk signal frequency of remote measurement commonly used is 65.536KHz.
Traditional Signal Spacing coupling scheme all carries out direct isolation coupling to simulating signal, and the coupling of high precision linear photoconductor, the coupling of wide-band linearity photoelectricity, transformer coupled three kinds of modes are arranged usually.Based on the Signal Spacing coupling scheme of high precision linear photoconductor coupling hour, can obtain good linear, and noise is less in bandwidth; But need accurately to regulate biasing, and be difficult in the frequency band range of broad, obtain preferable performance.Signal Spacing coupling scheme based on the coupling of wide-band linearity photoelectricity obtains consistent gain in big bandwidth; But need accurately to regulate biasing, and coupling coefficient is too little, causes noise bigger.Signal Spacing coupling scheme circuit based on transformer is very simple, and coupling coefficient is big, and noise figure is low, and high frequency characteristics is good; But low frequency characteristic is poor.
Three kinds of isolation coupling schemes of table 1. characteristics
| Coupling scheme | Operating frequency range | Noisiness |
| The coupling of high precision linear photoconductor | 51KΩ≤50KHz | Good |
| The coupling of wide-band linearity photoelectricity | (1□500)KHz | Bad |
| Transformer coupled | ≥50KHz | Good |
Three kinds of isolation coupling scheme characteristics are as shown in table 1, and its operating frequency range is limited or noisiness is bad.Therefore the application of taking Wideband isolation coupling scheme that telesignalisation is isolated adaptation has considerable meaning.
Three, summary of the invention
The purpose of this invention is to provide a kind of wideband digital telemetered signal isolating and matching method, adopted digitizing isolation coupling scheme, to the descending psk signal of remote measurement isolate, coupling and signal replication, provide a kind of valid approach for increasing the signal spectrum width of isolating adaptation, improved the spectral characteristic of isolating adaptation, the performance of satellite ground testing apparatus has been had great significance.
A kind of wideband digital telemetered signal isolating and matching method of the present invention, its theory diagram as shown in Figure 1, it may further comprise the steps:
Step 1, input signal are passed through to receive match circuit, finish reception, impedance matching, the anti-aliasing filter of input signal, realize single-ended signal slip sub-signal simultaneously and signal is carried out the amplitude adjustment to be fit to back level processing;
Step 2, pass through the modulus conversion chip sampled digitalization through the simulating signal behind the reception match circuit, because mutual electrical isolation between input, output channel, therefore the contact that will set up signal, must carry out the isolation coupling of signal, the digital signal after the analog to digital conversion realizes isolation coupling by digital coupler spare;
Step 3, digital signal through isolation coupling, the entering signal processing unit, gain calibration, the gain of finishing signal are provided with and optional bandpass filtering function, and optional bandpass filtering function is realized by signal down coversion, signal extraction, low pass signal filtering, signal interpolation and five parts of signal up-conversion;
Step 4, signal processing unit is controlled by man-machine interface, can carry out Long-distance Control on PC, and PC communicates by RS485 with isolation coupling hardware device;
Step 5, the digital signal of process signal processing unit reverts to simulating signal by analog-digital chip then by digital isolation coupling device isolation coupling;
The output of overdriving of step 6, the analog passband signal after the digital-to-analog conversion, driving circuit is made up of amplifier and series load resistance, during the modelled signal transfer ratio, needs to change according to the situation of actual loading resistance;
Step 7, therefore signal is isolated mutually between input block, signal processing unit and the output unit, requires that power supply and ground are isolated from each other between several modules, and the insulating power supply module adopts the electric isolation of voltage transitions chip realization;
Digitizing isolation coupling scheme has been avoided the coupling to simulating signal, all is digital signal processing in links such as the transfer ratio control of centre, signal replications, therefore has following characteristics:
√ does not need to regulate biasing;
√ circuit high conformity;
√ takes into account low frequency and high frequency characteristics;
√ can add digital processing algorithms such as digital filter;
Digitizing isolation coupling scheme is compared with three kinds of traditional isolation coupling schemes, and its advantage is as shown in table 2.
Table 2. digitizing isolation coupling scheme
| Coupling scheme | Operating frequency range | Noisiness |
| The digitizing isolation coupling | (1 500) KHz depends on analog to digital conversion/analog-digital chip type selecting | Good output amplitude is hour poor slightly |
Four, description of drawings
Fig. 1 is a principle of the invention block diagram;
Fig. 2 is that telesignalisation of the present invention is isolated coupling hardware device frame diagram;
Fig. 3 is a gain correction unit structural drawing of the present invention;
Fig. 4 is that the present invention gains the unit algorithm structural drawing is set;
Fig. 5 is the optional bandpass filtering unit algorithm of a present invention process flow diagram;
Fig. 6 is an insulating power supply schematic diagram of the present invention;
Symbol description is as follows among the figure:
Adc_d: the data that obtain after the modulus conversion chip collection;
Adc_ovr: the overflow indicator signal of modulus conversion chip;
Gain_adj: gain calibration parameter;
Gset: gain is provided with parameter;
Da_out: digital-to-analog conversion output;
CIC: cascade integrator comb wave filter;
LDO: low pressure difference linear voltage regulator;
DC-DC: DC-to-dc electric pressure converter;
Five, embodiment
The present invention is described in further detail below in conjunction with drawings and Examples.
This example accompanying drawings elaborates and adopts digital isolation coupling scheme to be applied in the concrete grammar that telesignalisation is isolated coupling, and telesignalisation is isolated coupling hardware device frame diagram as shown in Figure 2, can be divided into seven modules and be illustrated.
First's module is the signal receiving processing module, is used to finish the reception, impedance matching, anti-aliasing filter, single-ended signal slip sub-signal of input signal and signal is carried out the amplitude adjustment handle to be fit to the back level.Signal receiving circuit is that a voltage follower of being built by amplifier is realized, can select input impedance by wire jumper, thereby realize impedance matching.The anti-aliasing filter circuit is built realization with active filter, and active filter is realized the rough amplitude adjustment to input signal simultaneously, to adapt to the input requirement of back level analog to digital conversion circuit.Active amplifier wave filter back-end circuit connects discharge circuit, thereby realizes that single-ended input signal converts differential input signal to.
The second portion module is the digital-to-analog conversion and the isolation coupling module of input signal.The analog-digital chip that adopts in this example is the 14-bit quantified precision, and analog signal conversion is become digital signal.Because input, electrical isolation mutually between output channel, the therefore contact that will set up signal must be carried out the isolation coupling of signal.The input signal isolation coupling chip that adopts in this example is three ADUM3440 and a slice ADUM3441.Isolating chip ADUM3440 and ADUM3441 are the four-way digital isolators, can support the data rate of the highest 150Mbps, it is based on the iCoupler technology of ADI company, has therefore avoided current delivery rate uncertainty, the problem that influences in nonlinear transfer function and temperature and serviceable life.The supply voltage scope of isolating chip ADUM3440 and ADUM3441 both sides can be 3.0V～5.5V, can with the low-voltage system compatibility, simultaneously can also realize the level conversion function.Isolating chip ADUM3440 is four-way output, and isolating chip ADUM3441 is passage input, triple channel output.
The third part module is the SIGNALS MANAGEMENT module.Signal processing module realizes that the gain calibration of input signal, gain are provided with and optional bandpass filtering.
The full amplitude input range of the analog to digital conversion front-end circuit that designs among Fig. 2 is 6Vpp, and modulus conversion chip is the 14-bit quantified precision; The full amplitude output area of digital-to-analog conversion back-end circuit design also is 6Vpp, and analog-digital chip is the 16-bit quantified precision.The analog to digital conversion gain correction unit is mainly used in and solves two problems.One is that subsequent treatment is convenient, and the 14-bit quantized data of analog to digital conversion crude sampling need be converted to 16bit.After input block is identical with the output unit quantization digit, because the full amplitude voltage of both correspondences equates that the magnitude of voltage physical significance of digital quantity representative is identical in the field programmable gate array (FPGA); They are two years old, though the full amplitude of modulus conversion chip and analog-digital chip is 6Vpp in the design parameter of hardware circuit, because unavoidably there is certain error in the discreteness of component parameters, the analog to digital conversion correcting unit is used to eliminate interchannel difference, and equipment is more accurate.
The detailed structure of analog to digital conversion gain correction unit is .Adc_d[13:0 as shown in Figure 3] be the 14-bit quantized data that obtains after the modulus conversion chip collection, the corresponding full amplitude of exporting 16 of the full amplitude of 14-bit promptly needs Adc_d[13:0 in the expansion process in theory] multiply by 4.Adc_ovr is an overflow indicator signal of modulus conversion chip, if overflow, the modulus conversion chip amplitude limit detects logic and directly analog-to-digital data carried out hard-limiting, is about to data and is changed to positive maximal value 8191 or negative minimum value-8192.The expression formula of whole correcting algorithm is:
adj_out＝adc_d*(256+gain_adj)/64 (1)
Division arithmetic is for dividing exactly.Gain_adj is a gain calibration parameter.When gain_adj=0, do not comprise any correction.When gain_adj changed by-128 to 127, the scope gain=of corresponding input channel gain calibration ((256+gain_adj)/64)/4 was: 0.5 to 1.496; The every increase of gain_adj or reduce 1,1/256 times of change in gain.
Under standard conditions (temperature, humidity etc.), use signal source that a standard signal is provided, be 3Vpp as peak-to-peak value, channel gain is made as 1, observation output signal peak-to-peak value; When exporting peak-to-peak value less than 3Vpp, increase the value of gain_adj, when exporting peak-to-peak value, reduce the value of gain_adj greater than 3Vpp, the gain_adj numerical value when the value of output channel is 3Vpp is calibration value.
Gain is provided with the unit and comprises that gain is provided with and the output violent change holding circuit, and the scope that gain is provided with is 0 to 8.Gain is provided with the unit algorithm structure as shown in Figure 4.Among Fig. 4, when the load of output was high impedance, voltage gain (high resistant) with the pass of gain parameter setting was:
G
high＝Gset/8192 (2)
Divide operations is for dividing exactly, and corresponding gain quantization error is 1/8192.When output load was low-resistance, voltage gain (low-resistance) with the pass of gain parameter setting was:
G
50Ω＝Gset/16384 (3)
Optional bandpass filtering unit algorithm process flow diagram comprises signal down coversion, signal extraction, low pass signal filtering, signal interpolation and signal up-conversion as shown in Figure 5.Optional bandpass filtering unit carries out according to following steps.
Step 1, signal enter optional bandpass filtering unit, select whether to carry out bandpass filtering.If enter subsequent step; If not, directly jump out this unit.
Step 2 is provided with the centre frequency of input signal and the bandwidth of bandpass filtering on man-machine interface.
Step 3, if bandwidth is 312.5Hz, then input signal carries out 8 times of CIC and extracts through after the down coversion, enters low-pass filter unit then, the signal after the filtering output carries out 8 times of CIC interpolations, at last through up-conversion output.
Step 4, if bandwidth is 1.25KHz, then input signal is through after the down coversion, carry out 32 times of CIC and extract (8 times of CIC extract and 4 times of CIC extraction cascades), enter low-pass filter unit then, signal after the filtering output carries out 8 times of CIC interpolations (8 times of CIC interpolations and the cascade of 4 times of CIC interpolations), at last through up-conversion output.
Step 5, if bandwidth is 5KHz, then input signal is through after the down coversion, carry out 128 times of CIC and extract (8 times of CIC extractions, 4 times of CIC extract and 4 times of CIC extraction cascades), enter low-pass filter unit then, signal after the filtering output carries out 8 times of CIC interpolations (8 times of CIC interpolations, 4 times of CIC interpolations and the cascade of 4 times of CIC interpolations), at last through up-conversion output.
Step 6, if bandwidth is 20KHz, then input signal is through after the down coversion, carry out 128 times of CIC and extract (8 times of CIC extractions, 4 times of CIC extractions, 4 times of CIC extract and 4 times of CIC extraction cascades), enter low-pass filter unit then, signal after the filtering output carries out 8 times of CIC interpolations (8 times of CIC interpolations, 4 times of CIC interpolations, 4 times of CIC interpolations and the cascade of 4 times of CIC interpolations), at last through up-conversion output.
The 4th part of module is a man-machine interface, can carry out Long-distance Control on PC, and PC communicates by RS485 with isolation coupling hardware device.(this example comprises four simulating signal matching units for centre frequency, bandwidth and the amplitude gain of the real-time demonstration in left side output channel in the Long-distance Control interface, so show four kinds of passages), the right side can be provided with centre frequency, bandwidth and the amplitude gain of output channel.
The 5th part of module is the isolation coupling and the D/A converter module of FPGA output signal.Because input, electrical isolation mutually between output channel, the therefore contact that will set up signal must be carried out the isolation coupling of signal.The output signal isolation coupling chip that adopts in this example is four ADUM3440.The digital signal of D/A converter module after with isolation coupling converts simulating signal output to.The analog-digital chip that adopts in this example is the 16-bit quantified precision.
The 6th part of module is a signal output module, and this example has three output channels.Signal drives output by output matching circuit after digital-to-analog conversion.Signal output module is made up of amplifier and resistance in series.Amplifier works in degree of depth negative feedback pattern, and internal resistance is very little, and total adaptation internal resistance is determined by resistance in series.When external loading was high resistant, adaptation still can operate as normal, and just output amplitude is twice than low-resistance load.When the modelled signal transfer ratio, need to change according to the situation of actual loading.
The 7th part of module is the insulating power supply part.Signal is isolated mutually between input block, signal processing unit and the output unit, also requires signal to isolate mutually between three passages of output unit.Therefore require between these five modules power supply and be isolated from each other.The insulating power supply principle as shown in Figure 6, external two kinds of power supply+5V and+12V, electrical isolation each other.+ 5V power supply through LDO chip PTH05000 pressure limiting one-tenths+3V and+1.2V for signal processing unit provide power supply and; + 12V power supply converts to+the 5V power supply through 4 DC-DC chips W RA1205ZP, electric each other mutual isolation.
This example is in the actual test of satellite ground, and it is as follows to satisfy technical indicator:
The √ input signal frequency range is at (1 500) KHz;
√ signal transmission ratio scope is at 0.1 6, and stepping is 0.1;
The optional filtering output of √, bandwidth is respectively 312.5Hz, 1.25KHz, 5KHz and 20KHz;
√ signal one tunnel is imported three tunnel outputs, three tunnel output waveform amplitude unanimities;
√ input signal and output signal are isolated mutually, isolate mutually between the output signal;
√ can carry out Long-distance Control to Signal Spacing coupling hardware device on man-machine interface;
Actual test result has proved wideband digital telemetered signal isolating and matching method Application feasibility in the satellite ground test.
Claims (1)
1. wideband digital telemetered signal isolating and matching method, it is characterized in that: it may further comprise the steps:
Step 1, input signal be by receiving match circuit, finishes reception, impedance matching, anti-aliasing filter, the single-ended signal slip sub-signal of input signal and signal is carried out the amplitude adjustment handle to be fit to the back level;
Step 2, pass through the modulus conversion chip sampled digitalization through the simulating signal behind the reception match circuit, because mutual electrical isolation between input, output channel, therefore the contact that will set up signal, must carry out the isolation coupling of signal, the digital signal after the analog to digital conversion realizes isolation coupling by digital coupler spare;
Step 3, digital signal through isolation coupling, the entering signal processing unit, gain calibration, the gain of finishing signal are provided with and optional bandpass filtering function, and optional bandpass filtering function is realized by signal down coversion, signal extraction, low pass signal filtering, signal interpolation and five parts of signal up-conversion;
Step 4, signal processing unit is controlled by man-machine interface, can carry out Long-distance Control on PC, and PC communicates by RS485 with isolation coupling hardware device;
Step 5, the digital signal of process signal processing unit reverts to simulating signal by analog-digital chip then by digital isolation coupling device isolation coupling;
The output of overdriving of step 6, the analog passband signal after the digital-to-analog conversion, driving circuit is made up of amplifier and series load resistance, during the modelled signal transfer ratio, needs to change according to the situation of actual loading resistance;
Step 7, therefore signal is isolated mutually between input block, signal processing unit and the output unit, requires that power supply and ground are isolated from each other between several modules, and the insulating power supply module adopts the electric isolation of voltage transitions chip realization.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104917495A (en) * | 2015-05-23 | 2015-09-16 | 成都众孚理想科技有限公司 | Isolated high-frequency pulse generator |
| CN105162453A (en) * | 2015-09-11 | 2015-12-16 | 福建顺昌虹润精密仪器有限公司 | Passive signal isolator |
| CN108111051A (en) * | 2017-12-19 | 2018-06-01 | 天津津航技术物理研究所 | A kind of adjustable Piezoelectric Ceramic control device of filtering mode |
| CN108919745A (en) * | 2018-09-11 | 2018-11-30 | 上海辰竹仪表有限公司 | Isolation circuit, guard grating and isolator |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR100208194B1 (en) * | 1997-07-23 | 1999-07-15 | 서평원 | Self-test apparatus of microwave device |
| CN1161677C (en) * | 2002-01-29 | 2004-08-11 | 北京航空航天大学 | Telemetry system for coaxial double-rotary wing pilotless helicopter |
| CN2733377Y (en) * | 2004-09-07 | 2005-10-12 | 冯启龙 | Photo-electric distributor for amplifying and isolating radar signals |
| JP2006157503A (en) * | 2004-11-30 | 2006-06-15 | Seiko Epson Corp | Receiver, and correction back-diffusion code generating device and method therefor |
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- 2009-06-17 CN CN2009100866639A patent/CN101587181B/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104917495A (en) * | 2015-05-23 | 2015-09-16 | 成都众孚理想科技有限公司 | Isolated high-frequency pulse generator |
| CN104917495B (en) * | 2015-05-23 | 2018-03-06 | 成都众孚理想科技有限公司 | A kind of isolation type high frequency impulse generator |
| CN105162453A (en) * | 2015-09-11 | 2015-12-16 | 福建顺昌虹润精密仪器有限公司 | Passive signal isolator |
| CN105162453B (en) * | 2015-09-11 | 2017-11-21 | 福建顺昌虹润精密仪器有限公司 | A kind of passive signal isolator |
| CN108111051A (en) * | 2017-12-19 | 2018-06-01 | 天津津航技术物理研究所 | A kind of adjustable Piezoelectric Ceramic control device of filtering mode |
| CN108919745A (en) * | 2018-09-11 | 2018-11-30 | 上海辰竹仪表有限公司 | Isolation circuit, guard grating and isolator |
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