CN103488074B - A kind of amplitude variation signal transit time measurement device - Google Patents
A kind of amplitude variation signal transit time measurement device Download PDFInfo
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- CN103488074B CN103488074B CN201310418943.1A CN201310418943A CN103488074B CN 103488074 B CN103488074 B CN 103488074B CN 201310418943 A CN201310418943 A CN 201310418943A CN 103488074 B CN103488074 B CN 103488074B
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Abstract
The invention discloses a kind of amplitude variation signal transit time measurement device, be coupled in Received signal strength in crosstalk mode after sending into multi-way signal multiplexing device owing to transmitting, transmitting just becomes an overall signal with Received signal strength, and carry out identical follow-up signal process, can more adequately obtain like this transmitting and time interval between Received signal strength.Meanwhile, the present invention adopts RSSI envelope detection to received signal, and its edge more adequately reflects the time of transmitting and receiving signal, also improves the measuring accuracy in the time interval to a certain extent.
Description
Technical field
The invention belongs to signal processing technology field, more specifically say, relate to a kind of amplitude variation signal transit time measurement device.
Background technology
The measurement of time parameter all has a wide range of applications in a lot of field, and process aspect adopts such course of work mostly: the square-wave transmission signal starting certain frequency, open timer simultaneously, square-wave signal is launched after treatment, when transmission circuit receives signal, amplify and shaping the feeble signal received, export square wave, triggered timer stops counting.Received signal strength is feeble signal and amplitude is launched change along with environment and changes, and shaping amplification processes and adopts fixing compare threshold also can introduce certain error simply to received signal.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, a kind of amplitude variation signal transit time measurement device is provided, to realize transmitting and time interval between Received signal strength more adequately obtains.
For realizing above object, amplitude variation signal transit time measurement device of the present invention, comprising:
Multiple transmission signal generating circuit, for generation of transmitting, wherein, a time period, only has a transmission signal generating circuit job, produces one and transmits;
It is characterized in that, also comprise:
Multiple signals receiving circuit front end, is connected with multiple transmission signal generating circuit respectively, for transmitting, Received signal strength receives, and transmitting of receiving or Received signal strength sent into an input end of multi-way signal multiplexing device;
Multi-way signal multiplexing device, is connected with multiple signals receiving circuit front end respectively, and the Received signal strength gating received also is sent in receiving signal amplifier; The input end of described multi-way signal multiplexing device is after input signal exceedes certain threshold value, all can be coupled to other passages in the mode of crosstalk, like this, transmit be sent to signal behavior follower input end after, its amplitude is greater than described threshold value, transmits and is coupled in the Received signal strength of gating;
Receiving signal amplifier and RSSI(ReceivedSignalStrengthIndication, namely the signal intensity instruction received) envelope detector, the Received signal strength that signal multi-way signal multiplexing device is selected is amplified, then carry out RSSI envelope detection, the Received signal strength after detection process is sent in voltage comparator circuit;
Voltage comparator circuit, Received signal strength after wave detector process and the threshold voltage of voltage comparator circuit compare, obtain square-wave signal, what in square-wave signal, the rising edge time of first square wave was corresponding is as signal x time, the time of reception of the corresponding Received signal strength of rising edge time of second square wave;
Time measuring unit, measures the mistiming between first rising edge and second rising edge, obtains transmitting and time interval between Received signal strength and transit time.
The object of the present invention is achieved like this:
Amplitude variation signal transit time measurement device of the present invention, be coupled in Received signal strength in crosstalk mode after sending into multi-way signal multiplexing device owing to transmitting, transmitting just becomes an overall signal with Received signal strength, and carry out identical follow-up signal process, can more adequately obtain like this transmitting and time interval between Received signal strength.Meanwhile, the present invention adopts RSSI envelope detection to received signal, and its edge more adequately reflects the time of transmitting and receiving signal, also improves the measuring accuracy in the time interval to a certain extent.
Accompanying drawing explanation
Fig. 1 is the system construction drawing of a kind of embodiment of amplitude variation signal transit time measurement device of the present invention;
Fig. 2 sends into the pulse signal waveform figure that sensor actuation signal produces circuit in Fig. 1;
Fig. 3 is the signal behavior follower circuit diagram shown in Fig. 1;
Fig. 4 is the schematic diagram that the sensor actuation signal shown in Fig. 1 produces circuit;
Fig. 5 is the oscillogram of the drive singal shown in Fig. 1;
Fig. 6 is the oscillogram of the clamp rear drive signal shown in Fig. 1;
Fig. 7 is the multi-way signal multiplexing device shown in Fig. 1, receiving signal amplifier and RSSI envelope detector circuit diagram;
Fig. 8 is the Received signal strength oscillogram after the envelope detector of RSSI shown in Fig. 1 carries out envelope detection;
Fig. 9 is the schematic diagram of the inspection of floating threshold shown in Fig. 1 voltage comparator circuit;
Figure 10 adopts the reversion of fixed threshold comparator circuit level to obtain receiving square wave signal schematic representation;
Figure 11 adopts the reversion of floating threshold comparator circuit level to obtain receiving square wave signal schematic representation;
Figure 12 is the reception square wave signal waveforms shown in Fig. 1.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described, so that those skilled in the art understands the present invention better.Requiring particular attention is that, in the following description, when perhaps the detailed description of known function and design can desalinate main contents of the present invention, these are described in and will be left in the basket here.
Fig. 1 is the system construction drawing of a kind of embodiment of amplitude variation signal transit time measurement device of the present invention.
In the present embodiment, as shown in Figure 1, amplitude variation signal transit time measurement device of the present invention comprises three parts: as main control processor unit 1, time measuring unit 2, receiving and transmitting signal treating apparatus 3.
In the present embodiment, need the sensor 303 that four transmitting-receiving integrated, respectively corresponding four corners of the world four direction, the sensor emission in a direction goes out to transmit and is received by the sensor in its relative direction.In Fig. 1, for simplicity, only depict a sensor NORTH being positioned at north as transmitter and the sensor SOUTH being positioned at south as receiver, and the sensor actuation signal contacted with them respectively produces circuit NORTH and receiving circuit front end NORTH, SOUTH.
In the present embodiment, main control processor unit 1 control time measuring unit 2 produces pulse signal, and being used as the control signal that four road sensor actuation signals produce circuit 302 breaker in middle pipe MOSFET, pulse signal is sent into receiving and transmitting signal treating apparatus 3 and is completed the generation of sensor actuation signal and the work such as reception, process of Received signal strength.Namely receiving and transmitting signal treating apparatus 3 comprises multiple transmission signal generating circuit, multiple signals receiving circuit front end, multi-way signal multiplexing device, receiving signal amplifier, RSSI envelope detector and voltage comparator circuit.
The specific works flow process of amplitude variation signal transit time measurement device of the present invention is as follows: main control processor unit 1 control time measuring unit 2 produces the squared pulse trains and the pulse signal that send 5 330kHz every 10ms, transmission signal generating circuit in input receiving and transmitting signal treating apparatus 3, in this example, transmission signal generating circuit comprises sensor actuation signal generation circuit and the sensor as transmitter.In order to ensure a time period, only have a transmission signal generating circuit job, the present embodiment adopts, and outlet selector 301 realizes.
In the present embodiment, pulse signal is through signal outlet selector 301, send into and produce in circuit NORTH302 with the selected sensor actuation signal be connected as the sensor of transmitter, produce the pulse signal of the 360Vpp after boosting, and transmit as the sensor NORTH generation that drive singal is exported to as transmitter.Sensor SOUTH303 on correspondence direction receives as receiver and transmits and be converted to electric signal, to input as the Received signal strength in receiving and transmitting signal treating apparatus 3 and after being converted to the square-wave signal of 0-5V, input time, measuring unit 2 obtained the time interval transmitted and between Received signal strength, select the sensor in other directions, obtain transmitting and time interval between Received signal strength of this direction.
First produce by chip TDC-GP21 the pulse signal that 5 frequencies are the square wave sequence of 330kHz after amplitude variation signal transit time measurement device starts, as shown in Figure 2, (because this signal frequency is higher, by the impact of stray inductance on signal transmission path and stray capacitance, this standard block is caused to become the waveform shown in Fig. 2), sent into two-way four-way simulating signal multiplexer/signal outlet selector 74HCT4052, carried out gating by S0 and S1 two digital input pins be connected with main control processor I/O mouth.As shown in Figure 3, in the present embodiment, S0, S1 are 0,0, are held by the 1Y0 of signal outlet selector 301 i.e. multiplexer/signal outlet selector 74HCT4052 gating and drive singal DRIVE_NORTH to be loaded into the control signal of grid as driven MOS FT break-make that sensor actuation signal produces the MOSFET of pulse transformer front end in circuit NORTH302 like this.
Owing to needing four sensors in the present embodiment, therefore Jiu You tetra-road sensor actuation signal produces circuit, and this four roads circuit is identical, the sensor actuation signal that Fig. 4 gives a wherein road produces circuit, when sensor is signal receiving circuit front end 304 as a part of circuit of its rear end during receiver.
As shown in Figure 4,12VDC voltage is after two 100 Ω resistance R10, R11 current limlitings in parallel, and as the initial voltage that pulse transformer T1 boosts, wherein electric capacity C13, C14 is the filter capacitor of power supply VCC_+12V.The squared pulse trains of 330kHz is loaded on the MOSFET as pulse transformer primary coil on-off switch, can by the DC voltage of 12V after the pulse transformer T1 process through primary and secondary no-load voltage ratio being 1:30, boosting is for Vpp is close to the high-voltage pulse of 400V and drive singal, as shown in Figure 5, again this high-voltage pulse is loaded on sensor 303, encourages it to transmit.
As shown in Figure 4, when the secondary coil conducting of pulse transformer T1, the electric capacity C2 of an isolated DC is accessed in the rear end of sensor, owing to adding voltage very large (Vpp is about 360V) on a sensor, the withstand voltage that this capacitance is selected is 1000V, simultaneously in order to avoid high-voltage pulse causes damage to signal processing circuit below, the diode pair BAV99W of two reverse parallel connections is accessed over the ground in the rear end of capacitance, after the diode pair of two reverse parallel connections of such ground connection, the multiplexer/signal outlet selector 74HCT4052 input end of receiving circuit carries out clamper, after clamper, the voltage magnitude of signal is about 0.4V, as shown in Figure 6.
The diode pair BAV99W of electric capacity C2 and two reverse parallel connection of isolated DC forms signal receiving circuit front end, be applied to Received signal strength that drive singal on sensor or sensor receive after the electric capacity C2 of isolated DC, send in multi-way signal multiplexing device 305.
Simultaneously, because the sensor selected is transmitting-receiving integrated, in order to avoid forming loop when sensor as the secondary coil of Received signal strength during receiver and pulse transformer T1, between pulse transformer T1 and sensor, add the high-speed bidirectional diode chip for backlight unit BAV99W of a NXP company.
The signal that sensor receives is very faint, is the voltage signal of mV level.Forward voltage due to diode is 0.7V, and the amplitude of Received signal strength makes it not form loop by the secondary coil of BAV99W and pulse transformer, and can only enter the corresponding gating passage of multiplexer/outlet selector 74HCT4052.In the present embodiment, S0, S1 are 0,0, select 2Y0 input end to export.
As shown in Figure 7, because sensor SOUTH needs could export after the corresponding passage 2Y0 of gating multiplexer/outlet selector 74HCT4052 as the signal ECHO_NORTH received during receiver, now four passages only have one to be strobed.Sensor NORTH shown in Fig. 4 is connected with the selection input end 2Y4 of multiplexer/outlet selector 74HCT4052 as rear end during transmitter and the ECHO_SOUTH of signal receiving circuit front end, and therefore this signal is not strobed at multiplexer/outlet selector 74HCT4052.In the present embodiment, the two-way four-way simulating signal multiplexer/selection follower 74HCT4052 selected, if when the peak-to-peak value of the crosstalk signal through its a certain passage is more than 110mV, this signal will be coupled in the mode of crosstalk the passage be strobed, and then exports from the passage be strobed after the decay of-60dB.From Fig. 6, we can find out that the peak-to-peak value of this signal exceedes i.e. threshold value 110mV, therefore this signal is by multiplexer/selection follower 74HCT4052's in the mode of interchannel crosstalk, and the amplitude of the Received signal strength that receiver receives is mV magnitude, crosstalk can not be there is between the passage of multiplexer/selection follower 74HCT4052.Like this, as shown in Figure 7, the 2Y4 termination sensor NORTH of multiplexer/selection follower 74HCT405274HCT4052 is as rear end during transmitter and signal receiving circuit front end, after drive singal DRIVE_NORTH entered signal receiving circuit front end clamp, enter multiplexer/selection follower 74HCT4052 from 2Y4 end, the mode of then crosstalk to be coupled in Received signal strength ECHO_NORTH.Now, the Received signal strength of the ECHO_SOUTH in Fig. 7 is actual is drive singal DRIVE_NORTH after clamp.After carrying out rear like this manipulative, the signal that sensor drives the signal in moment and receiver to receive just becomes an overall signal.
Using the pulse signal of high-voltage pulse after voltage clamping circuit as the start signal of launching, by the original signal of this pulse signal as measuring intervals of TIME initial time.
Only use a slice 74HCT4052 chip in the present invention, when sensor makees transmitter, this chip is used as signal outlet selector 301 Fig. 3 and provides part, and when sensor makees receiver, this chip is used as multi-way signal multiplexing device 305 Fig. 7 and provides part.Being convenient to make the circuit after drafting understand, in the present invention chip 74HCT4052 being divided into two parts to draw according to multiplexer and signal behavior follower, seeing circuit shown in Fig. 4 and Fig. 7.
In the present embodiment, as shown in Fig. 1,7, receiving and transmitting signal treating apparatus also comprises three modular circuits: receiving signal amplifier, RSSI envelope detector and floating threshold voltage comparator circuit, Received signal strength could be converted to the square-wave signal of 0-5V after the process of these three modular circuits.
Because Received signal strength is very faint, amplitude is mV rank, just can carry out other and effectively process after needing to carry out filter amplifying processing.Because sensor has fixing physical characteristics, the signal that therefore receiver receives has good consistance, that is from the periodicity Mintrop wave point to peak point be identical, not by the impact of amplitude size.According to this feature of Received signal strength, the Received signal strength after filter and amplification is carried out envelope detection process, like this can acquisition time interval very accurately.
In the present embodiment, as shown in Figure 7, chip SA614AD is used to realize filter and amplification and the envelope detection process of Received signal strength.This chip internal is integrated with two-stage IF limiting amplifier, quadrature detector, squelch, logarthmic reception signal intensity instruction (RSSI).Use in the present invention the first order intermediate frequency amplifier of this chip achieve a butt joint collect mail number amplification, and then utilize RSSI module to amplify after Received signal strength realize RSSI envelope detection (utilizing logarithmic to realize envelope detection).
The Received signal strength received is entered chip SA614AD by pin 16 when doing receiving end by sensor after chip 74HCT4052 gating exports, in this chip, Received signal strength is first the amplification of the intermediate frequency amplifier of 39dB through gain, then the Received signal strength after amplification is carried out after envelope detection process through RSSI, export from pin 5, output waveform as shown in Figure 8.In the circuit shown in Fig. 7, C17, C22, C25, C31 are all the 100nF decoupling capacitor recommended in SA614A chip data.R19, C23, R18, C18, C19 are the IF input impedance of pin 16 according to SA614A, the limiter input impedance of the IF output impedance of pin 14 and pin 12 calculates.
In the present embodiment, as shown in Figure 1, Received signal strength amplify after filtering with RSSI envelope detection process after, need to make it be converted to the square-wave signal of 0 ~ 5V through floating threshold voltage comparator circuit 307 process, in the present invention, adopt hypervelocity, high precision, rail-to-rail comparer LMV7239M5 formation floating threshold voltage comparator circuit 307.In the present embodiment, the threshold voltage of voltage comparator circuit is not a fixed value, and it is determined jointly by Received signal strength and 5V power supply.Physical circuit as shown in Figure 9, comprises comparer LMV7239M5, and the Received signal strength RSSI_OUT after detection is input to the anode of comparer by a resistance R14; Supply voltage carries out dividing potential drop by resistance R12, R20 that two are connected in series to ground, series connection point is connected with the negative terminal of comparer, series connection point is connected with the anode of comparer by another resistance R17 simultaneously, two are connected in series to the resistance R20 two ends be connected to ground in resistance R12, the R20 on ground and are parallel with an electric capacity C24, and the output terminal of comparer exports and receives square-wave signal.
In circuit shown in Figure 10, when the Received signal strength after chip SA614A process does not also send into comparer positive terminal, the threshold voltage that can calculate comparer approximates 1V.When the Received signal strength after processing enters the positive terminal of comparer, Received signal strength can enter the end of oppisite phase of comparer by resistance R17.The Received signal strength being delivered to comparer is as shown in Figure 8 not the regular signal of constant amplitude, Received signal strength amplitude can change, but its phase place can not change substantially, therefore Received signal strength is non-constant-amplitude signal, if with the threshold voltage of fixed value as comparer, can because stochastic error be introduced in the change of Received signal strength amplitude.Take the threshold value changed, allow the threshold value of comparer adjust size according to the amplitude of input signal, just elimination Received signal strength amplitude to a certain degree can change the error introduced.In Fig. 9 design, if RSSI_OUT input signal is Vin, C24 both end voltage is Vo, then initial time has:
R12=1.5M, R20=1.5M, R14=1.5K, R17=499K, Vcc=5V in formula,
Substitution above formula obtains:
V
o=V
cc-V
o+3(V
in-V
o)（2）
Known by above formula (3), RSSI_OUT input signal increases along with amplitude, the voltage at Vo and electric capacity C24 two ends raises, electric capacity starts charging, and RSSI_OUT input signal amplitude is large, and rising edge slope is large, the voltage at C24 two ends also increases soon, electric capacity C24 charging rate is fast, thus raises the threshold voltage of comparer, can reduce the time interval measurement error that fixing threshold level causes when level overturns like this.
Be illustrated in fig. 10 shown below, two Received signal strength that in figure, curve S 1, S2 represents amplitude different respectively enter comparer, and comparator reference terminal voltage is L, adopt fixed threshold, and now, S1 input curve comparer triggers at A ' point, and the corresponding time is TA '; S2 input curve comparer triggers at B ' point, and the corresponding time is TB ', and therefore, the corresponding identical compare threshold phase place of two signals that S1, S2 amplitude is different has the error of TB '-TA '.And as shown in figure 11, adopt the threshold value of change, time comparer is input as S1, corresponding reference edge signal is curve L1, comparer triggers at A point, and comparer is when being input as S2, corresponding reference edge signal is curve L2, comparer triggers at B point, now can see that A and B point is less than the lead time than A ' in Figure 10 and B ' in time, the threshold value of change can reduce the error of phase place than fixed threshold, thus the time interval measurement error that the fixing threshold level of minimizing causes when level overturns.
The waveform of comparator output signal as shown in figure 12.As can be seen from Figure 12 transmit produce that time corresponding be the rising edge time of first square wave, sensor as that time of the signal received during receiver corresponding be the rising edge time of second square wave.Therefore the measurement in the time interval is exactly record the mistiming between first rising edge and second rising edge.
Although be described the illustrative embodiment of the present invention above; so that those skilled in the art understand the present invention; but should be clear; the invention is not restricted to the scope of embodiment; to those skilled in the art; as long as various change to limit and in the spirit and scope of the present invention determined, these changes are apparent, and all innovation and creation utilizing the present invention to conceive are all at the row of protection in appended claim.
Claims (2)
1. an amplitude variation signal transit time measurement device, comprising:
Multiple transmission signal generating circuit, for generation of transmitting, wherein, a time period, only has a transmission signal generating circuit job, produces one and transmits;
It is characterized in that, also comprise:
Multiple signals receiving circuit front end, be connected with multiple transmission signal generating circuit respectively, for to transmitting, Received signal strength receives, transmitting of receiving or Received signal strength are sent into the same input end of multi-way signal multiplexing device by signal receiving circuit front end;
Multi-way signal multiplexing device, is connected with multiple signals receiving circuit front end respectively, and the Received signal strength gating received also is sent in receiving signal amplifier; The input end of described multi-way signal multiplexing device is after input signal exceedes certain threshold value, all can be coupled to other passages in the mode of crosstalk, like this, transmit be sent to multi-way signal multiplexing device input end after, its amplitude is greater than described threshold value, transmits and is coupled in the Received signal strength of gating;
Receiving signal amplifier and RSSI (ReceivedSignalStrengthIndication, namely the signal intensity instruction received) envelope detector, the Received signal strength that multi-way signal multiplexing device is selected is amplified, then carry out RSSI envelope detection, the Received signal strength after detection process is sent in voltage comparator circuit;
Voltage comparator circuit, Received signal strength after wave detector process and the threshold voltage of voltage comparator circuit compare, obtain square-wave signal, what in square-wave signal, the rising edge time of first square wave was corresponding is as signal x time, the time of reception of the corresponding Received signal strength of rising edge time of second square wave;
Time measuring unit, measures the mistiming between first rising edge and second rising edge, namely obtains transmitting and time interval between Received signal strength and transit time.
2. time measurement device according to claim 1, is characterized in that, described voltage comparator circuit is floating threshold voltage comparator circuit, comprises a comparer, four resistance and an electric capacity;
Received signal strength after detection is input to the anode of comparer by a resistance R14; Supply voltage carries out dividing potential drop by resistance R12, R20 that another two are connected in series to ground, series connection point is connected with the negative terminal of comparer, series connection point is connected with the anode of comparer by the 4th resistance R17 simultaneously, another two are connected in series to the resistance R20 two ends that are connected to ground in resistance R12, the R20 on ground and are parallel with an electric capacity C24, and the output terminal of comparer exports and receives square-wave signal.
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