CN205898730U - Multichannel polytypic sensor capability test system - Google Patents

Abstract

The utility model relates to a multichannel polytypic sensor capability test system. The component of this system includes gas path module, test unit, button module, capture card and host computer, gas path module's constitution includes air chamber, miniature air pump, intake pipe, intake pipe, outlet duct, solenoid valve and solenoid valve, wherein, the route that intake pipe, intake pipe are joind links to each other with the air inlet of air chamber, outlet duct channel qi pump links to each other with the gas outlet of air chamber, be provided with solenoid valve and solenoid valve in intake pipe, the intake pipe respectively, solenoid valve and solenoid valve link to each other with the button module respectively. The utility model discloses not only can test different gases and like the dynamic response characteristic at different concentration lower sensor such as ammonia, hydrogen sulfide, still have the advantage of measurable quantity more than one channel, multiple sensor simultaneously, improve detection efficiency and also improved the experiment accuracy.

Description

A kind of multichannel polytypic sensor performance test system

Technical field

This utility model is related to a kind of gas sensor Performance Test System, more particularly, to a kind of multichannel, Multiple Type Sensor performance test system.

Background technology

Gas sensor is that a kind of inside active substance that passes through senses extraneous gas species and concentration, and will by transducer It is changed into the device that light, electricity etc. can measure physical quantity.According to its characteristic, gas sensor can be used for detecting various poisonous, easy Combustion, explosive gas or liquid vapour, therefore all have widely in every field such as industrial, civilian and national defense and military Application.

Static characteristic refers to sensor when each measured value is in steady statue, between output and input quantity Relation, typically requires keep linearly between sensor output under quiescent conditions and input, so to follow-up calculating meeting Bring compared with convenience.The static characteristic of sensor mainly have following target temperature drift, the impact of flow, linear correlation degree, zero Point drift, signal reproducibility and selectivity.Dynamic characteristic is the response characteristic to time dependent input quantity for the sensor.Dynamically Characteristic present's responding ability to variable signal for the sensor, for some occasions, such as monitoring extremely endangers the sensor of gas, Dynamic characteristic is even more important than static characteristic, in order to avoid there is major accident it is desired to sensor did within the time the shortest Go out response to be processed to adopt an effective measure.In order to lift its dynamic property, operative sensor employs peaker etc. Any special measures.

The method of testing of gas sensor mainly has constant-voltage method, constant flow method and electric resistance partial pressure method at present.Constant-voltage method be exactly Gas sensor two ends directly add constant voltage, determine its resistance value by measuring the electric current on gas sensor；Permanent Stream method is exactly directly to add constant-current source to gas sensor, determines its resistance by measuring the voltage at gas sensor two ends Value.The major defect of this 2 kinds of methods is because the change in resistance scope of gas sensor is very big, typically has 4,5 quantity The conversion of level, so that measurement curtage excursion is very big, causes difficulty to measurement.Electric resistance partial pressure method is exactly to sensing Device one build-out resistor of series connection, allows the resistance of build-out resistor and the resistance of sensor as close possible in sensor and coupling electricity Resistance two ends add constant voltage, by measuring the voltage at build-out resistor two ends, the method indirectly obtaining resistance of sensor.This side Method is easy to use, is also to adopt most methods both at home and abroad at present, therefore, determines that system adopts electric resistance partial pressure method.

The gas sensing research of foreign study mechanism is mostly based on the test platform that separate devices are built, for being highly prone to For the gas test of environmental disturbances, this kind of method is not only expensive, and tests effect and be heavily dependent on operator's Proficiency level.For the class ultra-high resistance test being likely to occur in air-sensitive test, a.flammin et al. proposes one kind and is based on The high resistant test circuit of capacitance integral, to fa level micro current effectively, when resistance larger current very little, accumulates threshold electricity Pressure needs several seconds even more than ten seconds.If enabling multiple channel test, parasitic capacitance during switching is likely to have influence on integrating capacitor Electricity.And increasingly difficult to resistance to the control ratio of the faint leakage current of electric capacity, it is difficult in actual applications to make.

Henan Chinese prestige is one of domestic earliest company entering gas sensing field, its test equipment hw-c30a quilt on sale Duo Suo research unit uses.There is basic multiple channel test function, but cannot voluntarily extend, and based on manual replacing exclusion Test mode, precision is difficult to ensure that.The test system for the research of mos gas sensor of Dalian University of Technology is carried in document To test collecting part built based on Agilent company 34980a data collecting card, carried out by gpib interface by pc machine on Position machine controls, and the function of gas cylinder distribution part then controls mass flowmenter by pc machine by pci interface operation d/a board (mfc) completing.This mode of building be also most mos gas sensor research worker and mechanism using by the way of.Using business Set up the test function of mos gas sensor key property with pattern block, come data acquisition and the work of checking.Test Mainboard is integrally placed in temperature and humidity control box, can preferably ensure the stability of ambient temperature and humidity.Systematic function depend on according to Rely the test performance being provided in commercial board and function it is difficult to according to the characteristic of some mos gas sensors and testing requirement Carry out free customization, be also not susceptible to be converted into real application research.

Utility model content

The purpose of this utility model is for can only detect single model sensor performance present in current techniques Deficiency, provides a kind of multichannel, polytypic gas sensor Performance Test System.This test system is joined by new gas path module Close the test cell being made up of power supply circuits, sensor array, signal condition amplifying circuit etc., coordinate capture card to complete to quilt Survey the signals collecting of sensor, finally realize signal is analyzed.This utility model not only can test gas with various such as ammonia Gas, hydrogen sulfide etc., in the dynamic response characteristic of variable concentrations lower sensor, also have simultaneously and can measure multiple passages, multiple sensing The advantage of device, improves detection efficiency and also improves experiment accuracy.

A kind of multichannel polytypic sensor performance test system, the composition of this system include gas path module, test cell, Key-press module, capture card and host computer；

The composition of described gas path module includes air chamber, micro air pump, air inlet pipe, air inlet pipe, escape pipe, electromagnetic valve and electromagnetism Valve；Wherein, the path that described air inlet pipe, air inlet pipe merge into is connected with the air inlet of air chamber；Escape pipe is through air pump and air chamber Gas outlet is connected；It is respectively arranged with electromagnetic valve and electromagnetic valve in air inlet pipe, air inlet pipe；Electromagnetic valve and electromagnetic valve respectively with button mould Block is connected；

Described test cell is arranged in air chamber, and its composition includes power supply circuits and composition eight passages of identical, each Passage composition includes sensor array, pre-amplification circuit and signal conditioning circuit；Its annexation is: power supply circuits respectively with The sensor array of each passage, pre-amplification circuit are connected；Sensor array, pre-amplification circuit and signal in each passage Modulate circuit is sequentially connected；The signal conditioning circuit of each passage is connected with capture card respectively, and capture card is connected with host computer.

The composition of described power supply circuits includes Switching Power Supply, three terminal regulator, positive low dropout voltage regulator and the negative electricity of 12v Pressure produce chip, wherein, the Switching Power Supply of 12v is connected with three terminal regulator, three terminal regulator respectively with positive low pressure drop voltage stabilizing Device, negative voltage produce chip and are connected.

The composition of described sensor array includes photoionization gas sensor socket and metal oxide sensor socket, The two is connected by wire jumper；Photoionization gas sensor socket is connected with three terminal regulator, metal oxide sensor socket It is connected with positive low dropout voltage regulator.

Described pre-amplification circuit composition includes chopper-zero-stabilized amplification chip；Three terminal regulator, negative voltage produce chip, light Ionized gas sensor socket, metal oxide sensor socket are connected respectively.

Described signal conditioning circuit composition includes a resistance, an electric capacity and a Zener diode, wherein resistance one Termination chopper-zero-stabilized amplification chip, the resistance other end and capacitances in series, the electric capacity other end is grounded, and electric capacity is with Zener diode simultaneously Connection, Zener diode positive ending grounding, negative terminal is connected with capture card.

The beneficial effects of the utility model are:

This utility model be a kind of new can test Multiple Type, the test system of multiple sensor simultaneously, existing Sensor testing system can not complete the multiple individual tests to variety classes sensor simultaneously.This patent is served a kind of new Type is combined stench detection means, and this device is directed to multiple sensor combinations that different detection environment adopt Multiple Type, in assembling Need to test used sensor characteristics before, the individuality being unsatisfactory for performance requirement is rejected, therefore this patent is permissible Test while realizing different sensors are combined, draws the response curve of different sensors under a certain same gas environment simultaneously Preserve, be analyzed obtaining a result by software program.

Below with reference to accompanying drawing, the technique effect of this utility model design, concrete structure and generation is described further, So that those skilled in the art is fully understood from the purpose of this utility model and effect.

Brief description

Fig. 1 is the overall structure block diagram of this multichannel polytypic sensor performance test system

Fig. 2 is the structured flowchart of this multichannel polytypic sensor performance test system and test unit

Fig. 3 is this multichannel polytypic sensor performance test system gas path module structural representation

Fig. 4 is tested sensor ageing experimental signal oscillogram, wherein,

Fig. 4 .1 is tested sensor ageing experiment first day evening eight oscillogram when late nine

Fig. 4 .2 is tested sensor ageing experiment second day evening eight oscillogram when late nine

Fig. 4 .3 is tested sensor ageing experiment the 3rd day evening eight oscillogram when late nine

Fig. 4 .4 is tested sensor ageing experiment the 4th day evening eight oscillogram when late nine

Fig. 4 .5 is tested sensor ageing experiment the 5th day evening eight oscillogram when late nine

Fig. 4 .6 is tested sensor ageing experiment the 6th day evening eight oscillogram when late nine

Fig. 4 .7 is tested sensor ageing experiment the 7th day evening eight oscillogram when late nine

Fig. 5 is tested sensor dynamic characteristic test experiments result oscillogram, wherein,

Fig. 5 .1 is first time tested sensor dynamic characteristic test experiments result oscillogram

Fig. 5 .2 is second tested sensor dynamic characteristic test experiments result oscillogram

Fig. 5 .3 is the tested sensor dynamic characteristic test experiments result oscillogram of third time

Fig. 6 is the gas concentration-response magnitude broken line graph of tested sensor

Specific embodiment

A kind of multichannel polytypic sensor performance test system, this system is by gas path module 1, test cell 2, button mould Block 3 capture card 4, host computer 5 five part composition.

Described gas path module 1, for fixing, connecting test unit, meets under gas with various concentration to gas sensor The needs of dynamic response performance test.

Described test cell 2 is used for installing sensor to be measured, carries out signal condition and amplification to output voltage signal, and will Signal transmission is to capture card 4.

The signal of described capture card 4 energy Real-time Collection test cell transmission simultaneously transmits to host computer 5, thus realizing in difference Test to sensor dynamic characteristic under the conditions of gas concentration.

Described host computer 5 installs test analysis software, the sensor signal collecting is analyzed process, draws tested The parameters of sensor.

Wherein,

The composition of described gas path module 1 as shown in figure 3, include air chamber 13, micro air pump 17, air inlet pipe 11, air inlet pipe 15, Escape pipe 18, electromagnetic valve 12, electromagnetic valve 16.

The path that described air inlet pipe 11, air inlet pipe 15 merge into is connected with the air inlet of air chamber 13；Escape pipe 18 is through air pump 17 are connected with the gas outlet of air chamber 13；It is respectively arranged with electromagnetic valve 12 and electromagnetic valve 16 in air inlet pipe 11, air inlet pipe 15；Electromagnetic valve 12 are connected with key-press module 3 respectively with electromagnetic valve 16；

Micro air pump is commercially available prod, and the qc-1s type air that model Beijing Municipal Institute of Labour Protection produces is adopted Sample instrument, is autonomous device, internal dry cell power supply, is provided with the function buttons such as startup, stopping, flow velocity plus-minus, manual control.

Described key-press module 3 is connected with the electromagnetic valve 12 in gas path module 1 and electromagnetic valve 16 respectively.This module is used for controlling Electromagnetic valve processed must close, and is known technology, commercially available.

Described test cell 2 is arranged in air chamber 13, and its composition is as shown in Fig. 2 inclusion power supply circuits 20 are identical with composition Eight passages, each passage composition include sensor array 21, pre-amplification circuit 22, signal conditioning circuit 23；It connects Relation is: power supply circuits 20 are connected with the sensor array 21 of eight passages, pre-amplification circuit 22 respectively；Pass in each passage Sensor array 21, pre-amplification circuit 22 and signal conditioning circuit 23 are sequentially connected；The signal conditioning circuit 23 of each passage with Capture card 4 is connected, and capture card 4 is connected with host computer 5.

The composition of described power supply circuits 20 includes the Switching Power Supply of 12v, l7805 three terminal regulator, ams1117 forward direction low pressure Fall manostat and max660 negative voltage produce chip, and wherein, the Switching Power Supply of 12v is connected with l7805 three terminal regulator, l7805 Three terminal regulator produces chip and is connected with ams1117 forward direction low dropout voltage regulator, max660 negative voltage respectively.The switch electricity of 12v Source is connected with l7805 three terminal regulator and is converted into+5v unidirectional current；L7805 three terminal regulator and ams1117 forward direction low pressure drop voltage stabilizing Device connects, and exports+3.3v unidirectional current；L7805 three terminal regulator produces chip with max660 negative voltage and is connected, and exports -5v direct current Electricity.

The composition of described sensor array 21 is included photoionization gas sensor socket and is inserted with metal oxide sensor Seat, the two is connected by wire jumper.Photoionization gas sensor socket is connected with l7805 three terminal regulator, and metal-oxide passes Sensor socket is connected with ams1117 forward direction low dropout voltage regulator.L7805 three terminal regulator connects the+5v unidirectional current producing and light Ionized gas sensor socket connects, and ams1117 forward direction low dropout voltage regulator connects the+3.3v unidirectional current producing and metal oxygen Compound sensor socket connects.

Described photoionization gas sensor socket is used for installing photoionization gas sensor to be measured.

Described metal oxide sensor socket is used for installing metal oxide sensor to be measured.

Described pre-amplification circuit 22 composition includes 7650 chopper-zero-stabilized amplification chips, l7805 three terminal regulator, max660 Negative voltage generation chip, photoionization gas sensor socket, metal oxide sensor socket are connected respectively.

L7805 three terminal regulator is connected the+5v unidirectional current producing and is connected with 7650 chopper-zero-stabilized amplification chips；Max660 bears - 5v the unidirectional current that voltage produces chip connection generation is connected with 7650 chopper-zero-stabilized amplification chips；Photoionization gas sensor The input signal being produced with metal oxide sensor is connected with 7650 chopper-zero-stabilized amplification chips.

Described signal conditioning circuit 23 composition includes a resistance, an electric capacity and a Zener diode, wherein resistance One termination 7650 chopper-zero-stabilized amplification chips, the resistance other end and capacitances in series, electric capacity other end ground connection, electric capacity and voltage stabilizing two pole Pipe is in parallel, Zener diode positive ending grounding, and negative terminal is connected with capture card 4.

The input signal that 7650 chopper-zero-stabilized amplification chips produce is connected with resistance.

Described electromagnetic valve 12,16 is used for controlling the inflow of sample gas or clean gas.

Described micro air pump 17 is used for providing negative pressure, by sample gas or clean gas suction air chamber 13.

Power supply circuits 20 are sensor array 21, pre-amplification circuit 22 provides running voltage；Sensor array 21 is used for Sensor to be measured is installed；The voltage signal that pre-amplification circuit 22 exports to sensor carries out scaling；Signal conditioning circuit Sensor signal after 23 pairs of amplifications is filtered processing.

Described upper computer software program is write with labview2012, can achieve and shows in real time and store capture card and adopt The signal collecting, and the characterisitic parameter of sensor is drawn by respective algorithms.Described software programming and related protocol are known Technology.

The index of dynamic characteristic is typically response time.Sensor all has time delay to the response of object gas, to electrochemistry Formula sensor response time is no more than 25 seconds, and the response time of pid sensor is no more than 3 seconds, metal oxide sensor The storage of response time and sensor during atmospheric condition, storage time length relevant.

This characteristic is responded according to sensor time delay, sets up single order delay model, transmission function is:

$h\left(s\right)=\frac{\mathrm{\τ}}{s+\mathrm{\τ}}---\left(1\right)$

Signal normalization responsing excitation is:

$x\left(t\right)=\frac{1}{u\left(t\right)}---\left(2\right)$

The frequency-domain expression of signal response is:

$y\left(s\right)=h\left(s\right)\·x\left(s\right)=\frac{\mathrm{\τ}}{s(s+\mathrm{\τ})}---\left(3\right)$

Signal response frequency-domain expression is carried out pull-type inverse transformation, the time-domain expression obtaining signal response is:

Y (t)=u (t) (1-e^-τt) (4)

Normalized is gone to signal response time-domain expression, obtains the model that each sensor responds to gas signal For:

Y (t)=a (1-e^-τt) (5)

Wherein a is the response quautity to gas signal for the sensor, and τ is the speed of response to gas signal for the sensor, and reflection passes The delay degree of sensor response.

Gas sensor, under best operating condition, contacts same gas, its resistance ratio r_s/r₀With gas concentration change Characteristic be referred to as sensitivity, represented with k:

K=r_s/r₀(6)

R in formula₀Be gas sensor under regular air conditions (in pure air) resistance value, r_sFor gas sensor Resistance value in finite concentration detected gas.

Specific embodiment one:

The sensor selecting is carried out with burin-in process, when experiment starts, control button module opens electromagnetic valve 12, same to seasonal epidemic pathogens Pump is started working, and nitrogen is pumped in gas path module 1, the metal oxide sensor socket of eight passages in test cell 2 Upper installation same model, the photoionization gas sensing with a batch of metal oxide sensor to be measured or in eight passages Same model is installed on device socket, is tested with a batch of photoionization gas sensor to be measured, test cell 2 will simultaneously In eight passages, the voltage signal of signal conditioning circuit 23 output is transmitted to host computer 5 by capture card 4.Ageing process continues Carry out 7 days totally 168 hours, preserve experimental data at the end of experiment and data is analyzed.Passed with brand-new metal-oxide As a example sensor tgs2602, according to its own characteristic, in ageing process early stage, sensor voltage signal is unstable, and fluctuation is relatively Greatly, when voltage signal undulate quantity is stablized ± 5%, illustrate that sensor ageing process terminates.

Intercept the waveform of time period when late nine in evening eight daily in tested sensor seven days respectively, choose one of quilt Average, oscillogram and the experimental result of surveying sensor ratio compared with every section of waveform in its seven days experimental periods are as shown in figure 4, seven sections of waveforms Average voltage be followed successively by 2.40v, 2.72v, 2.54v, 2.87v, 2.85v, 2.96v, 3.02v, in laboratory constant temperature, nitrogen be Under conditions of background gas, the average voltage in the daily same time period for the same sensor can reflect the zero point of this sensor Response condition, relatively above-mentioned seven numerical value can be found that the zero point response of this sensor is in that slow rising becomes with the increase of natural law Gesture is it was demonstrated that the zero point of this sensor occurs in that drift situation upwards in the experimental period of seven days.

Specific embodiment two:

Device is started working, control button module, and the first electromagnetic valve 12 is opened, and the second electromagnetic valve 16 closes, artificial behaviour The concentration having configured is the h of 5.1ppm by control micro air pump 17₂S gas is from sample gas air inlet pipe 11 suction built-in testing unit 2 air chamber 13 (described air chamber 13 is tubular structure, and test cell 2 integral installation is in the path of air chamber 13), test cell 2 In the tgs2602 type metal oxide sensor that is arranged on metal oxide sensor socket can produce corresponding voltage letter Number, voltage signal is amplified process via pre-amplification circuit 22, signal conditioning circuit 23 is filtered processing, and then passes through Capture card 4 finally transmits to host computer 5 to be drawn voltage change curve figure and preserves.The miniature gas of manual control after the completion of information processing Waste gas is discharged to the outside environment by exhaustor 18 by pump 17.Then electromagnetic valve 12 closes, and electromagnetic valve 16 is opened, and cleaning nitrogen is from clear Clean gas inlet pipe 15 enters the air chamber 13 being built-in with sensor array 21, and last manual control micro air pump 17 is by waste gas by arranging Trachea 18 is discharged to the outside environment, completes the cleaning of whole device.Above-mentioned experimentation repeats three times, Fig. 5 .1, figure 5.2nd, Fig. 5 .3 is respectively same is test for three experimental data waveforms that tgs2602 metal oxide sensor is collected, The timeconstantτ of three times is respectively 3.6070,3.6326,3.9088.

Specific embodiment three:

H with concentration as 5.1ppm when experiment starts₂S gas is calibrating gas, according to calibrating gas percentage is 5%th, 10%, 20%, 40%, 60%, 80%, 100% it is mixed with the h of seven kinds of concentration with nitrogen₂S gas, and press h₂S gas Concentration order from low to high is tested successively.Control button module, the first electromagnetic valve 12 is opened, and the second electromagnetic valve 16 closes Close, manual control micro air pump 17 is by the h of a certain concentration₂S gas is from sample gas air inlet pipe 11 suction built-in testing unit 2 Air chamber 13, the tsg2602 type metal oxide sensor meeting being arranged on metal oxide sensor socket in test cell 2 Produce corresponding voltage signal, voltage signal is amplified process via pre-amplification circuit 22, signal conditioning circuit 23 is carried out Filtering Processing, is then finally transmitted to host computer 5 by capture card 4 and draws voltage change curve figure and preserve.Information processing is complete After one-tenth, waste gas is discharged to the outside environment by exhaustor 18 by manual control micro air pump 17.Then electromagnetic valve 12 closes, electromagnetic valve 16 open, and cleaning nitrogen enters the air chamber 13 being built-in with sensor array 21, last manual control from clean gas air inlet pipe 15 Waste gas is discharged to the outside environment by exhaustor 18 by micro air pump 17, completes the cleaning of whole device.Selection one is tested Tgs2602 type metal oxide sensor is analyzed to its waveform voltage signal, and corresponding for variable concentrations response magnitude is made folding Line chart simultaneously simulates response curve, as shown in fig. 6, the straight line simulating represents tested sensor to variable concentrations hydrogen sulfide gas Response sensitivity.

The final purpose of this device is according to above test data, tested sensor to be screened, to being unsatisfactory for sensor The tested individuality of handbook regulation parameter is rejected, and individuality satisfactory to characteristic mates according to surveyed parameter, for outer Enclosing circuit design provides foundation.

This utility model unaccomplished matter is known technology.

Claims (5)

1. a kind of multichannel polytypic sensor performance test system, it is characterized by the composition of this system includes gas path module, survey Examination unit, key-press module, capture card and host computer；

The composition of described gas path module includes air chamber, micro air pump, air inlet pipe, air inlet pipe, escape pipe, electromagnetic valve and electromagnetic valve； Wherein, the path that described air inlet pipe, air inlet pipe merge into is connected with the air inlet of air chamber；Escape pipe is given vent to anger through air pump and air chamber Mouth is connected；It is respectively arranged with electromagnetic valve and electromagnetic valve in air inlet pipe, air inlet pipe；Electromagnetic valve and electromagnetic valve respectively with key-press module phase Even；

Described test cell is arranged in air chamber, and its composition includes power supply circuits and composition eight passages of identical, each passage Composition includes sensor array, pre-amplification circuit and signal conditioning circuit；Its annexation is: power supply circuits respectively with each The sensor array of passage, pre-amplification circuit are connected；Sensor array, pre-amplification circuit and signal condition in each passage Circuit is sequentially connected；The signal conditioning circuit of each passage is connected with capture card respectively, and capture card is connected with host computer.

2. multichannel polytypic sensor performance test system as claimed in claim 1, it is characterized by described power supply circuits Switching Power Supply, three terminal regulator, positive low dropout voltage regulator and negative voltage that composition includes 12v produce chip, wherein, 12v's Switching Power Supply is connected with three terminal regulator, and three terminal regulator produces chip with positive low dropout voltage regulator, negative voltage respectively and is connected.

3. multichannel polytypic sensor performance test system as claimed in claim 1, it is characterized by described sensor array Composition include photoionization gas sensor socket and metal oxide sensor socket, the two is connected by wire jumper；Light from Sub- activating QI body sensor socket is connected with three terminal regulator, and metal oxide sensor socket is with positive low dropout voltage regulator even Connect.

4. multichannel polytypic sensor performance test system as claimed in claim 1, it is characterized by described preposition amplification electricity Road composition includes chopper-zero-stabilized amplification chip；Three terminal regulator, negative voltage produce chip, photoionization gas sensor socket, Metal oxide sensor socket is connected respectively.

5. multichannel polytypic sensor performance test system as claimed in claim 1, it is characterized by described signal condition is electric Road composition includes a resistance, an electric capacity and a Zener diode, wherein resistance one termination chopper-zero-stabilized amplification chip, electricity The resistance other end and capacitances in series, the electric capacity other end is grounded, and electric capacity is in parallel with Zener diode, Zener diode positive ending grounding, bears End is connected with capture card.