Audio amplifier yog ib lo lus dav dav siv los piav txog lub voj voog uas tsim tawm thiab nthuav tawm cov qauv ntawm nws cov teeb liab tawm tswv yim. Txawm li cas los xij, tsis yog txhua qhov kev hloov pauv thev naus laus zis zoo ib yam li lawv tau muab cais raws li lawv cov kev teeb tsa thiab kev ua haujlwm.
Hauv cov khoom siv hluav taws xob, cov tshuab hluav taws xob me feem ntau siv vim tias lawv tuaj yeem ua kom lub suab nrov me me, xws li los ntawm lub ntsuas hluav taws xob xws li lub suab paj nruag, mus rau lub teeb liab tso zis ntau dua los tsav lub relay, teeb lossis lub suab nrov., thiab lwm yam
Muaj ntau hom hluav taws xob hluav taws xob faib ua cov khoom siv hluav taws xob, los ntawm kev ua haujlwm thiab cov teeb liab me me mus rau cov mem tes loj thiab lub zog hloov pauv. Kev faib tawm ntawm ib lub cuab yeej nyob ntawm qhov loj ntawm lub teeb liab, loj lossis me, nws lub cev kev teeb tsa, thiab yuav ua li cas cov kwj nkag tau ua tiav, uas yog, kev sib raug zoo ntawm qib input thiab tam sim no ntws hauv lub load.
Device Anatomy
Suab zaus amplifiers tuaj yeem pom raws li lub thawv yooj yimlos yog ib lub thaiv uas muaj cov cuab yeej, xws li bipolar, FET, los yog kev ua haujlwm sensor, uas muaj ob lub tswv yim thiab ob qhov tso zis tawm (hauv av yog qhov ntau). Ntxiv mus, lub teeb liab tso zis ntau dua vim nws hloov dua siab tshiab ntawm lub cuab yeej.
Ib qho zoo tshaj plaws teeb liab amplifier yuav muaj peb lub ntsiab:
- Input impedance, lossis (R IN).
- Tawm tawm tsis kam, lossis (R OUT).
- Gain, lossis (A).
Txawm hais tias lub zog ntawm lub tshuab hluav taws xob ua haujlwm nyuaj npaum li cas, cov qauv thaiv dav dav tuaj yeem siv los ua kom pom kev sib raug zoo ntawm peb lub zog.
Cov ntsiab lus dav dav
Lub suab nrov zoo yuav txawv ntawm qhov ua tau zoo. Txhua hom muaj qhov hloov pauv digital lossis analog. Cov lej raug teem kom cais lawv.
Qhov sib txawv ntawm cov tswv yim thiab cov zis tawm yog hu ua kev hloov pauv. Tau txais yog ib qho kev ntsuas ntawm ntau npaum li cas lub amplifier "transforms" lub teeb liab input. Piv txwv li, yog hais tias muaj ib theem input ntawm 1 volt thiab cov zis theem ntawm 50 volts, ces kev hloov dua siab tshiab yuav yog 50. Nyob rau hauv lwm yam lus, lub input teeb liab tau tsim 50 zaug. Lub suab zaus amplifier ua li ntawd xwb.
Kev suav hloov pauv tsuas yog qhov piv ntawm cov zis faib los ntawm cov tswv yim. Qhov system no tsis muaj units raws li nws qhov sib piv, tab sis hauv electronics lub cim A feem ntau yog siv rau kev nce. Qhov kev hloov dua siab tshiab yog tsuas yog xam raws li "cov zis faib los ntawm kev tawm tswv yim".
Power converters
Magnifier me meLub teeb liab amplifier feem ntau hu ua "voltage" amplifier vim nws nyiam hloov cov tswv yim me me mus rau qhov tso zis ntau dua. Qee lub sij hawm lub tshuab hluav taws xob yuav tsum tau tsav lub cev muaj zog lossis lub suab nrov, thiab rau cov kev siv no, qhov twg muaj kev hloov pauv siab, xav tau cov tshuab hloov hluav taws xob.
Raws li lub npe qhia, lub luag haujlwm tseem ceeb ntawm lub zog amplifier (tseem hu ua lub teeb liab amplifier loj) yog muab lub zog rau lub nra. Nws yog cov khoom siv hluav taws xob thiab tam sim no siv rau kev thauj khoom nrog lub zog tso zis ntau dua li theem teeb liab tawm tswv yim. Hauv lwm lo lus, lub converter nce lub zog ntawm tus neeg hais lus, yog li no hom thaiv Circuit Court yog siv nyob rau hauv cov theem sab nraud ntawm lub converters rau tsav cov neeg hais lus.
Txoj Cai Ua Haujlwm
Lub suab amplifier ua haujlwm ntawm lub hauv paus ntsiab lus ntawm kev hloov pauv DC lub zog rub los ntawm lub zog hluav taws xob rau hauv AC voltage teeb liab muab rau lub nra. Txawm hais tias kev hloov dua siab tshiab yog siab, qhov ua tau zoo ntawm DC fais fab mov mus rau AC voltage tso zis teeb liab feem ntau qis.
Ib qho thaiv zoo tshaj muab lub cuab yeej ua haujlwm ntawm 100% lossis tsawg kawg lub zog IN yuav sib npaug rau lub zog OUT.
chav faib
Yog tias cov neeg siv tau saib ntawm qhov tshwj xeeb ntawm lub tshuab hluav taws xob lub zog, lawv yuav tau pom cov chav kawm, feem ntau txhais los ntawm tsab ntawv lossisob. Cov hom thaiv feem ntau siv hauv cov neeg siv khoom hauv tsev niaj hnub no yog A, A / B, D, G, thiab H qhov tseem ceeb.
Cov chav kawm no tsis yog cov txheej txheem kev faib tawm yooj yim, tab sis cov lus piav qhia ntawm amplifier topology, uas yog, lawv ua haujlwm li cas ntawm qib tseem ceeb. Txawm hais tias txhua hom amplifier muaj nws tus kheej cov kev ua tau zoo thiab qhov tsis muaj zog, lawv qhov kev ua tau zoo (thiab qhov ntsuas qhov kawg li cas) tseem zoo ib yam.
Nws yog los hloov lub waveform xa los ntawm pre-unit yam tsis qhia kev cuam tshuam los yog tsawg kawg yog me ntsis distortion li sai tau.
Klass A
Piv rau lwm cov chav kawm ntawm lub suab lub zog amplifiers uas yuav tau piav qhia hauv qab no, Chav A qauv yog cov khoom siv yooj yim. Lub ntsiab lus txhais ntawm kev ua haujlwm yog tias tag nrho cov transducer tso zis blocks yuav tsum mus dhau 360-degree teeb liab voj voog.
Class A kuj tuaj yeem muab faib ua ib qho kawg thiab thawb-rub amplifiers. Push / rub txawv ntawm cov lus piav qhia tseem ceeb saum toj no los ntawm kev siv cov khoom siv tso tawm ua khub. Thaum ob lub cuab yeej khiav tag nrho 360-degree lub voj voog, ib lub cuab yeej yuav nqa feem ntau ntawm cov khoom thauj thaum lub sijhawm zoo ntawm lub voj voog, thaum lwm qhov yuav nqa ntau lub voj voog tsis zoo.
Qhov txiaj ntsig tseem ceeb ntawm qhov Circuit Court no txo qis kev sib txawv piv rau cov qauv tsim ib leeg, txij li txawm tias qhov kev txiav txim hloov pauv tau raug tshem tawm. Tsis tas li ntawd, Class A push-rub designs tsis tshua muaj suab nrov.
Vim tias cov txiaj ntsig zoo cuam tshuam nrog Class A kev ua tau zoo, nws suav tias yog tus qauv kub rau lub suab zoo hauv ntau daim ntawv thov acoustic. Txawm li cas los xij, cov qauv tsim no muaj ib qho tseem ceeb drawback - efficiency.
Yuav tsum tau rau Class A transistor audio amplifiers kom muaj tag nrho cov khoom tso tawm rau txhua lub sijhawm. Qhov kev ua no ua rau lub zog poob qis, uas thaum kawg hloov mus rau hauv tshav kub. Qhov no yog ntxiv exacerbated los ntawm qhov tseeb hais tias Class A designs yuav tsum tau cov theem siab ntawm quiescent tam sim no, uas yog tus nqi ntawm tam sim no ntws los ntawm cov tso zis li thaum lub amplifier yog tsim los zero output. Cov txiaj ntsig tiag tiag hauv ntiaj teb tuaj yeem nyob rau hauv qhov kev txiav txim ntawm 15-35%, nrog rau ib tus lej tau siv cov khoom siv zoo heev.
Klass B
Txawm hais tias tag nrho cov khoom tso tawm hauv chav kawm A lub suab amplifier siv 100% ntawm lub sijhawm ua haujlwm, chav kawm B siv thawb-rub circuitry xws li tsuas yog ib nrab ntawm cov khoom tso tawm tau ua txhua lub sijhawm.
Ib nrab npog qhov +180 degree ntawm qhov nthwv dej thaum lwm ib nrab npog qhov -180 degree. Raws li qhov tshwm sim, Class B amplifiers muaj txiaj ntsig zoo dua li lawv cov chav kawm A, nrog rau qhov theoretical siab tshaj plaws ntawm 78.5%. Muab qhov ua tau zoo heev, Chav B tau siv rau hauv qee qhov kev tshaj lij PA transducers nrog rau qee lub tshuab raj hauv tsev. Txawm lawvpom tseeb lub zog, txoj hauv kev tau txais cov chav kawm B block rau lub tsev yog xyaum xoom. Kev ntsuam xyuas ntawm lub suab amplifier pom qhov ua rau ntawm qhov no, hu ua crossover distortion.
Qhov teeb meem nrog latency hauv kev xa khoom ntawm cov khoom siv ua qhov zoo thiab qhov tsis zoo ntawm cov qauv nthwv dej yog suav tias yog qhov tseem ceeb. Nws mus yam tsis tau hais tias qhov kev hloov pauv no tau hnov hauv qhov ntau txaus, thiab thaum qee qhov Class B tsim tau zoo dua li lwm tus hauv qhov no, Chav B tau txais kev lees paub me me los ntawm cov neeg nyiam huv huv.
Klass A/B
Lub raj lub suab nrov tuaj yeem pom hauv ntau qhov chaw ua yeeb yam. Nws muaj kev ua haujlwm siab thiab tsis overheat. Tsis tas li ntawd, cov qauv yog pheej yig dua li ntau cov blocks digital. Tab sis kuj muaj deviations. Xws li ib tug module yuav tsis ua hauj lwm nrog tag nrho cov suab tawm tswv yim. Yog li ntawd, nws yog qhov zoo dua los siv cov cuab yeej ua ib feem ntawm kev teeb tsa kev ua haujlwm.
Class A / B sib xyaw ua ke zoo tshaj plaws ntawm txhua hom khoom siv los tsim ib chav tsev yam tsis muaj qhov tsis zoo ntawm ob qho tib si. Nrog rau qhov kev sib xyaw ua ke ntawm qhov zoo, chav kawm A / B amplifiers feem ntau ua rau cov neeg siv khoom lag luam.
Kev daws yog qhov yooj yim heev hauv lub tswv yim. Qhov twg hauv chav kawm B siv lub tshuab thawb-rub nrog txhua ib nrab ntawm cov zis theem ua 180 degrees, chav kawm A / B cov txheej txheem nce mus rau ~ 181-200 degrees. Yog li, muajTsis tshua muaj "kua kua muag" nyob rau hauv lub voj, thiab yog li ntawd tus crossover distortion poob mus rau qhov uas nws tsis muaj teeb meem.
Valve audio power amplifiers tuaj yeem nqus qhov cuam tshuam sai dua. Ua tsaug rau cov cuab yeej no, lub suab tawm ntawm lub cuab yeej ntau dua. Cov qauv ntawm cov yam ntxwv no feem ntau yog siv los hloov lub suab ntawm acoustic thiab hluav taws xob guitars.
Txaus siab rau nws hais tias Chav A / B xa tawm ntawm nws cov lus cog tseg, yooj yim ua haujlwm zoo dua Chav A tsim ntawm ~ 50-70% kev ua tau zoo hauv ntiaj teb. Qhov tseeb, ntawm chav kawm, nyob ntawm seb lub amplifier offset ntau npaum li cas, nrog rau cov khoom siv thiab lwm yam. Nws tseem tsim nyog sau cia tias qee qhov Class A / B designs mus rau ib kauj ruam ntxiv hauv lawv qhov kev tshawb nrhiav kom tshem tawm kev sib txawv ntawm kev sib txawv los ntawm kev khiav hauj lwm hauv hom ntshiab Class A mus txog ob peb watts ntawm lub zog. Qhov no muab qee qhov kev ua tau zoo ntawm qib qis, tab sis ua kom lub suab nrov tsis tig mus rau hauv lub qhov cub thaum siv lub zog loj.
Chav G thiab H
Lwm khub ntawm cov qauv tsim los txhim kho kev ua haujlwm zoo. Los ntawm kev pom, tsis muaj chav G lossis chav H amplifiers raug lees paub. Hloov chaw, lawv yog cov kev hloov pauv ntawm Chav Kawm A / B lub ntsiab lus siv lub npav hloov hluav taws xob thiab kev hloov tsheb npav, feem. Txawm li cas los xij, nyob rau hauv cov kev xav tau tsawg, lub kaw lus siv lub tsheb npav qis dua li cov chav kawm A / B amplifier zoo sib xws, uas loj heev.txo hwj chim noj. Thaum muaj hluav taws xob loj tshwm sim, lub kaw lus dynamically nce lub tsheb npav voltage (piv txwv li hloov mus rau lub tsheb npav siab) txhawm rau ua haujlwm siab amplitude transients.
Tseem muaj qhov tsis haum. Thawj ntawm lawv yog tus nqi siab. Tus thawj network hloov circuits siv bipolar transistors los tswj cov zis ntws, ntxiv complexity thiab nqi. Qhov zoo tshaj plaws lub suab nrov zaus amplifiers ntawm hom no muaj ntau, txawm hais tias tus nqi pib ntawm 50 txhiab rubles. Qhov thaiv yog suav tias yog cov txheej txheem kev tshaj lij rau kev ua haujlwm ntawm theem lossis kaw hauv studio. Muaj teeb meem nrog transistors. Raws li kev thauj khoom ntev, qee qhov ntawm lawv yuav ua tsis tiav.
Hnub no, tus nqi feem ntau txo qis rau qee qhov los ntawm kev siv MOSFETs tam sim no los xaiv lossis hloov cov lus qhia. Kev siv MOSFETs tsis yog tsuas yog txhim kho kev ua tau zoo thiab txo cov cua sov, tab sis kuj yuav tsum tau tsawg dua qhov chaw (feem ntau yog ib qho khoom siv ib lub xov tooj). Ntxiv rau tus nqi ntawm kev hloov tsheb npav, qhov kev hloov kho nws tus kheej, nws tseem tsim nyog sau cia tias qee chav G amplifiers siv cov khoom siv tso zis ntau dua li cov chav kawm A / B tsim.
Ib khub ntawm cov khoom siv yuav ua haujlwm hauv hom A / B, siv los ntawm cov hluav taws xob tsis tshua muaj hluav taws xob. Meanwhile, lwm tus yog nyob rau standby los ua ib tug voltage booster, activated tsuas yog nyob ntawm qhov xwm txheej. Nrog siab loads tsuas yog chav G thiab H,cuam tshuam nrog lub zog amplifiers, qhov twg qhov kev ua tau zoo dua them tawm. Cov qauv tsim qauv kuj tseem siv tau rau hauv chav kawm G / H topologies uas tsis yog A / B muab tias muaj peev xwm hloov mus rau hom qis zog txhais tau tias lawv tuaj yeem tawm mus nrog me ntsis heatsink.
Class D
hom khoom siv no tso cai rau koj los tsim koj tus kheej lub tshuab modular. Nrog kev pab los ntawm cov cuab yeej siv, kev ua haujlwm zoo ntawm tag nrho cov kwj tawm yuav tshwm sim. Tsim lub suab zaus lub zog amplifiers tso cai rau koj los tsim koj tus kheej multimedia system rau kev ua haujlwm lossis kev lom zem. Txawm li cas los xij, muaj qee qhov nuances ntawm no. Feem ntau erroneously hu ua digital amplification, chav kawm D converters yog ib tug guarantee ntawm chav tsev efficiency thiab ua tau zoo tshaj li ntawm 90% nyob rau hauv qhov tseeb xeem.
Ua ntej nws tsim nyog xav txog vim li cas qhov no yog chav kawm D yog "digital amplification" tsis raug. Nws tsuas yog tsab ntawv tom ntej hauv cov tsiaj ntawv, nrog rau chav kawm C siv hauv cov tshuab suab. Qhov tseem ceeb tshaj, yuav ua li cas 90% + kev ua tau zoo tuaj yeem ua tiav. Thaum tag nrho cov chav kawm amplifier tau hais dhau los muaj ib lossis ntau cov khoom siv tso tawm uas ua haujlwm tas li txawm tias lub converter tiag tiag nyob rau hauv hom standby, chav kawm D tau hloov pauv sai sai. Qhov no yooj yim heev thiab ua rau nws tuaj yeem siv lub module tsuas yog lub sijhawm zoo xwb.
Piv txwv li, kev suav ntawm chav kawm T suab amplifiers, uas yogTripath's class D kev siv, tsis zoo li cov cuab yeej siv yooj yim, siv cov zaus hloov pauv ntawm qhov kev txiav txim ntawm 50 MHz. Cov khoom tso zis feem ntau yog tswj los ntawm pulse width modulation. Qhov no yog thaum cov square nthwv dej ntawm qhov dav sib txawv yog tsim los ntawm lub modulator uas nthuav tawm cov teeb liab analog rau kev ua si. Nrog kev tswj hwm nruj ntawm cov khoom siv hauv qhov no, 100% kev ua tau zoo yog qhov ua tau raws li kev xav tau (txawm tias pom tseeb tsis tuaj yeem ua tiav hauv lub ntiaj teb tiag tiag).
Kev khawb mus rau hauv lub ntiaj teb ntawm chav kawm D suab amplifiers, koj tuaj yeem nrhiav tau hais txog analog thiab digital tswj modules. Cov kev tswj hwm no muaj cov teeb liab analog tawm tswv yim thiab cov kev tswj hwm analog, feem ntau nrog qee qhov kev tawm tswv yim kho qhov yuam kev. Ntawm qhov tod tes, digital conversion class D amplifiers siv digital tswj, uas hloov lub zog theem yam tsis muaj qhov yuam kev. Qhov kev txiav txim siab no kuj pom kev pom zoo, raws li kev tshuaj xyuas ntawm ntau tus neeg yuav khoom. Txawm li cas los xij, nqe nqe yog ntau dua ntawm no.
Kev tshawb fawb suab nrov tau pom tias cov chav kawm analog-driven D muaj qhov ua tau zoo dua li cov analog analog, raws li nws feem ntau muab cov khoom tso tawm qis dua (tsis kam) thiab txhim kho qhov sib txawv ntawm qhov profile. Qhov no nce qhov tseem ceeb ntawm qhov system ntawm nws qhov siab tshaj plaws load.
Cov kev txwv ntawm lub suab zaus amplifiers ntau dua li cov qauv ntawm cov qauv yooj yim. Nws yuav tsum to taub hais tias xws li kev xam yuav tsum tau tsuas yog rau kev tsim suab paj nruag nyob rau hauv lub studio. Rau cov neeg yuav khoom zoo tib yam, cov noCov yam ntxwv tuaj yeem hla.
Feem ntau yog L-circuit (inductor thiab capacitor) muab tso rau nruab nrab ntawm lub amplifier thiab lub suab nrov kom txo tau lub suab nrov cuam tshuam nrog chav kawm D. Lub lim yog qhov tseem ceeb heev. Kev tsim tsis zoo tuaj yeem cuam tshuam kev ua haujlwm, kev cia siab, thiab suab zoo. Tsis tas li ntawd, tawm tswv yim tom qab tso zis lim muaj nws qhov zoo. Txawm hais tias cov qauv tsim uas tsis siv cov lus tawm tswv yim ntawm theem no tuaj yeem kho lawv cov lus teb rau qhov tshwj xeeb impedance, thaum cov amplifiers muaj cov khoom hnyav (piv txwv li lub suab nrov tsis yog lub resistor), cov lus teb zaus tuaj yeem sib txawv heev nyob ntawm qhov load ntawm tus hais lus. Kev tawm tswv yim ua kom qhov teeb meem no ruaj khov los ntawm kev muab cov lus teb zoo rau kev thauj khoom nyuaj.
Thaum kawg, qhov nyuaj ntawm Class D audio amplifiers muaj nws cov txiaj ntsig. Kev ua tau zoo thiab, yog li ntawd, qhov hnyav dua. Txij li thaum lub zog me me tau siv rau ntawm tshav kub, ntau lub zog yuav tsum muaj tsawg. Raws li xws li, ntau chav kawm D amplifiers tau siv ua ke nrog cov khoom siv hluav taws xob hloov pauv (SMPS). Zoo li lub sijhawm tso zis, lub zog hluav taws xob nws tus kheej tuaj yeem qhib thiab tawm sai sai los tswj qhov hluav taws xob, ua rau muaj txiaj ntsig ntxiv thiab muaj peev xwm txo qhov hnyav dua li cov khoom siv hluav taws xob analog / linear.
Hauv kev sib sau, txawm tias muaj zog hauv chav kawm D amplifiers tuaj yeem hnyav li ob peb kilograms. Qhov tsis zoo ntawm SMPS cov khoom siv hluav taws xob piv rau cov khoom siv linear ib txwm muajuas yav tas los feem ntau tsis muaj headroom ntau.
Kev sim thiab ntau qhov kev sim ntawm chav kawm D lub suab amplifiers nrog cov khoom siv hluav taws xob tawm piv rau SMPS modules tau pom tias qhov no yog qhov tseeb. Thaum ob lub amplifiers tau tuav lub zog ntsuas, tab sis ib qho uas muaj cov khoom siv hluav taws xob tuaj yeem tsim hluav taws xob ntau dua. Txawm li cas los xij, SMPS cov qauv tsim tau dhau los ua ntau qhov chaw thiab koj tuaj yeem cia siab tias yuav pom cov tiam tom ntej zoo dua Chav D chav nyob siv cov duab zoo sib xws hauv khw.
Kev sib piv ntawm qhov ua tau zoo ntawm chav kawm AB thiab D
Txawm hais tias qhov ua tau zoo ntawm Chav Kawm A / B transistorized lub zog lub zog amplifier nce raws li qhov siab tshaj plaws tso zis hluav taws xob mus txog, Chav D tsim muaj kev ua haujlwm siab tshaj qhov kev ua haujlwm feem ntau. Yog li ntawd, kev ua tau zoo thiab lub suab zoo tau nce mus rau qhov kawg thaiv.
Siv ib lub transducer
Thaum siv tau zoo, ib qho ntawm cov blocks saum toj no sab nraud ntawm chav kawm B tuaj yeem tsim lub hauv paus ntawm lub siab ncaj ncees amplifier. Ib cag ntawm qhov muaj peev xwm ua tau zoo (uas yog qhov kev txiav txim siab tsim qauv ntau dua li cov chav kawm tshwj xeeb), kev xaiv thaiv hom yog qhov tseem ceeb ntawm tus nqi piv rau kev ua haujlwm zoo.
Nyob hauv kev lag luam niaj hnub no, Chav Kawm A/B yooj yim lub suab amplifier dominates, thiab yog vim li cas. Nws ua haujlwm zoo heev, kuj pheej yig, thiab nwskev ua tau zoo yog qhov tsim nyog rau kev siv hluav taws xob tsawg (>200W). Ntawm chav kawm, raws li converter manufacturers sim thawb lub hnab ntawv nrog, piv txwv li, 1000W Emotiva XPR-1 monoblock, lawv tig mus rau G / H thiab D chav kawm tsim qauv kom tsis txhob duplicating lawv cov amplifiers raws li cov tshuab muaj peev xwm ua kom sov cov khoom sai. Lub caij no, nyob rau sab nraud ntawm kev ua lag luam, muaj cov kiv cua hauv chav kawm A uas tuaj yeem zam txim rau qhov tsis ua haujlwm ntawm cov cuab yeej hauv kev cia siab ntawm lub suab huv.
Result
Tom qab tag nrho, cov chav kawm hloov pauv tsis yog qhov tseem ceeb. Tau kawg muaj qhov sib txawv tiag tiag, tshwj xeeb tshaj yog thaum nws los txog rau tus nqi, amplifier efficiency thiab yog li qhov hnyav. Tau kawg, 500W chav kawm A cov khoom siv yog lub tswv yim phem, tshwj tsis yog, tau kawg, tus neeg siv muaj lub zog txias txias. Ntawm qhov tod tes, qhov sib txawv ntawm cov chav kawm tsis txiav txim siab lub suab zoo. Thaum kawg, nws los rau kev tsim thiab siv koj tus kheej tej yaam num. Nws yog ib qho tseem ceeb kom nkag siab tias cov transducers tsuas yog ib qho cuab yeej uas yog ib feem ntawm lub suab.
