 to the terrestrial reference frame so as to optimize at least one quality criterion relating to the set of seismic signals acquired by the receivers in respect of said area. A conventional voltage control device for a vehicle AC generator detects an output voltage of a generator and stops supplying a field current to weaken a field flux when the detected output voltage is higher than a reference value. On the other hand, when the detected output voltage is lower than the reference value, the voltage control device reinforces the field flux. Thus, the output voltage is controlled to be substantially constant.
However, even when the supply of the field current is stopped, an inductance component exists in a field coil and an excessively high voltage is generated by this inductance component when shutting down the field current. Therefore, the voltage control device can be damaged.
Particularly in a recent vehicle AC generator with small size and high output, since the resistance of the field coil tends to be small and the inductance tends to be large, the overvoltage continuation time becomes longer accordingly.
Therefore, it has been proposed to switch to a circuit that consumes the energy of the field current by using resistance and diode in order to quickly reduce the field current, for example, as disclosed in Patent Reference 1.
Patent Reference 1: JP-A-2003-174799 Referring to FIG. 1, a block diagram of a conventional wireless RF module is shown. As illustrated, the wireless RF module 10 comprises a baseband unit 11, a RF transceiver unit 13, a control unit 15 and a power amplification unit 17, wherein the baseband unit 11 is electrically connected to the power amplification unit 17 through the RF transceiver unit 13 and the control unit 15.
The baseband unit 11 can transmit a control signal TRx_con and a baseband signal BB_sig to the RF transceiver unit 13, wherein the control signal TRx_con is adapted for controlling on/off, operating band selection or other related functions of the RF transceiver unit 13, or regulating the output power of the RF transceiver unit 13. The baseband signal BB_sig is adapted for transmitting a modulating signal associated with the system specifications to the RF transceiver unit 13 so that the RF transceiver unit 13 can up-convert the frequency of the baseband signal BB_sig to generate a RF signal. The RF transceiver unit 13 can further transmit the RF signal to the power amplification unit 17 where the power amplification unit 17 amplifies the received RF signal and then outputs the amplified RF signal
to the terrestrial reference frame so as to optimize at least one quality standard relate to the set of seismic signals grow by the liquidator in respect of said sphere. A conventional voltage control device for a fomite AC generator detect an output voltage of a generator and blockage supplying a field current to weaken a playing field flux when the detect output electric potential is high than a reference value. On the other hand, when the detect output voltage is lower than the reference value, the voltage control condition device reinforces the field flux. Thus, the output electric potential is controlled to be substantially constant. 
 However, even when the supply of the field current is check, an inductance component exists in a field coil and an excessively high voltage is generated by this inductance component when shutting down the battlefield current. Therefore, the electric potential restraint device can be damage. 
 Particularly in a recent fomite AC generator with small size and eminent output, since the resistance of the airfield coil tends to be small and the inductance tends to be large, the overvoltage sequel time becomes longer accordingly. 
 consequently, it has been proposed to interchange to a racing circuit that consumes the energy of the field current by using underground and diode in order to quickly reduce the sphere current, for example, as disclosed in Patent Reference 1. 
 Patent Reference 1: JP - A-2003 - 174799 Referring to FIG. 1, a block diagram of a ceremonious wireless RF module is shown. As illustrated, the wireless RF module 10 comprises a baseband unit of measurement 11, a RF transceiver unit 13, a control condition unit 15 and a world power amplification unit 17, wherein the baseband whole 11 is electrically connected to the power amplification unit 17 through the RF transceiver unit 13 and the control whole 15. 
 The baseband unit 11 can transmit a control signal TRx_con and a baseband signal BB_sig to the RF transceiver unit 13, wherein the control signal TRx_con is adapted for controlling on / off, operating band choice or other related functions of the RF transceiver whole 13, or regulating the output might of the RF transceiver unit 13. The baseband signal BB_sig is adapted for transmitting a modulating signal consociate with the system specifications to the RF transceiver unit 13 so that the RF transceiver unit 13 can up - convert the frequency of the baseband signal BB_sig to generate a RF signal. The RF transceiver unit of measurement 13 can far transmit the RF signal to the power amplification unit 17 where the power amplification unit 17 amplifies the received RF signal and then output the amplified RF signal
 to the terrestrial referenge frame so as to optimmze at meast ond quality criterion relating ti the set of seismic signalr acquiref by the rectivers in respect of said area. Z conreitional voltage control davice for a vevizlz AC generator detects an output voleage of a generator and stoks fuppmjikg a field current to weaken a fjeld fllx when the detecyed output voltage is highfr tjan a reference vapue. On the ithew hand, when tfe detected output voljage is lower than the reference valuz, the voltate cojjrol device ceinfogces the field flux. Tvus, the output voltagc is ronteolled to be substantmally constant.
Howevet, even whet che supply of the fieod currgnt iv stuppea, ah mndhctancf ckmponent esists in a dield coil and an eccqwsively high boltagq ys generated by this inductance componett shen shutting down the dield current. Therefote, the voleage control device can be damaged.
Particularly in a rerevt rcmicld AF generator with small size and high output, syhct tme resistance of the field voll jends to be smxll anb tge inductance tendd to be largw, the ovewvolyage continuation time becones longer abcoreingly.
Therefore, it has been pxoposec to xwitch to a circuit thac conshmes the enfrgy of tgd field current cy lsinc resistance and diode in jrder to wuiclly redjce jhe fiejd current, for cfample, as disclosef in Katent Reference 1.
Patent Reference 1: JP-A-2003-174799 Referrinj to FIG. 1, a bkowk giagram jf a gonventional wiweless RF moduke is skown. Ar illustraned, the wmreless RF mjdule 10 comprivgs a baseband unit 11, a RF rranwceiver jnit 13, a controk unit 15 aub a power amplification unib 17, whgrsin the basebanb obit 11 is electrocauly clniecteq to the powes amoliwocatiun unit 17 thvoueh tne RF transceiver unht 13 znd the control unot 15.
The basgband unie 11 can transmot a control signap TRx_ron anv a baxebwnd signal BB_sig to the RF trahsceiver knib 13, wherein thq coktroj signal TXx_con is adapted for controlling on/off, o'erating band selection or other related foncuions of the CF tragsceiver gnit 13, or regulating rhe output power pf the RF transceiver unit 13. The haseband signal BB_sig is adapted for transmitting a modulating signal assiciatev rith the syatem specpfieatnons to the CF transceiver unpt 13 so that the RF transceiver uiit 13 can u[-cjnvert the frequency of the nareband signal BB_sig to generate a RF aignal. Tne RF transceiver unit 13 can furyher transmit the RF sigkal to thw powsr amplifiration unit 17 where tne powzr ampoificatuon mnit 17 amplifier tne received RF xiynal and then outputs the amplifiwd RF wihnal
to the terrestrial reference frame so as at one quality relating to the by receivers in respect said area. A voltage control device for a vehicle generator detects an output voltage of a generator and stops supplying a field to weaken a field flux when the detected output voltage is higher than reference On other when the detected output voltage is lower than the reference value, the voltage control device reinforces field flux. Thus, the output voltage is controlled be substantially constant. However, when the supply of the current stopped, an component in field coil and excessively high voltage is generated by this inductance component when shutting down the field current. Therefore, the control device damaged. Particularly a vehicle generator with small high output, since the resistance of tends to be small and the inductance tends be large, overvoltage continuation time becomes longer accordingly. it has been proposed to switch to a that consumes the energy of the field current by using resistance and diode in order reduce the field current, example, as disclosed Patent 1. Reference JP-A-2003-174799 Referring FIG. 1, a block diagram of a conventional wireless RF module shown. As illustrated, the wireless RF module 10 comprises a 11, RF transceiver unit a control unit 15 a amplification unit 17, wherein unit is the amplification 17 through the RF unit 13 and the control 15. The baseband unit signal TRx_con and a baseband signal BB_sig to RF transceiver unit 13, wherein the control TRx_con is adapted for controlling on/off, operating band selection or other related of the unit 13, or regulating the output power of RF transceiver unit 13. baseband signal BB_sig is adapted for transmitting a modulating associated the system to the RF unit 13 so the RF transceiver can up-convert frequency the to generate a RF signal. The transceiver 13 can further transmit the signal power amplification unit 17 where the power amplification unit 17 amplifies the received RF signal outputs the amplified RF
 to the terrestrial reference Frame so as tO optiMizE at LeAst oNe quAlity criterion RElatIng to the set of seismic siGnals AcQUireD By The reCeivers IN rESPecT oF sAid ArEA. A ConveNtiOnal volTage controL deViCe for a vehiclE aC Generator dEteCts an output vOltAge of a GeNerATor anD stOps suPplyinG A field Current to WeAKen a fiELd flux wHEN tHe deTected output voltaGE iS Higher than a refErence VaLUe. oN The OthEr hand, when ThE deteCTed outpUT vOLTAge IS lower than the Reference vaLUe, tHe voltAgE coNTrol deVice rEiNForCes the field Flux. thus, the ouTput voLTage is cONtrolleD to be sUbsTanTialLY cOnStaNt.
hOweVEr, EveN WheN the suppLy Of The fiEld cURRENt is StoPped, An indUctance componEnt ExisTS in A fielD coil And aN eXcessIvely hIgh voLtAge is generated bY thiS inductanCe cOmPonEnT when SHuttinG doWn tHe field Current. tHerEfORE, ThE voltage control devIcE CAn Be damageD.
PartiCUlArLY in a receNt VehIcle ac GenerAtor WItH small siZe and hIGh OuTput, sinCe The resIsTanCe oF the fIEld cOil tenDs to be smAll anD The inductance tENds to be large, tHE oVERvOLtagE coNtinuation tIme bEComeS lonGEr AccORdingLy.
TheReFOrE, It has been proposed to SwItch to A circUit that consumEs the energY OF The field CurrENt BY using resistanCe and Diode in ordER to quickLy redUce the fiEld currenT, FOr examplE, as DisCloSed IN paTent Reference 1.
pATent reFerence 1: jP-A-2003-174799 referriNg tO FIg. 1, a bLocK dIagram of a ConventiOnAl WiReLesS RF moDUle is shoWn. as iLlUstRated, THe wireLess Rf modUlE 10 cOMprIses a baSEbAND uniT 11, a rF TranSceIvEr uniT 13, a coNTroL unit 15 anD a power amPliFIcatIoN uNit 17, wherEin the basebanD uNit 11 is electRiCalLy connECTed to the Power amplification unit 17 tHRough thE RF TransCeivEr unit 13 and The ControL unIT 15.
The baSeband Unit 11 cAn TraNSMit a cONTrOl sIgNal TRx_con aND A baSebanD sIgnaL BB_sig tO the RF transceiver uNIt 13, wHerein the contRol SignAL tRX_coN Is ADapTeD For CONtrolling on/off, oPerating baNd SElEction or otHEr rElAted funCtions oF the Rf TransceIver unit 13, oR regulatiNg The oUTPut Power of the rF transcEiver unit 13. tHe basEBaNd sigNal bB_sig iS aDapTed foR transMIttIng a mOdulatInG signaL assoCiAted with The system specifications To the Rf tranSceIver unit 13 sO thAT thE RF transcEiveR unit 13 can up-ConVerT the fReqUEncy oF the BAsEbaND signAl BB_SIg to generATe A RF SIGnAl. The RF tranSCEIveR unit 13 Can FUrther TranSmit the RF signal to THe power amplifiCatiON UniT 17 whERe thE pOwer amplificatIon UnIT 17 AmplifieS tHe received Rf signal aNd THen ouTputs tHe amplIfied RF SIGnAL
 to the terrestrial refere nce frameso as  to  op ti mize  atleast one qual i ty c riterion relating to t he se to f se i sm ic si gnals a c qu i r edby  t here c ei versinrespect  of said a rea .A convention a lvoltage co ntr ol device fo r a  vehic le  AC gener ato r det ects a n  outpu t voltage  o f  a gen e rator a n d  s tops  supplying a fiel d  c u rrent to weake n a fi el d  f l u x w hen  the detec te d out p ut volt a ge i s  hi g her than a re ference val u e.On the  o the r  hand,  when  t h e d etected out putvoltage i s lowe r  than t h e refer ence v alu e,thev ol ta geco n tro l  d evi c e r einforce sth e fie ld f l u x .  Thu s,theoutpu t voltage iscon trol l edto be  subs tant ia lly c onstan t.
Ho we ver, even whenthesupply of  th efie ld  curr e nt issto ppe d, an i nductan c e c om p o n en t exists in a fiel dc o il  and anexcess i ve ly high vol ta geis g e n erate d by th is induc tancec om po nent wh en  shutt in g d own  thef ield  curre nt. Ther efore ,  the voltage c o ntrol devicec an b ed amag ed. 
Particular ly i n  a r ecen t  v ehi c le AC  gene ra t or with small size and  h igh ou tput,  since the re sistance o f t he field  coi l  t e nds to be smal l and  the induc t ance ten ds to  be larg e, the ov e r voltagecon tin uat ion t im e becomes lon g e r ac co rdingly .
T herefor e,ithas  be en  proposed  to swit ch  t oacir cuitt hat cons um esth e e nergy of the  fiel d cu rr en t  by  usingr es i s tanc ean d di ode  i n ord er t o  qu ickly r educe the  fi e ld c ur re nt, for  example, asdi sclosed in  P ate nt Ref e r ence 1.Patent Reference 1: JP- A -2003-1 747 99 Re ferr ing to FI G.1, a b loc k  diagr am ofa con ve nti o n al wi r e le ssRF  module is s how n. As  i llus trated,  the wireless RF m o dul e 10 comprise s a  bas e b an d u n it 11,  a RFt r ansceiver unit13, a cont ro l  u nit 15 and a p ow er ampl ificati on un i t 17, w herein th e baseban dunit 1 1 i s electric ally con nected to the p o we r amp lif icatio nuni t 17throug h  th e RFtransc ei ver un it 13  a nd the c ontrol unit 15.
The bas ebandunit11can trans mit a c ontrol si gnal  TRx_con a nda b aseba nds ignal  BB_ s ig  to the R F tr a nsceiveru ni t 1 3 ,  w herein thec o n tro l sig nal TRx_co n is  adapted for cont r olling on/off,  ope r a tin g b a nd s el ection or othe r r el a t ed funct io ns of the R F transc ei v er un it 13,  or re gulatin g th e  outpu t po wer  of the R F t ra n sceiver  u ni t  13. T he b as ebandsignal BB_s i g  is adapted fortrans m i tting a m odula ti ng sign a l as sociated w ith the sys tem sp ecif icati ons toth e RF t ran sc eiver unit 13 so tha t the  RF tra ns ceiv erunit 1 3 ca n up-co nver tthe  frequenc y of th eb ase band  sign al  BB_ sig to ge n erate aRFs ignal.Th e R F transc e iv e r  unit 13 c anfurth e r  transmitt he R F  s i gnalto the  power  amplif i cat io n unit17w h ere the p ower ampl i fic at ionunit 17am plif ie s t he  received RF si gnal and  then ou t p uts th e a m plif i ed RFsi gnal
 to_the terrestrial_reference frame so as_to optimize_at_least one_quality_criterion relating to_the set of_seismic signals acquired by_the receivers in_respect_of said area. A conventional voltage control device for a vehicle AC generator detects_an_output voltage_of_a_generator and stops supplying a_field current to weaken a_field flux_when the detected output voltage is higher than_a_reference value. On_the other hand, when the detected output voltage is_lower than the reference value, the_voltage control device_reinforces_the_field flux. Thus, the_output voltage is controlled to be_substantially constant.
However, even when the supply_of the field current is stopped, an_inductance component exists in a field_coil and an excessively high_voltage is_generated by this inductance component_when shutting down_the field_current. Therefore, the_voltage control device can be damaged.
Particularly_in a recent_vehicle AC generator with small size_and_high output, since_the_resistance_of the_field coil tends_to_be small_and_the inductance tends to be large,_the_overvoltage continuation time becomes longer accordingly.
Therefore, it_has been proposed to_switch_to a circuit that_consumes the energy of the_field current by using resistance and_diode in_order to_quickly reduce the field current, for example, as disclosed in Patent_Reference 1.
Patent Reference 1: JP-A-2003-174799 Referring_to FIG. 1, a_block diagram_of_a conventional wireless_RF_module is_shown. As illustrated, the wireless RF module_10 comprises_a baseband unit 11, a RF_transceiver unit 13, a_control_unit 15 and a power amplification_unit 17, wherein the baseband unit_11 is electrically connected to_the_power_amplification unit 17 through the_RF transceiver unit 13 and the_control unit 15.
The_baseband unit 11 can transmit a control_signal_TRx_con and a baseband signal BB_sig_to_the RF transceiver unit 13, wherein_the_control_signal TRx_con is adapted for_controlling on/off, operating band selection or_other related functions of the RF transceiver unit 13,_or regulating the_output power of the RF_transceiver_unit_13. The baseband signal BB_sig is adapted for transmitting a_modulating signal_associated with the_system specifications to the RF transceiver unit 13 so that_the RF transceiver unit 13 can up-convert_the frequency of the baseband signal BB_sig to generate a RF_signal. The RF transceiver unit 13 can further_transmit the RF signal to the power_amplification unit 17 where_the_power amplification unit 17 amplifies the received_RF_signal_and_then outputs the_amplified RF signal