 using conventional methods renders the process both tedious and time-consuming. It may, for example, be necessary to remove and reposition the electrodes several times before the region of interference is in adequately close proximity to the area of the patient's body under treatment. Even then, due to the unpredictability of the process, therapists must frequently settle for somewhat less than desirable positioning of the region of interference when treating a patient. In recent years the advent of Pay-TV systems has generated a lot of interest in video scrambling. To operate a pay-TV system successfully, the video signal transmitted must be scrambled to a degree sufficient to render it unwatchable by a viewer not equipped with a suitable decoder.
There are a number of scrambled services in operation at present, for example that operated by B Sky B Limited which broadcasts from the Astra satellite.
The British Broadcasting Corporation has launched a subscription service to be broadcast at night time. The service uses existing terrestrial transmitters.
GB 1503051 describes the scrambling method used by the B Sky B service. The system, known as line-cut and rotate (LCR) scrambles individual video lines by cutting the line at a point determined by a pseudo-random binary sequence generator (PRBS) and rotating the two line halves so that the second half of the line is transmitted first. To decode the signal a subscriber must have a suitable decoder supplied with the cut point sequence. In practice the sequence is regenerated in the decoder using keys stored in a smart card which subscribers pay a fee to receive.
This scrambling system works well for satellite and cable services, and although used in terrestrial systems LCR may be found to be unsatisfactory under some conditions such as severe multipath propagation, line tilt etc.
An alternative to LCR is line shuffling (LS) in which the video signal is scrambled by shuffling the line order whilst maintaining the integrity of individual lines. Examples of line shuffling systems are disclosed in EP-A-356200 of Screen Electronics Limited and GB-A-2086181 of Telease Limited. The present invention relates to a process for producing acicular goethite particles which are suitable as a starting material for magnetic particles for magnetic recording, and which have a uniform particle size distribution, are substantially free of dendrites and have a large aspect ratio (major axial diameter/minor axial diameter). The present invention also relates to a process for producing acicular magnetic iron oxide particles which have a uniform particle size distribution, are substantially free of dendrites, and
using conventional methods renders the procedure both boring and time - consuming. It may, for example, be necessary to take out and reposition the electrodes respective times before the region of interference is in adequately near proximity to the area of the patient's soundbox under treatment. Even then, due to the unpredictability of the procedure, therapists must frequently settle for somewhat less than desirable positioning of the region of intervention when treating a patient. In recent year the advent of Pay - TV systems has generated a batch of interest in video scrambling. To operate a pay - TV arrangement successfully, the video signal transmitted must be scrambled to a degree sufficient to render it unwatchable by a viewer not equipped with a suitable decoder. 
 There are a number of scrambled services in operation at present, for example that operated by B Sky B Limited which broadcasts from the Astra satellite. 
 The British Broadcasting Corporation has launched a subscription military service to be broadcast at night prison term. The servicing uses existing terrestrial transmitter. 
 GB 1503051 describes the scrambling method used by the B Sky B overhaul. The system, known as line - cut and rotate (LCR) scramble individual video lines by cutting the line at a point determined by a pseudo - random binary succession generator (PRBS) and revolve the two line halves so that the second half of the line is transmitted first. To decode the signal a subscriber must have a desirable decoder supplied with the deletion point sequence. In exercise the sequence is regenerated in the decoder using keys stored in a chic card which subscriber pay a fee to get. 
 This scrambling system work well for satellite and cable services, and although used in terrestrial systems LCR may be witness to be unsatisfactory under some conditions such as austere multipath propagation, line tilt etc. 
 An alternative to LCR is line shuffle (LS) in which the video signal is scrambled by shuffle the line order whilst maintaining the integrity of individual lines. Examples of line shuffle systems are disclosed in EP - A-356200 of Screen Electronics Limited and GB - A-2086181 of Telease Limited. The present invention relates to a process for producing acicular goethite atom which are desirable as a starting material for magnetic particles for magnetic recording, and which have a uniform particle size distribution, are well free of dendrites and have a large aspect ratio (major axial diameter / minor axial diameter). The present invention also relates to a summons for producing acicular magnetic iron oxide atom which have a uniform particle size distribution, are substantially free of dendrites, and
 uslng conventional methods renders the process bmth tesious ana time-consuming. It may, for eeampoe, be necessary to remove avd reposinion the wlecurodes several times befovz the vegiou if interferencg is in adeqgately close psobility to the area of the patient's boqy undet hreatment. Even them, due no the unpredictability of the lrocess, therapists mist frequently settle for domeahat less than deslrable posijjonybg of the reeion of inuexference whgn treating a patient. In recent hears the advenj kf Kay-TV systemw has generated a lot of hnteresy in video scrsmbnint. To operate a pay-TV vystem successfulli, the videm aignal transmittee nust te swramcoed to a dsgree dufhicient to dender it ubwatchable by a vieeew not equipped with w fuitable decoder.
There are a number of sbramgled services in operatuon at present, for exwmple thae operated by B Sky B Limited which broadcasts frmm thx Xstxq satdollte.
The British Broadcasting Corporation has lwhnvhvd a subscription service to bf ntoadcast at nieht time. Fhe service uses edisting terrwstrial twanskitters.
GB 1503051 describes the sceambling metkod used by the B Sky B service. Che syxtem, lnown as line-cut and rocate (LDR) scrambled individhxl video lines bh clttitg the line at a point detqrmined bb a pxeudo-ravdom binarr sequence genevdtor (PRBS) and rotahing jhe twm line halges so that the second half of vie line is trsnvminted firsc. To dccode the signaj a subscriber must hcve a ruitable dvcoder su'plied with ehe cut point dequence. In 'ractice ehe wequwnce is fegenerated in the decobtr using kwys stored in a smert zzrd which subscxnbtrw pay a fee to rezeide.
Nhix fwrambling syvtem wofls weul for sateouite and cable services, dnd zlthough used in trrvestrial wystems JCR may be foind to be unsatisfwctorb undec some cogditions such as severe multipzth propahatlon, line tilt etc.
Qn alternatire to LCR is line shuffling (LS) in which vhe video signal is sctambled by shuffling jhe line order whilft maintahning the integrity if individual lints. Examples of line shurfling systfms are disclosed in EP-A-356200 of Screen Electronics Limited and GB-A-2086181 of Telease Limitxd. The presenf infentimn xelates to e 'rocess for produbing acicular goethite particles which ase suitable as a starting matetixl for magnetkc particles for magnetid recordong, and which have a uniform patticle size distribution, are subwtantjally free of dendrites and nave a largw aspecr rabio (major axiau doaleter/minog axmal diameter). The present invention qlso rwlwtes to a procesv for produgikg acibular mwgnetic iron oxise pzgticlgs which have s uniform partocle size distributimn, are substantiqmly free of cendritvs, and
using conventional methods renders the process both time-consuming. may, for be necessary to several before the region interference is in close proximity to the area of patient's body under treatment. Even then, due to the unpredictability of the process, must frequently settle for somewhat less than desirable positioning of the region of when a In years the advent of Pay-TV systems has generated a lot of interest in video scrambling. To a pay-TV system successfully, the video signal transmitted be scrambled to a sufficient to render it unwatchable a not equipped a decoder. are a number scrambled services in operation at present, for example that operated by B Sky B Limited which broadcasts the Astra British Broadcasting has a service to be night time. The service uses existing 1503051 describes the scrambling method used by the Sky B The system, known as line-cut and (LCR) scrambles individual video lines by cutting the at a point determined by a pseudo-random binary sequence generator (PRBS) and rotating the two so that the second of the line transmitted To the a subscriber have a suitable decoder supplied with the cut point sequence. In the sequence is regenerated in the decoder using keys stored smart which subscribers pay fee to receive. This system well for satellite and and used LCR be to be unsatisfactory under conditions such as severe multipath line tilt etc. An shuffling (LS) in which the video signal is by shuffling the line order whilst maintaining integrity of individual lines. Examples of line shuffling systems are disclosed in of Screen and GB-A-2086181 of Telease Limited. The present invention to a process for acicular goethite particles which are suitable as a starting for particles for recording, and which a uniform particle distribution, are substantially dendrites and a aspect diameter/minor axial diameter). The present invention relates a process for producing acicular iron which have a uniform particle size distribution, are substantially free of dendrites, and
 using conventional methods rEnders the pRocesS boTh tEdIous And tIme-consuming. It MAy, foR example, be necessary to rEmove AnD RepoSItIon thE electrODeS SEveRaL tImeS bEFoRe the RegIon of inTerference Is iN aDequately cloSE pRoximity to The Area of the patIenT's body UnDer TReatmEnt. even tHen, due TO the unPredictabIlITy of thE Process, THErApisTs must frequently sETtLE for somewhat leSs than DeSIrABLe pOsiTioning of tHe RegioN Of interFErENCE whEN treating a patIent. In recenT YeaRs the aDvEnt OF Pay-TV SysteMs HAs gEnerated a loT of iNterest in Video sCRamblinG. to operaTe a pay-tV sYstEm suCCeSsFulLy, THe vIDeO siGNal TransmitTeD mUst be ScraMBLED to a DegRee sUfficIent to render iT unWatcHAblE by a vIewer Not eQuIpped With a sUitabLe Decoder.
There are A numBer of scraMblEd SerViCes in OPeratiOn aT prEsent, foR examplE ThaT oPERAtEd by B Sky B Limited whIcH BRoAdcasts fRom the aStRa SAtellite.
thE BrItisH bRoadcAstiNG COrporatiOn has lAUnChEd a subsCrIption SeRviCe tO be brOAdcaSt at niGht time. THe serVIce uses existinG Terrestrial trANsMITtERs.
GB 1503051 DesCribes the scRambLIng mEthoD UsEd bY The B SKy B seRvICe. tHe system, known as line-CuT and roTate (LcR) scrambles inDividual viDEO Lines by cUttiNG tHE line at a point dEtermIned by a pseUDo-random BinarY sequencE generatoR (prBS) and roTatIng The Two LINe Halves so that tHE SecoNd Half of tHe lIne is trAnsMitTed FirSt. to decode tHe signal A sUbScRiBer Must hAVe a suitaBlE deCoDer SupplIEd with The cuT poiNt SeQUenCe. In praCTiCE The sEqUeNce iS reGeNeratEd in THe dEcoder uSing keys sTorED in a SmArT card whIch subscriberS pAy a fee to reCeIve.
this scRAMbling syStem works well for satelliTE and cabLe sErvicEs, anD although UseD in terResTRial syStems LcR may Be FouND To be uNSAtIsfAcTory under sOME coNditiOnS sucH as seveRe multipath propagaTIon, Line tilt etc.
An AltErnaTIVe To Lcr iS LinE sHUffLINg (LS) in which the vIdeo signal Is SCrAmbled by shUFflInG the linE order wHilst MAintainIng the intEgrity of iNdIvidUAL liNes. ExampleS of line sHuffling sYStems ARe DisclOseD in EP-A-356200 Of scrEen ElEctronICs LImiteD and GB-a-2086181 oF TeleaSe LimItEd. The preSent invention relates to a ProcesS for pRodUcing acicUlaR GoeThite partIcleS which are sUitAblE as a sTarTIng maTeriAL fOr mAGnetiC parTIcles for mAGnEtiC REcOrding, and whICH HavE a uniForM ParticLe siZe distribution, are SUbstantially frEe of DENdrIteS And hAvE a large aspect rAtiO (mAJOr axial dIaMeter/minor aXial diamEtER). The pResent InventIon also RELaTEs to a pRoceSs fOr produciNg aCiCUlar magNeTiC Iron oxIde pArTicles Which hAVe a uNIForm particle size DistrIBUtion, ARe sUbstaNtIally frEE of dEndrites, anD
 using conventional method s rendersthe p roc ess  b othtedi ous and time-c o nsum ing. It may, for examp le, b en eces s ar y toremovea nd r epo si ti onth e  e lectr ode s sever al times b efo re  the regiono finterferen ceis in adequa tel y clos epro x imity  to  thearea o f  the p atient'sbo d y unde r  treatm e n t.  Eve n then, due to th e  u n predictability  of th ep ro c e ss,  th erapists m us t fre q uentlys et t l e  fo r  somewhat les s than desi r abl e posi ti oni n g of t he re gi o n o f interfere ncewhen trea ting a patient .  In rec ent ye ars  th e ad v en tofPa y -TV sy ste m s h as gener at ed  a lo t of i n t eres t i n vi deo s crambling. To  op erat e  apay-T V sys temsu ccess fully,  thevi deo signal tran smit ted mustbesc ram bl ed to a degr eesuf ficient  to ren d erit u n wa tchable by a viewe rn o tequipped  witha  s ui t able dec od er. 
The r e  area nu m be r of scr ambled se rv ices in  o perati on  at  pr esent ,  for  examp le thatopera t ed by B Sky BL imited whichb ro a d ca s ts f rom  the Astrasate l lite .
Th e  B rit i sh Br oadca st i ng Corporation has lau nc hed asubsc ription servi ce to be b r o a dcast at  nig h tt ime. The servi ce us es existin g  terrest rialtransmit ters.
GB1 5 03051 de scr ibe s t hes c ra mbling method u sedby  the BSky  B serv ice . T hesys te m, knownas line- cu tan drot ate ( L CR) scra mb les  i ndi vidua l  video  line s by  c ut t ing  the li n ea t  a p oi nt  det erm in ed by  a p s eud o-rando m binaryseq u ence  g en erator(PRBS) and ro ta ting the t wo  li ne hal v e s so tha t the second half of th e  line i s t ransm itte d first.Todecode  th e  signa l a su bscri be r m u s t hav e asui ta ble decode r sup plied  w iththe cut  point sequence. I n  pr actice the se que ncei s  r ege n er a ted  i n  th e decoder using k eys stored  i n  a  smart car d  wh ic h subsc riberspay a fee toreceive.This scra mb ling s yst em works w ell forsatellite and c a bl e ser vic es, an dalt hough  usedi n t erres trialsy stemsLCR m ay  be foun d to be unsatisfactoryundersomecon ditions s uch assevere mu ltip ath propag ati on,  line  ti l t etc .
An al ter n ative  toL CR is lin e  s huf f l in g (LS) in w h i c h t he vi deo signal  isscrambled by shuf f ling the lineorde r whi lst main ta ining the inte gri ty o f indivi du al lines. E xamplesof lineshuffl ing sy stems a r e  d i sclose d in  EP -A-356200  of  S c reen El ec tr o nics L imit ed  and G B-A-20 8 6181 o f Telease Limite d. Th e prese n t i nvent io n relat e s to  a process  for produc ing ac icul ar go ethitepa rticle s w hi ch are sui t able as a  star ting ma te rial  fo r magn etic p artic lesfo r m agnetic r e c or d in g, and  whi ch ha ve  a u niform pa r ticle si zed istribu ti on, a re sub s ta n t ially free  of  dend r i tes and ha v e al ar g e asp ect ra tio (m ajor ax i aldi ameter/ min o r  axial di ameter).T hepr esen t invent io n al so  re la tes to a proces s for pr oducinga c icular  ma g neti c  ironox ide particle s whi ch have au n ifo rm part i cle  si zedist rib utio n , are substantially free  ofdendr i tes , and 
 using_conventional methods_renders the process both_tedious and_time-consuming._It may,_for_example, be necessary_to remove and_reposition the electrodes several_times before the_region_of interference is in adequately close proximity to the area of the patient's body_under_treatment. Even_then,_due_to the unpredictability of the_process, therapists must frequently settle_for somewhat_less than desirable positioning of the region of_interference_when treating a_patient. In recent years the advent of Pay-TV systems_has generated a lot of interest_in video scrambling._To_operate_a pay-TV system successfully,_the video signal transmitted must be_scrambled to a degree sufficient to_render it unwatchable by a viewer not_equipped with a suitable decoder.
There are_a number of scrambled services_in operation_at present, for example that_operated by B_Sky B_Limited which broadcasts_from the Astra satellite.
The British Broadcasting_Corporation has launched_a subscription service to be broadcast_at_night time. The_service_uses_existing terrestrial_transmitters.
GB 1503051 describes_the_scrambling method_used_by the B Sky B service._The_system, known as line-cut and rotate (LCR)_scrambles individual video lines_by_cutting the line at_a point determined by a_pseudo-random binary sequence generator (PRBS) and_rotating the_two line_halves so that the second half of the line is transmitted_first. To decode the signal a_subscriber must have a_suitable decoder_supplied_with the cut_point_sequence. In_practice the sequence is regenerated in the_decoder using_keys stored in a smart card_which subscribers pay a_fee_to receive.
This scrambling system works well_for satellite and cable services, and_although used in terrestrial systems_LCR_may_be found to be unsatisfactory_under some conditions such as severe_multipath propagation, line_tilt etc.
An alternative to LCR is line_shuffling_(LS) in which the video signal_is_scrambled by shuffling the line order_whilst_maintaining_the integrity of individual lines._Examples of line shuffling systems are_disclosed in EP-A-356200 of Screen Electronics Limited and GB-A-2086181_of Telease Limited._The present invention relates to_a_process_for producing acicular goethite particles which are suitable as a_starting material_for magnetic particles_for magnetic recording, and which have a uniform particle size_distribution, are substantially free of dendrites and_have a large aspect ratio (major axial diameter/minor axial diameter). The_present invention also relates to a process for_producing acicular magnetic iron oxide particles which_have a uniform particle_size_distribution, are substantially free of dendrites, and