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Home , John Logie Baird, Progressive scan

HISTORY

Digitol vi sions

ls digirol new? Moybe not, but Boird's television system wos certoinly o pig in o poke: wosn't it? Don Mcleon hos some new evidence.

he much-hailed start of digital cally-scanned television - viewed for focus, lcd, digital data recorder and television may not be quite the decades with disdain - will then, I computer interflace. giant leap you think. Digital tele- believe, sit alongside electronic ana- We should neither revere nor ridicule vision - converting pro- logue tv as an equally valid engineer- historic technologies - they are merely gramme distribution to a fully digital ing solution to 'television'. the best solutions available at the time, environment - is just one small step in Fig. 1. a steady 'technology refresh'. Mechanically-scorned tv This engineering process started over Today though, most of us have accept- A new view on the past twenty years ago and will continue for ed a view originating from the BBC To be objective about early television, many years yet. Fully , back in the late thirties. We think of what we need - and have not had up and digital scanning standards, will 's low-definition tele- until now - is evidence. Without it, his- emerge when the flat-screen tv replaces vision system of the twenties and early torians have had to rely on written or the cathode-ray tube in our television thirties as somehow 'wrong', and of eyewitness accounts, some of them sets. Then, analogue tv and all its trap- electronic television as being 'right'. made decades after the event and most pings, such as PAL (or NTSC) coding, Part of this comes from 'technology of them dismissive and derogatory. sync pulses, colour bursts and interlace, arrogance'. In the sixties, the BBCI ln 19962 and early 1998, hard evi- will be history. seriously questioned Baird's achieve- dence turned up in the form of home That digital future, with our current ments because no part of his technolo- recordings made from BBC tv analogue tv obsolete, will give us a gy was in sixties' television systems. programme transmissions in the thir- new view of television's engineering But, today, nothing directly of sixties' ties. Until then, the entire mechanical- history. The early years of mechani- technology is in a nineties' consumer ly-scanned era of television was camcorder - with its chip thought to be devoid of any such Donald F Mclean BSc(Hons) CEng FIEE sensor, image stabilisation, digital auto- recording. These digitally restored

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Fig. t. Mechanically-scanned television is in use today by the military. ln airborne reconnaissance, the high-resolution television cameras on RAF Tornado GRIA aircraft use mirror' drum scanning. Coincidentally the aspect ratio is similar to that of Baird's 3?-line standard, (from Crown Copyright original)

Fig. 2. One of the many consumer devices that recorded audio onto aluminium discs. On more than one occasion, machines such as this were used by viewers to record the video signal of the BBC's SoJine broadcasts, recordings now challenge the long- exploited their existing broadcast established view. infrastructure to the full. To understand why this is so, let us fast rewind to just after Baird's exper- No recordings? If the BBC or the imental period of the years around Baird Company ever attempted record- 1930. ing their programmes, there is today no record of it. Fortunately for us, a few BBC chooses Baird's 3O-line system. enthusiastic viewers made crude video Fig. 3. With no ln 1932 the BBC chose Baird's 30-line recordings on their domestic audio different speeds, the starting point was clue as to date or standard for its television service, equipment, Fig. 2, from BBC broad- that the signal matched Baird's 3Oline authenticity, one despite higher definition being avail- casts. They had been inspired by video standard. Without a date to go of the discs has a able. It was chiefly the lack of suitable Baird's attempts to make a practical by, I had to rely on comparing the hand-written wide-band hardware that videodisc player in the late twenties3 video content with knowledge of the messaS,e forced the BBC into using an existing and were encouraged by articles development of 30-line television in Large solution. describing how to do it.a order to determine whether they were "Woman. Head". This The 30-line video signal was low Recently, Jon Weller, a collector of authentic or recent. unflattering enough in to be transmitted old electronics equipment, retrieved a meqsage on an existing BBC fie- collection of direct-cut aluminium The evidence describes the quency normally used for audio. The discs from a house clearance. The Once restoration started, the clues main disc of Betty public simply used their existing discs were previously owned and began to appear. In the collection, there Bolton's BBC tv for the audio channel and a second possibly recorded by Marcus Games, are eleven separate recordings of 30- pertormance in for the video channel. a keen amateur movie enthusiast. Jon line video. Each recording is a frag- the thirties. Only the display had to be bought - or later discovered that several discs in ment from a programme and lasts no in some cases built. that collection had unusual material more than a minute. There were two Baird's mature 3O-line system - on them, Fig. 3.5 types of programme - one type featur- developed in the late twenties - pro- ing four individual singers and the vided the BBC with an exceptionally What are the recordings of? other containing what may be material low-cost engineering solution that Although the discs were recorded at from children' s programmes.

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Sconning options Thc digitalll,' l'cstored irnrgcs lrorn thc sct ol discs do not show thc distor- Two main types of nrechanical scannin14 were usecl ior l0-line (anler.ls ancl clisplavs: tion causecl hl arc-scanning. Thr. onlv Nipkow disc and mirror-drunt. Tl.re Nipkorv ciisc a spiral ring oi.rlrerturcs areupcl the altcrnative cantert \\,as onc hascd on a outer eclge of the disc - createci a curvecl inrage that was sranncrl in an arc. The nrirror nr i rror-dru rn. drum, shown in Fig.4, however scannecl in straight lincs u,ith a slight 'lrorv-lir,'rlistgrti9p. Mirnrr-drurn cuntcras lirr 30-lincs The BBC transmittec.l its images fronr a nrirror clrur-r c.rnrer.r systenr, yet lrrost viervers had a lixccl vcrtical ficlcl-o1'-r,ieu,' ol' rx'cr 20". excludinr blankirrg. used receiver-clisplays basecl on the Nipkow-clisc. They n,ere cheal;r,r.rncl easier lo r-p.rke. .just Hence thc sin-uers who we see in medi- Viewers accepted the ntinor clistortion jr-rst as toclay they sr,rrltrisirrr.rly accept a rr6rptal urr shot werc around 9- l0 t'cct. i.c.2.1- television picture stretchecl to fit a wicle-screen rlisltlay. 3nr. lhrnt the canrcra. With thc bottorn ol'thc blck u,all of the studio in shot. thc irnages shou,that the studio r,r,as largc and thc' callcra \) stcnl u il\ scnrilir c. Shori int e rrrlcrlr teatures colnrnon with thc l9-13 '[-ookin-!r In' rccorclin-u. the quality of carncra-u,ork appcars superior. itrply- ins a latcr date. Relative to \\,hat antatcurs todav achiel'c6 and relativc- to a -senuine -10- linc re-nrake ol'a I 9-10 play7. the inher- ent quality of the vision signrl is excel- lent. With no dctectablc inrasc- crrors. lltc tttirrttr (lrunl cunlerir \\it: ir plL'ei- sion-built r.nechanism. Lishtins. cant- cra-work and production have all been pcrfectll, nratchecl to the 30-line sys- tcnl. Allowin-s lirr the alntost 'cltctaphonc' rccordrng quality. tlte honte-rccor.dcd cliscs shorv details that hare bccn

talkcd about bctitre.s but nor sccn .

BBC's first television service Thesc then are undoubtcdlv recordings rradc- titrn thc tirst BBC tclcvision ser- vice of l93l-3-5. Thc clLres above sus- gest the tftrnsrnissions cante from the BBC tv stuclio at Portlancl place hetu'cen 193-l and'15. With thc. l9.j-3 prourantnre. 'Looking In'.') rve now have the total contple- nretrt ol t idco rccordinss ol'broadcast te le vision at least in thc UK belirrc thc f ifiics. Since thcy r.,n,erc discovcred and restored only tn the last tuo ycars suggcsts that nrore ntiltcrial may yct irppeirr. Fig. 4. The mirror-drum camera of the thirties scanned the scene uting u proiiii flyirgipotii- Nipkow camera disc of Baird's video recording experiments of the twenties used more traclitional - bul less efficient - lens-based imaging. Singer without the song. Onlv one of thc singers is easily rccognisable hy her clistinctive l'eatures and hair-stylc - Betty Bolton. Fig. 5 As an accom- Fig. 5. Betty plishecl contralto. she rccorcled ntany Bolton. The photo tlitncc-hlrttl \on!\ in lhe latc l\\cnlic\ on the left and its ancl carly thirties. simulated 3O-line Betu'cen 1929 and 193-5 she per- equivalent show lirrrred well o.n,er a dozen tintes on 30- Betty in 1929. The linc broadcasts includint being the tirst two pictures on ,} perlirrnrer on thc openine nisht ol'the the right have BBC Teler,'ision Sen,icc in August been restored off- I 932. disc. One shows Betty' s pertirrr.nancc exucles prot'cs- the glint off sronalisnr. Herc is a highly accorn- Betty's hair and plished pcrtirrrner. pcri'ectly natural in the other, her lhrnt ol' a television camera. When I distinctive profile showed the inrages to her. she inrnte- with kiss-curl and diately recognisecl hersell tiorn her hair clasp. appcarance and actions.

162 ELECTRONICS WORLD FebrLrarv 1999 HISTORY

Fig. 6. An unknown male operatic singer. Details of Fig. 7. An unknown female singer performs in silence through a rain of noise. On the right she is caught part'way through his collar, tie and iacket show up well considering high disc-surface that the computer-restored sequence originated from blowing, a kiss at us. a rlictaphone quality audio recording.

Fig, 8. Captured at 12\rev/min, this female singer's performance is spread across three of the eleven separate recordings. They have been brought back together digitally as one long sequence.

RECORDED Fig. 9. The 30Jine video test disc TELEYISION manufactured and sold Thc glossy shine of her hair. the glint Company engineer described these dig- ?iovlsloNAL ?arENt Itlal,L for seven shillings by gem itally restored pictures as about as bad Radiovision of her tiny silver hair-clasps. her l OOUSLE.SIOED .t.od t'Yint r the'Major An.'.t, ol pi(ruG .q^i'nt k necklace and the pattern on her dress as they got.l0 ' 'o mrnuta on .r(h $dG. D,ic..nr Company'under F. durruon t!rc.t(h! irc Go.dcd 6 are all rcr.r.uu'kably clcar. A well- @6ic nd6 to an.Dlc Yr.iour trF ol Plew. The only plct-!p. (o b. cmplold. Rd.e defined dark streak either side ol'hcr The first commercial video xl-up lsdr to ob(In . n.trt'va ot r recording of 30-line i6ki{ rl

February 1999 ELECTRONICS WORLD HISTORY

Fig. 10. Animated because one of them is slid in twice. cessful demonstration of 'true' televi- binary images of second the time backwards. The sion in 1926, the early pioneers demon- the mid-twenties recording shows the characteristic dis- strated video pictures of silhouettes and pre-dated Baird's tortion from using a Nipkow disc as a shadows. Here, an intense light was successful camera at a time when cameras - used shone on the scanning area with the demonstration in' mirror-drums. photocell behind it. Animated silhou- 1926. The Major Back in the early twenties, people ettes, Fig. 10, a Maltese cross, even Radiovision disc laid down rules to establish what was waggling fingers were all 'subjects'. of 1934-5 has and was 'television'. not They decided However this was not 'true' television_ more in common that 'true' television should encompass Likewise, the 'Ma.jor Radiovision' test with those early the ability to see subjects in reflected disc, made in that way is not'true'. images than'true' light. Although sold as a test disc, the television. many years For before Baird's suc- whole recording is marred by a 5kHz 'ringing'on transirions, Fig. 11. The fact that these are stills without move- ment means that the full capability of the 30-line system is nor realised. Fig. 12. There is a 'sister' disc of stillsll, made in the same way as the 'Major Radiovision' disc but containing dif- ferent subject matter. Strangely. whilst the recording is clear. none of the lantern-slides are even remotely recog- nisable, Fig. 13.

The new television system Low definition TV had virtually national coverage with at least eight thousand viewing sets. After the last of 1,500 programmes was transmitted on I I September I935. these viewers found that their 30-line TV receivers had become obsolete. The new high definition service began a year later.

True revolution. Unlike digital televi- sion today, the transition from the 30- line service to the new high definition service was not an enhancement. it was a total revolution. Thirty-line tv was designed to use existing radio channels intended for audio broadcasting. The BBC had used mature technology for its 30-line tele- vision studio. It had also used its exist- ing audio distribution channels and radio frequencies tbr vision transmis- t sion, leaving the public to buy or even build their own receivers. In sharp contrast, a totally new infiastructure supported the high defi- nition system. Virtually everything had to be developed from scratch - cam- eras, cables, distribution amplitiers, routers, . receivers and dis- plays. Fig. 1l . The time-base corrected image The investment directly off-disc shown on the left was enormous but the time was suffers from'ringing' at around SkHz. right and the public were crying out lbr On the right, signal processing has a lull television service. The potential returns greatly reduced the distortion and the for the right solu- made proper arc-scan pattern has been tion the investment appear restored. secure. Trial by television Fig. 12. A composite of most of the When test transmissions pictures from the'Major Radiovision, started in 1936 from RadioOlympia, test disc. The strange pattern at the price of receivers, full the bottom right is a high frequency test of latest technology, left the public pattern. lar behind. Much like the start of BBC Choice in September

164 ELECTRONICS WORLD Fetrruary 1999 HISTORY

Fig. 13. ldentical in every way but content to the 'Major Radiovision' 30- line test disc, a second disc contains test stills that are clear yet Fig, 14, lohn Logie Baird - Britain's foremost television pioneer, lBBB-1946. unrecognisable.

1998 on the digital service. hardly any Baird developed. demonstrated and References ol the public had the new receivers to patented almost every aspect of televi- l. BBC, "The Discovery of Television", watch it. sion including colour. intia-red, 3D, Documentary celebrating 25 years of Television coverage shrank from and video recording. He introduced and Television. l96l most of Britain to London and the tunded a broadcast television service. 2. Mclean, D F "First Frames", immediate vicinity. Initially, television His 30-line system was adopted - and Electronics World. November 1998 sets had to be dual-standard: the choice hence sanctioned - by the BBC fbr 3. McLean, D F "Restoring Baird's between the Baird Company's totally their first television service. Image", Electronics World. October new 240-line system That he lost the prime competition I 998 and rival Marconi-EMI's 405-line fbr supplying the BBC's high defini- .1. Practical Television. "Canned interlaced system was to be resolved tion service to Marconi-EMl in 1936 is Television", Banon Chapple, November on-air. unfortunate - the all-electronic system 1934 Dual standard reception made the was simply better. This does not detract 5. Weller. J. Private Communication. Jan- first electronic even more from his remarkable achievements and March 1998 costly. By January 1937, the all-elec- innovations throughout the dawn of 6. NBTVA - Narrow Band Television tronic 405-line system had been television and, indeed, fbr the rest of Association - uses low definition TV as selected. his life. an alternative mode Don will be describing Viewers outside the London area, Baird received only one honour - 7. Remake of "The Man With The Flower his work in a lecture who switched otf their 3O-line honourary Fellowship of the Royal In His Mouth", 1967, ILEA, produced to be given at the receivers tbr the last time in 1935. had Society ol' Edinburgh.ll If we recog- by Lance Sieveking (the original 1930 lEE, Savoy Place, to wait more than fifteen years tbr tele- nise comedians and retired politicians producer) and filmed entirely in 30-lines LondononllMay vision to return. It took until l9-5212 lbr and their secretaries through our coun- by Bill Elliou. 1999 at 6pm. coverage to reach and Wales try's honour system, then the time is 8. Bridgewater, T H "Just a Few Lines", Admission is free and and 195.1-54 lbr prices ol'receivers to long overdue to bestow proper honours British Vintage Society, 1992 open to non- become atlbrdable to the average on John Logie Baird. 9. Mclean. D F ibid Electronics World. mernbers. The working tamily. November 1998 multimedia Acknowledgments. I would like to 10. Herbert R M. Private Communication, presentation will rely But what of Baird? thank Jon Weller, the owner of alu- June 1998 heavily on the video John Logie Baird, Fig. 14, has easily minium discs described here and to I I . A tape copy of this disc was supptied by restorations'and will earned the acclaim of Britain's fbre- Eliot Levin of Symposium Records, Doug Pitt, NBTVA, 1982. The source of be entitled "Restoring most television pioneer. His list of who tieely gave up his time to transt-er this tape is unknown. Baird's lmage: the achievements is legendary. He devel- the discs expertly and professionally. l2.Briggs, A. "The BBC: The First Fifty restoration of the oped and demonstrated the world's first Final thanks go to Betty Bolton, the Years". OUP 1985 world's earliest- practical solution to television. earliest video star. who has charmed 13. Baird. Prof M H I. privute communica- known television Uniquely amongst the tv pioneers. me both on disc and in person. r tion, Sep 1998 recordings."

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