Automat 1 on in Broadcasting Studios As
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i THE UNIVERSITY OF NEW SOUTH WALES AUTOMAT 1 ON IN BROADCASTING STUDIOS BY A. S. GRAY .Submitted for the degree of Master of Engineering on 3rd March, 1972. UNIVERSITY OF N.S.W. ] 311S7 16. MAY 72 I LIBRARY ii CERTIFICATE This is to certify that this thesis has not been submitted for a degree or similar award to any other University or Institution. A. S. GRAY iii ACKN QWLEDGSM3NT I wish to thank the Australian Broadcasting Commission and especially Mr. K. N. Middleton, Controller of Technical Services for allowing this work to be undertaken, I would also like to thank my Supervisors, Dr. John Hiller of University of New South Wales and Mr. Carl Wilhelm of A.B.C. for their encouragement and patience. I must state however, that the responsibility for statements made herein rests solely with myself. iiKe finally, I would^to thank ray wife for her help in typing the thesis. NOTE A peculiar difficulty in writing the thesis was the usage of the term "program", which is used both in broadcasting and in computing. I have used " programme " to mean the set of broadcasting items to be presented and " program " to mean the set of instructions executed by the computer. SUMMARY Broadcasting is a form of communications in which emphasis is placed on the uninterrupted transmission and smooth presentation of material, rather than the speed of message handling. Broadcasting entities range from one studio- transmitter stations to decentralised studio network which exchange and merge items to suit a particular programme of operations. The sporadic heavy demands on broadcast operators controlling presentation lead to errors in production and make uneconomic use of staff. Automation offers advantages of reliable operation and fast response to control time-sensitive operations which are mainly mechanical tasks. Errors can be minimised and staff released to make more artistic contributions. Broadcasting automation systems range from permanently-wired event sequencers to large information-processing computer systems such as UHKfs, for resources control. The automation system described here utilises a small process control computer system which costs about $60,000 including auxiliary units such as disc memory and display terminals. Three important features considered are an accurate reliable clock system, a method of entering and storage of operations schedules using alphanumeric displays and systems of automatic time announcements. V TABLE OF CONTENTS PAGE PART A DESCRIPTION OF BROADCASTING- SYSTEMS AND OPERATIONS 1 CHAPTER 1 INTRODUCTION - BROADCASTING AS A FORM OF COMMUNICATIONS 2 1.1 COMPARISON WITH OTHER FORMS OF COMMUNICATIONS SYSTEMS 4 1.2 USES AND USERS OF THE BROADCASTING SYSTEM 9 1.3 CLASSIFICATION OF BROADCASTING ITEMS 13 1.4 THE SENSE OF HEARING 21 CHAPTER 2 THE DEVELOPMENT OF BROADCASTING 39 2.1 RADIO BROADCASTING 40 2.2 WIRE BROADCASTING 42 2.3 STUDIO OPERATIONS AND EQUIPMENT 44 2.4 AUTOMATION SYSTEMS 50 CHAPTER 3 PRESENT TECHNICAL OPERATIONS SYSTEMS 72 3.1 METHODS OF ITEM PRODUCTION 74 3.2 METHODS OF PROGRAMME ITEM PRESENTATION 83 3.3 CONSTRAINTS ON TIMING OF OPERATIONS 90 3.4 TECHNIQUES OF ITEM PRESENTATION 94 3.5 MANUAL SYSTEMS OF OPERATION 97 vi PART B AUTOMATION SYSTEMS FOR BROADCASTING 103 CHAPTER 4 THE CASE FOR AUTOMATION 104 4.1 THE TASKS IN A BROADCASTING STATION 105 4.2 TYPES OP AUTOMATION SYSTEMS 106 4.3 RELIABILITY OP AUTOMATED SYSTEMS 111 4.4 DEFICIENCIES OP THE MANUAL SYSTEMS 121 4.5 ADVANTAGES AND DISADVANTAGES OP AUTOMATION 123 CHAPTER 5 DESIGN OP A COMPUTER CONTROLLED SYSTEM 126 5.1 SERVICING OP TASKS 128 5.2 DERIVATION OP OPERATIONAL TIME 132 5.3 SCHEDULING OP OPERATIONS 136 5.4 ITEM PRESENTATION METHODS 152 5.5 THE COMPUTER AND PERIPHERALS 186 5.6 REVIEW OP COMPLETE SYSTEM 192 CHAPTER 6 STUDIO BROADCASTING OPE.RATIONS 194 6.1 PREPARATION OP ITEMS FOR PRESENTATION 195 6.2 ON-AIR COMMENCEMENT 212 6.3 OPERATIONS DURING BROADCASTING 223 CHAPTER 7 CONCLUSIONS 22? 7.1 COSTS 227 7.2 BENEFITS 227 vii APPENDIX A IN -■ BAND SIGNALLING 229 APPENDIX B PAPER : "FACTORS IN THE PURCHASE OF A SMALL PROCESS 243 CONTROL COMPUTER” (Submitted as supporting material) PART - A DESCRIPTION OP BROADCASTING SYSTEMS AND OPERATIONS 2 CHAPTER 1 INTRODUCTION - BROADCASTING- A3 A FORM OP COMMUNICATIONS 1.1 COMPARISON WITH OTHER FORMS OP COMMUNICATIONS SYSTEMS 4 1.2 USES AND USERS OF THE BROADCASTING SYSTEM 9 1 .2.1 Profit -■ Seeking Broadcasters 10 1 .2.2 Non-Profit-Seeking Stations 11 1.3 CLASSIFICATION OF BROADCASTING ITEMS 13 1.3.1 Material. Used as Broadcasting Items 13 1.3.1.1 Entertainment Material 13 1.3.1.2 Information - disseminating Items 16 1.3.1.3 Composite Items 19 1.3.2 Methods of Item Production 19 1.3.2.1 "Packaged" Items 20 1.3.2.2 Occasional - demand Items 20 1.3.2.3 Heavy - demand Items 21 1.4 THE SENSE OF HEARING 21 1.4.1 The Physics of Sound 21 C\J • • Hearing : The Perception of Sounds 25 1.4.2.1 The Attributes of Hearing 25 1.4.2.2 Some Phenomena of Hearing 28 1.4.3 Constraints of Hearing on Broadcasting 33 CHAPTER 1 - REFERENCES 36 - 3 - /\£ECEI V£D S/&A/AL CJOMMMICATtotfS A MESSAGE FIC. /-/ COMMUNICATIONS SYSTEM - 4 - CHAPTER 1 INTRODUCTION - BROADCASTING AS A FORM OP COMMUNICATIONS 1.1 COMPARISON WITH OTHER FORMS OP COMMUNICATIONS SYSTEMS Communication is the act of passing a message, or item of information, from its source to a destination. A communications system achieves this by coupling the source and destination by means of a transmitter, a receiver and a channel between them. 1 * This is illustrated in figure 1-1, on the opposite page. The term ’’system" implies an assemblage of diverse elements or units that are mutually 2 related and interdependent. A typical task of a communications system is that of message switching. The system is required to route messages from a number of sources to specified destinations. The messages are variable in the amount of information contained (measured in binary units, called "bits") and in the rate at which they arrive for transmission. The linking communications channel has a fixed capacity to pass messages, measured in bits per unit time. The aim is to despatch the messages in an error-free condition as quickly as possible, so the success of a message-switching system-design is measured in terms of the delay a message experiences between the time it is presented by the source to the time it reaches its destination. Broadcasting is another method of communication, which has a different set of aims. In this method a single transmitter serves a small number of sources, and communicates * References are located at the end of each chapter - 5 - with a large number of destinations simultaneously; hence the name "broad-casting". This is a convenient means by which an individual or small group can disseminate information to a large population of destinations, and so it is exploited both by government agencies and by commercial and other common-goal groups. Whilst broadcasting is an instrumental form of communication^ (that is, the source desires a response from the destination) assessment of the response is not immediate, so that at the instant of broadcasting the act is a one-way, one-to-many operation. However, in cases where the set of possible destinations, the "audience" has a choice of a number of transmitters with which to link, then the wishes of the audience influence the material broadcast by the competing sources/transmitters (stations). In general, audiences tend to assess material in terms of its entertainment value^. Thus a criterion for successful operation becomes: "the most pleasing, or entertaining presentation of material being broadcast". Sections of items which are boring or unintelligble must be avoided. For example periods of silence between items and loss of parts of a message because another message interrupts the first are distasteful to audiences, so broadcasters try to avoid these blemishes. So the station operator, or broadcaster, becomes primarily concerned v/ith the "smooth" flow of items to the communicant ion channel, rather than with the rate of flow of messages; the - 6 - rate of message passing in broadcasting can be slow or rapid, provided the result is not disjointed. To achieve smooth presentation the broadcaster must know the duration of each item of information and the intervals of time, or time slots, available for item presentation so that he can plan a schedule of operations accordingly. In addition, a competing broadcaster must communicate to his potential audience details of items to be broadcast. This enables the audience to plan its schedules of listening, but imposes the necessity on the broadcaster for synchronisation of his operations with his advertised programme, or schedule of items. If mis-timing does occur, he is obliged to ensure that items do not commence early, by the use of short unadvertised items as "fill-ins”. Hence the broadcaster has two operational goals: (1) adherence to his advertised schedule of items to be broadcast. (2) pleasing continuity, or flow, of programme items. In order to compare more closely the two forms of communications systems, message switching and broadcasting, consider the following example. Let the message length in the message switching system be exponentially distributed about an average of 1/n bits. Also, let the arrival rate of messages be exponentially distributed with an average of 1 per second.' (The exponential distribution is chosen because it is time independent, i.e., has no memory of previous - 7 - events). The communications channel has a certain capacity to pass messages, measured in hits per unit time. Taking the capacity as C hits/second, messages will he despatched immediately on arrival, provided the instantaneous arrival rate of messages never exceeds the channel capacity.