Fullscreen HTML5Med Res (??MB)HTML4

BOOKSHELF Sound & Recording: An Introduction Sound and Recording – An Introduction, by Francis Rumsey & Tim McCormick. Published 1992 by Butterworth Heinemann, London. Soft covers, 318 pages, 234 x 156mm, ISBN 0-24051313-4, $85.00. If you’re looking for a good general introduction to the world of sound recording, then you’ll definitely need to look at this one. “Sound and Recording” is a good reference book which covers just about every issue related to sound recording, from audio perception through to the latest digital techniques. Chapter 1 covers the basics of how sound travels, units of measurement and the frequency spectrum. Chapter 2 continues on how we hear sound, from the mechanics of the ear to how we perceive sound direction. Chapter 3 deals with the signal path from source to speakers and introduces the basic components of sound record­ing. Chapter 4 deals with these in detail, starting with micro­phones, how they work, how their responses are measured and plotted, as well as looking at the various types available. Chapter 5 progresses to loudspeakers, giving basic mechani­ cal theory that relates to today’s common systems as well as ideas on positioning speakers for best response. Chapters 6 & 7 deal with mixers and they cover various features from fade to pan and how each of the controls works. Chapter 8 talks about the world of analog tape recording, giving some brief history and then discussing the recording process, including equalisation and biasing requirements. Various recording formats are also looked at as well as different types of recorders. Chapter 9 moves on to noise reduction and gives background information on the well-known examples; ie, Dolby A/B/C and dbx. Chapter 10 explains the basics behind digital recording and explains quite well some of those sometimes confusing topics of sampling and quantisation. Various formats are also presented including R-DAT and Nagra-D and Sony’s PCM system. The chapter then moves on to discuss hard disc recording techniques including discussion on how hard discs are built and finally, optical discs. Sony’s Mini Disc is not covered, as you might expect, since it is so recent. Chapter 11 covers the principles of operation of the record player, including lateral tracking of the tonearm, RIAA equalisa­ tion and arm design. Discussion then carries over to turntable design. Chapter 12 looks at power amplifiers and topics such as distortion, crosstalk, signal-to-noise ratio and frequency re­sponse, while chapter 13 looks at the important area of signal lines and interconnections, covering topics such as hum loops, transformers and balanced line systems. Chapter 14 looks at add-on equipment which can improve the apparent quality of sound from graphic equalisers, dynamic range limiters and compressors as well as effects such as reverb and echo. Chapter 15 takes a brief look at MIDI, what it is and where it’s used, as well as explaining how it works from a user’s perspective. All throughout the book, little “fact file” panels concisely explain common concepts relevant to the current chapter and are ideal for those looking for more in-depth information. Overall, this is quite a good book and ideal for anyone who wants to find out more about audio or for those who want a basic reference for their bookshelf. (D.B.Y.) In Marconi’s Footsteps: Early Radio In Marconi’s Footsteps – Early Radio by Peter Jensen. Pub­lished 1994 by Kangaroo Press, Sydney. Hard covers, 176 pages, 286 x 220mm, ISBN 0-86417-607-4, $49.95. If you’re looking for a good read on how radio began, then this is the book! It follows the early steps of one Guglielmo Marconi and how his idea of a “wire-less” telegraphy system transformed the European stage. The first half of the book is an historical perspective on Marconi. It covers his childhood, his arrival in England as a young man with ambition, through to his chance meetings that helped to establish “wire-less” as the newest form of mass commu­nication. Other areas covered include the Clifden Radio station, the first transmission from England to Australia in 1918, and the effect that the sinking of the Titanic had on wireless. The second half of the book is of a more technical nature, with circuits and diagrams of some of the early transmitters and receivers, including the coherer detector and the crystal set. The schematics and mechanical diagrams presented are quite detailed continued on page 88 January 1995  71 Physical Agents Directive. The BTE220 is designed to erase Hi-8, 8mm, VHS and S-VHS video cassettes, as well as all formats of audio cassettes and cartridges, includ­ ing DAT and DCC. The new BTE220 incorporates a powerful erase coil, enabling Hi-8 and 8mm video cassettes to be erased at a rate of six per opera­tion. The BTE220 is compact, with dimensions of 383 x 364 x 177mm. With Weircliffe’s magnetic shielding, the unit requires no additional free space surrounding it and may be located in close proximity to sensitive instruments. In addition, the BTE220’s internally shielded degaussing compartment gives enhanced protection to the operator from extraneous magnetic fields, in line with current NRPB recommendations. The BTE220 offers better than -80dBR erasure with Hi-8/8mm me­dia coercivity and features simple and efficient operation. The easily acces­sible media degaussing compartment is electromagnetically interlocked with the unit’s semi-automated erase head assembly and automatically en­gages the dual pass erasure cycle when the compartment is closed. For further information, contact Amber Technology Pty Ltd, Unit B, 5 Skyline Place, Frenchs Forest, NSW 2086. Phone (02) 975-1211. Fischertechnik robotic construction kit Fischertechnik has released a new robotic construction kit for use with the IBM-PC, PS/2, Amiga and Atari computers. Known as PROFI COMPUTING, the kit provides 888 parts with a 164-page manual describing the construction of 12 computer-controlled models. These include a CD player, a parcel-turning machine and a robot with a motor-driven gripper. Book Reviews – continued from page 71 and will probably spark some to head off for the tool shed and workbench. While some of the larger designs may be impracticable for most people, there is enough to interest the more determined. The book also contains many photos, some in colour, of the earliest Marconi equipment. 88  Silicon Chip This kit is useful for educational and training purposes in the fields of computer control, factory automation and mechanical and electrical engineering. It is also useful for simula­tion and prototyping applications. The Fischertechnik interface provides eight digital and two analog in­puts and four bidirectional motor out­puts. It connects to any parallel printer port and allows a second unit to be connected for a total of 16 digital in­puts and eight motor outputs (or 16 lamp outputs). The analog inputs may be used with potentiometers (for position control), light dependent resis­tors (for measuring light), thermistors (for measuring temperature), or with any resistive device from 0 to 5kW. Fischertechnik software called Lucky Logic provides an interactive, mouse-driven, user interface that is similar to a Sequential Flow Chart (SFC) style of control that is used by major industrial equipment suppliers such as Allen Bradley. Also available is a Programmable Control Language (PLC), developed by Procon Technology, that simulates the operation of relay-ladder-logic control. Finally, ex­ample programs are also available in C.BASIC and Pascal. The kit provides three motors and gears, six microswitches, two phototransistors, a 20-pin connection socket and construction base plate. For further information, contact Peter King, Procon Technology, PO Box 655, Mount Waverley, Vic 3149. Phone (03) 807 5660. Some of the more interesting photos include a look at a couple of early Australian transmitters at Queenscliff, Victoria and Devonport, Tasmania. There are seven appendixes which include letters between Marconi and his long time supporter, Sir W M. Preece, the first two technical reports on the Marconi system, two early pat­ents and a report made by Capt. H. B. Jackson to the Admiralty on the worthiness of the Marconi system for the Royal Navy. There is also an extract from the 1912 New York Times from the wireless operator on board the Titanic. Overall, this is a great read. For anyone who has ever been captivated by the thought of transmitting their voice over the air waves, this book will serve as a good reminder of how it all began. (D.B.Y.) SC