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Digital Radio – Production & Transmission Technologies

Digital Radio – Production & Transmission Technologies. Presentation by: Yogendra Pal Director (Engg.) All India Radio, New Delhi. Agenda. Vinyl Disc to Optical & Magneto-optical Discs Tape to Hard Disc & Flash Memory Digital Audio Workstations Solid-state Recorders

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Digital Radio – Production & Transmission Technologies

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  1. Digital Radio – Production & Transmission Technologies Presentation by: Yogendra Pal Director (Engg.) All India Radio, New Delhi

  2. Agenda • Vinyl Disc to Optical & Magneto-optical Discs • Tape to Hard Disc & Flash Memory • Digital Audio Workstations • Solid-state Recorders • Digital Interfaces • IP-based audio networks • Issues for consideration

  3. Vinyl Discs toOptical & Magneto-optical Discs MO Disc

  4. Tape to Hard Disc & Flash Memory DAW Solid-state Recorders

  5. Digital Audio Workstation (DAW) • Complete automation, scheduling, production, play out, archiving etc. • Familiar transport control: Play, stop, forward, rewind, pause • Keyboard short cuts • Touch screens • Nonlinear access • Waveform with zoom facility • Metadata • Large storage capacity

  6. DAW – Controls & features 7 8 11 4 6 9 12 3 1 10 13 2 5 15 21 16 14 17 20 19 18 23 22 24 25

  7. DAW -- Metadata

  8. DAW -- Recording • Two or more tracks • Insert markers • Play & edit while recording • Recording by time & level • Selectable: • Sampling frequency • Bit resolution • Compressed/uncompressed

  9. DAW -- Editing Non-destructive with: • Cut/trim • Cut & paste • Copy & paste • Fade-in/out & cross-fade • Slip • Time indication • Time stretch, compress • Level changes • Colours for cuts

  10. DAW -- Scheduling • Play list by drag & drop • Fade-in/out & cross-fade • Schedule part of programme without copy • Block formation/insertion • Monitoring & editing transition points • Copy of schedules • Last minute changes • Automatic schedule preparation for criterion

  11. DAW – Playback • Manual, auto & live-assist play • Two & more virtual play panels • Monitoring start/end points • Assignable hot keys • Fader start/stop • Auto play • Protection from accidental exit

  12. DAW – Effects & signal processing Processing of: • Spectrum • Time • Amplitude • Noise

  13. DAW – Other features • Traffic & Billing • Report generation/printing • Log printing • Purging • Logging • Archiving • Networking Internet Storage

  14. Solid-state Recorders • No moving parts • Flash memory card as recording media: • PCMCIA card • Compact Flash • SD card • Smart Media • Cards capacity: up to 16 GB • Uncompressed & compressed recording • Easy transfer to DAW

  15. Solid-state Portable Recorders Sonifex (Courier) YouCom (Parrot) Fostex (FR-2) Marantz (PMD Series) Nagra (ARES-BB+)

  16. Solid-state Handheld Recorders AEQ (PAW 120) Edirol (R-09) Samson (H-4) Nagra (ARES-M) HHB (DRM 85)

  17. Typical Set up of a Radio Station Router Transmitter Land Lines Mixing Console From other Mixing Consoles

  18. Scenario & Options? Audio Networking

  19. Scenario • Analog: Professional & consumer, with XLR, RCA, DB-9, DB-15, ¼” phone, mini phone and RJ-45 connectors • Digital: AES3, TDIF, MADI etc. • Digital: Proprietary systems over fiber & copper • Ethernet: Networking of DAWs

  20. AES3 • One-way communication • Single source per cable limitation • Control and data possible but for very simple, low rate functions • Lack of flexibility

  21. USB and FireWire • Good for data transfer into and out of computer • Can’t extend to multiple ports

  22. Proprietary Audio networks • Used for connecting routers to each other and terminals • Expensive • Closed – all components from single vendor • Connection to outside world still via analog, AES or MADI etc.

  23. Ethernet • Already in use: Computer network • Packet-switched network • Fast developments: 10 to 100 to 1000 Mbps speed & new protocol (IPv6) • Low cost – economies of scale • Standard, off-the-shelf products • RJ-45 plugs – fast & easy to install • Single network for audio, data, telephony etc • Scalable

  24. Ethernet – Issues & Options • Not designed for continuous stream of time critical data • A number of proprietary systems now available which tackle the issue: • Livewire from Axia Audio (Telos) • Visiblu from Digigram • CobraNet from CobraNet Audio • Wheatstone from Wheatstone Corporation

  25. Livewire • Uses Internet IP standard • RTP/IP for audio • No sound cards • Full-duplex links with priority assignment to audio streams • Two types of streams: • Live streams – small, fast packets • Standard streams – bigger, non-critical data Contd…

  26. LivewireContd.. • Single Ethernet cable carries: • Real-time uncompressed digital audio • Device control messages • Programme associated data • Routine network traffic • Clock signal for synchronization • 50 audio channels (48 kHz, 20-bit) • Ethernet switch isolates links and route audio • Converged network

  27. Livewire -- Schematic

  28. Visiblu

  29. CobraNet

  30. Wheatstone system

  31. Issues for consideration • Virus • Backup • Disaster management • Sampling frequency and quantisation bits • Compression • Low cost systems

  32. Thank You For further reference, please email at: ypal@air.org.in or yogendrapal@gmail.com

  33. Compact Disc (CD) • Developed as replacement of gramophone records • Optical disc • Type Diameter Storage Audio capacity Std 120 mm 650 & 700 MB 74 & 80 minutes Mini 80 mm 184 MB 21 minutes • Format: 2-channel, 16-bit PCM at 44.1 kHz • CD-ROM, CD-R & CD-RW came up later Back

  34. DVD • Diameter & thickness of CD • High data capacity: up to 17.1 GB • No. of Formats • DVD-A: • Options for many channels at various sampling frequencies and sample rates • Distribution media for high-fidelity audio • Robust copy protection Back

  35. Super Audio CD (SACD) • Read-only, optical audio disc • Looks exactly like CD • Capacity: up to 7.95 GB • Frequency response: DC to 100 kHz • Dynamic range: 120 dB • Audio format: Direct Stream Digital (DSD) • Built-in copy protection features • 3 types: • Hybrid, Single and Dual layer Back

  36. Mini Disc • Removable, low cost & rewritable media • Two types: • Regular 74-minutes for 2-track • Data disc for multitrack • Records at 44.1 kHz, 16-bit. 24-bit also available • ATRAC: Adaptive TRansform Acoustic Coding compression Mindisc in cartridge (left), exposed minidisc (right) and protective cartridge holder (rear) Sony MZ-NHF800 Yamaha MD8 Back

  37. MODisc • 5.25” & 3.5” form factors • Casing • Information checking, reporting & correction (Not available in CD-R & DVD-R) • Dirt & scratch resistant: • Wide diameter of laser beam on disc surface but narrow towards recording layer • Dropouts reproduced by error correction • No direct contact with disc surface • High transfer speed – 5.92 MB/s • Capacity – up to 1.3GB (3.5”), 2.6GB (5.25”) Back

  38. AES/EBU (AES3) • Serial transmission of 2-channel digital audio • Balanced, 3-conductor, 110-ohm shielded twisted pair cable with XLR connectors • Data rate depends on sampling rate 3.072 Mb/s at 48kHz • Distance: up to 100 meters • Clock rate recovered by encoding data • For professional equipment • Can also be carried over an Asynchronous Transfer Mode (ATM) network

  39. AES/EBU (AES3)

  40. SPDIF • Digital Audio standard developed by Sony/Philips • Consumer version of AES3 • Unbalanced interface • 75-ohm coaxial with RCA jacks or fiber cable with TOSLINK connectors Back

  41. USB (Universal Serial Bus) • Serial bus standard • Max. devices: 127 per host • Originally designed for computers • No termination needed • Hot plugging of devices • Latest version: USB 2.0 • Transfer speeds: 1.5, 12 & 480 Mbps • Connectors: Series ‘A’, Series ‘B’, Mini ‘A’, Mini ‘B’ & Mini ‘AB’ Series A Plug Mini-A plug (left), Mini-B plug (right)

  42. FireWire • Serial bus standard • Proprietary name of Apple Inc. • Max. devices: 63 in tree topology • Designed to replace parallel SCSI • Supports multiple hosts per bus • Supports plug-&-play and Hot swapping • Transfer speeds: 100,200 & 400 Mbps for FireWire 400 and 800, 1600 & 3200 Mbps for FireWire 800 • Connectors: 4, 6 and 9 pins 4-pin and 6-pin Plugs 9-pin connector Back

  43. TDIF • Tascam Digital Interface • Proprietary format • Bi-directional connection to transmit and/or receive up to 8-channels • Separate cable for wordclock required in TDIF-1 but not in TDIF-2 protocol • Uses 25-pin D-sub cable

  44. MADI(Multichannel Audio Digital Interface) • Serial digital transmission over coaxial cable or fiber-optic line • Supports 28, 56 or 64 channels, with sampling rates up to 96 kHz & resolution up to 24-bit per channel • Bit-level description and features of AES3 • Known as AES10 Back

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