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

Digital Radio –Digital Radio –Production & Transmission Production & Transmission

TechnologiesTechnologies

Presentation by: Yogendra PalYogendra PalDirector (Engg.)

All India Radio, New Delhi

AgendaAgenda

• 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

Vinyl Discs toVinyl Discs toOptical & Magneto-optical DiscsOptical & Magneto-optical Discs

MO DiscMO Disc

Tape to Hard Disc & Tape to Hard Disc & Flash MemoryFlash Memory

Solid-state Recorders

DAW

Digital Audio Workstation (DAW)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

DAW – Controls & featuresDAW – Controls & features

12

34

5

67

10

98

13

12

11

2116

15

24

23

17

18

20

19

22

25

14

DAW -- MetadataDAW -- Metadata

DAW -- RecordingDAW -- Recording

• Two or more tracks

• Insert markers

• Play & edit while recording

• Recording by time & level

• Selectable:– Sampling frequency– Bit resolution– Compressed/uncompressed

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

DAW -- SchedulingDAW -- 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

DAW – PlaybackDAW – 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

DAW – Effects & signal processingDAW – Effects & signal processing

Processing of:

• Spectrum

• Time

• Amplitude

• Noise

DAW – Other featuresDAW – Other features

• Traffic & Billing

• Report generation/printing

• Log printing

• Purging

• Logging

• Archiving

• Networking

Storage

Internet

Solid-state RecordersSolid-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

Solid-state Portable RecordersSolid-state Portable Recorders

Sonifex (Courier)

Fostex (FR-2)

Marantz (PMD Series)

YouCom (Parrot)

Nagra (ARES-BB+)

Solid-state Handheld Solid-state Handheld RecordersRecorders

Edirol (R-09)

AEQ (PAW 120)

Nagra (ARES-M)

Samson (H-4)

HHB (DRM 85)

Land Lines

Typical Set up of a Radio Station

TransmitterRouter

From other Mixing Consoles

Mixing Console

Scenario & Options?

Audio NetworkingAudio Networking

ScenarioScenario

• 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

AES3AES3

• One-way communication

• Single source per cable limitation

• Control and data possible but for very simple, low rate functions

• Lack of flexibility

USB and FireWireUSB and FireWire

• Good for data transfer into and out of computer

• Can’t extend to multiple ports

Proprietary Audio networksProprietary 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.

EthernetEthernet• 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

Ethernet – Issues & OptionsEthernet – 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

LivewireLivewire

• 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…

LivewireLivewire Contd..

• 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

Livewire -- SchematicLivewire -- Schematic

VisibluVisiblu

CobraNetCobraNet

Wheatstone systemWheatstone system

Issues for considerationIssues for consideration

• Virus

• Backup

• Disaster management

• Sampling frequency and quantisation bits

• Compression

• Low cost systems

For further reference, please email at:

[email protected]

[email protected]

Compact Disc (CD)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

DVDDVD

• 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 protectionBack

Super Audio CD (SACD)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

Mini DiscMini Disc

Yamaha MD8

Mindisc in cartridge (left), exposed minidisc (right) and protective cartridge holder (rear)

Back

Sony MZ-NHF800

• 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

MOMO DiscDisc

• 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

AES/EBU (AES3)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

AES/EBU (AES3)AES/EBU (AES3)

SPDIFSPDIF

• 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

USB (Universal Serial Bus)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’Mini-A plug (left), Mini-B plug (right)

Series A Plug

FireWireFireWire

• 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

9-pin connector

4-pin and 6-pin Plugs

Back

TDIFTDIF

• 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

MADIMADI(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