Digital Audio Analyzer DAA-11

Transcription

1 Lawo AG Am Oberwald 8 D Rastatt, Germany interstage Phistersvej 31, 2900 Hellerup, Danmark Telefon , fax pro audio with a smile Tel.: +49(0) 7222/ Fax: +49(0) 7222/ Web: Nov 98 product information page 1

2 page 2 product information Nov 98

3 Contents Contents... page 3 MADI-Format... page 5 AES/EBU format description... page 5 Block Diagram... page 9 System integration... page 11 Monitoring in General... page 12 Monitoring via integrated loudspeakers and Analog-... page 13 Monitoring via headphones... page 13 Monitoring via AES/EBU... page 13 Transmitting via AES/EBU... page 13 Transmitting of Generator Signals... page 13 Clocking... page 15 Menu and LED displays... page 17 Monitor LEDs... page 17 User navigation via LCD and RS page 18 General menu options... page 19 Control via RS page 20 Views and Technical Data... page 21 Standard configuration of the TAXI-interface... page 22 Technical Specifications... page 22 Nov 98 product information page 3

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5 MADI-Format AES/EBU format description The AES/EBU format consists of a frame of 64 bits. Two audio channels of 32 bits are defined as subframe. Each subframe includes 20 audio bits and 4 auxiliary bits. The latter can be used freely but may be combined with the audio bits to a 24-bit audio word. A subframe includes further 4 bits (bit 28-31): channel status (C-bit) user data (U-bit) validity (V-bit) parity (P-bit) The bits of the AES/EBU format preamble auxiliary audio sample word V U C P The 4 bits remaining per subframe (bit 0-3) are used for bi-phasecoding, if selected. With these, each channel (left, right), is labelled and, at the same time, is used for channel block synchronization. These preambles are called X, Y and Z. Status 0 1 channel coding X subframe 1 Y subframe 2 Z subframe 1 and block start AES/EBU block synchonization X Channel 1 Y Channel 2 Z Channel 1 Y Channel 2 X Channel 1 Y Channel 2 Subframe 1 Subframe 2 Frame 191 Frame 0 Frame 1 Block Start As shown above, one AES3 block is built of 192 frames. This block structure makes it possible to identify the received C-data-bits as a data stream with 192 C-bits per block period. It means that each block contains the information of 24 bytes. C-data-bits contain information such as sample rate, selected emphasis, setting of either consumer or professional mode etc. (for further information see e. g. AES papers). The U-bit is not pre-defined and may be used freely by the user. The remaining V-bit and P-bit indicate the validity both of the audio data and the parity of the whole subframe. Nov 98 product information page 5

6 Definition and History of the MADI Format The MADI standard (Multichannel Audio Digital Interface) is a modification of the industrial standard FDDI (Fibre Distributed Digital Interface) which is used in the computer environment by a transfer rate of 125 Mbit/s for coaxial transmission up to ca. 200 m or for fibre optic transmission up to ca m. The exact distances depend on the transmitting interfaces and their equalizing. The input word is divided into blocks of 4 bits each. Each block is transcoded by the 4B/5B-procedure into a 5-bit word. This increase of the number of bits causes a NRZI-coding (Non-Return-to-Zero Recording) which needs a smaller relative bandwidth for transmission than the original AES/EBU-signal. Owing to its biphase coding, the latter uses double bandwidth to regenerate the clock from the signal. By this 4:5 expansion, 100 Mbit out of a transfer rate of 125 Mbit/s are available purely for data transmission. In the MADI-modification, 56 AES/EBU channels according to AES3 (32 bit per subframe) can be transmitted in the time division multiplex in real time. This number is born out of the demand for a sample rate of 48 khz with a positive varispeed variation of 12.5%: (48 kbits/s %) * 32 (bits) * 56 (channels) = 96,768 Mbits/s Without the varispeed option up to 64 channels can be transmitted: 48 kbits/s * 32 (bits) * 56 (channels) = 98,304 Mbits/s page 6 product information Nov 98

7 The bits of one AES/EBU channel in the MADI-format Bit Nummer Bit Name Description Definition MADI Cannel 0 MADI Aktiv MADI B/A MADI Sync Frame Sync Bit Kanal aktiv Bit AES Stereo B/A Kanal Block Sync 1 = true 1 = true 1=B 1 = true 4-27 Audio Daten Bits AES V AES U AES C AES P Validity Bit User Daten Bit Status Daten Bit Parity Bit 0 = true 0 = true 0 = true even As the MADI-format does without the biphase coding of the AES/EBU-format, generating a 4B/5B-coding instead, the bits 0-3 can be additionally used for MADI-synchronization. MADI-bit 0 frame sync This bit labels the first channel of a MADI-block and is with all other channels false ( 0 ). This enables the receiver at the block start to trigger a reset for a new receiving block. MADI-bit 1 channel-active bit Not always all 56 channels of the MADI-channel are used. Is the bit not set ( 1 ) it means that this channel holds valid data. If it is not set the channel is ignored by the receiver and the bits V, U, C and P are set 0 by the transmitter. For using only 24 channels with one MADI-channel, for channel 0-23 the active bit must be set without gap and deleted for the remaining 32 channels. MADI-bit 2 AES stereo B/A The channels in the AES-signal are distinguished by the preambles X and Y and the distinction of stereo signals in the MADI-channel are made by the MADI-bit 2. MADI-bit 3 channel block sync Marks the block beginning of the bits U and C of the AES channels, and is important for the correct interpretation of user data and status data, similar to the AES Z preamble. Nov 98 product information page 7

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9 Block Diagram Tw.Pair (Modul 1) Option LWL (Modul 2) Option RS 232 EEPROM Power Select Microcontroller Sync TAXI TAXI DSP AES3 AES3 D/A LED Display FSYNC AES/EBU ANALOG TAXI Nov 98 product information page 9

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11 LAWO ANALOG LAWO ANALOG MADI - TESTER LAWO GmbH MADI - Tester FSYNC MADI - TESTER LAWO GmbH MADI - Tester FSYNC TAXI TAXI USER 1 TAXI - Parity - ERROR USER 2 TAXI - Violation USER 3 MADI - ERROR USER 4 TAXI - Transmit ERROR USER 5 Lock 48 khz PLL USER 6 Lock 12,288 MHz PLL USER 7 AES/EBU - ERROR USER Power USER 1 TAXI - Parity - ERROR USER 2 TAXI - Violation USER 3 MADI - ERROR USER 4 TAXI - Transmit ERROR USER 5 Lock 48 khz PLL USER 6 Lock 12,288 MHz PLL USER 7 AES/EBU - ERROR USER Power Headphone AES/EBU Headphone AES/EBU System integration The selection of monitoring either the TX or the RX line is realized by differently marked plugs. Monitoring of the TX-line of TAXI-Unit 1 TAXI - Unit 1 TX- Plug TX TAXI - Unit 2 RX RX- Plug Monitoring of the RX-line of TAXI-Unit 1 TAXI - Unit 1 RX- Plug RX TAXI - Unit 2 TX TX- Plug Nov 98 product information page 11

12 Monitoring in General Transmitting into the TAXI - line TAXI - Receiver TAXI - Transmitter Monitor Channel Insert Channel Generator AES/EBU Transmitter I 2 S I 2 S Signal Processor I 2 S AES/EBU Receiver D/A - Converter (Loudspeaker) Transmitting into the AES/EBU - line (TAXI - Receiver - NORM = off) TAXI - Receiver TAXI - Transmitter Monitor Channel Insert Channel Generator AES/EBU Transmitter I 2 S I 2 S Signal Processor I 2 S AES/EBU Receiver D/A - Converter (Loudspeaker) Note : AES/EBU-transmitter and D/A converter will output the same signal. page 12 product information Nov 98

13 Monitoring via integrated loudspeakers and Analog- In both cases channel A of the AES/EBU transmitter menu is monitored. The Analog- is directly set at the D/A converter output (600 ohm), the loudspeaker is operated via a small main amplifier. Monitoring via headphones Channel A (left) and channel B (right) of the AES/EBU-transmitter menue are monitored via headphones. By inserting the jack of the headphones the integrated loudspeakers are cut off. The volume can be set by menu. Monitoring via AES/EBU Here channel A and channel B of the AES/EBU transmitter menue is monitored. Transmitting via AES/EBU If at this input a valid AES/EBU - signal is recognized the AES/EBU - ERROR LED goes out. In this case channel A and channel B of the AES/EBU-Receiver menu are transmitted into the TAXI-channel. Transmitting of Generator Signals With the generator it is possible to select with Cs (channel start) the start-off and with Cl (channel length) the number of into the TAXI-channel () inserted sinus signals. A valid AES/EBU-receiver signal being transmitted at the same time at the same channel possesses higher priority than the sinus signals. Nov 98 product information page 13

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15 Clocking As clock source for the 48 khz and 41.1 khz framesync four inputs are possible. a MADI: the MADI-receiver sends a signal that generates a framesync signal via PLL. b FSYNC : a 48 khz or 41.1 khz clock frequency can be transmitted via the FSYNC jack. c AES/EBU : by biphase-coding of the Signal, a framesync signal is received on the AES/EBU input Internal: the crystal-generator s clock frequency of MHz is divided down to 48 khz or 41.1 khz. Nov 98 product information page 15

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17 Menu and LED displays Monitor LEDs Parity-error: Is the received parity not correctly recognized by the TAXIreceiver, a parity error is displayed. TAXI-violation On the basis of the 4 bit / 5 bit coding the TAXI-receiver can identify transmitting errors. MADI-Error The received signal is not in accordance to the MADI-Frame. TAXI-Transmit-Error Shows synchronizing problems of the TAXI-Transmitter. Lock PLL 1 This is important with the synchronizing with the TAXI-signal. When the LED shows, the 48 khz / 41.1 khz - PLL is locked. Now it is possible to synchronize with the received TAXI-Signal. Lock PLL 2 When this LED shows PLL 2 is locked. This should be usually the case as otherwise synchronizing is incorrect; e. g. the AES/EBU-Transmitter is not synchronized with the target s framesync. AES/EBU-error Here it is displayed whether the AES/EBU - receiver is driven correctly. One possible error is a wrong sampling rate. User Not yet implemented. Nov 98 product information page 17

18 User navigation via LCD and RS232 Press Button Press Turn TAXI Mode NORM: Madi LAWO KLOTZ Channel: off Word length: TAXI Mode NORM: Madi LAWO KLOTZ Channel: Word length: FSYNC Source TAXI FSYNC AES/EBU Intern AES/EBU Channel - A: Channel - B: AES/EBU Channel - A: Channel - B: Volume TAXI Type BNC 75 Ohm Tw.Pair LWL Tw.Pair <> LWL Generator Funktion: Sin. off Channel start: Channel length: ,4,6,8,10 FSYNC Rate FSYNC 48KHz FSYNC 44,1KHz page 18 product information Nov 98

19 General menu options TAXI MODE N = NORM (MADI, LAWO, KLOTZ, off) Setting of mode of the TAXI - Receiver. In OFF - position the TAXI-Receiver is switched off. Thus, it is possible to loop the AES/EBU-receiver through to the AES/EBU-Transmitter with monitoring via the analog output channels. C = Channel length (56, 64, 72) Number of audio channels in the TAXI - channel. Wl = Word length (24, 32) Bit-number of the audio samples. Note: Owing to the TAXI-channel capacity, a channel length of 72 with a word length of 32 is not permitted. It can be set though for detecting a wrong configuration of the interface. TAXI MODE N = NORM (MADI, LAWO, KLOTZ) Settings of the TAXI-Transmitter s operational mode. C = Channel length (56, 64, 72) see above Wl = Word length (24, 32) see above FSYNC source (TAXI, FSYNC, AES/EBU, Intern 48 khz) see no. 2 AES/EBU (01..56, 64, 72) The maximum channel number (56, 64, 72) depends on the channel length of the TAXI - transmitter. AES/EBU (01..56, 64, 72) The maximum channel number (56, 64, 72) depends on the channel length of the TAXI - transmitter. Volume (00..18) In the position 00 the D/A-converter is switched off. The volume can be selected between the positions 01 and 18. The AES/EBU-signal is left undisturbed. TAXI Type BNC 75 ohm: Monitoring via unit 2 possible Twisted Pair (unit 1): Monitoring via BNC output (TAXI-) possible. Nov 98 product information page 19

20 OWG (unit 2): Monitoring via BNC output (TAXI-) possible. Twisted Pair <> OWG (unit 1 and 2): May be used for adapting from Twisted Pair to OWG with unit 1 as input and unit 2 as output. Monitoring via BNC-output (TAXI-) possible. Generator F = FUNCTION (sin, off) OFF : The generator is switched off. With sin sinus signals in ascending frequency (distance 178 Hz) are transmitted into the TAXI channel. CS = Channel Start (01..56, 64,72) Shows the channel into which the first sinus signal is being transmitted. The maximum of the selectable number depends on the setting of the channel length of the TAXI-transmitter CL = Channel length (2, 4, 6, 8, 10) Number of the into the TAXI-channel transmitted sinus signals (10 max.) FSYNC Rate: FSYNC 48 khz / 44.1 khz Control via RS232 By aid of a null modem wire this device can be remote-controlled via the RS232 interface (baud rate 9800N81). For this, only a terminal Programm like e. g. TELIX or PROCOMM is needed. The same settings as on the device can be carried out. Wiring of a suitable cable with SUBD 9-pin connector : Pins TXD RXD GND Pins page 20 product information Nov 98

21 Views and Technical Data Front LAWO MADI - TESTER USER 1 TAXI - Parity - ERROR Headphone LAWO GmbH MADI - Tester USER 2 TAXI - Violation USER 3 MADI - ERROR USER 4 TAXI - Transmit ERROR USER 5 Lock 48 khz PLL USER 6 Lock 12,288 MHz PLL AES/EBU USER 7 AES/EBU - ERROR ANALOG FSYNC TAXI USER Power Back RS 232 Modul 2 Modul 1 Reset LCD display with LED illumination 2 Status monitor LEDs 3 Headphones jack (4 ohms) 4 Analog Output (600 ohms) 5 FSYNC input and output (75 ohms) 6 TAXI input and output coaxial (75 ohms) 7 Rotary control 8 AES/EBU input and output 9 Handle 10 Power connector (IEC) 11 Ventilation 12 General reset button 13 RS 232 interface 14 Taxi-module 2 (option) 15 TAXI-module 1 (option) Nov 98 product information page 21

22 Standard configuration of the TAXI-interface norm MADI (with varispeed) MADI (without varispeed) KLOTZ LAWO 1 LAWO 2 LAWO 3 channel number bits per channel Technical Specifications Dimensions: 28 x 25 x 8 cm (width x depth x height) Weight: 2.4 kg Sample rate: 48 khz, 44.1 khz Connectors 1. TAXI in/out according AES-10 standard; Coaxial, 75 ohms (standard); Fibre optic SC/ST-connector; 1300 nm / 800 nm; 62.5 um (option 1); Twisted-pair 9-pin D (option 2); 2. AES/EBU in/out according to AES-3 standard (transformer balanced); 3. PC interface: serial RS 232 interface 4. mains supply: 230 V/ Hz; IEC-norm Standard equipment: coaxial input and output for the MADI/TAXI-signal Options: fibre optical modules, twisted-pair modules with adapter cable interstage Phistersvej 31, 2900 Hellerup, Danmark Telefon , fax pro audio with a smile page 22 product information Nov 98