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IQBADX

SECTION 28c

IQBADXOPS

050804

www.snellwilcox.com

Version 1 Issue 5

28c.20

Extractor Operation

The SMPTE 272M standard specification allows for
up to four groups of digital audio to be embedded
in a component D1 digital video stream.
Each group consists of two stereo pairs (four
channels), giving a total of sixteen audio channels
for all four groups.
A single IQBADX module is capable of extracting
four stereo pairs, or eight channels, so two
IQBADX cards are required to extract all sixteen
possible channels.

The embedded AES audio data must be sampled
at 48 KHz, clock synchronous to the video stream.
Asynchronous operation is not supported.

The IQBADX module contains four independent
extractors, each one assignable to any of the
possible embedded audio pairs.  If any of the
extractors are set to the same address they all will
output that extracted pair.  Additionally, any output
can provide an AES test tone (1 KHz, -20 dB) or
‘digital silence’.

A total of exactly 1920 audio samples occur within
one frame of 625-line video.  For 525-line video the
relationship is 8008 audio samples over five video
frames.

The audio data is usually distributed evenly
throughout each video frame, situated in the non-
active picture regions between the end of one line
and the start of the next.  The majority of lines
contain three audio samples, some four, and
certain reserved lines may contain no samples.
Other sample counts are also possible.

These differences in sample count between lines
mean that some FIFO buffering is required to
supply output audio samples during lines
containing no samples, and to absorb the excess
from lines with several.

An audio extractor should be able to process
ancillary packets where ever and whenever they
appear.  However, there are usually practical and
operational limitations such as the finite length of
the extractor FIFO buffer, and the length of the
audio delay introduced by the buffering process.

IQBADX FIFO Buffer Length :

A FIFO buffer requires that before any samples are read out a minimum number must be written in.  This
number determines the latency (delay) and implies limitations on the embedded sample distribution. So-called
‘smart buffers’ make assumptions about the distribution of audio samples within the video frame and so can
utilise smaller FIFOs. The 24-bit sample distribution given in SMPTE-272M for example requires a ‘smart
buffer’ length of 57 samples with a read-write offset of 17 samples. A simple buffer however needs to be 80
samples long with 40 samples offset.  In both cases the buffers can handle a maximum change in usage of 40
samples but the ‘smart’ buffer knows when this happens and so can use less memory and have a lower
latency.
For any known sample distribution the required buffer capacity can be calculated. The simple buffer needs to
be twice this in length

SMPTE-272M,  24-bit example

40 samples

Panasonic D5 VTR, 625 lines  

6 samples

Sony Digital Betacam, DVW-500P  

5 samples

S&W  IQBAI / BAIR  inserter modules

14 samples

Tektronix  TSG-422  

7 samples

S&W MDD-3000 digital decoder  

7 samples

Содержание IQBADX-2-B

Страница 1: ...impots Extraction may be from any group and pair independently for each channel pair Extraction is fully compliant with SMPTE 291M and SMPTE 272M A for synchronous to video audio at 48 kHz When audio data is absent from a selected channel pair address the output will be silence or tone selectable The SDI input is equalized to 200 m of cable Full EDH monitoring is included All analogue audio connec...

Страница 2: ...able They are not interchangeable between the two styles of enclosures However the cards may be fitted into any style of enclosure A Style Enclosure Rear panels with the suffix A may only be fitted into the A style enclosure shown below IQ Enclosure order codes IQH3A E 0 IQH3A E P IQH3A 0 0 IQH3A 0 P O Style Enclosures Rear panels without the suffix A may only be fitted into the 0 style enclosures...

Страница 3: ... DAC DAC DAC DAC DAC Features Demultiplexes four audio pairs from serial 4 2 2 video Simultaneous Analog and AES EBU digital outputs Audio extraction independently selectable by pair Channel 1 2 mapping 1 2 2 1 1 1 2 2 20 bit digital to analog conversion 95 dB THD N FS Analog output level manually adjustable 12 to 24 dBu for 0 dB FS in Crystal PLL for low jitter Automatic 525 and 625 line operatio...

Страница 4: ...alanced unbalanced Standards SMPTE 259M C 1997 SMPTE 272M A 1994 AES3 1992 Specifications Serial Input Return Loss Better than 15 dB to 270 MHz Serial Input Receive length 200 m Analog Audio Outputs Level Manually Adjustable 12 dBu to 24 dBu Output Impedance 45 to 55 ohms AES Audio Outputs Typically 3 V pk to pk into 110 ohms Transformer Balanced via 25 way D connector AES Audio Outputs Unbalanced...

Страница 5: ...ade via this BNC connector which terminates in 75 Ohms AES Reference Input The AES reference input connection is made via a BNC connector If a suitable AES reference signal is present the digital outputs will be frame synchronised to this signal 48 kHz only SERIAL IN IQBADX 2 B D IQBADX 2A B D SERIAL IN AES REF IQBADX 2 D AES REF IQBADX 2 B 0 IQBADX 2A D ...

Страница 6: ...available For connection data consult the tables on page 5 If a suitable AES reference signal is present the digital outputs will be frame synchronised to this signal 48 kHz only IQBADX B 2A B Analog audio output connections are made via the 25 way female D type connector There are four balanced analog outputs available For connection data consult the tables on page 5 IQB AUDIO OUTPUTS IQBADX 2 D ...

Страница 7: ...re made via these four BNC connectors There are four unbalanced AES outputs available Serial Digital Video IQBADX 2 D 2A D only These are the three isolated Serial Digital outputs of the unit via BNC connectors for 75 Ohms AES OUTPUTS 1 2 3 4 IQBADX 2 B 0 IQBADX 2A B SERIAL OUTPUTS 1 2 3 IQBADX 2 D IQBADX 2A D ...

Страница 8: ...1 16 5 9 AES OUT 2 17 6 22 AES OUT 2 18 6 10 AES 2 GND 19 GND6 23 AES 3 GND 20 GND7 11 AES OUT 3 21 7 24 AES OUT 3 22 7 12 AES OUT 4 23 8 25 AES OUT 4 24 8 13 AES 4 GND 25 GND8 Connection Details IQBADX B 1 Chassis 1 CHASSIS 14 ANALOG OUT 1 GND 2 GND1 2 ANALOG OUT 1 Left 3 1 15 ANALOG OUT 1 Left 4 1 3 ANALOG OUT 1 Right 5 2 16 ANALOG OUT 1 Right 6 2 4 ANALOG OUT 1 GND 7 GND2 17 ANALOG OUT 2 GND 8 ...

Страница 9: ...9 Analog Output 1 Left Analog Output 2 Left AES Output 1 AES Output 3 Analog Output 1 Right Analog Output 2 Right AES Output 2 AES Output 4 Analog Output 1 Right Analog Output 2 Right Not Used Not Used Analog Output 1 Left Analog Output 2 Left Not Used Not Used IQBADX B IQBADX D ...

Страница 10: ... factory default settings of parameters not available as card edge adjustments are loaded With the link in the CLOSED ON position the card will power up with the last settings stored in the non volatile memory LED INDICATORS PWR Power These two PWR indicators are illuminated when the positive and negative supplies are present D1 Loss This LED will become illuminated when there is no D1 input ANC E...

Страница 11: ...etected EDH MINUTE HOUR These LED s provide the EDH error minute hour history indicating occurrence of errors within their respective time periods These LED s will remain OFF if no errors have occurred within their time period or it the incoming D1 video does not contain EDH data BCD SELECT SWITCHES These switches select which embedded channel or tone silence is to be output Settings are as follow...

Страница 12: ...4 EDH RESET When enabled this will clear EDH error history SMPTE 272M SUPPORT The cards conform to SMPTE 272M A A synchronous audio at 48 kHz 20 bit audio data packets The cards do not support SMPTE 272M B C D E F G H I J B synchronous audio for composite video C 48 kHz synchronous with audio extended data packets D asynchronous audio E 44 1 kHz audio F 32 kHz audio G 32 kHz to 48 kHz continuous s...

Страница 13: ... can be done either by de embedding an embedded tone or the card s internal tone generator may be used In all cases the card must be supplied with a valid SDI digital video source Using the card s internal tone generator Connect the analog outputs to an audio level meter Via RollCall set outputs A and B to 0dBFS_1kHz Adjust the multi turn trimpots for the required analog headroom Using an SDI feed...

Страница 14: ...IQBADX SECTION 28c IQBADXOPS 050804 www snellwilcox com Version 1 Issue 5 28c 14 ...

Страница 15: ...ver a menu item is selected the parameters of that selection will be displayed in the Information window of the front panel Where the selection is purely a mode selection and does not enable a sub menu the text will become reversed white on black indicating that the mode is active If the mode is not available for selection the text will remain normal Outputs The outputs can be set to any of the ei...

Страница 16: ...llows the settings of all items to be saved Up to 4 different set ups may be saved in the 8 memory locations They can all be renamed using the Name_User_Memory menu item Name_User_Memory This selection allows renaming of memory 1 to 4 locations To rename a memory location when operating in a particular standard select Name Memory to reveal the sub menu Select the memory location to be renamed e g ...

Страница 17: ... operation Off When selected the function is not active Latch When the contact is closed the function is activated when the contact is open the function is de activated Edge Edge triggered With each open to closed trigger the GPI function is toggled between activated and de activated GPI_Function The action resulting from the GPI input being activated may be programmed from this list Output_A_Sile...

Страница 18: ...FS_500Hz 20dBFS_250Hz 60dBFS_1KHz 1dBFS_1KHz 0dBFS_1KHz Preset setting is L R_Tone Names Default names are given to the outputs and the possible embedded inputs which are little more than relative descriptions These names may be edited to provide more meaningful information related to the equipment installation To edit a name select either Output_Names or Input_Names or Preset_Names returns to def...

Страница 19: ...formation to be made available for logging Factory preset is nothing enabled Preset_Unit Selecting this item sets all adjustment functions that include a preset facility to their preset values Note that this is a momentary action and the text will not become reversed Software_Version Selecting this item reveals a display showing the version of the software fitted in the module Select OK to return ...

Страница 20: ...ossible These differences in sample count between lines mean that some FIFO buffering is required to supply output audio samples during lines containing no samples and to absorb the excess from lines with several An audio extractor should be able to process ancillary packets where ever and whenever they appear However there are usually practical and operational limitations such as the finite lengt...

Страница 21: ...on No Issue No Change Comments 180100 1 1 First Issue 161000 1 2 O P controls added channel topair New manual issued 280302 1 3 Now includes information for the 3A enclosure module New manual issued 010403 1 4 Power consumption added to techspec New manual issued 050804 1 5 No Lock data corrected New manual issued ...

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