Solid State Logic 1266 Frequently Asked Questions, Power, Synchronisation, SampleRateConverters

Frequently Asked Questions

Power:

Q:Can Irun SDI-MADI with justone PSU (AC inlet) cable?

A:Yes, although it is always recommended that two AC inlet cables are connected in order to provide a level of redundancy. The two AC inlet cables should be connected to mains circuits which are as independent of each other as possible.

SDI:

Q:How do you selectbetween SDI formats?

A:The XLogic SDI-MADI automatically determines what the incoming SDI format is and configures itself accordingly. Status of each individual SDI input (SD, HD or 3G) is indicated on the front panel.

Synchronisation:

Q:SDI-MADI is notsynchronisingto wordclock.

A:Ensure that the incoming wordclock is derived from a 75 ohm terminated source, as per the AES-11 standard.

Q:Whatis the most commonly recommended configuration for synchronisation?

A:The most commonly used and recommended synchronisation method for SDI-MADI is slaving it to wordclock via the Ref In connector. Ensure that wordclock sync has been selected using the front

panel selection switch (WK LED should illuminate) and that all four sample rate converter switches are set to ON.

SampleRateConverters:

Q:Whatare the Sample Rate Converters for?

A:In the traditional sense, Sample Rate Converters (SRC) do as they say; convert an incoming or outgoing audio source from one sample rate to another. In the case of SDI-MADI, the SRCs perform two functions:

a)The sample rate converters compensate for any minor frequency differences between the incoming SDI 48 kHz and the reference 48 kHz, thus locking the audio to the reference 48 kHz.

b)The sample rate converters are used to phase align the audio content within the independent SDI sources prior to them being combined and transmitted as a MADI stream. Unless synchronising to an SDI source that incorporates Dolby ® encoded material it is important to ensure that all four SRC switches are set to ON. If set to OFF it could be possible for audible clicks to be present on the MADI receiving device. Note: If SDI-MADI detects that phase alignment between incoming SDI streams is significantly out (and that all SCRs are set to OFF), SDI-MADI will mute the MADI output.

Q:When should an SRC switch be set to OFF?

A:The only time an SRC switch should be set to OFF is when Dolby ® content is embedded within the SDI stream. If this situation does arise then SDI-MADI synchronisation must be set to reference that specific SDI input. SDI-MADI will then become the sync master reference source. Ensure that other equipment then synchronises to the unit’s Wordclock output (WK Out).

Note: only one SRC should be set to OFF at any one time. The possibility of sync issues could arise if the separate SDI sources are not phase aligned.

Q:Can Idaisy-chain other devices to SDI-MADI to when synchronising to Wordclock?

A:This is possible by using the wordclock loop-through connector (WK Out). WK Out is a buffered copy of the incoming wordclock.

Q:Can SDI-MADIbe used as amaster syncgenerator?

A:In the majority of installations SDI-MADI should not be used as a master sync generator. The only situation that would dictate use as a master clock reference would be when SDI-MADI is synchronised to an incoming SDI source that contains Dolby® bit streams. In this situation the appropriate SDI’s Sample Rate Converter (SRC) switch should be set to OFF and all other external audio equipment should be synchronised to the SDI-MADI’s wordclock output (WK Out).

Q:Is the wordclock input terminated?

A: Yes, it is internally terminated at 75 ohms.

Q:Can Sample Rate Conversionbe applied to the AES outputs?

A:Yes, depending whether the SRCs are set to ON or not. If set to OFF, synchronisation of each AES pair will be as per the specific input SDI source.

Audio Outputs:

Q:Is there an easier way to access the AES outputs than wiring directly to the 37-way Dsub?

A:Yes, SSL also manufacture a 1U AES3-id breakout unit (ASBO) that connects directly to SDI-MADI and provides the 32 unbalanced AES outputs on BNC connectors (75 ohm). Contact your SSL dealer for further information.

Q:Are the audio outputs always available?

A:Yes, de-embedded audio is simultaneously available as 32 x AES3- id, and optical & coaxial MADI.

Q:Whatfibre opticMADI cable should Iuse?

Recommended fibre types are 62.5/125 µm or 50/125 µm, multimode. An ST type fibre optic connector is fitted to SDI-MADI.

Q:Ihave no MADI output?

A:Check that synchronisation is valid. MADI will not be transmitted if synchronisation is invalid.

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