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The Domesday Duplicator is intended to allow high-quality back-ups of the analogue information contained on the laserdiscs by bypassing most of the 30-year-old electronics in the players. Direct RF sampling also allows all information on the LaserDiscs to be stored (unlike conventional RGB or YUV sampling of the video output).
Since AIV LaserDiscs are a combination of video, pictures, sound and data (as well as numerous VBI streams), direct RF sampling is the preferred method of preservation.
The Domesday Duplicator is a USB3-based DAQ capable of 40 million samples per second acquisition of analogue RF data.
The Domesday Duplicator (DdD) Rev 3.0
The hardware is a USB 3.0 based 10-bit analogue to digital converter originally designed to allow the backup of Domesday AIV LaserDiscs (as well as generic LaserDiscs) through the direct sampling of the FM RF data from the optical head (laser) pre-amplifyer stage of a LaserDisc player
It also supports capturing of other single channel formats such as Video8/Hi8 or BetaMax NTSC very well, but has been super-seeded in some regards by CX Cards with the Clockgen Mod & MISRC for multichannel format capture formats such as VHS.
The hardware/software solution was designed to act as a sampling front-end to the ld-decode project (software decoder of LaserDiscs) and replaces the generic or professional TV signal capture cards to provide high-frequency sampling with 4 times the sample resolution 4fsc and time base correction for a native Composite on file to YUV video workflow, that is entirely software defined.
This has since expanded into a family of "decode" projects such as vhs-decode (handling a wide range of tape formats), cvbs-decode (handling baseband raw composite captures) and HiFi-Decode (handling FM HiFi audio).
There are 3 main components that make up the Domesday Duplicator (DdD)
The custom ADC board based around the Texas Instruments ADS825 10-Bit, 40MSPS analogue to digital converter, the RF input is physically provided by a BNC connector.
This board contains an RF amplifier (Texas Instruments OPA690 and conditioner (to amplify the output from a RF tap on the format you wish to capture from and condition it for the single-ended ADC chip) as well as 2 rows of header pins for both the DE0-Nano FPGA development board and Cypress FX3 SuperSpeed Explorer board.
The DE0-Nano is a low-cost FPGA development board containing an Altera Cyclone IV FPGA. The DE0-Nano is used to process the raw 10-bit ADC data stream and provides FIFO buffering (towards the FX3) and sample conversion from unsigned 10-bit to scaled 16-bit signed data.
The FPGA provides a dual-clock FIFO; receiving ADC data at a maximum of 40 MSPS (million samples per second) and transmitting the data to the FX3 at a maximum of 60 MSPS. This is to ensure that no data is lost during sustained transfers (as RF sampling of a disc can take more than 40 minutes).
The FX3 is a low-cost USB3 development board from Cypress. The FX3 is used to buffer captured RF data from the FPGA and provide it to a host computer using USB 3.0 Type B interface.
Note
USB 3.0 or faster is required for this application due to the high-data bandwidth necessary for high-speed/high-resolution sampling.