Analog Reconstruction Filter for HDTV Using the THS8133, THS8134, THS8135, THS8200

The THS8133, THS8134, THS8135, and the THS8200 devices are part of a family of chips for graphics and video applications, which contain triple DACs that operate up to 240 MSPS. For television applications, an analog low-pass filter is required to reconstruct the signal that is input to the monitor. High definition television (HDTV) requires a sampling frequency of 74.25 MHz and has pass-band, transition-band, and stop-band attenuation requirements, which affect the complexity of the filter. A higher sampling rate results in a lower filter complexity.

The THS8133, THS8134, THS8135, and THS8200 comprise a family of graphics/video chips that have triple digital-to-analog converters (DACs) that convert digital graphics signals GBR/YPbPr to analog. They insert bilevel or trilevel syncs into the green/luma signal. The trilevel sync is used for horizontal synchronization of high definition (HD) television signals. Table 1 lists the chips and their capabilities. The THS8200 incorporates a 1:2 upsampling and interpolation filter, which results in a simplification of the filter design that is used to reconstruct the analog output signal. The advantages of 2x oversampling are examined for the high definition (HD) television application.

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Spin-On By-Pass Filter Installation and Servicing Instructions

Attaching the filter mount
1. Survey the engine compartment for possible mounting locations. Solid structures such as the firewall, fender well, radiator support or frame are normal locations. (Do not mount on engine.) Refer to diagram B for minimum area requirements and consider accessibility for servicing.
2. Refer to diagram A for preferred mounting positions.
3. When the location has been determined, use the mounting template provided to locate and mark mounting holes. This can be easily done with a center punch and hammer.
4. Install adapter fittings (BP-208) on filter mount using provided thread sealant as noted in diagram C. If desired, 90° angle fitting (BP-52) may also be used. Using a 7⁄16 wrench, tighten fittings 2-3 turns beyond finger tight. Keep in mind the direction you wish to have the hoses intersect the mount.
5. With a 5⁄16 drill bit, drill out the previously marked mounting holes and attach the mount using the 5⁄16 bolts, nuts, small washer and fender washers provided. Bolts should be tightened to 16-18 foot pounds. 1/2 wrenches or socket will be required for this operation.
6. Fill the By-Pass Filter element with the same motor oil being used in the vehicle. Lubricate the filter gasket with oil and spin filter onto mount. Tighten per instruc- tions on the filter.

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