The receive data path contains several analog-to-digital converters (ADCs) to accommodate the various set-top box functions described earlier. The designers of the Analog Devices AD9873 took advantage of both their experience in set-top-box technology and their inventory of high-performance topological block core designs of the kind that would be needed to integrate the essential high-performance analog and mixed-signal functions on a single chip.įigure 3 is a block diagram of the AD9873 Analog Front End Converter for Set-Top Boxes and Cable Modems. ASICs that include significant digital and analog content are often difficult to schedule due to the time needed to handle the inherent design challenges and the frequent need for customer feedback. Besides all this, time to market is equally important for both the IC vendor and the OEM. Low cost is of vital importance, so selecting a proper technology is key to a successful design. The definition of a mixed-signal front-end for a set-top box must take into account the amount of functionality required from the transmit and receive data paths. The mixed-signal front-end, which can be implemented using the AD9873, is central to the set-top box (Figure 2). #Analog to digital converter box for motorola tvTherefore, selecting a proper partition for integrated functions becomes a key requirement for combining high quality TV reception and high data rates in a cable modem at low cost. In addition, compatibility with analog TV calls for clean analog signal processing from the wall TV cable outlet to the TV set. The large amount of digital processing required, combined with the high-quality reception requirements of high-definition digital TV, pose numerous challenges to digital set-top box architects. The multiplicity and complexity of all these blocks impose significant challenges on designers at both the component and board levels. The box can also include an out-of-band (OOB) control channel and a phone line interface. #Analog to digital converter box for motorola driverSince Internet access implies an upstream channel, a cable driver is included it can be implemented using a member of the AD832x family. High data rates allow streaming-in MPEG movies as well as high-quality telephony (voice-packet) service.Ī digital set-top box, like that shown in Figure 2, comprises several major sub-systems to implement such functions as a TV tuner, base-band transceivers, a channel 3/4 modulator (for compatibility with analog TV sets), MPEG and NTSC decoders and encoders, physical layer (PHY) and media access control (MAC) for cable modems. Several services can be unified in this fashion, including Internet access, cable TV and even phone services. Figure 1 shows a digital set-top box connected to the head-end and to various devices inside the residence (or office). Transmitting analog information in digital bits is not only more robust but also makes use of available bandwidth more efficiently. Instead of analog vestigial-sideband modulated (VSB) channels, digital set-top boxes receive TV programming and exchange information with the head-end station using quadrature amplitude modulation (QAM). This effort resulted in the development of digital set-top boxes from several established vendors, including Scientific Atlanta and Motorola (General Instrument). Widespread deployment of TV cable has led to extensive research in providing better quality and increased variety in TV programming and cable-modem functionality. AD9873 Mixed-Signal Front-End (MxFE) for Broadband Digital Set-Top Boxes
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |