Cisco Headend System Release 2.7

Glossary

78-745238-01 Rev D

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provision

The process of preparing a device or service so that the DNCS recognizes the device, which

allows the device to operate properly.

QAM

quadrature amplitude modulation. A frequency modulation technique primarily used for

program audio and video. QAM supports data rates from 27 Mbps to 36 Mbps.

QAM modulator

A device that uses QAM techniques to modulate a digital signal onto an HFC network to

deliver voice, video, and data to a DHCT.

QPSK

Quadrature Phase-Shift Keying. Digital modulation scheme that send data by modulating the

phase of a reference signal (the carrier wave).

QPSK modulator/demodulator

The QPSK modulator works with the QPSK demodulator and the DHCT to provide forward

signaling and a reverse communications path for interactive video and data services. The

QPSK modulator and demodulator convert digital bit streams to RF format and RF signals to

digital bits, respectively.

SAM

Service Application Manager. Associates a specific service with an application that defines the

medium to be used for that service, such as the World Wide Web. The SAM maintains the

application in a specific directory to be used when needed by the DHCTs.

SARA

SA Resident Application. The set of operating programs that is “permanently” loaded into the

DHCT. These programs are immediately available to the subscriber upon activation of the

DHCT.

source

In the DBDS, a source is the actual program or data that is made available to the DHCT as a

service to the subscriber. Sources can include: MPEG-2 digital broadcast services that are non-

secure, non-encrypted, audio/video programs; Internet connections from an Internet service

provider (ISP); Digital PPVs that are secure, encrypted, digital MPEG-2 programs; Digital

music services; Analog programs that are modulated in the traditional format or converted

into MPEG-2 format.