CX81801-74 查看數據表（PDF） - Conexant Systems

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产品描述 (功能)

生产厂家

CX81801-74

SmartV.XX Modem

Conexant Systems 

2.5.2

2.5.3

2.6

2.6.1

2.6.2

2.6.3

2.6.4

CX81801-7x/8x SmartV.XX Modem Data Sheet

Quick Connect

The quick connect function enables the modem to shorten the connect time of subsequent

calls to a server supporting quick connect. The quick connect feature is supported by the

+PQC command.

PCM Upstream

PCM upstream boosts the upstream data rates between the user and ISP to reduce upload

times for large files and email attachments. A maximum of 48 kbps upstream rate is

supported with PCM upstream enabled, in contrast to a maximum of 32.2 kbps upstream

rate with PCM upstream not enabled. PCM upstream is supported by the +PIG command.

PCM upstream is disabled by default.

Error Correction and Data Compression

V.42 Error Correction

V.42 supports two methods of error correction: LAPM and, as a fallback, MNP 4. The

modem provides a detection and negotiation technique for determining and establishing

the best method of error correction between two modems.

MNP 2-4 Error Correction

MNP 2-4 is a data link protocol that uses error correction algorithms to ensure data

integrity. Supporting stream mode, the modem sends data frames in varying lengths

depending on the amount of time between characters coming from the DTE.

V.44 Data Compression

V.44 data compression mode, enabled by the +DS44 command, encodes pages and files

associated with Web pages. These files include WEB pages, graphics and image files,

and document files. V.44 can provide an effective data throughput rate up to DTE rate for

a 56-kbps connection. The improved performance amount varies both with the actual

format and with the content of individual pages and files.

V.42 bis Data Compression

V.42 bis data compression mode, enabled by the %Cn command or S46 register, operates

when a LAPM connection is established.

The V.42 bis data compression employs a “string learning” algorithm in which a string of

characters from the DTE is encoded as a fixed length codeword. Two 2-KB dictionaries

are used to store the strings. These dictionaries are dynamically updated during normal

operation.

2-6

Conexant

102199B

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