DS28-L189-071 Ver la hoja de datos (PDF) - Conexant Systems

Número de pieza

componentes Descripción

Lista de partido

DS28-L189-071

SmartSCM Modem

Conexant Systems 

SmartSCM Modem Data Sheet

DTE Signal Monitoring (Serial DTE Interface Only)

DTR#. When DTR# is asserted, the modem responds in accordance with the &Dn and &Qn commands.

RTS#. RTS# is used for flow control if enabled by the &K command in normal or error-correction mode.

2.5 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.42 bis Data Compression

V.42 bis data compression mode, enabled by the %Cn command or S46 register, operates when a LAPM or MNP 10

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 2k-byte dictionaries are used to store the strings. These dictionaries are dynamically

updated during normal operation.

MNP 5 Data Compression

MNP 5 data compression mode, enabled by the %Cn command, operates during an MNP connection.

In MNP 5, the modem increases its throughput by compressing data into tokens before transmitting it to the remote modem,

and by decompressing encoded received data before sending it to the DTE.

2.6 MNP 10 Data Throughput Enhancement

MNP 10 protocol and MNP Extended Services enhance performance under adverse channel conditions such as those found

in rural, long distance, or cellular environments. An MNP 10 connection is established when an MNP 2-4 connection is

negotiated with a remote modem supporting MNP 10.

MNP Extended Services. The modem can quickly switch to MNP 10 operation when the remote modem supports MNP 10

and both modems are configured to operate in V.42.

V.42 bis/MNP 5 Support. V.42 bis/MNP 10 can operate with V.42 bis or MNP 5 data compression.

2.7 MNP 10EC™ Enhanced Cellular Connection

A traditional landline modem, when used for high-speed cellular data transmission, typically encounters frequent signal

interference and degradation in the connection due to the characteristics of the analog cellular network. In this case, cellular-

specific network impairments, such as non-linear distortion, fading, hand-offs, and high signal-to-noise ratio, contribute to an

unreliable connection and lower data transfer performance. Implementations relying solely on protocol layer methods, such as

MNP 10, generally cannot compensate for the landline modem's degraded cellular channel performance.

The modem achieves higher cellular performance by implementing enhanced cellular connection techniques at both the

physical and protocol layers, depending on modem model. The modem enhances the physical layer within the modulation by

optimizing its responses to sudden changes in the cellular connection. The MNP 10EC protocol layer implemented in the

modem firmware improves data error identification/correction and maximizes data throughput by dynamically adjusting speed

and packet size based on signal quality and data error performance.

2-4

Conexant

100490C

Share Link: