An Overview of Analog Dialup Modem Performance, Environments, and Impairments.

REVISED 7/20/98 12

DOC. NUM. PRT/005A/0798

Interoperability

n Data Interoperability

This testing verifies that the Compaq modem is able to successfully connect with a broad variety of

party modem products – including both client-end modems and host-end modem racks,

concentrators an other type of high-density RAS equipment. This type of testing helps to ensure

maximum compatibility with other modem products in the field. All of the applicable modulation,

error correction, and data compression protocols are tested.

n Fax Interoperability

This test verifies that the Compaq modem will be able to negotiate and send/receive faxes from a

broad range of stand-alone fax machines and other fax modem products. The test is performed in an

automated environment that can emulate over 75 different fax devices, and ensure compliance with

the T-30 fax protocol set.

Miscellaneous

In addition to the testing above, the Compaq modem products are tested in a variety of other ways.

These would include –

n Speakerphone and Telephony testing, if applicable

n Compatibility with 3

party communications applications

n Special PSTN features (Caller ID, Distinctive Ringing), if applicable

n Training robustness

n Regulatory compliance (FCC Part 68)

n RF/EMI testing

n Cellular data testing, if applicable

n AT Command set functions and features testing

Glossary

ADPCM – Adaptive differential pulse-coded modulation. Used to compress the data in voice calls

to increase switch capacity.

Baud – this is defined as the rate of state transitions, or symbol rate, on the phone line. This unit is

used as a base rate upon which the modems encode multiple bits per baud, which yields the final

BPS data rate of the modem. For instance, a modem that transmits data at 14,400bps is using a

2400 baud carrier and is encoding 6 bits per baud (via trellis coding) for 14,400bps. In the old days

of modem technology, baud and bps meant pretty much the same thing – that is no longer true of

today’s high-speed modems, and the terms should not be used interchangeably.