Courier® Technology

The technology of a Courier modem is no longer thought of as complex or state of the art. Rather, the Courier modem is looked upon as “old reliable” for the transfer of data over phone lines. Below is a brief description of how modems work. Click through to “Why Buy Courier?” to learn how the Courier modem sets itself apart from the competition.

How Modems Work

Modems 101: The Basics

Most phone lines were designed to carry tonal (analog) signals. The Public Switched Telephone Network (PSTN) uses these signals to send voice communication over the telephone network.

How does a computer use a phone line?

"Modem" is an acronym for MOdulator/DEModulator. It converts the digital signal from your computer into an analog signal that can be carried by the phone line, and vice versa.

Why use a modem?

Modems are ideal for applications where an “always-on” connection is not required, such as sales kiosks and point of sales terminals. They are also ideal for secondary and tertiary backup systems behind today’s high speed Internet connections. Many companies use modems to ensure their network will remain functional in the event their T1, ADSL, or cable Internet connection is unavailable or disabled.

What are the different types of modems?


Modems are distinguished from one another by their architecture, that is, where the processing takes place: in the modem or in the PC. A hardware modem is a "Controller-based" modem, and it does all of the work. This type of modem provides the best power and performance, and it does not utilize the PC's processing power. All three components [Microcontroller Unit (MCU), the Data Pump Unit (DPU), and the Data Access Arrangement (DAA)] are in the modem itself. It can work with many operating systems, and functionality may be upgradeable through ROM uploads.

What are Controllerless or Winmodems?

Controllerless modems (or Winmodems), as the name implies, do not have an onboard Microcontroller. As a result, data compression and the generation of AT commands are performed by the PC. Since most PCs sold today run the Windows operating system, the microcontroller program is usually written specifically for Windows, hence the name "Winmodem." They are useful in laptops, as they tend to use less power. Winmodems are usually software upgradeable.

What are Softmodems?

Softmodems are, quite simply, software modems. All processing is done by the PC, and the "modem" is little more than an interface to plug in the phone jack. These modems require the PC to do all of the work, and they will only run in the Windows operating system. Many PC makers put Softmodems in the PCs that they sell to consumers, as they are extremely inexpensive. They are upgradeable.

What does the Microcontroller Unit do?

The Microcontroller Unit checks data for errors and performs compression. It may also convert a parallel transmission into a serial transmission. It utilizes the AT command set to send and receive signals. It sends the data on to the Data Pump Unit.

What does the Data Pump Unit do?

When turned on, the Data Pump Unit gets instructions and settings from ROM, the unit's permanent memory. The DSP (Digital Signal Processor) uses RAM (Random Access Memory) while performing its calculations. If your modem has instructions in EEPROM (Electronically Erasable Programmable ROM), it may be possible to upgrade the instruction set in a modem, giving it new features. After processing, the output is sent to the Data Access Arrangement.

What does the Data Access Arrangement do?

The Direct Access Arrangement (DAA) serves as the hardware interface to the Public Switched Telephone System (PSTN). A standard RJ-11 jack connects the modem to the phone line. The interface allows the modem to detect signals on the line: dial tone, busy signal, etc.

History of USRobotics Modems

USRobotics was one of the first companies to offer high-speed dialup modems. The Courier modem brand, first introduced in 1983, was just one of the company’s many products designed to connect people to the Internet and each other. It is the Courier, and the USRobotics Sportster® modem, that made USRobotics modems the modem of choice for the Internet revolution.

Throughout the years, the Courier brand of modems has seen many changes, including the addition of such features as full duplex communications, error correction, adaptive speed leveling, and many other, now common features. In addition, the Courier 1200 operated at 1,200 bits per second. Today’s Courier operates at 56,000 bits per second, an increase of almost fifty times.

The USR3453 Courier 56K Business Modem remains the gold standard among modems for its world-class performance, reliability, and features. Click “Why Buy Courier?” to learn more.

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