PORTABLE USB MODEM

5.Type AT&T6 and press ENTER. The local modem responds to this command by transmitting an unscrambled marking signal, which causes the remote modem to place itself in digital loopback mode. Then the local modem exits online command mode and enters data mode.

6.Enter data from your keyboard. For this test, typing multiple uppercase U characters is a good way to send an alternating test pattern of binary ones and zeroes. Data received by the remote modem enters its analog receiver, is converted to digital data, is reconverted into analog, and then is transmitted back to your modem. Your modem passes this test if the data received on your monitor is the same as the data entered from your keyboard.

7.To exit the test, type the escape sequence +++AT and press ENTER. This puts the modem in online command mode. The modem should respond with an OK message. If you wish to stay on line with the remote modem for normal data transmission, type AT&T and press ENTER to exit the test, then type ATO and press ENTER to return on line. If you wish to terminate the call, type ATH and press ENTER to hang up.

B.4 Local Digital Loopback Test (V.54 Loop 2)

The local digital loopback test is identical to the remote digital loopback test with one exception. Instead of using your modem to signal a remote modem to place itself in digital loopback mode, your modem is placed in digital loopback mode while the remote modem is not. Data is entered and transmitted from the remote modem, sent across the phone line to your modem, and looped back to the remote modem.

AT&T3

OK

UUUUUUUUU UUUUU

Digital AnalogAnalog Digital

Local Portable

Remote Portable

Computer or Terminal Local MultiModem

Remote MultiModem Computer or Terminal

USB Modem

USB Modem

Figure B-3. Local digital loopback test.

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Black Box MD403A user manual Local Digital Loopback Test V.54 Loop, Figure B-3. Local digital loopback test

MD403A specifications

The Black Box MD403A is a powerful and versatile device widely recognized for its advanced technology and its ability to streamline data communication. Ideal for both personal and professional use, the MD403A is designed to cater to various environments, from small offices to larger enterprises.

One of the main features of the MD403A is its robust connectivity options. It supports multiple interfaces, including USB, HDMI, and Ethernet, allowing seamless integration with various devices such as computers, projectors, and IP networks. This flexibility makes it a popular choice for businesses that require reliable data transmission across different platforms.

The device is equipped with advanced signal processing capabilities that ensure high-quality data transfer. Utilizing cutting-edge technology, the MD403A minimizes signal loss, thereby enhancing performance and ensuring that the transmitted data remains intact. This feature is particularly crucial in scenarios where large amounts of data need to be transmitted quickly and without loss of quality.

Another significant characteristic of the Black Box MD403A is its user-friendly design. The interface is intuitive, making it easy for users of all technical abilities to navigate the system effortlessly. It typically comes with a straightforward setup process, minimizing downtime and allowing users to get up and running quickly.

The MD403A also boasts advanced security features. It employs multiple encryption protocols to safeguard sensitive information during transmission. With increased cybersecurity concerns, this feature is essential for businesses that handle confidential data, ensuring compliance with various regulatory requirements.

Additionally, the device supports various video resolutions, making it suitable for both standard and high-definition applications. This feature is particularly beneficial for users who want to deliver high-quality presentations or video content without compromising on clarity.

In terms of durability, the MD403A has a sturdy design that can withstand the rigors of daily use. Its compact form factor allows for easy portability, making it an ideal choice for professionals who are always on the move.

In summary, the Black Box MD403A combines advanced features, multiple connectivity options, robust security, and ease of use, making it an essential tool for modern communication needs. Its adaptability and performance make it a preferred choice for users seeking reliable data transfer solutions in diverse settings.