Andrew Corporation is noted as the world's premier provider of complete RF subsystem solutions for evolving global communications. The company is a global leader in the design, manufacture, and supply of communications equipment systems and services. The company’s products and services provide proven solutions for wireless, fixed-line, broadband service providers and broadcasters throughout the world. This division in Addison, Ill is part of the wireless products group.
Tasks performed include:
The H3 project was the development of a LabVIEW based program to communicate with and download firmware to the H3’s embedded computer. The H3 is a computer controlled RF amplifier used as the amplifier at cellular telephone towers. The internal computer is used to monitor and control numerous amplifier functions, from monitoring and controlling the cooling fan speed to controlling the output power of the amplifier. Communication with it is through two serial ports, one dedicated to the individual device the other a RS-485 based serial port that is connected in parallel with up to 12 other amplifiers. This specific implementation of the RS-485 standard, using a 9 bit protocol allowed addressing multiple H3’s. The system had to provide a 9th “address” bit in the serial data when sending a device address and then revert to normal 8 bit for the bulk of the communication, all within very tight time tolerances.
The test of the H3 consists of sending variations of its several commands and parsing the correct response, which for some command variations was an extensive response defining the device under test’s (DUT) internal status. While the communications through the 485 based serial port were in progress the status of some of the devices other internal status was being queried through the standard RS-232 port. These included the current status of the devices indicator LED’s and a read back of internal RF power measurements.
A complete test of the device consists of over 300 command/response sets, which are initiated from a set of test scripts defining the specific command, response and expected response. Each of these test “sets” result in an individual data file being created, allowing the individual tests to be easily evaluated after the conclusion of testing. This evaluation is done largely by an additional LabVIEW based utility which parses the data file for the respective data received from the 485 port and the 282 ports’ data.
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