1996 May

Noise Figure Computer Automated Test

Noise Figure Computer Automated Test

• The Need:
  • A customer was using an existing computer automated test software to provide noise figure measurements for RF amplifiers. The program was written in HP BASIC, and the software was run on an older HP computer. The software was antiquated and not user-friendly, the computer was aging and unreliable (used 5 1/4 inch floppies, etc). The test setup was limited to about 750 MHz in frequency coverage.
  • The amplifiers were used for CATV distribution amplifiers, and the test setup was used by Incoming Inspection and Test to verify specification compliance.
  • The Customer wanted to upgrade the software to HT BASIC, replace the computer with a newer PC compatible computer, provide a better, more user-friendly interface, allow different devices to be tested to different specifications, and increase the measurement capability to provide accurate measurements up to 1000 MHz.
• The Solution:
  • R. A. Wood Associates transferred the existing software over to HT BASIC, which was then developed on a PC compatible computer. The software was completely re-written to provide a menu-based test setup, where the user could select parameters for calibration, test, and set up specification limits. Once the test parameters were set up, the test person could just insert the devices into a "quick connect" fixture and push the "TEST" button for quick verification.
  • A user-friendly test interface was designed and implemented.
  • The test procedure was revised using improved test and calibration techniques to provide accurate noise figure and gain measurements for frequencies up to 1500 MHz.
• Other Points to Make:
  • The software was developed at R. A. Wood Associates, and installed and verified at the customer's location.
  • User-defined test and calibration frequencies allowed the operator to greatly reduce test time
    • which helped save money for the customer.
  • The software was designed to be user-friendly:
    • A menu based structure was designed.
    • New test parameters could be easily be added.
    • Press "RETURN" for default parameters saved re-typing current parameters.
    • The software was structured for minimal maintenance and easy upgrades.
  • A complete user documentation package was provided to the customer for training purposes.
  • The test setup used HPIB interfacing and HP 8970A Noise Figure Meter.
  • The setup was designed to test devices in a 75-Ohm environment.
  • For the entire effort, we kept the customer's needs in mind as a primary objective.