The Use of Arbs in CDMA Signal Simulation

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The Use of Arbs in CDMA Signal Simulation Application Data (305.48 KB)

Noise is used for testing circuits in many types of instrumentation, including those in the growing wireless digital communications industry. One example of noise being used as a test signal is the simulation of Code Division Multiple Access (CDMA).

CDMA is a modulation technique used for signal transmission in a number of digital cellular telephones. Using CDMA, a caller's voice is first digitized, then the data is summed with a pseudo-random bit sequence that spreads the information over a specified frequency bandwidth. Many callers can share the same frequency spectrum simultaneously by using a distinctive bit sequence for each caller. The transmitter circuit in a cellular telephone must be tested for intermodulation distortion and noise. Rather than generate an actual CDMA signal to test the circuits, a band of noise can be used to simulate the desired properties of the signal. This signal is input to the transmitter, and inter-modulation distortion between the transmitter's input and output is measured.