Consisting of precision dual-output noise sources and sophisticated control circuitry, the model UFX-9835 test source from Noise Com (Parsippany, NJ) is designed to generate near-end crosstalk (NEXT) and far-end crosstalk (FEXT) for production testing of DSL modems. Suitable for evaluating ADSL, HDSL, and xDSL equipment, the high-performance source provides frequency coverage of 50 Hz to 2 MHz with a 3-dB output bandwidth between 3 and 5 MHz. Each of the two independent noise generators can be controlled for output levels from -140 to -130 dBm/Hz, allowing for simultaneous testing of NEXT and FEXT. The two outputs are each balanced with output impedance higher than 10,000 ohms, which meets the high-impedance crosstalk injection requirements of various T1 standards. The rack-mount instrument boasts high-crest-factor noise outputs, with a peak-to-average ratio of better than 5:1.

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