Abstract: Two intensity modulated test signals are generated with precise frequency offset from a single laser source, and multiplexed into a combined test signal. The two modulated signals are demultiplexed at a receiver using a fixed periodic optical filter with complementary output ports. Group velocity dispersion/chromatic dispersion is measured over a large dynamic range, using pseudo-random intensity modulation and digital demodulation techniques.

Abstract: An apparatus and method for frequency sweeping a CATV network, suitable for an upstream path frequency sweeping, is presented. A narrowband test signal is injected into the network by a generator coupled to a cable modem during a time interval allocated by the head end for the cable modem to transmit a modulated digital signal. The amplitude of the test signal is lower than the amplitude of the modulated digital signal, so as not to impair reception of said digital signal at the head end. The frequency of the test signal is swept, and the amplitude of the received test signal is measured. A telemetry or a digital signal transmission is used to communicated the values of the amplitude of the test signals between the injection and the measurement locations of the network.