Abstract: An apparatus includes a finite impulse response demodulator. The finite impulse response demodulator includes least one stage. Each stage includes a cascaded pair of interferometers. The cascaded pair of interferometers includes a first interferometer and a second interferometer. Optionally, the first interferometer includes a first delay. The second interferometer includes a second delay. The first delay and the second delay are fixed or variable. Optionally, the first delay is unequal or equal to said second delay. Optionally, the first interferometer includes first internal power monitors, and the second interferometer includes second internal power monitors. The first power monitors monitor phase bias conditions within the first interferometer. The second power monitors monitor phase bias conditions within the second interferometer. Optionally, the first interferometer includes a first adjustable coupler, and the second interferometer comprises a second adjustable coupler.

Abstract: In an elastic cable exerciser an improved bar is provided. The bar has a groove in its upper surface to receive the cable. The groove extends from one end to the other to provide a downward run of cable at each end of the bar. Finger-like projections at each end of the bar retain the cable so that the cable is wound up on the bar as the bar is rotated.