Abstract: A method of characterizing a modulated carrier signal by generating electrical signals which represent arithmetic ratios and which can be used to construct a histogram indicative of the quality of the modulated carrier signal. For a digitally modulated carrier signal, time spaced samples of in band amplitude dispersion of the signal are generated and first counts are made of the number of occurrences of particular values of in band dispersion, over a range of such values. The error ratio of the decoded modulated carrier signal is also monitored and seconds counts are accummulated, of the numbers of occurrences of respective values of in band amplitude dispersions which at least substantially coincide with the value of said error ratio crossing a predetermined level.

Abstract: Optical fibre cable laying apparatus comprising a mobile carrier for paying out cable from a reel and laying the cable in a trench formed by a tyne on the carrier. The reel is rotated, to effect paying out, in a fashion such as to control the tension in the cable. A slack loop is formed in the cable during paying out and the amount of cable in that slack loop is monitored. When the amount of cable in the slack loop decreases, the rate of paying out is increased, and when there is a greater amount of cable in the slack loop, the rate of paying out is decreased. Tension rollers are employed to further minimize tension in the cable as laid.

Abstract: Digital conference bridge for use with a plurality of telephones (#1 . . . #n) and arranged whereby in accordance with predetermined output conditions from the telephones, as existing from time to time during use of the telephones for communication therebetween, the output signal from one telephone is directed to the remainder of the telephones and the output signals of the remainder are suppressed. The bridge generates products x.sub.n .multidot.g.sub.n and x.sub.i .multidot.g.sub.i where x.sub.n and x.sub.i are instantaneous magnitudes of samples of all of the signals and of the selected signal respectively, and g.sub.n and g.sub.i are predetermined gain factors for all of the signals and for the selected signal respectively. A register (60) storing the value of "i", designating the presently selected telephone, is updated by a circuit including comparators (42,52) connected to a gate (44) whereby to surplant a selection of an existing value of "i" by a new value under the following conditions:x.sub.n .

Abstract: This specification discloses a new termination for optical light guides, the termination can be integrally formed at the ends of long light guides or made as discrete termination pieces which can be attached to light guides. The new terminations exhibit excellent input and output coupling characteristics and thus are especially suitable for photometric reflectometry measurement and for optical communications systems.

Abstract: A transversal filter having an overall impulse response of the form ##EQU1## and producing, from an applied input x(t) an output ##EQU2## where y(t) is obtained by lowpass filtering of a waveform z(t) in use generated in the filter, where z(t) takes the form: ##EQU3## where h.sub.i represents a set of stored coefficients,f(.tau.) is an impulse response accounting for fixed linear filtering at the input and output, independent of the settings h.sub.i, and.delta.(.tau.-.tau..sub.i) is the Dirac delta function defined as a function of time interval .tau. and of a set of time delays .tau..sub.i, where .tau..sub.i is not equal to iT.

Abstract: Instruments are disclosed for testing the susceptibility of PCM regenerators to rear end and far end crosstalk noise. The instruments of the invention are more compatible with PCM system engineering rules since certain important PCM system parameters are synthesized in the circuitry. The instrument for measuring susceptibility to rear end crosstalk includes a filter having a voltage transfer function 1/R.sub.3 .vertline.f/.sub.fo .vertline..sup.3/4 and the instrument for measuring susceptibility to far end crosstalk includes a filter having a voltage transfer function 1/R.sub.3 .vertline.f/.sub.fo .vertline..