Abstract: An apparatus and method for reducing the effect of noise in a signal handling system which includes a noise-susceptible link (12). The apparatus also includes a first signal processor (13) positioned upstream from the link (12) with a sampled data filter (23) having an inverse high-pass characteristic, and a second signal processor (16) positioned downstream from the link (12) with a sampled data first filter (26) having a high-pass characteristic and a second filter (27) having a low-pass characteristic. The two sampled data filters have reciprocal responses and each employ modulo N arithmetic, i.e., when the output reaches a level N it overflows. Thus, the filter (26) downstream of the link (12), which is preferably a digital filter, has a transfer function (P(z)) modulo N, while the filter (23) upstream of the link, also preferably a digital filter, has the inverse transfer function (1/P(z)) modulo N.

Abstract: In a receiver for the reception of satellite television signals sub-carrier signals carrying, for example, data are recovered from the demodulated television signal and themselves demodulated to provide data outputs. Prior to the second demodulation, each sub-carrier signal is averaged to improve its signal-to-noise, ratio, thereby taking advantage of the relatively small basic bandwidth of the sub-carrier signal to enable satisfactory reception of the signal in poor reception conditions when the received signal is too weak to obtain an acceptable television picture signal. Impulse noise in the received signal is reduced prior to averaging. To avoid intermodulation products being generated by the transmission and reception of several sub-carriers together, direct sequence modulation of the transmitted sub-carriers can be used to spread their power over a wider frequency band.

Abstract: In an improved demodulator, which is primarily applicable to the demodulation of angle modulated signals with a poor carrier-to-noise ratio (e.g. satellite TV signals received with a small aperture dish antenna), an intermediate frequency stage (20) is coupled to a differential phase circuit (48,50,52,54) in which delayed in-phase and quadrature components of the intermediate frequency signal are multiplied with the intermediate frequency signal itself to generate a pair of baseband differential phase quadrature signal components having a reduced noise content.These differential phase quadrature signal components are than averaged by filters (56,58) to further improve the signal to noise ratio, and then digitized and fed as digital samples to a PROM circuit (38) which performs an inverse tangent operation to derive a demodulated digital signal representative of the angle modulation .phi., where cos .phi. and sin .phi. are the differential phase components.

Abstract: A data stream is impressed on a carrier by forming from the data stream a succession of binary symbol words which control the modulation level of the carrier during respective modulation time intervals. To generate the symbol words from the data stream, the latter is first divided into a base bit stream (14) and one or more second bit streams (15). These second streams (15) are then subjected to error control coding before being used to define the least significant bits of the symbol words; the most significant bits are provided by the base bit stream. As a result, although the least significant bits of the transmitted symbol words (IV,III,II,I) are more prone to noise corruption than the most significant bits this tendency is compensated for by the error coding employed. The overall effect is to minimize power requirements while retaining good bandwidth efficiency.

Abstract: A waste transfer packer having a horizontally reciprocable ram operating in a hollow spigot to deliver and compress waste material from a chute or hopper, has a spigot adapted to extend into a container through a pair of doors hinged about horizontal axes. Problems can arise on disconnection of the container from the packer due to re-expansion of the load within the container.The invention provides a spigot extending almost to the position of maximum penetration of the ram so as to continue to support the load while the ram is withdrawn and during disconnection of the container. The spigot shape can provide a sloping or stepped by a suitable profiling of the spigot front face.

Abstract: Loading doors for a container such as a transfer container for domestic waste which cooperates with a compactor loader having a horizontally reciprocating ram comprise a plurality of flaps which effectively close an opening sized to correspond with a spigot of the compactor loader the doors being opened by mechanical connection with a part of the compactor loader and resulting from relative movement between it and the door.

Abstract: A method of tracing sewage effluent is described in which samples of fluid flows are subjected to high performance liquid chromatography with respective elution systems capable of eluting different selected compounds therefrom, and the concentration of each compound in the sample is determined spectroscopically. The method is used to determine sewage flow paths in natural water bodies, such as rivers, to check for contamination by sewage, to determine possible sewage sources, the detection of uric acid, for example, being indicative of a human source; and to monitor the effluent from sewage treatment plants.