Abstract: A dielectric composition including a ternary system comprising non-stoichiometric lead magnesium niobate, non-stoichiometric lead zinc niobate and non-stoichiometric lead iron niobate, and a small amount of one or more oxide additives which serves to reduce the tan .delta. value in comparison with the ternary system alone. The one or more additives may be chosen from the group consisting of nickel oxide, stoichiometric lead nickel niobate, ceric oxide, lead oxide, zirconium oxide, silver oxide, manganese dioxide, lanthanum oxide and cobalt oxide. Compositions with firing temperatures in the range 950.degree. to 1100.degree. C. have dielectric constants in the range 10700 to 16600 (at 20.degree. C.) making the composition particularly useful for high silver content multilayer ceramic capacitors.

Abstract: Two portions (B,C) of one arm of an optical fibre Mach-Zehnder interferometer are magnetically sensitized and each has applied thereto an a.c. bias fields at a respective different frequency (w.sub.1, w.sub.2). One portion (A) of the other arm of the interferometer is magnetically sensitized and has two a.c. bias fields applied thereto, each at one of the different frequencies (w.sub.1,w.sub.2). The fields for portion A and C are aligned with a first direction (x) whereas those for A and B are parallel, A and B being separated in a second direction (y). The detected output of the interferometer at frequency w.sub.1 is related to the magnetic gradient in the y direction, whereas the detected output at frequency w.sub.2 is related to the magnetic gradient in the x direction. Thus using two bias frequencies allows one interferometer to be used to detect two gradients (FIG. 8).

Abstract: A rumen bolus for supplying a mineral supplement to a ruminant animal comprises a water soluble glass incorporating the mineral and contained in an apertured insert, e.g. plastics, housing. Typically the glass is in the form of tubes or pellets so as to provide a substantially constant dissolution rate.

Abstract: A semiconductor flip-flop memory circuit having a particular spatial format to correct an obvious error.

Abstract: In an information transmission system for use for inter-node trunks, both circuit-switched and packet-switched traffic is handled, the former being given priority. The system uses successive equal-length envelopes each providing a number of bits usable to provide a number of frames each usable for either sort of traffic. Circuit-switched traffic has priority and uses frames at the beginnings of the envelopes, after which packets are handled. The envelope is of such a size that it provides frames for all circuit-switched channels to be catered for, and in most cases the remainder of the envelope can handle packet traffic.

Abstract: In a telephone with repertory dialling and redial (which includes repeat last number), when dialling out from a PABX, one emits an access code and then the wanted number. The access code causes the sender to pause for a second dial tone before continuing to send. When dialling manually the user pauses and listens for the second dial tone, so that in the redial case no access pause code appears in the redial store. In the present system of the first digit is an access code, the digit sender checks the repertory dialler for an access pause code, and if it finds one there, it inserts such a pause in the dialled out number.

Abstract: For a voltage follower unity gain amplifier, used, for instance, as a buffer in a transceiver associated with a data bus, the input signal is fed forward to a comparator (T2-T3) to which the output is also applied. The input is also applied via an amplifier stage (T5-T6) to a transistor (T4) in the commoned circuit of the comparator, which is a long-tailed pair. Thus, with a connection from the output of the circuit which includes another transistor (T9), provides negative feedback round the comparator, gives a highly stable current.

Abstract: An optical undersea telecommunications system has a main cable (1) which branches (BU1) near a landfall to two separate stations. Each branch (71,81) supplies half the current of the main cable (1) for powering the regenerators. In the event of a fault in a branch (e.g. 81) caused by an anchor or fishing gear, the operations branch (71) regenerator (e.g 11) can supply the full current (I) via a zener diode power feed and bypass circuit and high voltage diodes (D1,D2) automatically prevent leakage of current back to the fault.

Abstract: A coating material is applied to drawn lightguide fibre (36') by an applicator (6) which tilts about x and y axes under the control of a concentricity monitor (7) to maintain the coating of the coated fibre (36) concentric about the fibre.

Abstract: An interlock arrangement for two slide switches in a radio pager eliminates incorrect switch operation. The casing contains two switches (A and B) with respective switch members (15, 16) located inside the casing. Switch member (15) has a cam follower (15b) on a resilient arm which co-operates with one or the other of two indents (13, 14). Switch member (16) has a chamfered end (16a). The chamfered end (16a) and the cam follower (15b) are shaped so that when switch member (15) is in position 1, the other switch member (16) locks switch member (15). If switch member (15) is inadvertently operated toward position 2, the chamfered end (16a) of switch member (16) will abut against the undersurface of the resilient arm cam follower (15b) thereby forcing the cam follower into more positive engagement with indent (13). Each switch (A or B) has two positions. In order for the interlock arrangement to be effective, each switch member must be located in the same position, for example position 1 or position 2.

Abstract: A direct conversion receiver in which the quadrature I and Q signals are converted into pulse density modulated digital data streams by delta-sigma modulators 14, 15. The resultant digital data streams are then processed in a logic block 18 according to predetermined logic truth tables. The digital output of the processor 18 is then converted back to an analogue signal.