Abstract: A method of communicating between two or more radios each capable of transmitting and receiving signals between one another on two or more radio channels wherein the radios hop from channel to channel in a pseudo-random sequence. The method comprises establishing hop synchronization between the radios utilizing a first cycle and operating the radios in a communication mode utilizing a second cycle. The first cycle is shorter than the second cycle so as to facilitate rapid synchronization while preserving the benefits and security obtained through the use of longer cycle length during communication mode.

Abstract: An alternative power supply apparatus for use in association with systems having a base unit connected to an external power supply and an associated battery-powered portable unit. The alternative power supply apparatus includes two rechargeable batteries one of which serves to provide electrical power to the portable unit. There are two ports associated with the base unit, each port operably and detachably accepts one of the two rechargeable batteries. The apparatus further includes a voltage regulator which provides regulated voltage to circuitry in the base unit. Two current sources each associated with a respective one of the two ports provides an electrical current to the batteries when they are operably accepted by the ports. The second rechargeable battery, which is interchangeable with the first rechargeable battery, provides a source voltage to the voltage regulator upon failure of the external power supply.

Abstract: An adapter (13) for enabling an external antenna, e.g. an antenna fitted to a vehicle, to be connected in place of an existing antenna (7) on a radio, particularly a portable radio telephone (1). The adapter is slidably located in a passageway (6) which may be part of an integral moulding of a radio casing (2). The existing antenna (7) may be slidably located in the passageway such that it can be displaced and so disconnected from the radio when the adapter is fitted. Alteratively, the radio has an internal existing antenna which is switched out when the adapter makes an external antenna connection, e.g., by means of contacts (15,16) mounted in the adapter and in the passageway (FIGS. 3 and 4). The slidable antenna (7) may be in the form of a tape having a bowed cross-section.

Abstract: A retractable antenna is in the form of a tape (7) which is slidably mounted in a passageway (6). An electrical contact (9) for making connection to the antenna is provided on the rear wall (3) of the passageway. The tape (7) or the passageway (6) or both are shaped so as to form a bend, e.g. a bow, across the width of the tape so that (a) the convex side of the tape confronts the contact (9) and (b) rigidity is imparted to the tape to keep it upright when extended from the passageway. This antenna is slim and lightweight and therefore ideally suited for use with a compact portable radio telephone.