US 4,056,779 A · Vehicular repeater

Abstract

In a two-way communications system involving portable-mobile-base station transmission, a priortization method prevents interference caused by more than one mobile repeater at a single location relaying simultaneously, or by a lowband transmission skipping in from another location. When a repeater enters the system at a location, it monitors the base and portable channels, and if there is transmission activity on either channel it goes to a non-priority state. If there is no activity, a silent carrier burst is momentarily transmitted on the base channel, then the repeater goes to a non-priority state. Unless a repeater at the scene is in the priority state, each other mobile unit, upon detecting the burst, begins to repeat it out on the portable channel. When interrupted by its interrupt clock, the repeater listens for a short interval on the portable channel and if any transmission is heard, remains inhibited or in "receive" mode. The last mobile repeater to be interrupted will, of course, hear no other transmission and will return to "transmit". This unit will be established as the only unit in the priority state at that location. Any portable channel transmission will prevent base channel transmission from being repeated out on the portable channel, thus a portable-to-portable or portable-to-base transmission will have priority over base-to-portable or "skipped-in" transmission. When the unit in priority leaves or switches channels it is removed from the priority state and transmits a momentary silent carrier burst so that a new priority unit is established as before.

Claims23

Dependent claims

In a two-way communication system having a base station operating on a first frequency, and a plurality of vehicular installations each comprised of a mobile station operating on the first frequency, a detachable portable unit operable on a second frequency and a repeater unit for repeating out on one of said frequencies information received on the other of said frequencies, apparatus for prioritizing the repeater operation, including in combination:

first detect means for detecting received transmissions on the first frequency;
second detect means for detecting received transmissions on the second frequency;
switching means for activating one of the receive and transmit functions at the second frequency;
means coupled to the switching means for providing momentary interrupt periods in the repeater function when repeating out on the second frequency;
latching means coupled to the switching means for enabling the repeater function;
first circuit means coupled to the first and second detect means to the latching means for delatching the latching means when substantially simultaneous transmissions are received on the first and second frequencies during at least one of said interrupt periods;
delay means for relatching the latching means a predetermined period of time after the detection of received transmission;
second circuit means for disenabling repeating out on the second frequency when transmission is received on the second frequency during at least one of said interrupt periods.

5 more elements

A prioritized two-way communication system, the system including a base station for receiving and transmitting at a first frequency, a plurality of mobile units for receiving and transmitting at the first frequency, a portable unit associated with each one of the mobile units and adapted to receive and transmit at a second frequency when the portable unit is separated from the mobile unit, and a repeater unit coupled to each one of the mobile units, the repeater unit comprising:

circuit means for receiving signals at the second frequency;
circuit means for transmitting signals at the second frequency;
antenna means;
first switch means for selectively coupling the antenna means to one of the second frequency receiving and transmitting means;
second switch means for selectively coupling the receiving circuit means to the mobile transmitter;
clock circuitry;
first detector means responsive to the reception by the associated mobile unit of signals at the first frequency;
second detector means coupled to the receiving circuit means and responsive to the reception by the receiving circuit means of signals at the second frequency;
third detector means coupled to the receiving circuit means and responsive to a predetermined signal associated with received second frequency signals;
first logic circuitry for providing an output in response to the connection and separation of the portable unit and the mobile unit;
second logic circuitry for providing a first output at a first output terminal in response to the output of the first and second detector means, a second output at a second output terminal in response to the outputs of the second and third detector means, and a third output at a third output terminal in response to the outputs of the first, second and third detector means;
prioritizing means coupled to the output of the first logic circuitry and to the third output terminal of the second logic circuitry for enabling transmission by the mobile unit and the second frequency transmission means;
and
third logic circuitry coupled to the outputs of the first logic circuitry, the first output terminal of the second logic circuitry, the clock circuitry, and the prioritizing means for activating the first switch means and the second switch means.

11 more elements

Dependencies are inferred from the claim text.

Vehicular repeater

Life of this patent

Vehicular repeater

Life of this patent

Abstract

Claims23