# US 4,399,557 A · Minimum power, feedback controller, transmit/receive switch > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,399,557 A - Document ID: US4399557A - Status: Granted - Kind: A - Application number: 06/330,979 - Filed: 1981-12-15 - Granted: 1983-08-16 - Earliest claimed: 1981-12-15 - Assignees: Motorola, Inc. - Inventors: Robert P. Muszkiewicz - Web page: https://patentgrep.com/patent/US4399557A ## CPC - H04B 1/44: Transmit/receive switching - H04B: TRANSMISSION ## Abstract A transmit/receive switch incorporating a latching relay in a feedback circuit so that the relay is energized only when it is commanded into a different mode (transmit or receive) than it is in, and the energization is removed as soon as the relay switches into the correct mode. ## Claims ### Claim 1 In a transceiver comprising an antenna and transmitting and receiving devices alternatively sharing use of said antenna by switching means controllable to selectively couple a selected one of said transmitting and receiving devices to said antenna in response to a selected transmit/receive control signal from a control signal source, the improvement for minimizing power consumption by said switching means and for assuring that the selected device is coupled to said antenna in response to said control signal comprising: logic means coupled to the source of said transmit/receive control signal and to said switching means for comparing the status of said switching means with said control signal and actively energizing said switching means only when its status disagrees with the status commanded by said transmit/receive control signal. ### Claim 2 (depends on 1) The improvement of claim 1 wherein said switching means includes a latching relay. ### Claim 3 (depends on 2) The improvement of claim 2 wherein said switching means further includes feedback coupling means coupling said logic means and said latching relay for feeding back a signal to said logic means representative of the switched status of said latching relay. ### Claim 4 (depends on 3) The improvement of claim 3 wherein said logic means includes output signal means coupled to said latching relay and selectively activated to output a latching relay drive control signal for controlling the switched status of said latching relay only when the feedback signal coupled to said logic means by said feedback coupling means disagrees with the switch status of said latching relay commanded by said transmit/receive control signal. ### Claim 5 (depends on 4) The improvement of claim 4 wherein said logic means further comprises: means for outputting a latching relay drive control signal when said latching relay is in receive status, coupling said receiving device to said antenna, and said transmit/receive control signal commands transmit status of said latching switch means, coupling said transmitting device to said antenna; and means for inhibiting the output of a latching relay drive control signal when said latching relay has been activated to switch to transmit status in accord with said transmit/receive control signal command. ### Claim 6 (depends on 5) The improvement of claim 5 wherein said logic means further comprises: means for outputting a latching relay drive control signal when said latching relay is in transmit status, and said transmit/receive control signal commands receive status of said latching relay; and means for inhibiting the output of a latching relay drive control signal when said latching relay has been activated to switch to receive status in accord with said transmit/receive control signal command. ### Claim 7 (depends on 6) The improvement of claim 6 further comprising latching relay drive means coupled between said latching relay and said means for outputting latching relay drive control signals for selectively outputting a latching relay drive signal in response to the latching relay drive control signal output by said logic means. ### Claim 8 (depends on 7) The improvement of claim 7 wherein said latching relay comprises a single pole, double throw (SPDT) latching relay. ### Claim 9 (depends on 8) The improvement of claim 8 wherein said feedback coupling means includes circuitry for coupling the single pole of said SPDT latching relay to both said antenna and said logic means. ### Claim 10 (depends on 7) The improvement of claim 7 wherein said latching relay comprises a double pole, double throw (DPDT) latching relay. ### Claim 11 (depends on 10) The improvement of claim 10 wherein a first pole of said DPDT latching relay is coupled to said antenna and a second pole of said DPDT latching relay is coupled to said logic means. ### Claim 12 (depends on 3) The improvement of claim 3 wherein said logic means comprises means for outputting latching relay control signals in response to transmit/receive control signals to actively energize said latching relay and in further response to initial feedback signals and resultant feedback signals coupled to said logic means by said feedback coupling means in accord with the following logic truth table: ______________________________________ T/R IFB Q1 Q2 RFB ______________________________________ 1 1 0 0 1 0 0 0 0 0 1 0 0 1 1 0 1 1 0 0 ______________________________________ where T/R are the transmit/receive control signals, IFB and RFB are the initial and resultant feedback signals respectively, Q1 and Q2 are the latching relay control signals.