Abstract The large capacitive reactance of piezoelectric materials such as, barium titanate, Rochelle salt, or quartz, that are used as the driving elements in transducers has required large inductances to bring the power factor to unity to ensure efficient power transfer between a transducer and a transceiver. A transmitter-transformer couples a transmitter to the transducer, at high-energy output levels, and a series connected receiver-transformer, tuned to pass signals with an identical frequency characteristic at significantly lower levels of energy, eliminates a problem arising when one transformer is used. When employing a single transformer having a high permeability core, its inductance varies when the transformer transfer energy separated levels of energy thusly changing the tuning of associated circuits at these different levels of operation. Shunting switches across the transmitter-transformer winding and the receiver-transformer winding, enable the selective disconnection of either of the transformers from a common coupling circuit when the other mode of operation is proceeding. A pair of back-to-back diodes forming the shunting circuit across the primary of the receiver-transformer, have a forward voltage drop greater than the magnitude of the received signal to ensure the transfer of received signals when they appear across the primary winding. These same diodes have a forward voltage drop far below the level of the high-power output appearing across the secondary winding of the transmitter-transformer to ensure that this signal is shorted around the primary of the receivertransformer to eliminate the possibility of damaging the inherently more delicate receiver-transformer.
A device for coupling an electromechanical transducer to a tuned transmitter and an identically tuned receiver comprising: a first inductor configured for coupling a high-power transmitted signal from said tuned transmitter to said transducer being constructed to provide an inductive reactance electrically cooperating with the capacitive reactance of said transducer to ensure an electrically tuned transfer of said transmitted signal; a switching means connected across said first inductor adapted to short thereacross during periods of nontransmission; a second inductor serially connected with said first inductor and configured for coupling a low-power received signal from said transducer to said tuned receiver being constructed to provide an inductive reactance electrically cooperating with said capacitive reactance to ensure an identical said electrically tuned transfer of said received signal; and a shunting circuit connected across said second inductor including, bidirectional conducting means in the form of a pair of back-toback diodes having a forward voltage drop of lesser magnitude than said transmitted signal and of greater magnitude than said received signal, upon transmitting said high-power transmitted signal, effectively shorting said receiver and a shunt resistor for receiving said low-power received signal to provide a linear load for passing said received signal to said second inductor and to said tuned receiver.
Claim 2
Independent Claim
206 words
A device for coupling an electromechanical transducer to a tuned transmitter and an identically tuned receiver comprising: a first inductor configured for coupling a high-power transmitted signal from said tuned transmitter to said transducer being constructed to provide an inductive reactance electrically cooperating with the capacitive reactance of said transducer to ensure an electrically tuned transfer of said transmitted signal; a switching means connected across said first inductor adapted to short thereacross during periods of nontransmission; a second inductor serially connected with said first inductor and configured for coupling a low-power received signal from said transducer to said tuned receiver being constructed to provide an inductive reactance electrically cooperating with said capacitive reactance to ensure an identical said electrically tuned transfer of said received signal; and a shunting circuit connected across said second inductor including, bidirectional conducting means in the form of a pair of back-toback diodes having a forward voltage drop of lesser magnitude than said transmitted signal and of greater magnitude than said received signal, upon transmitting said high-power transmitted signal, effectively shorting said receiver and a shunt resistor for receiving said low-power received signal to provide a linear load for passing said received signal to said second inductor and to said tuned receiver.
Claim 3
Dependent Claim
30 words
A device according to claim 1 in which said switching means is a relay energized to remain in the open position during transmission and in the closed position during nontransmission.
Claim 4
Dependent Claim
33 words
A device according to claim 2 in which said first inductor is the secondary of a transformer formed of materials having a permeability ensuring a predetermined tuned response to said high-power transmitted signal.
Claim 5
Dependent Claim
34 words
A devicE according to claim 3 in which said second inductor is the primary of a transformer formed of materials having a permeability ensuring an identical predetermined tuned response to said low-power received signal.