Abstract: A method and apparatus for a ladder filter (400) incorporating same. The filter (400) includes a substrate and a first series resonator (100, 403) disposed on the substrate and electrically coupled in series between the first electrical port (401) and a first node. The first series resonator (100, 403) includes a first series acoustic reflector (115), a first series gap (112), a first series transducer (105, 403), a second series gap (112) and a second series acoustic reflector (115′) collectively disposed in an in-line configuration along a principal axis of the substrate. The filter (400) also includes a first shunt resonator (100, 404) disposed on the substrate and electrically coupled in shunt between the first node and ground. The first shunt transducer (105, 404) and the first series transducer (105, 403), if reflectors (115, 115′) are included, have an optimized number of reflective elements (116, 116′) included therein.

Abstract: A temperature compensated resonator (15) and method for making the temperature compensated resonator (15). The temperature compensated resonator (15) has a substrate (110) including a cavity (120, 160) and a resonator layer (150). A bonding medium (159, 160) couples the substrate (110) to the resonator layer (150). The resonator layer (150) is bonded atop the cavity (120, 160). A conductor (215) is included on the resonator layer (150). The conductor (215) heats the resonator layer (150) in response to a current passing through the conductor (215).

Abstract: A fast Fourier transformer (160) includes an FFT engine (162) having a twiddle index input and a memory bus coupled to a data input (167), a memory (164) coupled to the memory bus, an address generator (163) coupled to the memory (164), a twiddle index generator (150) including an output coupled to the twiddle index input, a counter (161) having an output coupled to inputs of the twiddle index generator (150) and the address generator (163) and a data output (168) coupled to the FFT engine (162) and to the memory (164).

Abstract: A high quality factor resonator (15) including a substrate (110) and a resonator layer (150). The resonator layer includes a first electrode (157). The resonator layer (150) is disposed on a surface of the substrate (110). The first electrode (157) is disposed on a distal surface of the resonator layer (150). A cavity (120) is disposed between the substrate (110) and the resonator layer (150) and a second electrode (159) is disposed on the substrate (110) and on a surface of the cavity (120) remote from the resonator layer (150) and is separated from the resonator layer (150) by a thin gap.

Abstract: A power supply (10) including a virtual resistor. The power supply (10) includes (i) a power stage (11) having an input (12) for accepting unregulated power, an output (14) for providing regulated power, a control input (13) and a current sense output (16); (ii) a control circuit (15) including an error amplifier (19) having an inverting input coupled to the output (14) and an output coupled to the control input (13); and (iii) a virtual resistance generator (25) having an input coupled to the output of the error amplifier (19) and an output coupled to a non inverting input of the error amplifier (19). The virtual resistance generator (25) is for supplying a reference voltage (27) to the control circuit (15) such that a voltage present at the output for providing regulated power (14) as a function of current leaving the output for providing regulated power (14) provides an output virtual resistance.

Abstract: An improved shield and ceramic filter. The shield includes (i) an upright portion (16) comprising a conductive material, (ii) a chamfered portion (22) disposed atop the upright portion (16), (iii) a horizontal portion (18) disposed on a distal portion of the chamfered portion (22) and (iv) one or more openings (20) disposed on the chamfered portion (22). The improved shield (12) desirably but not essentially further includes at least one slot (26) cut into a basal section of the upright portion (16). The at least one slot (26) allows a microstrip transmission line to pass under a portion of the shield (12).

Abstract: A secure, portable position locating radio has a geolocation receiver providing local position and timing information from geolocation means (e.g. GPS satellites) and a local transceiver for sending local position information to a communication system (e.g., an airborne or orbiting transceiver). A crypto unit is provided between the receiver and local transceiver for encrypting the local position information prior to transmission. A data processor coupled to the local transceiver, receiver and crypto unit controls operation of the device, including storing local position information and separating signals broadcast by the communication system into those intended or not intended for the device. An external interface and display and a real-time clock (e.g., slaved to the GPS receiver) are also coupled to the data processor. Encryption keys and message abbreviation codes are conveniently loaded into the device from a demountable accessory unit at the interface, and stored therein.

Abstract: A battery compartment (12) adapted to accommodate any of several different types of batteries (30, 32, 34). The compartment (12) includes a hollow region having a length equivalent to that of one or more batteries (31, 33, 35) and includes a positive contact (65) disposed at one end thereof. The compartment also includes a cap (14) adapted to couple to an end of the compartment (12) remote from the one end. The one end includes a first contact (65) and one or more additional positive contacts (63). The additional positive contacts (63) are coupled to anodes of diodes (64) having cathodes coupled to the positive contact (65).

Abstract: A method for making an acoustic wave device. The method has steps of providing a substrate suitable for acoustic wave devices and processing the substrate to provide a patterned metallization thereon. The patterned metallization includes an acoustic wave filter pattern. The method also has steps of measuring a sheet resistance associated with the acoustic wave filter pattern, determining a resistance of a test pattern associated with the acoustic wave filter pattern to provide a measured resistance and computing an estimated average linewidth for the acoustic wave filter pattern from the measured resistance and the sheet resistance.

Abstract: A temperature compensated resonator (15) and method for making the temperature compensated resonator (15). The temperature compensated resonator (15) has a substrate (110) including a cavity (120, 160) and a resonator layer (150). A bonding medium (159, 160) couples the substrate (110) to the resonator layer (150). The resonator layer (150) is bonded atop the cavity (120, 160). A conductor (215) is included on the resonator layer (150). The conductor (215) heats the resonator layer (150) in response to a current passing through the conductor (215).

Abstract: An apparatus and accompanying method for demodulating with baseband Doppler frequency shift compensation. An RF section (20) down-converts received data communication signals (12) to baseband. A/D converters (24, 26) digitize I, Q quadrature baseband signal components. Phase (32) and frequency (50) tracking loops reside on a common digital ASIC substrate (28). A complex multiplier (30) rotates digitized baseband signals by a digitized oscillation signal, producing Doppler shift compensated signals. The phase tracking loop (32) estimates data and generates a pure phase error signal from which data modulation and Doppler shift compensation influences have been removed, which drives a frequency discriminator (52) that identifies either clockwise or counterclockwise phase rotation for each symbol (18). An integrator (54) combines identification results over a burst and a numerically controlled oscillator (56) adjusts the digitized oscillation signal frequency in a constant frequency step.

Abstract: Working assets (26) are equipped with ID tags (56) that respond to interrogations from interrogators (50). Each interrogated tag (56) sends response codes that identify the tag (56) and working asset (26), can describe an amount of use experienced by the working asset (26), and can describe unused capacity available for holding a consumable commodity, such as fuel. Interrogators (50) are positioned at normally closed portals (40, 42, 62, 64) of staging areas (22, 24). A database (94) contains information concerning working assets (26), users (28) to whom working assets (26) have been assigned, and caretakers (38) who may be authorized to transport various working assets (26). The caretakers (38) also have ID tags (58). A portal (40, 42, 62, 64) temporarily opens or remains closed in response to the interrogation that takes place at the portal (40, 42, 62, 64) and data stored in the database (94).

Abstract: A population of locatable personal detection units (PDUs) (20) are worn by users. Any number of locators (14) are placed at known locations within an area (10) where the users tend to be. When an alarm event for an individual user occurs, a request signal is transmitted from the user's PDU (20). The request signal is received at several of the locators (14), each of which measure the power level of the request signal. A central computer (16) selects some of these locators (14) in response to the power level measurements. In sequence, the selected locators (14) transmit an interrogation signal to the PDU (20), the PDU (20) replies to the interrogation signal, and the locators (14) measure the duration transpiring between the interrogation and the reply. Based on the durations measured for at least three of the locators, the central computer (16) uses a multilateration process to localize the PDU (20).

Abstract: A full duplex radio (10) having improved properties obtained by using surface acoustic wave (SAW) filters (92, 100, 100') having asymmetric frequency responses (76', 76", 140). The filters (92, 100, 100') are composed of series (50.sub.1, 50.sub.1 ') and parallel (50.sub.2, 50.sub.2 ') coupled SAW resonators. Asymmetry is obtained by altering the metallization thickness of either of the series (50.sub.1, 50.sub.1 ') or parallel (50.sub.2, 50.sub.2 ') resonators of each filter (92, 100, 100') to increase or decrease the SAW coupling coefficient of some of the resonators (50.sub.1, 50.sub.1 ', 50.sub.2, 50.sub.2 ') relative to the remainder of the resonators (50.sub.1, 50.sub.1 ', 50.sub.2, 50.sub.2 '). The filters (92, 100, 100') are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts (93, 95) of the frequency responses (76', 76", 140) are adjacent. Greater passband bandwidths (91', 91") can be obtained without adverse affect on transmitter and receiver isolation.

Abstract: A system (10) includes any number of Boundary-Scan integrated circuits (28), a common bus (14), and a Boundary-Scan master (22). The integrated circuits (28) include mode selection logic (58) that isolates pins (30, 32) from core logic (34) during Capture-DR, Update-DR, Run-Test/Idle, and Select-DR-Scan states (66, 88, 62, 64) when a system action instruction is active so that a system action may be asserted. During all other states, including a Shift-DR state (82), the pins (30, 32) remain coupled to the core logic (34). The Boundary-Scan master (22) includes an arbitration interface (112). The arbitration interface (112) requests control of the common bus (14) prior to the time when the integrated circuits (28) assert a system action. The Boundary-Scan master arbitration interface (112) then releases control of the common bus after system action by the integrated circuits (28) is completed.

Abstract: A method and apparatus for a ladder filter (300, 400) incorporating same. The filter (100) includes a substrate and a first series resonator (100, 305, 403) disposed on the substrate and electrically coupled in series between the first electrical port (301, 401) and a first node. The first series resonator (100, 305, 403) includes a first series acoustic reflector (303), a first series gap (112), a first series transducer (105, 304, 403), a second series gap (112) and a second series acoustic reflector (115', 306) collectively disposed in an in-line configuration along a principal axis of the substrate. The filter (300, 400) also includes a first shunt resonator (100', 310, 404) disposed on the substrate and electrically coupled in shunt between the first node and ground.

Abstract: An acoustic wave filter (200, 300) having a substrate for supporting propagation of acoustic waves, and first (220, 315), second (235, 330) and third (210, 310) acoustic wave transducers disposed on the substrate. The first acoustic wave transducer (220, 315) includes at least one bus bar (221, 316) electrically coupled to a first electrical port (205, 305) of the acoustic wave filter (200, 300). The second acoustic wave transducer (235, 330) is disposed on the substrate in line with the first acoustic wave transducer (220, 315) and is acoustically coupled thereto. The second acoustic wave transducer (235, 330) includes at least one bus bar (236', 331) electrically coupled to a second electrical port (240, 345) of the acoustic wave filter (200, 300). The third acoustic wave transducer (210, 310) includes at least one bus bar (211, 311') electrically coupled to the first electrical port (205, 305).

Abstract: A full duplex radio having improved properties is obtained by using asymmetric surface acoustic wave (SAW) filters, the filters are composed of series and parallel coupled SAW resonators. Asymmetry is obtained by covering either of the series or parallel resonators of each filter with a dielectric layer to increase the SAW coupling coefficient of the covered resonators relative to the uncovered resonators. The filters are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts of the frequency response are adjacent. Greater pass-bandwidths can be obtained without adverse affect on transmitter and receiver isolation.

Abstract: A method for excitation synchronous time encoding of speech signals. The method includes steps of providing an input speech signal, processing the input speech signal to characterize qualities including linear predictive coding (LPC) coefficients, epoch length and voicing and characterizing the input speech signals on a single epoch time domain basis when the input speech signals comprise voiced speech to provide a parameterized voiced excitation function. The method further includes steps of characterizing the input speech signals for at least a portion of a frame when the input speech signals comprise unvoiced speech to provide a parameterized unvoiced excitation function and encoding a composite excitation function including the parameterized unvoiced excitation function and the parameterized voiced excitation function to provide a digital output signal representing the input speech signal.

Abstract: In a communication system (10), a receiving node (14) estimates bit error rate (BER) and the accuracy of the BER estimate based upon a single burst of a data communication signal (12). An appropriate decision rule (92) is selected (90) in response to the BER accuracy estimate. Different decision rules (92) are available to bias different decisions to favor desired outcomes. The bias is configured in response to the BER accuracy estimate. The selected decision rule (92) is evaluated (96) in view of an estimated BER. In response to this evaluation, a transmitting node (14) may be instructed (104) to increase or decrease its transmit power level. In addition, the BER may be measured, and the measurement used to verify the appropriateness of the decision rules (92).