Garimella R Sarma

US Patent:

7132838, Nov 7, 2006

Filed:

Feb 9, 2005

Appl. No.:

11/054642

Inventors:

Garimella R. Sarma - Newport News VA, US
Siva M. Mangalam - Williamsburg VA, US

Assignee:

Tao of Systems Integration, Inc. - Hampton VA

International Classification:

G01R 27/08
G01L 1/00

US Classification:

324721, 324691, 73766, 702 42

Abstract:

A sensor circuit is provided that includes a first T-network including a first impedance serially connected to a second impedance at a first junction and a first variable resistance sensor element connected at a first end to the first junction and at a second end to ground. The sensor circuit also includes a second T-network including a third impedance serially connected to a fourth impedance at a third junction and a second variable resistance sensor element having first and second sensor element ends. The first sensor element end is connected to the third junction and the fourth impedance is connected to the second junction. The sensor circuit further includes a constant voltage source connected to the third impedance and to ground. The second end of the second variable resistance sensor element is connected to a fourth junction intermediate the constant voltage source and ground.

US Patent:

7301352, Nov 27, 2007

Filed:

Jun 27, 2006

Appl. No.:

11/475303

Inventors:

Garimella R. Sarma - Newport News VA, US

International Classification:

G01R 27/08

US Classification:

324691, 324713

Abstract:

A sensor interface circuit is provided to interface many sensors simultaneously in a simple circuit arrangement consisting of two parts. Sensors in both parts operate under identical constant voltage. The circuit provides higher front end sensitivity than the Wheatstone bridge, with temperature compensation from all sensors. The circuit also can provide output zeroing to obtain high resolution measurements. The invention can be used as a unique constant voltage anemometer with auto zeroing, and with much higher sensitivity than related devices. Further, in the constant voltage anemometer embodiment, the time constant and the overheat of the hot-wire/hot-film can be measured in true in situ mode under actual test conditions. In another embodiment, the circuit can be used to measure dynamic capacitance from capacitance sensors, without any effect of associated cable capacitance.

US Patent:

7268566, Sep 11, 2007

Filed:

Nov 3, 2006

Appl. No.:

11/592509

Inventors:

Garimella R. Sarma - Newport News VA, US
Siva M. Mangalam - Williamsburg VA, US

Assignee:

Tao of Systems Integration, Inc. - Hampton VA

International Classification:

G01R 27/08
G01L 1/00

US Classification:

324721, 324691, 73766, 702 42

Abstract:

A sensor circuit is provided that includes at least one pair of interconnected T-networks. Each pair has a first T-network including a first impedance serially connected to second impedance at a first junction and a first variable resistance sensor element connected to the first junction. Each pair also has a second T-network including a third impedance serially connected to a fourth impedance at a second junction and a second variable resistance sensor element connected to the second junction. The sensor circuit further includes an operational amplifier connected to the first T-network of a selected one of the at least one pair of T-networks and a constant voltage source connected to the second T-network of the selected T-network pair.

US Patent:

61349593, Oct 24, 2000

Filed:

Aug 17, 1998

Appl. No.:

9/135282

Inventors:

Garimella Ramakrishna Sarma - Newport News VA

Assignee:

Tao of Systems Integration, Inc. - Williamsburg VA

International Classification:

G01F 1300
G01P 500

US Classification:

7317012

Abstract:

A method is provided for detecting flow bifurcation during sonic flow conditions to identify shock location. The method includes setting the initial test conditions, either by setting up an altitude and airspeed in a test aircraft or by setting up an initial flow condition in a wind tunnel. The method for detecting flow bifurcation during sonic flow conditions to identify shock location requires an array of hot films be attached to an aerodynamic surface where shock is expected to impinge. These hot-films are connected to a bank of Constant Voltage Anemometers (CVA), one CVA for each hot film. After reaching the altitude where the testing is to be done, (or attaining the reference condition in a wind tunnel), a pilot initiates an auto-initializing sequence before the onset of a shock, typically at a low speed condition. This sets the current in each sensor to identical values and sets the sensor temperature above ambient temperature of the reference conditions. An auto zero sequence is then initiated to provide zero output current and create a reference point before the onset of the shock.

US Patent:

50741470, Dec 24, 1991

Filed:

Mar 8, 1990

Appl. No.:

7/490318

Inventors:

Garimella R. Sarma - Hampton VA

Assignee:

Analytical Services & Materials, Inc. - Hampton VA

International Classification:

G01F 168

US Classification:

7320415

Abstract:

The invention is a new and novel flow rate measuring appartus comprising constant voltage or constant power anemometers with unique electronic circuits for maintaining constant voltage or constant power to a hot film or hot wire sensor. The constant power or constant voltage mode of operation is achieved by providing an operational amplifier with a negative feedback circuit driving the hot element sensor. The hot element sensor is located along the negative feedback path of the circuit between a first and second impedance. Amplifying and filtering circuits are also provided.

US Patent:

6101429, Aug 8, 2000

Filed:

Apr 7, 1998

Appl. No.:

9/056328

Inventors:

Garimella Ramakrishna Sarma - Newport News VA

Assignee:

Tao of Systems Integration, Inc. - Williamsburg VA

International Classification:

G01C 2110

US Classification:

701 7

Abstract:

A broad-range, multi-directional aircraft airspeed measuring system is provided. The airspeed measuring system has multiple vortex generating probes located within a venturi section. At least one rearward facing probe and one forward facing probe are included. Additional probes can be added to extend the high speed range of the airspeed indicator. A splitter plate or plates separate flow channels from each other to provide a separate flow channel for each vortex probe. Each vortex probe has a hot film sensor and anemometer.

US Patent:

58544259, Dec 29, 1998

Filed:

Jun 9, 1998

Appl. No.:

/094336

Inventors:

Garimella Ramakrishna Sarma - Newport News VA

Assignee:

Tao of Systems Integration, Inc. - Williamsburg VA

International Classification:

G03F 168

US Classification:

7320418

Abstract:

A method for compensating for the time constant (delay time) of hot-wire/hot-film in a constant voltage anemometer is provided. The method is a two-part series of steps, the first series for measuring the time constant in a particular wind tunnel setup and a second series for compensating for the measured time constant. The first series or measuring steps include setting up a hot-wire/hot film for a particular test at a specific operating point. A step increase in sensor current is applied and the resistance change of the sensor is measured. The time to reach 63% of the final resistance value is recorded. (The time constant is defined as the time to reach 63% of the resistance value). The measured time constant value is used to match the time constant in the CVA circuit.

US Patent:

20150027199, Jan 29, 2015

Filed:

Mar 27, 2014

Appl. No.:

14/227192

Inventors:

Garimella R Sarma - Newport News VA, US

International Classification:

G01P 21/00

US Classification:

73 137

Abstract:

A compensation circuit connected to an accelerometer's output extends the frequency response of the accelerometer, while reducing noise produced by the accelerometer. The compensation circuit has a gain as a function of frequency that is (i) constant up to a first frequency that is less than the accelerometer's natural resonance frequency, and (ii) reduced to approximately zero at a second frequency that is greater than the accelerometer's natural resonance frequency.