Application Briefs and Papers

Below is a growing list of an application briefs and papers related to Precision Filters' products and technologies. Documents have a brief description or an overview, click the 'more' button to view full PDF document.

Papers

• Ground Loop Problems with Measurement Systems and How to Avoid Them

• Signal Conditioning for Gas Turbine Engine Testing

• LDTEDS: A Method for Long Distance Communication to Smart Transducers with TEDS

• Balanced Constant Current Excitation for Dynamic Strain Measurements

• Aliasing and Anti-Alias Filters

Other Information Sources

• Product Information

• Product brochures and specifications  

• Recent press releases

• Training and Education Resources

Ground Loop Problems with Measurement Systems and How to Avoid Them

This pdf presentation by Alan Szary, explores electromagnetic noise coupling in a cabling system, the errors that magnetic coupling introduce in a measurement system and the causes of ground loop problems. The discussion concludes with the difficulties of cabling IPEP type accelerometers and Precision Filters’ unique technique to provide optimal signal conditioning for triaxial accelerometers.

Signal Conditioning for Gas Turbine Engine Testing

Designers of measurement systems for gas turbine engine testing deal with a complex set of environmental conditions that challenge their ability to ensure their data is valid. Hundreds of sensors and lead wires are collecting data on pressure, strain, vibration and temperature while interacting with the extremes of these very same conditions. In addition, the test environment is further complicated by the corrosive effects of hot gasses, magnetic fields, and multiple opportunities for noise pick-up. To account for these issues, the implementation of a variety of signal conditioning and wiring techniques is essential to sort out the data from the noise and to ensure that the data is valid.

LDTEDS: A Method for Long Distance Communication to Smart Transducers with TEDS

The IEEE 1451.4 standard defines a Mixed-Mode Interface (MMI) that is alternately used for both Transducer Electronic Data Sheet (TEDS) data and analog signals. For some sensors such as IEPE accelerometers, the TEDS contains essential data pertaining to the transducer that the connected system may read via the same wires that the analog signal is delivered. Presently, the distance between TEDS transducers and the interrogating instrument is limited to 400 feet due to communication protocol and design of the 1-wire memory devices. In many shock and vibration test applications, safety, environment or other factors dictate that the cable runs to the transducers are in excess of 400 feet. In this paper, we present a method that we call Long Distance TEDS (LDTEDS) that allows instruments to communicate with TEDS equipped devices to 1500 feet.

Balanced Constant Current Excitation for Dynamic Strain Measurements

Balanced constant current excitation uses a pair of matched constant current sources to excite a single active strain gage. The technique provides enhanced immunity from electrostatic noise pickup and may be employed for dynamic strain measurement applications that require only two wires to the transducer. In this paper, the properties of balanced constant current excitation will be examined and compared against traditional techniques using the Wheatstone bridge or single-ended constant current excitation. A method to verify transducer health and cabling will also presented.

Aliasing and Anti-Alias Filters

The analysis of continuous analog signals by digital signal processing equipment requires that the analog signal be converted into a sampled, digitized record of finite length.