Browse Prior Art Database

Method for Transmitting Electrical Sensor Data Wirelessly

IP.com Disclosure Number: IPCOM000008480D
Original Publication Date: 2002-Jun-17
Included in the Prior Art Database: 2002-Jun-17
Document File: 4 page(s) / 246K

Publishing Venue

Motorola

Related People

Tom Weber: AUTHOR

Related Documents

http://www.measurementsgroup.com: URL

Abstract

A good method to obtain quantitative reliability data for Motorola products is drop reliability testing. Instrumented mechanical impact testing is required for Motorola portable products in order to validate the mechanical reliability of our products. Currently instrumented tests are conducted by acquiring strain data through long, thin wires. The wires are tedious to work with and tend to break. This issue suggests that a wireless method for acquiring strain data be developed. Implementing a wireless system for transmitting strain data will reduce cycle time by reducing the need to repair gage wires. The development of a wireless transmission method for transmitting electrical sensor data has resulted in a RF system capable of transmitting mechanical impact data. The wireless system is compact and lightweight enough for the wireless system to have minimal impact on the mechanical test.

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Method for transmitting electrical sensor data wirelessly

Tom Weber

Abstract:

A good method to obtain quantitative reliability data for Motorola products is drop reliability testing.  Instrumented mechanical impact testing is required for Motorola portable products in order to validate the mechanical reliability of our products.  Currently instrumented tests are conducted by acquiring strain data through long, thin wires.  The wires are tedious to work with and tend to break.  This issue suggests that a wireless method for acquiring strain data be developed.  Implementing a wireless system for transmitting strain data will reduce cycle time by reducing the need to repair gage wires.

The development of a wireless transmission method for transmitting electrical sensor data has resulted in a RF system capable of transmitting mechanical impact data.  The wireless system is compact and lightweight enough for the wireless system to have minimal impact on the mechanical test.

Discussion:

In order to obtain mechanical impact measurements, strain gages are attached to the portable product with long thin wires that are routed from the product to the data acquisition system.  Strain gages are composed of a thin metal foil that when attached to a surface experiencing elongation results in a resistance change, Figure 1.  The wires that are used must be thin in order to minimize their effect on the mechanical impact test and are therefore delicate in nature.  The result is that the wires tend to break after multiple tests and require a significant maintenance time to repair the broken connections. 

Figure 1. Thin Foil Strain Gage.

 

To address these issues a wireless measurement system has been developed.  The system uses an analog electrical sensor as a component directly in a square wave oscillator circuit for use in a wireless transmitter.  The electrical sensor variation in resistance controls the oscillators output frequency, Figure 2.

The purpose of the system is to transmit strain gage measurements wirelessly during mechanical impact testing, although the development described can be implemented with a variety of...