Interference Rejection Module for Medical Telemetry Dynamic Range

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Solution Overview

Problem

Medical device telemetry systems face interference issues, particularly with low dynamic range receivers being susceptible to both in-band and out-of-band interference signals, which impairs communication and requires higher power transmission, shortening battery life in implantable devices.

Innovation Solution

Incorporating an interference rejection module (IRM) with pre-selector filters, low noise amplifiers, image filters, and intermediate frequency filters to attenuate interference signals while maintaining the desired communication signal, effectively adapting low dynamic range telemetry modules to function as higher dynamic range systems without altering the transceiver.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If telemetry modules operate using low current to prevent excessive battery drain, then battery longevity is improved, but the receiver becomes susceptible to interference signals both within and outside the communication bandwidth

Engineering Contradiction:

Improvebattery longevityVSAvoidinterference susceptibility

Core Design Contradiction:

Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The interference rejection module performs preliminary filtering of interference signals before they reach the low dynamic range receiver. Pre-selector filters and image filters are positioned in the signal path to attenuate out-of-band and image frequency interference signals in advance, protecting the sensitive low-current receiver from being overwhelmed by strong interference signals.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The interference rejection module acts as an intermediary component between the antenna and the receiver. It includes pre-selector filters, low noise amplifiers, image filters, and intermediate frequency filters that collectively mediate the signal path, selectively attenuating interference signals while preserving the desired communication signals for the low dynamic range receiver.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If the telemetry receiver has low dynamic range to reduce power consumption, then energy efficiency is improved, but the receiver cannot tolerate strong interference signals

Engineering Contradiction:

Improvepower consumptionVSAvoidinterference tolerance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The interference rejection module applies preliminary anti-action by attenuating strong interference signals before they can adversely affect the low dynamic range receiver. The pre-selector filters and image filters are configured to reduce the amplitude of out-of-band and image frequency interference signals, preventing them from saturating the receiver's limited dynamic range.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system converts the limitation of low dynamic range into a benefit by using the interference rejection module to pre-process signals. The low dynamic range receiver, which would normally be vulnerable to strong signals, is protected by the filtering stage, allowing it to operate efficiently at low power while maintaining reliability through the combined system approach.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If distance telemetry is implemented without a programming head to simplify the system, then device complexity is reduced, but interference rejection becomes more challenging

Engineering Contradiction:

Improvesystem complexityVSAvoidinterference rejection difficulty

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The interference rejection functionality is segmented into distinct modular components: pre-selector filters, low noise amplifiers, image filters, and intermediate frequency filters. This segmentation allows each component to be optimized for its specific function while maintaining overall system simplicity and enabling independent selection and adjustment of filtering characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The interference rejection module provides multi-functional protection for the distance telemetry system. It simultaneously handles out-of-band interference, image frequency interference, and signal amplification, making the simplified distance telemetry system robust against various interference types without requiring complex additional circuitry.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The IRM significantly reduces susceptibility to interference, extending the dynamic range of telemetry systems and maintaining signal integrity, thus enhancing communication reliability and battery longevity in medical device telemetry.

Implementation Method 1

The pre-selector filter has a pass band that passes signal frequencies corresponding to a range of operating channels

Methodology Applied

Scientific EffectFiltering: Filter (electronic)

Implementation Method 2

a low noise amplifier that amplifies an output signal from the pre-selector filter

Methodology Applied

Scientific EffectSignal amplification:

Implementation Method 3

an image filter that attenuates an output signal from the low noise amplifier

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Implementation Method 4

a mixer that translates a filtered output signal from the image filter to an intermediate frequency

Methodology Applied

Scientific EffectFrequency mixing:

Implementation Method 5

an intermediate frequency filter that attenuates an output signal from the mixer

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Implementation Method 6

a post-mixer that translates an output signal from the intermediate frequency filter

Methodology Applied

Scientific EffectFrequency mixing:

Implementation Method 7

a variable gain amplifier that provides a fixed gain output signal

Methodology Applied

Scientific EffectSignal amplification with variable gain:

Data Source

PatentUS8855591B2Preselector interference rejection and dynamic range extension

Publication Date: 2014.10.07 MEDTRONIC INC

AI summary

A wireless telemetry module and associated method reject interference in a received signal. The wireless telemetry module includes an antenna receives a communication signal transmitted at a desired channel frequency and having a channel bandwidth. A transceiver is controlled to operate in receiving and transmitting modes by a processor. An interference rejection module receives control signals from the processor corresponding to the desired channel frequency and is coupled between the antenna and the transceiver when the transceiver is operating in the receiving mode.