System and Method for Acoustic Data Transmission

Abstract

Embodiments of the present invention are directed to acoustic data transmission using a spreading code. A system for acoustic data transmission includes an ingestible capsule and an acoustic receiver. The ingestible capsule includes a modulator, a spreader, and an acoustic transmitter. The modulator modulates data according to a modulation scheme. The spreader spreads the modulated data according to a spreading code. The acoustic transmitter acoustically transmits the modulated and spread data through a body of an animal. The acoustic receiver includes an acoustic transducer a de-spreader and a demodulator. The acoustic transducer receives the acoustically transmitted signal and forms an electrical signal therefrom. The de-spreader de-spreads the received signal in accordance with the spreading code. The demodulator demodulates the received and de-spread signal in accordance with the modulation scheme, wherein a phase of the spreading code is synchronized with the received signal whereby a signal-to-noise ratio of the received signal is increased.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims the benefit of U.S. Provisional Patent Appl. No. 60 / 842,360, filed Sep. 6, 2006, and U.S. Provisional Patent Appl. No. 60 / 941,184, filed May 31, 2007, each of which is incorporated by reference herein in its entirety.BACKGROUND[0002]1. Field of the Invention[0003]The present invention is generally directed to medical device communications, and in particular, to communication with an ingestible medical device.[0004]2. Related Art[0005]An ingestible medical device may be used to diagnose and / or treat a patient. For example, the ingestible medical device may be used to collect data regarding the patient's internal body chemistry. This data can then be transmitted to an external device for diagnostic purposes. Such a diagnostic technique is easy to administer and less invasive compared to conventional diagnostic techniques, such as surgery.[0006]Conventional ingestible medical devices use a radio frequency (RF) ...

AI Technical Summary

Benefits of technology

[0014]The present invention meets the above-described need by providing systems and methods of acoustic data transmission which spread a data signal using a spreading code. The spreading code is quasi-orthogonal to reduce inter-symbol interference and improved system performance.

[0016]In embodiments, phase shift keying or differential phase shift keying is used in combination with a simple Barker spreading code, collectively providing substantial inter-symbol interference mitigation. In an embodiment, the Barker code is implemented as an 11-element cyclic shift register which conserves area and reduces power consumption, enabling an ingestible capsule of the present invention to be relatively small.

Problems solved by technology

However, the RF signal platform is problematic for several reasons.

First, the extent to which RF signals cause harm to human tissue is not fully understood.

The potential for harm only increases as the source of the RF signals comes closer to the human tissue.

Accordingly, patients may be apprehensive about ingesting a device that emits RF signals.

Second, ingestible medical devices based on an RF signal platform consume a significant amount of power.

To provide the requisite amount of power, RF-based ingestible medical devices include a relatively large power supply, making the overall size of such devices quite large.

In fact, conventional RF-based ingestible medical devices are so large that they cannot be swallowed by a portion of the patient population.

And, even if a patient can swallow a conventional RF-based ingestible medical device, its large size may cause it to become lodged in the patient's gastrointestinal tract, which would require surgery to remove.

Despite these and other advantages, acoustically transmitting data inside a human's body is problematic.

Even worse, this acoustic reverberation chamber is dynamic, with the echo characteristics changing over time.

As a result, an acoustic signal in the body will create a noise signal which is a complicated function of the multiple echoes of previously transmitted signals and which is amplitude modulated by the dynamic changes of the body cavity.

This dynamic noise background significantly complicates acoustic data transmission within the body.

During data transmission, multi-path propagation causes inter-symbol interference and signal fading in the time and frequency domains.

Inter-symbol interference and signal fading (such as, Rayleigh fading) significantly decrease system performance, restrict data rate, dramatically increase power consumption, and sometimes even lead to complete transmission degradation.

However, this method cannot be used to achieve high data rates.

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