An efficient hardware-optimized compression algorithm for wireless capsule endoscopy image transmission

AbstractA dedicated image compression algorithm was developed for wireless capsule endoscopy (WCE). The proposed approach reduces the amount image data without compromising the image quality. This allows an increase in image throughput to improve the real-time vision capabilities of a WCE system. The algorithm is based on a normalized Haar-wavelet transformation, aiming at a hardware-optimized implementation in a low-power FPGA or telemetry ASIC for wireless capsule endoscopes. Taking advantage of the limited color content of endoscopic images, this solution uses the YCbCr color space combined with efficient recoding of the wavelet transformation data. In this way adequate compression ratios at decent image qualities can be achieved in a hardware efficient thus low power implementation, outperforming existing hardware implemented algorithms

Telemetry for Capsule Endoscopy - Design & Implementations (Telemetrie voor capsule endoscopie - ontwerp & implementaties)

In June 1957, the publication in the scientific journal Nature of a paper titled Endoradiosonde by Mackay and Jacobson was a fact. It described the first biomedical telemetry device ever developed and tested: a miniature swallowable RF transmitter, transmitting pressure and temperature information from within the gastro-intestinal tract. It was the start of a new era in biomedicine and biology, enabling measurements and insights that were until then merely a sweet dream to many scientists. Numerous applications and variations followed, but only 20 years later, the first patent was filed on capsule endoscopy with vision capabilities - at the time no more than an analog camera with an electronic shutter. Another 20 years of developments, prototypes and patents later (2001) led to the first commercially available wireless endoscopic vision capsule by Given Imaging. Ever since, the evolution of wireless capsules has been rather slacking: the frame rate and image quality have hardly improved, and very limited additional functionality has been added. This was mainly due to the fundamentally limited amount of energy that could be stored inside a swallowable capsule, inherently constraining the degree of integrateable functionality. Recently, the PhD research of Carta (2010) proved the concept of transferring an unlimited amount of energy to the volume of 2 coin cells, by means of a wireless 3D inductive link. This development allows the use of better imagers and higher frame rates, which has been the main driver for the work described in this manuscript.This work focuses on one aspect of the developments enabled by 3D inductive powering: the telemetry or wireless data link. The image data has to be transmitted efficiently from inside the bowel to an externally carried receiver. The requirements for this link seem quite straight-forward: small in volume, streaming high data rate, low power consumption and adequate in-vivo transmission - as opposed to the mutual trade-offs. Ideally, the image data is transmitted at a low carrier frequency, limiting human tissue absorption. On the other hand, the inherently small antenna volume limits the antenna efficiency and bandwidth at these frequencies, while increasing the transmission power will again counteract the low-power requirement...There are no off-the-shelf solutions that allow efficient streaming high data rate connections at a biocompatible frequency, while trading off the link requirements. In search for the right compromise, a hardware receiver platform was developed, allowing flexible design space exploration, both in carrier frequency as in modulation scheme. On the capsule side, a new simplified compression algorithm is proposed, while the transmitter boundaries are explored through practical designs, implementations and in-vivo tests, supported by a hands-on theoretical background.nrpages: 225status: publishe

ADC for programmable logic uses one capacitor

This Design Idea describes a method for adding a low-end ADC to a single programmable- logic I/O pin. The circuit charges a capacitor through a resistor while measuring the time to charge the capacitor to a certain voltage.status: publishe

A Flexible Multiband Reconfigurable Receiver for Wireless Endoscopic Capsule Streaming Video

An on-the-fly reconfigurable wireless receiver was developed to demodulate high-speed, multi-band modulated signals in the sub-GHz band. The extreme flexibility is enabled by an FPGA as central processing core, reconfigurable at runtime with any demodulation core. The receiver front-end is entirely controllable from a software GUI. The software platform allows high-speed real time transfer of demodulated wireless endoscopic capsule image data from the FPGA through a USB interface IC, for further processing on a PC. A newly developed FSK demodulation core is used as case study for assessing the receiver’s quality. The extreme receiver flexibility allows for efficient practical design space exploration in research for the most optimal high-speed communication system for wireless endoscopic capsule links.status: publishe

An efficient hardware-optimized compression algorithm for wireless capsule endoscopy image transmission

A dedicated image compression algorithm was developed for wireless capsule endoscopy (WCE). The proposed approach reduces the amount image data without compromising the image quality. This allows an increase in image throughput to improve the real-time vision capabilities of a WCE system. The algorithm is based on a normalized Haar-wavelet transformation, aiming at a hardware-optimized implementation in a low-power FPGA or telemetry ASIC for wireless capsule endoscopes. Taking advantage of the limited color content of endoscopic images, this solution uses the YCbCr color space combined with efficient recoding of the wavelet transformation data. In this way adequate compression ratios at decent image qualities can be achieved in a hardware efficient thus low power implementation, outperforming existing hardware implemented algorithms.status: publishe

Electronic spinal posture detection

A wearable automatic monitoring system for back posture has been developed and tested. Making use of only five accelerometers placed on strategic locations on the back, a stand alone system enables detection, logging and feedback of the patient’s posture. The system enables alerting the patient of a bad posture, or long-term data logging to analyze the patient’s posture over a prolonged period.status: publishe

A 650 V, 3 A three-phase fully-integrated BLDC motor driver with charge pump and level shifters

A 650 V three-phase IGBT motor driver is presented in this article. Apart from the power transistors and predrivers, also freewheeling diodes are present in the output power stage to drive inductive loads. The 15 V overdrive voltage as well as all other floating supplies are generated on-chip by means of a charge pump and cascoded current mirrors. The input signals for all switches are at ground level and level-shifted internally. Each half-bridge is able to switch at 20 kHz a 1.5 A current at 600 V and a 3 A current at 300 V. The ground connection contains a current shunt and a sense-amplifier, which can be used as a feedback signal in the BLDC control loop. The system is implemented in a 1 μm SoI technology with 650 V IGBT transistors.status: publishe

Design of a 2 Mbps FSK near-field transmitter for wireless capsule endoscopy

This paper introduces a novel and simple topology for an efficient, miniaturized, low power but high data rate transmitter, suitable for implanted devices. The application envisaged is in capsular endoscopy, where high quality images of the gastro-intestinal tract need to be transmitted continuously through the human body to an external receiver. A 2 Mbps Frequency Shift Keying transmitter is developed, consuming 2 mW at 1.8 V, working at biocompatible frequencies.status: publishe