Andrzej Malcher

Hybrid QRS detection circuit based on dynamic reconfigurable field programmable analog array.

Abstract In many medical applications it is important to detect the QRS complex in the electrocardiogram (ECG) waveform with possibly low time delay. Traditional software detectors of the QRS complex implement algorithms usually based on cascades of digital filters introduce delays up to parts of a second. Hardware QRS detectors fulfill the low delay requirements, but have worse adaptive features for the changing ECG shape. In this paper a new approach to QRS detection is presented. The proposed detector is based on a Field Programmable Analog Array (FPAA). The most interesting feature of the FPAA is the dynamic reconfigurability. This solution makes it possible to modify the parameters of particular blocks of the detector or even the whole structure during runtime, without any changes in hardware and disturbance of the system functionality. The prototype QRS detector was built using AN221E04 circuit from the Anadigm company. The reconfiguration data are calculated by the AD7020 microcontroller and downloaded to the FPAA after each QRS detection.

Some Properties of FPAA-based Analog Signal Processing Applications

Abstract Field programmable analog arrays (FPAA) offer the electronic equipment designers new possibilities in quick, interactive and flexible design process, simple verifying, prototyping and modifying of many circuit solutions. The detailed research results of the selected parameters of the AN221E04 device delivered by Anadigm ® are presented. Some features not mentioned in the data sheets were noted and analyzed, concerning e.g. the device input and output filters. Based on the examined AN221E04 device the example application of the automatic gain control (AGC) circuit was built. The advantages of this design, its obtainable parameters and the problems involved by application of FPAA are presented in the paper.The paper presents description of three different protocol gateways for interfacing HART pressure sensors. The gateways have been designed, programmed and realized as hardware prototypes. The first gateway is a wireless transducer between the HART interface of the sensor and a Bluetooth network. The second gateway connects the sensor to an Ethernet network with Modbus protocol. The third gateway is a wireless transducer for ZigBee networks. The gateways are based on embedded microcontrollers with the required interfaces. The software implementation is done in C using protocol libraries. Hardware and enclosure are designed for industrial applications. The gateways are adapted for use with HART pressure sensors.

A Passive FPAA-Based RF Scatter Meteor Detector

In the article we present a hardware meteor detector. The detection principle is based on the electromagnetic wave reflection from the ionized meteor trail in the atmosphere. The detector uses the ANADIGM field programmable analogue array (FPAA), which is an attractive alternative for a typically used detecting equipment - a PC computer with dedicated software. We implement an analog signal path using most of available FPAA resources to obtain precise audio signal detection. Our new detector was verified in collaboration with the Polish Fireball Network - the organization which monitors meteor activity in Poland. When compared with currently used signal processing PC software employing real radio meteor scatter signals, our low-cost detector proved to be more precise and reliable. Due to its cost and efficiency superiority over the current solution, the presented module is going to be implemented in the planned distributed detectors system.

Generating time intervals in Programmable Logic Controllers

Abstract The paper presents a review of methods of implementing timers in Programmable Logic Controllers, along with a discussion of the timer properties. The authors focus on software implementations, as this approach has dominated practical solutions. An important part of the discussion is analysis of errors in time delay generation, and possible error sources. A typical case of a PLC generating a predefined time delay is analyzed. The discussion is concluded with recommendations on implementing timers, intended for PLC designers.

A Modified Current-Differencing Transconductance Amplifier and Its Applications

This paper presents a new current-mode active element. The idea is based on the Current-Controlled Current-Differencing Transconductance Amplifier (CCCDTA) known from the literature. The modifications introduced to the original CCCDTA circuit made it possible to obtain a component with very wide area of applications. The main parameters of the circuit (resistances, transconductance) can be electrically controlled. Thanks to these features the modified CCCDTA can be used as the basic building block of a continuous time Field Programmable Analog Array (FPAA).

Resistorless universal biquad filter based on digitally programmable current follower transconductance amplifier

The work presents a modification of an active component called Current Follower Transconductance Amplifier, which enables digital control of transconductance. The paper contains the characteristics and paramétrés obtained as the result of SPICE simulation. The component can be used in a digitally programmable current-mode continuous time biquad filter. The obtained characteristics confirm the possibility to implement the presented circuit as a part of a mixed-mode signal processing system.