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[2021-01-09]


[2021-01-09]

Building Hard Real-Time Systems on AVR Microprocessors

Wide availability, versatility, and modest power requirements of 8-bit AVR microcontrollers, as well as the plethora of available low-power peripherals, make 8-bit AVR ideal for embedded systems. However, relatively small RAM and Flash memory (especially on the lower-power chips) make parallel sensor interrogation challenging due to the overhead of running a multi-processing environment. On the other hand, serial IO may result in the lack of a guaranteed system response time that is a mandatory requirement for hard real-time systems. This is especially true for peripherals with variable response times.

As requested by my "embedded systems" interest group, here I will share my preferred "universal" solution for the asynchronous IO that allows real-time interaction with multiple peripherals.
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[2021-01-05]


[2021-01-05]

Building SoC Soft Real-Time Systems

The ever-increasing compute capabilities of SoC ("system on chip") devices that now match top-of-the-line desktop systems of a decade ago create unprecedented opportunities for ubiquitous embedded and "edge" computing. Embedded hardware can now take on a greater share of data processing. However, systems that do not run operating environments specifically designed for real-time applications (such as RTOS) are hampered by tail latencies associated with the overhead of running "consumer" OS (such as Linux). While tail latencies can be reduced by scaling up hardware specifications and restricting the process space, such devices can best serve as "soft" real-time systems, outside of critical "hard" real-rime applications where system response should be known with certainty.

Design and implementation of hard real-time systems unencumbered by OS and user-space software will be the subject of a future post (please check back in later). In this article I discuss a continuous environmental monitoring project based on the RP3B platform. I have completed this project as an example of a high-availability "soft" real-time system that can handle highly heterogeneous data streams.
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Example of high PM concentration readings


[2014-09-09]


[2014-09-09]

Model-difference regularization in joint 4DFWI

Check out my presentation at the joint SEG-AGU research workshop on Advances in Active+Passive Full Wavefield Imaging (22-24 July, 2014, Vancouver).


Joint 4DFWI with model-difference regularization


[2011-06-02]


[2011-06-02]

Efficient One-way Wave-equation Migration in Tilted Transvesally Isotropic Medium

Presented technique allows computationally efficient and accurate migration of seismic data in TTI media. Click on the thumbnail on the left to view the extended abstract of the paper presented at the 73rd Annual Conference of the European Association of Geophysicists and Engineers, held 23-26 May 2011 in Vienna....display full article text



[2010-08-06]


[2010-08-06]

Using DDS Data Formats in Octave/Matlab

Save the link on the left as a .pdf file for a short demonstration of how DDS dictionaries and binaries can be manipulated in Octave and Matlab. The Free Data Dictionary System (FreeDDS) is an open-source seismic data processing system developed by BP (see references in the document)



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