Potato Cannon and Chronograph- Part II

Details about building a pneumatic-based potato cannon. The more interesting part is its performance assessment. Link to Part I. Link to Part II.

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Tunable LC Bandpass Filter- Part III

I’ve just completed the final part of a design document for tunable bandpass filters using varactors. A number of helpful closed-form solutions are included. Link to Part I. Link to Part II. Link to Part III.

Microwave Filter Design, RF Filter Design Leave a comment

4×10 Workbench with Pneumatic Lift

I wanted a large workbench with surface dimensions a bit larger than the standard 4×8 foot material I frequently work on. I also wanted it (almost) rock-solid to do some optics-related work. The workbench is very heavy- but I designed in pneumatic lifters so that I can easily put the bench on wheels when I want to move it around. Link to Paper.

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Potato Cannon with Chronograph- Part I

Details about building a pneumatic-based potato cannon. The more interesting part is its performance assessment. Link to Part I.

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Tunable LC Bandpass Filters- Part I & II

I’ve just completed Parts I and II of a design document for tunable bandpass filters using varactors. A number of helpful closed-form solutions are included. Link to Part I. Link to Part II.

RF and Microwave Design, RF Filter Design, Uncategorized Leave a comment

Using Companion Models for Time-Domain Simulation of ODE’s

Companion models can be used to quickly formulate the solution of simultaneous ordinary differential equations like those associated with analog circuitry. This approach is particularly helpful when this capability must be embedded in tools like MATLAB / SIMULINK / C++. The PDF file is located by following this link.

Digital Signal Processing, Mathematics, Software and Programming Leave a comment

CNC Router & Interview Questions

I have just added two new sections, one for my CNC Router related projects and a second one for interview related questions. Both are works in progress.

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Book chapter added on Direct Digital Synthesis

Extensive chapter added about Direct Digital Synthesis.

Digital Signal Processing, Frequency Synthesis Leave a comment

Updated Filter Design Documentation

Major revision to my filter design documentation 5.74 MB

Mathematics, RF Filter Design, Software and Programming Leave a comment

New Programming Projects 26Dec2012

Two new software/programming projects added. One for the design of lumped-element lowpass Butterworth, Chebyshev, and elliptic filters. The second for the design of resistive pi- and tee-pad resistive attenuators. Look at the bottom of the Projects page.

Software and Programming Leave a comment

New Book Chapter

I just posted a free book chapter on the site for anyone who has subscribed. The chapter is about 80 pages long and goes into a wide range of topics related to direct digital frequency synthesis (DDS). Definitely worth a read or a place in your reference material as this is not the same DDS perspective of years gone by.

The chapter is posted under the “More Articles” tab as the first article under the “Frequency Synthesis” category.

Digital Signal Processing, Frequency Synthesis Leave a comment

New Article in Microwaves and RF Out

My article in Microwaves & RF finally hit. The web version has a lot of typos in it, however, so you will probably find the PDF version a lot easier read. Follow this link and you’ll see the file link. Thanks for your interest.

Phase-Locked Loops (PLL), Uncategorized Leave a comment

New Article in May Microwaves & RF

I have a feature design article that is to be published in the May issue of Microwaves & RF. After it runs, I will post a copy of the complete article in PDF format for easier reading. The article presents several nonconventional methods that can help with demanding PLL designs.

Phase-Locked Loops (PLL), RF and Microwave Design Leave a comment

Approximation for RMS

Approximation for SQRT( I2 + Q2 ) with Gaussian Noise Present

When a complex signal is represented in terms of in-phase (I) and quadrature-phase (Q) components, a commonly used approximation for the signal root-mean-square (RMS) value is

Assuming a large number of OFDM subcarriers in the intended application, I and Q appear to both be Gaussian thereby making r a Rayleigh-distributed random variable where

We are interested in the ratio

From symmetry, it suffices to consider a limited range for θ as π/4 . Letting

leads to

and

where γ = 0.375. It is worthwhile evaluating just how good this choice for γ really is. We seek then to minimize the mean-square error given by

To read the article in its entirety in PDF format, please follow this link.

Digital Signal Processing, Mathematics Leave a comment

Computing Data Windows Recursively

Data windows are indispensable for computing the spectral characteristics of signal waveforms that are not periodic in time. In the context of hardware-based digital signal processing, most if not all data windows are expressed in terms of fairly complex function that are not convenient for embedding in a FPGA or custom ASIC. This memo presents several simple recursive results that can be used to compute these windows without excessive memory requirements and computationally intensive functions. The techniques described here can also be extended to other windowing functions as well.

This paper is offered for sale here.

Digital Signal Processing, Mathematics, Uncategorized Leave a comment