User Tools

Site Tools


Dave's Thoughts and Ideas

10 questions about your QRP operations

QRP Quarterly has a column asking 10 questions of QRP operators. I offered mine for the April 2019 issue. I don't think there's any issue with publishing it here in advance:

→

2019/03/07 05:23 · davek · 0 Comments · 0 Linkbacks

FFT scaling factor

What's often confusing about the FFT is that the transform seems to have numbers that are too big. Let's call this the “FFT scale factor” problem (it's a reasonable google search). The frequency domain seems to have much more energy (much higher values) than one might expect from the time-domain waveform from which it originated.

When trying to understand this, the uninitiated user will google something like “FFT scale factor” and get lots of really good explanations about how the math produces values that are N times larger than one might expect, N being the size of the FFT.

But really, these users are trying to figure out why, not how. I'm mean, isn't that wrong? Why is it N times larger? Shouldn't someone be dividing by N?

→

2019/02/25 19:00 · davek · 0 Comments · 0 Linkbacks

Setting up dokuwiki

I've been a fan of dokuwiki for years and years, going back to my startup in 2005 when I used it to document our designs, usage, actions, etc. It's similar to the popular Mediawiki but offers better ACL. I've set it up multiple times in multiple ways, always a little concerned about security. I've had installed plugins with security flaws and it's just hard to stay on top. Most of the time I've deployed it for internal use inside a firewall.

Having worked at a startup for over 2 years that's heavily invested in docker, I've gotten to know docker really well. Not having had a website for quite a while, I finally decided to dip my toe in the water again using docker to contain my dokuwiki site.

→

2019/02/11 02:07 · davek · 0 Linkbacks
start.txt · Last modified: 2019/02/11 02:25 by davek