Karl Uppiano

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Sunday, November 15, 2009

WxService Update Available
Minor bug fixes. 
  • WxService ow4j091115
    • Fixed failure to read anemometer data.gust.interval property; always used defaults.

(download ow4j091115)

4:06 pm pst

Saturday, May 2, 2009

WxService Update Available
WxService now supports the WS603 1-Wire Weather Instrument Kit! This is the all-new 1-Wire weather instrument from AAG, which features several improvements over the original Dallas design.
  • WxService ow4j090501
    • Added support for WS603 1-Wire Weather Instrument Kit

(download ow4j090501)

12:11 pm pdt

Sunday, April 12, 2009

Audio Bit Rate Reduction (MP3, AAC, etc.)
I haven't posted here in a while, but I have been playing with iTunes because I received an iPod Shuffle as a gift a while back and I finally got serious about putting my CD collection on my hard drive so that I could load up my iPod. Since I am an audiophile, and I was exposed to the hideous early attempts at audio bit rate reduction back in the 1980s, I was very suspicious of the compression options.
 
I scanned the internet and read articles on the various formats and their perceptual differences, including double-blind tests (so called A-B-X tests) with charts showing the statistical variations between the various encoding algorithms running at their supported bit rates.
 
As an aside, I was surprised not to find any "difference files". One powerful way to analyze and understand intuitively the effect of an audio processing device is to listen to the difference between the original source and the processed version. It is very simple to implement: Simply invert the phase of one of the signals and add them back together. If the signals are exactly the same, the sum will be zero -- absolute silence. Any changes in phase, amplitude, distortion, etc., will be clearly audible. Linear effects can be eliminated by simple attenuation and time-shifting. I might try this and publish the results here eventually.
 
Anyway, I decided to copy my CD collection to the hard drive in lossless format, so that I would have reference copies to work with. However the iPod Shuffle cannot play lossless files. It insists on converting them to 128kbps AAC CBR even though it can play 256kbps AAC VBR. I wanted the higher quality on my iPod. So after careful listening on my AKG K-501s and my old knock-around Sennheiser HD-435s, I discovered that 256kbps AAC VBR was practically indistinguishable from lossless to my ear. So I decided to store the CDs on my hard drive as AAC 256 VBR.
4:57 pm pdt

Thursday, February 26, 2009

FTP Server Problems Resolved
I think I have fixed the FTP server problem that was preventing WxServer downloads. I turned off Advanced Settings/Services/FTP Server in the Windows Firewall, and instead added FileZilla.exe as an exception.
 
I am guessing that Advanced Settings/Services/FTP Server is for active FTP, whereas a program exceptions allows Windows Firewall to track the open service ports for passive FTP. That's how it was acting, anyway. I don't know for sure because I have not been able to find any authoritative source that explains the Windows Firewall policy in enough detail. And don't start with me on running Ubuntu. I have my reasons.
5:02 pm pst

Sunday, February 22, 2009

FTP Server Problems
For some reason, Windows Firewall started blocking my FTP server in random and unpredictable ways. If you are having trouble downloading WxServer, you might want to retry the connection a few times. If that doesn't work, use the form at the bottom of the page to send me email. I will email a copy to you.
 
Windows Firewall is supposed to be a stateful firewall, and FTP support includes opening ports for PASV FTP. It seems to work sometimes, but after a while, it stops working. I'll figure it out eventually. In the meantime, please bear with me.
12:05 pm pst

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Welcome!
This site is dedicated to my interest in engineering. I use it as a place to just put stuff "out there" for anyone who might be interested, as well as a job search tool. This page contains my engineering web log (to your left). Anything that seems timeless enough, or too involved for a log entry may get it's own page as a full-blown article. And, of course, my resume is here for anyone who might be considering hiring me to do something. Email me.

About Me
I have worked as a broadcast engineer, electronics designer (analog and digital) and software developer. I especially enjoy audio engineering, although I've been writing software for the last several years, since that's where the opportunities are in the Pacific Northwest (this is Microsoft country after all). I'm currently working as a Senior Staff Engineer -- Resume at another large independent software vendor in Washington State.

Futurama Web Site
(not my best side)

I majored in mathematics and physics in college. Other interests include music appreciation (baroque, classical and early romantic, ragtime, and 60's and 70's rock & roll), high fidelity audio electronics, meteorology and of course, computing hardware and software. I tend to think a lot like this guy.