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Neil Martinsen-Burrell
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Arduino I/Q Audio Frequency DDS

A 16 MHz microprocessor without a DAC isn't a great platform for a DDS since you have to use PWM and a low-pass filter to output analog voltages which limits the frequency range that is available, but for low audio frequencies, it is just fine and the Arduino certainly makes it easy to get started.

It also has multiple output pins, so in this case we can make two audio waveforms with a defined phase relationship, both in-phase and quadrature.

http://neilmb.github.io/cheapnewham/2015/07/21/Arduino-IQ-Audio-Frequency-DDS.html
I have a long-term dream to design a single-signal direct-conversion receiver using a microcontroller for the audio processing. In trying to figure out how I—a relative newbie to digital and RF design—could design a transceiver, I figured that I needed some basic test gear and a way to gain ...
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William Laakkonen's profile photoLuke Rohn's profile photoJoerg Sonnenschein's profile photo
 
Nice little project Neil- well done. 73 N4BKT
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A little education goes a long way

You send one daughter to a Shakespeare class in the afternoons and all of a sudden your FOUR YEAR OLD is greeting you in the morning with "Have you no modesty? No maiden shame? Fie fie you counterfeit, you puppet you!
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My brother was studying Shakespeare while I was in elementary, and I helped him learn some lines from Julius Caesar.

A friend of mine got in trouble for using the word "stuff" in a sentence, and the teacher claimed it was not a real word.  I walked up to her and recited:
"Thrice I offered Caesar the crown, and thrice he refused; yet Brutus says he is ambitious! Ambition should be made of sterner stuff."

She glared at me and sat down.  I got no recognition from the lady teaching us English for quoting the Bard.  You gotta love public education.
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DTRT vs. DWIM

Apparently, Apple's Mavericks OS introduces a "feature" that tries to auto-create typographical niceties such as smart quotes, ellipses, en-, and em-dashes. Word processors such as Microsoft Word have been doing this, but with Apple's longstanding commitment to typography, I can see where they wanted to add this on the OS level.

The problem is that the OS cannot know the context of what I am typing.  If I'm in a Slack chat with another developer discussing the "`--no-splits`" option then the backticks indicate that I want literal text and those two initial dashes should be preserved as is. But Mac OS X doesn't know anything about Slack and Markdown syntax so it tries to Do The Right Thing (DTRT) and convert the double-hyphens to an en-dash. D'oh!

I think that this is an Achilles heel for the OS trying to DTRT. It doesn't know the context and so it has no idea how to Do What I Mean (DWIM). Boo, Apple. If you want your computer to keep doing what you tell it to, go now and turn this "feature" off.

#mavericks #dwim #dtrt  
Hi,. Since I upgraded to Mavericks, Mail.app started persistently auto-correcting three consecutive periods (dots) into the "ellipses" (single) character. This is not one of my System Preferences/Keyboard/Text/ replacement rules. Is there another place where such auto-correction rules are ...
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Shush, Apple knows best. Always.
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I'm in Seattle this week to start my new job with +Moz​. Very excited for the new opportunity and to meet a great group of people in person. I'll train here this week, then it's back to Iowa where I'll be working remotely. 
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Moz
 
{High Five} friend!
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Mucca Pazza Tiny Desk Concert

These lovable freaks make me wish I could play a band instrument. Maybe there's room for a second

http://www.npr.org/event/music/384964401/mucca-pazza-tiny-desk-concert
With 23 members, the performance-art marching band is the biggest ever to play the Tiny Desk, complete with horns, woodwinds, strings, percussion and several cheerleaders.
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super bande encore....!
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"She believed collage was the greatest of all the arts"

After finishing building my homebrew Arduino keyer, it worked great, but it was unwieldy with a loose piece of copper-clad board with the circuit components that were jumpered over to the Arduino.  In fact, the copper-clad board shorted out the pins on the Arduino power connector and seemingly fried the voltage regulator.  On a second Arduino board, with some more careful insulation (a sheet of paper) it worked well enough for me to want to package it up.

I'm a "use what you have" kind of ham so I cut down a cardboard box from the recycling to the size I wanted.  I used aluminum foil and double-sided tape for shielding on the inside of the box.  Finally, I needed to cover an ugly ding in the top of the box (what do you expect from the recycle bin).

So, I cut out a picture from the latest QST and taped it on top!  It won't fool anyone for long, but I get a chuckle out of seeing my dream radio on top of my very humble homebrew morse code keyer.

(_Song lyric from "Estelle" by Dan Bern: http://danbern.com/lyrics/estelle/_)
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Bob Beeman's profile photoGunnar Widell's profile photoIWTREERREIV - OM/CB/SWL's profile photo
 
Great idea on the KX3 pic. If you want a good little keyer that doesn't cost much, just build a PicoKeyer kit from hamgadgets. $28 including plastic box.
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Gimmick Key

A capacitor formed from two strands of wire is a gimmick capacitor, so this must be a gimmick key for CW.

I was vacationing with my family in Northern Wisconsin and threw my QRP portable bag in the back when I was loading the car.  On our second night, I put the end-fed half wave up in the tree, and then I realized that I had left my morse code key on the radio bench back home. (I'm not the kind of guy to have multiple keys in my stable.).  I did a little listening that night but gave up dejected.

The next night, I realized that my bag still had the cable I use to connect the straight key to the radio.  It's made out of a piece of coax cable with the two conductors twisted to go in the key terminals.  With a little practice holding the loose ends in my left hand, I was able to key reasonably enough to have a short QSO with W6OGC with 5W and a couple of wires!

What a gimmick!
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Nice one. There's an episode of Adam-12 where the officer is pinned down by gunfire and for some reason his radio microphone was broken. He stripped the wires and used it to send a Morse Code message to dispatch. 
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Homebrew SWR indicator following the design of Dan Tayloe N7VE. A PCB kit is available from qrpkits.com, but this version was very easy to make.

The male BNC pigtail attaches directly to the radio, while the coax to the tuner connects to the female BNC. When the tuner is tuned for a 50 ohm load, then the LED goes out. I will replace the resistors with larger ones with a higher power rating, then package it up with some soldered PCB stock.
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Josiah Ritchie's profile photoNeil Martinsen-Burrell's profile photoDavid Snyder's profile photoMatt Hyde's profile photo
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That's right. The LED Is in the circuit across a resistive (Wheatstone) bridge so that no current will flow in it when the attached impedance is 50 ohms. So, the indicator is attached between the radio and the tuner and then the tuner is tuned until the LED goes out indicating a perfect impedance match. In practice, the LED goes out somewhere around 1.3:1 which is as close to perfect as any transceiver could need.
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Now I know I am old. I drive the same car as my mom.

New ten year old Prius picked up in Rochester this morning. 
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"ten year old Prius" seems to be an age indicator too!
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Apparently I have some many messages in the mailbox that the message counter wrapped over to negative numbers. That's better than Inbox Zero!
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I have hope they use different technology in their autonomous cars...
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Brin Knows Privacy

Science fiction author (and futurist even) +David Brin  is the most cogent voice talking about privacy in the modern world.  As he does on most topics, he veers away from knee-jerk techno panic while also avoiding head-in-the-sand ignorance of repercussions.

After listening to +Leo Laporte and +Jeff Jarvis too many times on This Week in Google argue childishly about privacy, I submit this modest proposal.  +Leo Laporte should interview +David Brin on his show Triangulation about The Transparent Society (http://www.amazon.com/The-Transparent-Society-Technology-Between/dp/0738201448) a book published 15 years ago that presages everything we have seen this past year from Snowden to Ferguson.

Let's make this idea viral enough to actual happen.  Re-share this post if you'd like to see it happen
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Daryl Fallin (theDaryl)'s profile photoRobert Anstett's profile photoJack Matthews's profile photo
 
I second this to have +David Brin on Triangulation.  +Leo Laporte 
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Homebrew Arduino Morse Code Keyer

This is a homebrew Morse Code keyer based on an Arduino Leonardo from Borderless Electronics and the code/schematic from K3NG (blog.radioartisan.com/arduino-cw-keyer).  The hookup between the board that I built and the Arduino is a little hairy but I took good notes on the color scheme.   I already had a couple of these Arduino boards from a very nice +Indiegogo campaign and I knew one of them was destined for this project.

There are two buttons, a command button and a single memory slot.  (When you've been sending CQ by hand on a straight key, one memory seems like complete luxury.)  I installed a piezo buzzer for audio feedback from the command system but I expect that I will use my radio's sidetone when sending CW.  The key line is an RCA jack to differentiate it and to match the connector on my TenTec Omni C which is where I intend to primarily use this.

I had considered trying to be elegant and create a sort of shield from header pins that would plug in atop the Arduino, but without PCB etching and a drill press, I didn't think that I could achieve the necessary accuracy.  This was the simplest setup that I could dream up with what I had on hand. The USB and power jacks are still usable and the Arduino could very easily be switched out for a Nano board (e.g. http://www.ebay.com/itm/271545629048) for packaging in a small enclosure.

Now I need to finish my homebrew paddle like +Steve wGØAT.

#arduino #hamradio
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Independent Statistics Educator
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  • Stats With Neil
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Teacher, geek, father
Introduction
I'm an independent statistics educator.  I work as a consultant with graduate students and companies who aren't statistics experts.  I've been involved in teaching math for over fifteen years and I love to share my experience.

In other news, I'm also a gadget lover, a ham radio operator, and a farmer.
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Burrell