Posts Tagged ‘Check This Out’
Taking the Plunge
I’ve been considering getting a Raspberry Pi for awhile. Several folks have asked me if I would port my Arduino Keyer code to it. So I decided to take the plunge and acquire a Pi from Newark / Element 14, along with some “fixins”. I got the Model A Pi, along with a WiFi dongle, and a cute little enclosure.
Big Things Come in Small Packages
I didn’t realize just how small the Pi was until I held one in my hand. It’s just amazing this is a full blown computer. It’s quite a leap from the VIC 20, the first computer I used 30 years ago as a teenager.
The Raspberry Pi was surprisingly easy to fire up. I bought a 16 GB SD card locally and burned a copy or Raspian on it. After plumbing up a monitor to the HDMI port and connecting a USB keyboard and mouse, the unit booted right up, displaying messages familiar to anyone who runs Linux. A few minutes later I entered startx and I was in XWindows. Of course I just had to bring up a terminal window and verify this was really a ‘nix box and run top.
Nifty Little Pi Enclosure
Now that I have my Pi humming away, what projects should I do? As I’ve mentioned a few folks have inquired about porting my keyer code to the Pi. Googling around I found someone has ported the Wiring development platform , which is the basis for the Arduino environment, to the Raspberry Pi and aptly called it Wiring Pi. Naturally it’s not 100% compatible and it’s not as easy as just plugging in the Arduino IDE and uploading compiled code. I’m debating whether to take this approach of getting the keyer code to run under Wiring Pi, or just start from scratch with good old C and gcc for the compiler. I could get the core functionality going and then port over parts of the code from the Arduino for ancillary functions, if it makes sense. Certain things don’t make sense to port, like the CW memories code. On the Pi you don’t have to deal with EEPROM like you do on the Arduino. Anything that needs to be persistent across reboots can just be written to a good old file on the file system. While certain things like persistent memory and sound support are easier on a Pi, deterministic and precise timing, which is needed for CW timing, is challenging on a multi-tasking environment like Linux. This realtime kernel may be just the ticket.
Compared to the Arduino, there aren’t a whole lot of interfacing pins on the Pi. To really get the power of this board you need to do I2C. I’m thinking about what it would take to port my antenna tuner to the Pi. That project uses I2C for controlling many relays, but there is also a need to monitor the voltages of the SWR bridge. The Pi doesn’t have this capability natively, so an I2C device would be needed to supply this functionality.
All in all the Raspberry Pi is a versatile and powerful little board. To get my feet wet I think I’m going to write a little bare bones C and see if I can get a basic keyer working and see where this takes me. This is going to be fun.
WRTC Radio and Software Data
The World Radiosport Team Championship 2014 team has posted data on the radio equipment and software used by the teams. There are a few interesting take-aways for me:
The top two radios used are no surprise, the Elecraft K3 by a wide margin at 64%, and the Yaesu FTdx5000 at 7%. The third choice surprisingly was the modest Kenwood TS-590 at 6% usage. I’ve often thought this rig is one of the best in amateur radio today based on the price, features, performance, and value. Despite Kenwood getting the number 3 spot with the TS-590, there was only one other Kenwood rig used, a single TS-850. Ten Tec had a meager showing with two Orion II rigs. Various other Icom and Yaesu rigs rounded out the statistics. I find it sad that Kenwood doesn’t have more product offerings in these statistics. The data suggests that there’s an opportunity in the market for another high performance $2.5K to $3K USD compact rig.
For software I expected the N1MM contest program to be the most popular choice, however Win-Test was used in 68% of the stations and N1MM garnered only 25% usage. Perhaps it’s time I try Win-Test. Despite the price of the N1MM program being attractive, the lack of source code for this freeware program has concerned me. Win-Test costs 50 Euros or about $67 USD, however with the features listed it may be worth it. There must be some “secret sauce” in the program that hardcore contesters like.
There are dozens of QRP rig designs and new kits that pop up each year, the majority of which are reiterations of previous designs. For the past ten years it seems we’ve been in a bit of a rut building NE602 based direct conversion and superhet rigs. But once in awhile a groundbreaking design is released, and everyone follows. Rigs like this are truly memorable, like the W7ZOI Ugly Weekender, the NEophyte, the Norcal 40, the 2N2/40, and the K2. I think the Minima, a new transceiver designed by Ashhar Farhan is one such design. The design has really impressive and innovative features:
- 1 to 30 Mhz coverage
- CW and SSB operation
- Si570 DDS local oscillator
- 20 Mhz IF
- KISS Mixer
- Arduino controlled, with open source software
- Other than a few ICs, most of the active components are general purpose NPN and PNP transistors
- A relatively simple and reproducible design
Looking at the schematic, you can see immediately how unique it is starting at the front end. From the antenna jack, you go into a high pass or low pass filter and then hit a mixer with two FETs. After that is an IF amplifier constructed from bipolar transistors, a BFO mixer and then the audio chain, again built from bipolar transistors. The transmitter chain works essentially the same, in reverse, with the mixer as the final active stage and providing a one watt output.
I’ve been eager to build something ugly style on a sheet of copper clad PC board, and this is just the ticket. And it’s Arduino controlled which is icing on the cake!
I have published a page on my Frankenrotator project, a cheap homebrew azimuth and elevation rotation system using a Yaesu rotator mated with a Radio Shack TV rotator. The brain of the unit is an Arduino Mega and complete schematics are provided.
The project illustrates how to build a power supply for both DC and AC rotators, replacing commercial rotator controllers. The main control unit powers and controls both rotators and interfaces to a computer using the Arduino native USB port. Logging and control programs command the system via Yaesu GS-232B emulation. The project also demonstrates the use of a remote slave microcontroller. A small waterproof box located at the rotator senses azimuth and elevation. The remote microcontroller is periodically queried by the master unit via a serial link.
I still have to build some antennas to rotate with this system, which I hope to complete before winter sets in here in Pennsylvania. Hopefully I’ll get to chase some satellites in between ice fishing!
Here’s a cool little video from HowToLou.com (I’m guessing this guy is named Lou) with a third prototype of a homemade engine made strictly from hardware store parts. It’s not quite working yet, but it’s rather interesting and I think he’s on the right track.
I’m more electronically inclined than mechanical and have some ideas on how to make the timing of the spark and the exhaust valve better, using electronics. But I probably couldn’t do it with just hardware store parts, unless perhaps the hardware store sells radios that I can scrounge parts from.
One of these homebrew engines coupled with a homebrew generator connected to a QRP rig would make a nifty little project to show at your local ham club or field day.
Your Own Drone?
The Drone It Yourself is a kit to take ordinary objects and turn them into flying remote-controlled drones. The concept is simple: clamp four electric motors with propellers and a control unit onto whatever object you desire, and fly it around the neighborhood.
While it may be fun to terrorize the XYL or spy on the neighbors with this, I see this possibly having some useful real life applications in amateur radio. I’m not sure of what kind of battery life this unit has, but imagine hovering a remote controlled HT at 80 feet for an ad hoc repeater.
A guy could really get into some trouble with one of these :-)