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Raspberry Pi + TNC ISS iGate
radio : by Tommy - April 8th 2014, 02:04PM
radio
Not so long ago I completed construction of my Raspberry Pi TNC, the TNCPi. Construction of this kit was very straight forward. A few additional pictures would have made this a great kit for beginners, but still the same it's an easy build.

Building Tips
A couple of items to note regarding construction. Ensure the correct polarity of the electrolytic capacitor (C1): The negative stripe goes toward C15.
The transistor (Q1) PN2222's flat side goes away from the edge of the board.
The voltage regulator (U1) MCP1700's flat edge goes toward the edge of the board.
Crystal X2 (20MHz) is near U1. Crystal X1 (3.57MHz) is neat Q1.
Note the pin 1 position of all ICs.

Interface cable
After completing assembly of the TNC, I set to work on creating a radio interface cable to connect to the DB9 port on the TNCpi.

The pinout for the TNC Pi matches the TinyTrak cabling:
    
pinfunction
Pin 1TX Audio
Pin 3PTT
Pin 5RX Audio
Pin 6Ground

Tuning Audio Output
After creating the cable, I set the audio output level as noted in the instructions. To do this, you'll need two radios. I used 2 HTs, one that I had created the interface cable for and a spare. Tune the radios to the same frequency (I used 144.44). On the radio with the interface cable, I pressed the PTT button and heard a tone being transmitted to the neighboring radio. Adjust R7 to it's maximum volume before it begins to distort.

After tuning the audio, the TNC Pi project is complete. How you plan to implement the TNC Pi is entirely up to the software you choose. For many, this may be Xastir for an APRS GUI. For others, it may be aprx to create an APRS beacon, iGate, digipeater or any combination of the three.

tags: raspi aprs ariss iss tnc rasperrypi

( Comments : 0 | Full article )

 
HOWTO: Configure Hamlib for Linux Hams - Part 2
radio : by Tommy - December 3rd 2013, 06:48PM
radio
This is a continuation of a two part series about how to configure hamlib for Linux ham radio users.
To get started, be sure to read through Part 1.

In the last post, I pointed out that hamlib was create to simplify the once fragmented world of computer control for amateur radio. With hamlib in place, developers can interact with hamlib which serves as an abstraction layer of sorts for software development. Developers don't need to worry that you're running a particular model of radio, so long as you get your radio working with hamlib, your radio is supported.
I'm going to assume you have /dev/radio and /dev/rotator already configured (since we did that in the previous post). Now, we're going to configure the daemons (servers) that allow a myriad of radio related applications to interact with your amateur radio equipment.

Daemons
Hamlib centers around two core daemons: rigctld and rotctld. The daemons receive commands from applications via TCP. It is possible to have these daemons controlled via the network if you so wish. That functionality is a bit beyond the scope of this article, but the concepts below are exactly the same and just requires the correct ports be opened. Speaking of ports, rigctld and rotctld use ports 4532 and 4533, respectively. Also note that there is no security built into these devices. Should you need external connectivity, you should create an SSH tunnel.

Find your equipment
The first step in configuring rigctld is to find if your particular radio (and rotator for rotctld) is supported. Here is a list of all supported radios for rigctld (chances are, if it's a modern radio with computer interface, it's supported). For rotctld, things get a little more difficult. In order to see if your rotator controller is supported, you need to identify which protocol is supported.

Continue reading...

tags: ham radio hamlib linux satellite

( Comments : 2 | Full article )

 
HOWTO: Configure Hamlib for Linux Hams - Part 1
radio : by Tommy - December 2nd 2013, 8:11PM
radio
Linux and ham radio, where two of the geek worlds collide. Fortunately, with so many geeks involved in both pursuits, a lot of great tools have emerged. Unfortunately, documentation on how to configure some of it was hard to come by. (At least, it seemed that way to me.) Here, I hope to layout as quickly and easily as possible the steps required for other hams to configure hamlib on their linux computers. I'm going to assume you're running a modern version of linux and have a USB connection to your radio and/or rotator.

What is Hamlib?
First of all, Hamlib is a set of ham radio control libraries that allows amateur radio operators to control their radio and antenna rotators via their computer. Hamlib abstracts many device-specific control issues from application developers, allowing for a more robust user experience across several programs. Prior to hamlib, there were several different tools and libraries. None of these tools provided a common API for programmers to interface. As a result, the application landscape was fragmented and functionality suffered. Now, with hamlib, programmers can utilize hamlib to interact with a whole range of devices.

Interface
To use hamlib, you must first have a computer interface cable from your radio to your computer. Without this, everything else here is pretty useless. If you don't have a cable yet, look on eBay for cables tailored to your radio. (It's where I found mine.)
My radio is a Yaesu FT-847 which has a DB9 serial port for CAT computer control. To interface with my computer, I use a cheap USB-to-serial adapter - nothing special. My antenna rotator is a Yaesu FT-5500 with the brilliantly simple WA8SME Satellite Tracker Interface from the ARRL.

USB, Linux and udev
Most modern distributions of Linux include a subsystem to handle when USB devices are inserted.

Continue reading...

tags: ham radio hamlib linux satellite

( Comments : 0 | Full article )

 
Higher Ed Enrollment Database
news : by Tommy - September 3rd 2013, 11:45PM
news
This is something I thought today during a meeting...

I recently learned we have had several students not report *all* institutions they've attended before. (Ex: One student "forgot" to mention they had taken courses with Univ of Phoenix for ~70hrs and stopped attending. Univ of Phoenix is holding that student's transcript until they settle up on their bill. [Transcripts are the one thing a school can hold over a student for failure to pay.] It came to light when the student's Financial Aid was processing...)
School's usually require this because prior scholastic work is taken into consideration when placing the student in courses, academic standing, etc. and ensures a students will make good on their financial obligations - like a gentlemen's agreement among institutions. I asked in our Registrar's office what happens if a student doesn't divulge all schools they've attended, "What's the worst that could happen to them?" "It could get them suspended from our school." In the grand scheme of things, so what? They could move down the road to another school and take classes there. It would be a huge headache for the student, but a driven and motivated student could navigate the system and get their degree one way or another from some institution. (especially from certain schools that are willing to do anything to get money and could care less about the other schools down the road...)

So. What's the big deal? The trouble is Financial Aid fraud.
Unscrupulous individuals will solicit the school for financial aid, scholarships, grants, etc. in hopes the grants and loan money comes to them directly and/or any overage in scholarship/grant money gets sent to them directly, all the while never intending to *actually* take classes. Before any financial aid is disbursed, the student will usually sign a short-term loan with the school to cover the courses in the meantime.

Continue reading...

tags: highered college education

( Comments : 0 | Full article )

 
HOWTO: NOAA Weather Satellites
radio : by Tommy - August 7th 2013, 11:31AM
radio
Most people are aware that every day weather satellites pass overhead to get a glimpse of the nation's weather patterns. Many people, especially those outside the ham radio community, are unaware that the signals these NOAA weather satellites transmit are readily accessible with a minimum amount of equipment. These satellites use a technology known as APT, or Automatic Picture Transmission. NOAA-19 is perhaps the easiest APT satellite to receive because it provides the best, strongest signal for visual satellite imagery. Because of this, we'll focus on NOAA-19 for this post.

Hardware
All you really need to receive the satellite's signal is a radio receiver like an old police scanner (found at thrift stores) or a simple 2m ham radio handitalkie (like the Baofeng UV5R). An external antenna is usually better, but not a requirement for casual reception of the image. Other than the radio, the only other pieces are a computer with sound input and an audio cable (to get the audio out from the radio to the input on the computer).
If you would like to get the best images possible from every pass of the satellite, use an outdoor antenna connected to your radio. Discone antennas for scanners work well, as will any 2m amateur radio antenna. These antennas do suffer from "fades" where the gain of the antenna is weakest. To minimize these anomalies, eggbeater antennas or the very common quadrifilar helical antenna are used by serious hobbyists and weather professionals.

Software
Once you have the required hardware, download the free WxToImg software which is available for Windows, Mac and Linux. There are other features and enhancements to the software if you upgrade, but it's still not a requirement.
Once the program installs, the first time you start the program you will be prompted to enter your Latitude and Longitude.

Continue reading...

tags: radio noaa-19 wx satellite howto

( Comments : 1 | Full article )

 
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