Category Archives: Digital

APRS

Posted by on February 18, 2011 Comments Off on APRS

Finally, I’ve gotten my APRS stations coordinated. I have a weather station transmitting via TCP/IP APRS, my iPhone portable station transmitting via TCP/IP APRS, and my mobile station transmitting via RF (using a TinyTrak4 by Byonics).

APRS works by sending a digital packet of information, via RF, to a receiving station (anyone can have a receiving station at their house with a receiver, computer, and Internet service), and then that station (referred to as an iGate) sends the information to the APRS servers via the Internet. The default 2-meter frequency used is 144.3900MHz, and so as you’re out driving (for example), you set your transceiver to 144.390, turn on your APRS TNC (in my case, a TinyTrak4), and it does the rest.

There are also “digipeaters” that listen for your packets and repeat them again, so they may be passed to an iGate, to be uploaded to the Internet APRS servers. I have my TinyTrak4 set up as a digipeater to repeat any path requests with “TEMP” or “SAR” in them. That means if my station hears another station with “TEMP” or “SAR” programmed in, it will repeat it for them. I do this because “TEMP” is used for temporary situations, such as Field Day or perhaps emergency or other situations, and “SAR” is used for search and rescue operations. If I participate in such events, I’m already set up to be of assistance by helping to get their packets out to an iGate, which can upload them to the Internet APRS servers.

There’s lots of reading out there on APRS; just go to Google and type in APRS Amateur Radio!




January ARRL Contests

Posted by on January 3, 2011 Comments Off on January ARRL Contests

Happy New Year. Hope this one is fun! Let’s talk about the ARRL Contests that are yet to come this month. You can always get a look at the contest calendar by following this link: http://www.arrl.org/contest-calendar.

January 8-9 – RTTY Roundup

From the ARRL’s Contest Website:

Amateurs worldwide contact and exchange QSO information with other amateurs using digital modes (Baudot RTTY, ASCII, AMTOR, PSK31, and Packet …

EDIT: This post has been lost due to operator error! Sorry!

Strange Digital

Posted by on December 27, 2010 Comments Off on Strange Digital

I was tuning around this morning at about 0730 Zulu, and I flipped my radio to 5 MHz. I stopped on 5.332, where I heard a strange digital sound, rapidly pulsing. I opened up Digital Master 780, and took a couple of screenshots of what I heard. If you can identify this mode, I would be very interested in finding out what it is, so I can receive and possibly transmit it!

The two squiggley lines are non-related. The vertical lines are the signal as depicted by Digital Master 780’s waterfall display. Click the image to view larger.

20-meter BPSK31

Posted by on December 1, 2010 Comments Off on 20-meter BPSK31

Tons of activity on 20-meter BPSK31 this afternoon at about 20:00 UTC. The signals are represented on this waterfall display as “lines.”

HF Digital

Posted by on November 30, 2010 Comments Off on HF Digital

I’ve been enjoying some HF Digital work lately, since I’ve finally gotten my sound card to output the audio through the correct port. I’ve been working on 20-meters, around 14.070 MHz, where most of the BPSK-31 is centered. There have been a lot of stations on, even with less than ideal band conditions. I worked as far as Scotland (2M0YIO), South Africa (ZS2CR), and some Special Event Stations, such as CG3MUG (Canadian Coast Guard) and VE3IYOB (Canadian International Year of Biodiversity).

Digital can be a lot of fun. The mode I was operating, BPSK-31, can be described as a whiny tone that might not be fun to listen to (to most people). You can turn down the volume on the receiver, though, and just watch the waterfall display on your computer. There are also other modes that sound much different. When you see a signal, you click on it and read the text that is decoded by your computer. It allows you to work with much less power than SSB phone, and, therefore, has greater distance capabilities. Also, as compared to SSB phone, your computer can more easily hear and decode the digital signals.

Amateurs can also operate a mode known as Slow Scan Television (SSTV). I operated a little SSTV today, and made my first ever contact! Here is what that looked like:
SSTV QSL
SSTV can take a minute or two to send and receive, so it’s not a very efficient mode of QSO, but it’s really neat to send images back and forth! As they say, sometimes a picture is worth a thousand words. Also, via ARISS (Amateur Radio on the International Space Station), the astronauts send SSTV images that you can download on VHF, so that’s pretty neat!

Here’s what one of the more popular programs (Digital Master 780) looks like:
Digital Master 780 in BPSK-31 mode

To get started with digital operation, you need a TNC to interface between your radio and your computer. There are many options, and it would be good to research online or from other hams to check on the most affordable routes to go. I use a very simple TNC that has a CAT connection to my radio, then a mic/phone connection to my computer’s sound card. That enables me to use my netbook when I am Mobile or Portable! Good luck!

P.S. One trick, if you want to just listen: tune to a digital frequency (such as 14.070 MHz on 20-meters) and then set your microphone next to your radio speaker (or turn up the radio) and open a digital program, such as HamScope. It should be able to at least decode what it hears, so you can read what you are listening to!