In December 2012, Pete M0PSX and Tom 2E0TNC presented a talk on how to get started in the various digital modes, such as WSPR, RTTY, PSK31, JT65 and Packet. Here’s a summary of the basics on how to start out operating the amateur radio digital modes.
Why data modes are worth a look:
- Data tends to work well with low power
- More bandwidth-friendly than voice
- Helps with language barriers for non-English speakers
- Electronic logging is often very easy with data modes
Getting started with data:
Here’s what you’ll need to get started with digital modes:
- A TNC (Terminal Node Controller) – See below
- Cables to connect between the computer, radio and TNC
- A computer with a soundcard (mic and speaker sockets)
- Software – There are various different packages depending on what mode you want to work
- The right frequencies – Each mode typically has a dedicated frequency for each band
TNC: Terminal Node Controller
The TNC is the interface between your radio and the computer. There are various types and features. Here’s what you need to know:
- CAT – Computer Aided Tuning… these allow your computer to change the frequencies and settings on your radio
- PTT – This means that your computer can use the TNV to get your radio to transmit
- DATA – Your TNC needs to be able to handle data transfert and balancing the audio levels between the radio and computer. It also needs to support the baud rate used by the data mode in question
- CW – If you’re looking to use your computer to send and receive Morse, check that your TNC supports CW
- Connectivity – Make sure that your TNC is suitable to connect to your radio, and get the correct leads
Balancing the Audio
All of the data modes we’re covering here rely on audio being sent and received over-the-air. Your computer;s audio soundcard does much of the work. The key to working data modes is to get the audio levels to and from the computer to be ideal:
Level into computer: Make sure that the software is getting the right audio level from the computer. You may need to adjust the soundcard volume, input volume on the software, or the level from the TNC. Software will have an “ideal” range, and you should hit this
Level from the computer: You need to make sure that the audio leaving the computer is of the correct volume (and not distorting). You may need to adjust the soundcard output volume, or the transmit level from the TNC. You also need to make sure that your radio is not activating the ALC (Automatic level control) as this can alter the quality of the data being sent.
WSPR (Weak Signal Propagation Reporter)
This mode is a send-only mode. You send out, over the course of a minute, a data signal containing your location and callsign, and can then check online which stations received your signal.
- Download the WSPR software, free from physics.princeton.edu/pulsar/K1JT
- Keep your PC clock in sync with Dimension 4
- Check how far out your signal is reaching on WSPR Net: wsprnet.org
Want to give WSPR a try? See Getting Started with WSPR
This is a little like WSPR, but allows a two-way exchange. To avoid splatter with other transmissions, keep the power low (max 25 watts). With JT65, you transmit for a minute, listen for a reply for the next minute, then transmit on the next minute.
Messages are typically 13 characters long, and a QSO takes 7 one minute cycles: “CQ with location, Reply with location, RST, RST, Report Received, 73, 73″
As with WSPR, the PC clock must be spot on. Keep your PC clock in sync with Dimension 4
- You can download the JT65 software for free from sourceforge.net/projects/jt65-hf
- Keep your clock in sync with Dimension 4
Want to work JT65? See our What is JT65? page
Standing for Radio Teletype, this mode supports two-way QSOs – you type in real-time, and your message is displayed at the other station almost instantly. It was the forerunner to PSK31.
Stands for Phase Shift Keying with a bandwidth of 31.25Hz. This allows a two-way QSO, and typically uses macros for common phrases.
- We recommend the Ham Radio Deluxe package for PSK31
For more on PSK, see our PSK31 – The Basics page
Slow Scan TV
Send and receive images. Formats include Robot / Scottie and Martin. Images use around 3kHz of bandwidth and take between 1 and 2 minutes to download.
- The most well-respected package for SSTV is MMSSTV, which is free from: hamsoft.ca/pages/mmsstv.php
Want to find out more about Slow Scan TV? See our SSTV – The Basics page
Packet data is sent in short bursts, typically as Beacons, for APRS location or for BBS (Bulletin Boards). You’ll need a TNC capable of handling packet d
If you tune in to 144.800MHz, you’ll hear APRS packets containing status messages, locations and weather information. To use APRS, you’ll need a TNC, GPS receiver and either a Transceiver or the Internet.
- Software: We recommend UI-View available from www.ui-view.org
- To check out Essex amateurs, see the map at : www.aprs.fi
Want to find out more about APRS in Essex? See our APRS in Essex guide
Data to the ISS
It’s possible to send and receive APRS packets from the ISS. To do this, you’ll need to be set up for APRS. These links will help too. If you’re interested, we can create a more detailed explanation of how to work ISS in packet.
- Check when the ISS is in line-of site using www.isstracker.com or Orbitron software
- Check if the ISS Packet is active here: www.issfanclub.com
- Send and receive APRS packets with UI-View software
- Check if your packet was relayed at www.ariss.net
More on working the ISS: Working the International Space Station
The are applications available for iOS and Android devices for Packet, APRS, PSK31, SSTV and RTTY. Check iTunes Store or Google Play
See also: Handy iPhone apps for amateur radio use