VOICE OPERATIONS

UMARS is equipped to operate in voice modes, including AM (amplitude modulation), FM (frequency modulation), PM (phase modulation), and SSB (single-side band).

In addition to voice, many other modes are used at UMARS.

• Morse Code
• Packet (PSK, PSK31)
• AMTOR
• RTTY
• DX
• Contesting

MORSE CODE

Although the number of good Morse code operators is shrinking, it is still one of the most efficient ways to communicate on little power. UMARS and Winnipeg have always had such operators. For example, Tom Tessier, VE4TRT, is a very good Morse code operator.

PACKET

UMARS has packet equipment to transmit data over amateur radio, both HF and VHF using the standard .AX25 protocol.

OTHER DIGITAL MODES

UMARS has also communicated using AMTOR and RTTY, and other experimental modes such as PSK31.

AMTOR improves on RTTY by incorporating either error detection, or error correction techniques by automatic repeat request (ARQ). The protocol performs well even in poor and noisy HF conditions. AMTOR is still used for broadcast bulletins.

PSK31 improves on AMTOR. Due its phase modulation and natural resilience to noise and even channel fading, is has little or no error control. It uses a varicode (frequently-occurring characters have shorter codes, while the rarer characters have longer codes). The half-duplex protocol performs well even in poor and noisy HF conditions.

The different modes differ in the spectrum efficiency, as shown in the figure below [Wiki07a].

DX

UMARS has also communicated using DX modes. For years, a tri-band Yagi directional antenna, located on the roof of the University Centre, provided the means to reach very distant countries. However, the antenna is no longer in use, because it had to be disassembled due to safety considerations.