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Weak Signal Modes

      Tests and experiments have been carried out on HF, VHF and UHF with modes JT65, Opera and WSPR over a period of several months. There are numerous variations on these modes and many new ones appearing on a regular basis. Some of the pros and cons discovered are briefly discussed below. What is surprising on HF is just how easy getting signals to the other side of the world can be with modest power and basic antennas, even under poor propagation conditions. Most modes working with such low level signals are prone to occasional false decodes. As clever and useful in some respects as these modes might be, they have tended to severely reduce phone activity and are all computer (or some form of processor) dependent, the operator once set up can go away and leave the computer to do the job - this is probably why round here they are known as 'moron modes'.

      JT65

      Computer generated sequence of tones and transmitter activation, separate program with internet connection required to view reports. Some beacons, but mostly a slow alpha numeric QSO mode. Transmitter/receiver stability and timing can be an issue.

      Opera

      Computer generated keyed carrier, so only requires a basic set-up and can be sent via the CW key socket on the transceiver and there are no timing issues. If the computer is connected to the internet the program sends and receives reports quickly. Mainly a beacon mode with brief details. Not as popular as other modes, surprising considering how easy, simple and effective it is to operate.

      WSPR

      Computer generated tone and transmitter activation, separate program with internet connection required to view reports. Slow beacon mode much abused by unnecessary frequent repeated transmissions (mostly unattended and with no RX), many 24/7. Transmitter/receiver stability can be a major issue, some stations drifting out of the expected passband on a regular basis, especially on VHF or above. Timing is also very important as transmissions are made in timed 'slots'.Very sensitive, however, on VHF/UHF aircraft reflections can destroy reception if the direct signal is not dominant. Most useful for building up propagation patterns, wspr.net can generate maps from received reports.