Monday, March 19, 2012

Brief mode refresher

The availability and channelization of the 5MHz amateur radio band has encouraged a lot of us to:
  • review our understanding of our principal modes of communications (AM, LSB, USB, and CW) and to;

  • reread our receiver (transceiver) documentation.
A Software Defined Radio (SDR) panadapter is a excellent way to "look at" each of these modes.

The panadapter display is a graphic representation of a radio frequency signal. The x-axis, reading from left to right, is frequency. The height of the graphic is signal strength. Figure 1, is an amplitude modulated (AM) signal on 3.740 MHz as indicated by the red line. Note you can see the carrier energy rising to -50 on the y-axis shown on the left hand side of Figure 1.

To the left and right of the carrier, you can see the lower side band and the upper side band respectively.

Figure 1 -- Amplitude Modulation (AM)

Source: KE4ID

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