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5.14 - Demodulator Setup

5.14.1 - Adjusting Bandwidth

Interfering signal

You can adjust either edge of the demodulator's bandwidth by pointing at the left or right edge of the demodulator bar until you see a cursor appear that looks like a tilted, double-headed arrow, then clicking and dragging with either mouse button, or using the mouse roller while you hold the mouse button down.

You can also adjust the demodulator bandwidth by →Left-click KLK, then using the ^ ↑, ^ ↓, ^ → and ^ ← keys on the keyboard. You can remap these function with Ref.

You can also adjust the demodulator bandwidth by clicking one of the bandwidth memories, BW1 through BW7; you can store new values in these memories by either holding Shift while you click the memory, or →Left-click STO prior to clicking the memory. →Left-click STO (while it is still blinking) cancels the store operation. Each demodulator mode ( AM, USB, etc.) has its own set of seven memories, or in other words, setting the values for AM does not change the values for USB or LSB

→Right-click BW4 will set the BW2 through BW6 bandwidth memories to values evenly spaced between BW1 and BW7. If -Ri is on when you do this, then all bandwidth memories will set -Ri; if it is not on at the time you →Right-click BW4, then all bandwidth memories will set -Ri instead.

The LEDs on the bandwidth memories illuminate when the current bandwidth matches that stored in the bandwidth memory. If the settings are identical to those in the memory, the LED will be white: BWx. However, if the bandwidth is the same, but is shifted, then matching memory LED(s) will be red BWx or green BWx

Example:

A memory set to 100:2800 is 2700 Hz bandwidth. So if the demodulator is set to 100:2800, which exactly matches the setting, then BWx.

The same memory will be BWx if the demodulator is set to 150:2850 because this is still 2700 Hz bandwidth, but the bandwidth is shifted up, that is, starts and ends at higher points.

The same memory will be BWx if the demodulator is set to 50:2750 because this is still 2700 Hz bandwidth, but the bandwidth is shifted down, that is, starts and ends at lower points.

Note: In some versions of OS X, some of the keystrokes you may want to use have been "taken over" by the operating system. If you wish to use them with SdrDx instead of for the purposes OS X has assigned them, open the OS X preferences (the control panel application) and disable the operating system's use of the keystrokes and the SdrDx application will then be able to see them.

Left SAM demod edge
adjusted to cut
interference

With AM and FM, the left and right edges adjust together, or symmetrically. With USB, LSB, FSU, FSL, CW, and SAM, the left and right edges adjust independently.

5.14.2 - IF Shift

Independent demodulator edge controls are the equivalent of independent left and right IF shift controls with automatic passband compensation on an analog radio.

However, you can also perform an actual IF shift (without passband compensation) in USB, LSB, FSU, FSL, CWU and CWL modes.

To shift up, press ^ Q

To shift down, press ^ V