Stream DC Offset

Macro : Offset, OffsetMode

Offset here means 'level shift', not the opposite of 'onset'.

The DC Offset control adds or subtracts a constant value from the stream wave, effectively sliding it up or down within its range. The total of DC Offset and Level must ordinarily not exceed 100%, assuming a normal waveform that uses all of its range. If you add or subtract too much, the wave slides up or down so far that it is "clipped" to the maximum or minimum value. This produces distortion, which gets worse as more of the wave is clipped off.

Note that sound cards block constant (DC) values from ever reaching the output, so unless clipping is present there will be no audible effect. So, why bother to have this control at all?

The DC Offset control is useful when the Stream is used as the modulation source for another Stream, allowing you to provide some constant amount of modulation on top of whatever is provided by the simple waveform. DC Offset is also sometimes useful when adding Pulse Streams together.

The button to the right of the DC Offset control toggles between 'All' and 'Burst'. In Burst mode the DC Offset is only applied to the region included in the burst; in All mode (default) it is applied everywhere, including regions where the burst is off.

The Burst mode is especially useful when you are adding Burst Streams together, such as when creating complex waves for Arb files.

You may not need DC Offset often, but remember that it is available... when you need it, it will usually be obvious.

Macro Notes:

L.3.Offset=50 directly sets Left Stream 3 Offset to 50%. L.3.Offset=-50 sets -50%. Alternatively, L.3.Offset=>1 increments and L.3.Offset=>-1 decrements the current Offset by 1%. Only steps of +/- 1% are allowed with this format.

L.3.OffsetMode=Burst (or 1 sets the Left Stream 3 Offset mode to Burst, while L.3.OffsetMode=All (or 0 sets All. L.3.OffsetMode=x toggles the current mode to the opposite state. It is a good idea to always set a known state with OffsetMode before giving an Offset command.

See also Stream Dialog, Signal Generator Control Dialog.