CHANGE-SIDEBAND

Modifies the spectrum header parameters to those appropriate to the image sideband. For GSD data obtained before mid-1993, the SPECX header does not have any information about the current sideband, nor on the first intermediate frequency, and this information must be supplied by the user. For later data where the IF and LO frequencies are known, the task runs unaided.

Relevant flags:

SIDEBAND	C1	U (upper) or L (lower)
FIRST_IF	R8	First intermediate frequency in GHz.

Examples:

    >> change-sideband<CR>
    Current sideband? (U/L) [U] <CR>
    First i.f.? (GHz) [ 3.950000] <CR>
    ..