Frequency switched

In this case, all the time is spent in the direction of the source. However, the frequency switching also implies that all this times can be counted as on-source and off-source times. Thus

$$\ensuremath{t_\ensuremath{\mathrm{onoff}}}= \ensuremath{t_\... ...emath{\mathrm{on}}}= \ensuremath{t_\ensuremath{\mathrm{off}}},$$ (6)

$$\ensuremath{t_\ensuremath{\mathrm{sig}}}= \frac{\ensuremath... ...}}}{2} = \frac{\ensuremath{t_\ensuremath{\mathrm{onoff}}}}{2},$$ (7)

and

$$\ensuremath{\sigma_\ensuremath{\mathrm{fsw}}} = \frac{\sqrt... ...th{\mathrm{tel}}}\,\ensuremath{t_\ensuremath{\mathrm{tel}}}}}.$$ (8)