Yaesu FT DX 1200 Operation Manual

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Page 54 FT DX 1200 O PERATING M ANUALA B CI NTERFERENCE REJECTIONWIDTH (IF DSP BANDWIDTH) TUNING (SSB/CW/RTTY/DATA MODES)The IF WI'TH tuning system allows you to vary the width of the 'S3 IF passband, to reduce or eliminate interference.0oreover, the bandwidth may actually be expanded from its default setting, should you wish to enhance incoming sig-nal ¿delity when interference on the band is low.1. 5otate the [WIDTH] knob to the left or right to re-duce the interference.A DVICE :The freTuency display will show the bandwidth ofthe IF passband for 3 seconds whenever the [WIDTH]knob is turned.[WIDTH] Knob5eferring to Figure “B”, you can see the defaultbandwidth on the SSB mode.By rotating the [WIDTH] knob to the left, thebandwidth will narrow see Figure “A”, whilerotation of the [WIDTH] knob to the right, asdepicted in Figure “C”, will increase the band-width.A B CThe default bandwidths, and total bandwidth ad-justment range, will vary according to the operat-ing modeSSB 0ode 1.8 kH] a 4.0 kH] default .4 kH]).CW 0ode 00 H] a .4 kH] default .4 kH])5TTY'$T$ 0odes 00 H] a .4 kH] default00 H])Using IF SHIFT and WIDTH TogetherThe IF SHIFT and Variable IF WI'TH featurestogether form a very effective interference-¿ght-ing ¿ltering system.For example, in Figure “A”, you can see howinterference has appeared both on the highand low sides of the desired signal. 5otate the[WIDTH] knob, the interference from one sidecan be eliminated Figure “B”). 1ext, rotate the[SHIFT] knob to re-position the passband Figure“C”), the interference on the opposite side can beremoved, without re-introducing the interferencepreviously eliminated in Figure “B”.A DVICE:For best interference reduction, the WI'TH andSHIFT features are the primary tools you shoulduse, after narrowing the bandwidth WI'TH)andor adjusting the center of the passbandSHIFT). The Contour control may then yieldadditional signal-enhancement benefits onthe net residual bandwidth. (ven more, the IF12TCH Filter described later) may also beused, in conjunction with these ¿lter systems, tosigni¿cant advantage.WIDTH INDICATORIF BANDWIDTH IF BANDWIDTH IF BANDWIDTHSHIFT SHIFT SHIFT Desired Signal Desired Signal Desired SignalQRMQRMQRMQRMQRMQRMIF BANDWIDTH IF BANDWIDTH IF BANDWIDTH