Yaesu FT-897 Operating Manual

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Yaesu FT-897 Operating Manual Manual pdf 28 page image

Page 26 FT-897 OPERATING MANUALDSP CW P EAKING F ILTERIn the CW mode, pressing the [C](DBF) key in Multi Func-tion Row “p” [DNR, DNF, DBF] activates a narrow-band-width peaking filter, which may be ideal for use under verycrowded conditions. The DSP CW Peaking Filter also isespecially helpful under VHF/UHF weak-signal situations.The center frequency of the DSP CW Peaking Filter is auto-matically aligned to be centered on the response you haveselected via the Menu Mode in item No-027 [CW PITCH].See page 55 for details.To change the bandwidth of the DSP CW Peaking Filter:1. Press and hold in the [C](DBF) key for one second onthe CW mode. This instantly activates Menu Mode No-045 [DSP BPF WIDTH], which allows selection of thebandwidth of the DSP CW Peaking Filter.2. Rotate the DIAL to select the desired bandwidth. Theavailable values are 60 Hz, 120 Hz, and 240 Hz (defaultvalue: 240 Hz).3. When you have made your selection, press and hold inthe [F] key for one second to save the new setting andreturn to normal operation.DSP N OISE R EDUCTION (NR)The Noise Reduction feature of the DSP system may be usedto enhance signal-to-noise ratio on weak signals.1. Press the [DSP] key momentarily. This instantly acti-vates Multi Function Row “p” [DNR, DNF, DBF].2. Press the [A](DNR) key to activate the DSP Noise Re-duction feature. “Parentheses” will appear on the bothsides of the “DNR” indication, and the “DSP” will ap-pear at the center top on the display.3. Now press and hold in the [A](DNR) key for one sec-ond. This instantly activates Menu Mode No-049 [DSPNR LEVEL], which allows adjustment of the DSP NoiseReduction level.4. Rotate the DIAL to find the point where best signal-to-noise ratio is obtained under the current noise condi-tions.5. Press and hold in the [F] key for one second to save thenew setting and exit to normal operation.6. To turn off the DSP Noise Reduction feature, press the[A](DNR) key again.If noise is present at a level which causes indi-cation on the S-meter, the performance of theNoise Reduction filter may be enhanced by ro-tating the SQL/RF (RF Gain) control in a counter-clock-wise direction so as to set the (fixed) S-meter reading atthe same level as the noise peaks. This adjustment raisesthe AGC threshold of the receiver.DSP N OTCH F ILTERThe DSP system’s Notch Filter may be helpful in removingone or more offending carrier or heterodyne signals fromthe audio passband.1. Press the [DSP] key momentarily. This instantly acti-vates Multi Function Row “p” [DNR, DNF, DBF].2. Press the [B](DNF) key to activate the Notch Filter. “Pa-rentheses” will appear on the both sides of the “DNF”indication, and the “DSP” will appear at the center topon the display. You will notice that the audio level of thecarrier signal is now being reduced.3. Press the [B](DNF) key once more to turn the NotchFilter off.Do not activate this filter in the CW mode, asincoming CW signals will be notched out of theaudio passband!RECEIVER ACCESSORIES60 Hz120 Hz240 Hz