Icom IC-7610 Instruction Manual basic - Page 33

4 RECEIVING AND TRANSMITTING Using the Twin PBT SSB, CW, RTTY, PSK and AM modes To reject interference, the Twin PBT (Passband Tuning) narrows the IF passband width by electronically shifting the IF frequency slightly above or below the IF center frequency. The IC-7610 uses DSP for the PBT function. 1. Rotate TWIN PBT CLR inner (PBT1) and outer (PBT2) in the opposite direction from each other. LLInformatio ••Match both the TWIN PBT CLR (inner) (PBT1) and outer (PBT2) filters before operating the Twin PBT. ••Rejects interference of both higher and lower passbands. ••If you rotate the control too much, the received audio may not be heard because the passband width is too narrow. ••Displays the passband width and shift value. ••Hold down TWIN PBT CLR for 1 second to clear the PBT setting. ••The PBT is adjustable in 50 Hz steps in the SSB, CW, and RTTY modes, and 200 Hz in the AM mode. In this case, the center shift value changes in 25 Hz steps in the SSB, CW, and RTTY modes, and 100 Hz in the AM mode. ••Rotating both the inner and outer controls together to the same position shifts the IF left or right. 2. Hold down FILTER for 1 second to display the current passband width and shift frequency. ••Opens the FILTER screen. 3. To close the FILTER screen, push EXIT . NOTE: While rotating TWIN PBT CLR , you may hear noise. This comes from the DSP unit and does not indicate an equipment malfunction. TWIN PBT CLR FILTER ••When rotating TWIN PBT CLR Filter width Shifting value Passband width (Duplicated with PB1 and PB2) Selected IF filter ••The FILTER screen when rotating TWIN PBT CLR SFT: Shift value IF center frequency Passband center frequency PBT1 PBT2 BW: Passband width PBT is OFF PBT2 PBT1 Cutting the lower passband PBT2 PBT1 Passband Cutting both higher and lower passbands PBT2 PBT1 Passband 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 IF center frequency Interference Desired signal 4-3 Interference Desired signal Interference