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Black Bars Appearing while using ClearVü and SideVü
ClearVu and SideVu image may have the appearance of black bars along the side. There are two sources that cause this type of image.
The first result is from nulls (black bars) in the beam pattern. These nulls occur if the ClearVu or SideVu are operating on the secondary frequency. The beam pattern is optimized to avoid the nulls and provide the best image on the primary frequency. For example, on the GT51M if run on 455kHz rather than on the 260kHz.
The second cause is called grating lobes. Grating lobes results due to interference between the ClearVu and SideVu elements when simultaneously transmitting the same frequency, commonly seen in acoustics. To eliminate the effects of grating lobes, run the SideVu at the primary frequency (260kHz) and ClearVu at the secondary frequency (455kHz).