Two sets of less-frequently-used controls are available in a drawer, which you can open by pressing the IF/DSP button to the right of the frequency-jog buttons. Pressing the button again (or dragging the drawer closed) will close the drawer. Opening and closing the drawer has no effect on the settings made by controls in the drawer.
The left half of the drawer contains a slider for controlling intermediate-frequency (IF) shift. A radio signal occupies a band of frequencies to either side (or in the case of sideband signals, to one side) of the nominal frequency of the signal. The filters in the IF stage of the receiver mask out frequencies beyond a (more or less) narrow range of the tuned frequency; you can think of them as giving a “keyhole” view of the radio spectrum.
The IF Shift control allows you to adjust that keyhole up or down by as much as 1280 Hz. This allows you to keep the receiver tuned on the signal you want, and then move the filters to exclude unwanted interference, or to include portions of the signal that would otherwise be filtered out.
The shift display lets you visualize this process.
To restore IF shift to its neutral setting, press the 0 (zero) button in the middle of the slider.
The Shift Display and Center Meter
The shift display and center meter is the black box just under the signal-strength meter.
![[Shift meter showing 6 kHz envelope centered]](AM6kHzCenter.png)
When the receiver is in a mode that spreads to both sides of the tuned frequency (CW, AM, FM), the tuned frequency is represented by a vertical white line with a triangle at its base. The filter envelope is represented by a red bracket extending to either side of the center line.
When the receiver is in a sideband mode (LSB or USB), the tuned-frequency line appears at one end or the other of the shift display, depending on which sideband is being tuned. The illustration here shows a 6 kHz filter envelope, unshifted, in lower-sideband mode.
The filter envelope includes two vertical red lines bracketing the place where the tuned frequency would be if IF shift were zero. If, for instance, you were to set the IF shift downward, the shift display would look like this.
The filter-envelope bracket broadens and narrows to match the selected filter width. Filter widths of 50 kHz and 230 kHz are too wide to fit in the shift display. As these filters are too wide to make a 1280 Hz IF shift significant, this is not expected to give trouble.
In the narrow and wide FM modes, the IC–PCR1000 can detect whether the tuned frequency is (roughly) correct for the signal being heard, or whether the receiver should be tuned higher or lower for best reception. When no FM signal is being received, or FM tuning is sufficiently close, a blue vertical bar will appear in the top center of the shift and centering display (this may be hard to see against the white of the tuning centerline). If the signal frequency is lower than the tuned frequency, the blue bar will be replaced by a blue arrow pointing left. If the correct frequency is higher, and you should tune up, a blue arrow pointing right will appear.
The right-hand side of the drawer is occupied by controls for the UT–106 Digital Signal Processing (DSP) unit. This is an optional installation in the IC–PCR1000, and these controls will be active only if the DSP unit is installed.
Pressing the power button in the drawer activates the DSP controls if the DSP unit is installed. There are two digital filters available.
The noise filter removes random, sharp static from the audio signal, such as might be generated by a noisy electrical motor or lamp. This is controlled by the DSP Noise Filter slider, and is off in the full-left position, and at full intensity in the full-right position. You will generally find that the lower settings are the most useful, as the higher ones eliminate portions of the desired audio signal.
The notch filter is controlled by the DSP Autonotch Filter check box. This filter detects single loud tones overlaying the audio signal (such as adjacent carriers), and removes them.