9
This section explains the operation of the ANC-4 controls. See Figure 1
for the location of Front Panel Controls.
The NOISE PHASE control adjusts the phase angle of the signal from the
noise antenna to 180 degrees for maximum cancellation of the local noise.
The PHASE RANGE pushbutton provides two different networks to
allow greater range of adjustment of the NOISE PHASE control to achieve
the deepest null of local noise interference. When the button is pushed in,
the phase network is in the “A” position, which is used for most situations.
When the button is out, the phase network is in the “B” position. No
position on this switch is more “right” than the other. The proper or “right”
position is that which gives the best null. The FREQ RANGE button can
be used in conjunction with this pushbutton to give even greater phase
nulling range at low frequencies by placing it in the HI position.
The FREQ RANGE pushbutton extends the frequency range over which
the NOISE PHASE and NOISE GAIN controls are effective. In the “IN”
position (LO), the network is set for frequencies below 20 MHz. In the
“OUT” position (HI), the network is set for frequencies above 20 MHz.
Note that the HI position is also usable for low frequencies and may be
required if a satisfactory phase null cannot be obtained with the switch in
the LO position.
The NOISE GAIN control adjusts the level of the signal picked up by the
noise antenna so that the magnitude of the offending interference can be
cancelled. When the ANC-4 is used as an active antenna, this control
adjusts the gain of the antenna.
NOISE GAIN
SECTION 4
CONTROLS &
INDICATORS
NOISE PHASE
CONTROL
PHASE RANGE
PUSHBUTTON
FREQ RANGE
PUSHBUTTON
