Belar FMHD-1, Руководство оператора

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FMHD-1 Operator’s Manual
Page 30 FMHD-1
falling anywhere across the display window. Highlighting C1 with the encoder and rotating the knob
positions the amplitude cursor vertically on the spectrum display. Note that if changes in the dB or VR
display parameters would result in the C1 cursor falling above or below limits of the vertical scale, the
setting for C1 is automatically set to the appropriate vertical axis limit.
HR:
The “
HR
”, for horizontal resolution, equivalently is the frequency resolution of the displayed
spectrum. It is the number of Hertz (Hz) assigned to each horizontal pixel in the domain of the display.
The range is 50 Hz-per-pixel to 1,500 Hz-per-pixel. The total frequency range displayed is the product of
the number of columns of pixels in the spectrum display, 501, multiplied by the resolution, in Hz-per-
pixel.
C2:
The C2 cursor parameter sets the frequency (horizontal position) of an adjustable yellow vertical line
(“Cursor 2”) spanning the height of the display. Adjusting the C2 parameter with the encoder positions
the cursor at the precise frequency indicated numerically to the right of “
C2
” in the upper-right corner of
the display. This helps to determine the frequency of a specific feature of spectrum, or indicates where to
look on the display to find an element of the spectrum.
Note that when the C2 cursor is visible, changes to the frequency resolution (“
HR
”) parameter will
automatically adjust the frequency axis to keep the cursor near the center of the display. In order to zoom
in or out at a particular frequency, place the C2 cursor at that frequency and adjust the frequency
resolution “
HR ”. The C2 cursor also provides a numerical readout of the spectral amplitude present at the
C2 frequency. The numerical value is displayed directly below the C2 parameter in the upper-right corner
of the spectrum display. This number corresponds to the Y-axis value of the display.
kHz:
The “
kHz
” parameter (for kilohertz), effectively changes the portion of the frequency spectrum that
is visible on the display by moving the frequency axis of the display horizontally to the left or to the right.
Note that the “frequency-span”, or the difference between the lowest and highest frequencies displayed, is
not changed by the kHz parameter. To change the frequency span of the display, adjust the “
HR ”
parameter as required.
7.3 The RF Spectrum Popup Menu
The RF Spectrum Popup Menu is selected by pressing in and holding down the encoder knob until the
Popup Menu directory appears, rotating the encoder to select "Spectrum”, and then momentarily
depressing the encoder knob to enter.
Following are the parameters and controls which appear in the FMHD-1 RF Spectrum Popup Menu.
Display Mode:
Realtime
- The entire spectral display is updated at the completion of each FFT spectrum calculation.
The values are RMS.
Peak Hold
- The display holds the largest spectral amplitude occurring in each spectral bin during the
previous number of FFT computations set by the "Hold Count" parameter. Once displayed, the peak
amplitudes in each spectral bin are held until the completion of the next set of FFT computations and
update.
Average
- The display computes the average spectral amplitude occurring in each spectral bin over the
number of FFT computations set by the "Avg Count" parameters. Once displayed, the average amplitudes
in each spectral bin are held until the completion of the next set of FFT computations.