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Spectrum screen is similar screen to the Oscilloscope screen but visualizes data in the frequency domain instead
of oscilloscope's time domain. It uses SMΩRF's peak detector data and with help of Digital Signal Processing
(DSP) translates them into frequency domain using Fast Fourier Transformation (FFT).
CONTROLS:
FREQUENCY
1.
Sets frequency (X axis) scale
and offset.
Turning knob changes
Horizontal Scale, maximal and
minimal frequency. Horizontal scale is in Hertz [Hz]. There are three linear horizontal scales and three
logarithmic horizontal scales available. There is no equivalent of "horizontal offset" setting.
AMPLITUDE
2.
Sets amplitude (Y axis) scale and offset.
Turning knob changed Amplitude Offset. When pushed and turned, it changes Vertical Amplitude Scale.
Scale is labeled in decibel [dB] units.
CURSORS MODE
3.
Same as in Oscilloscope screen, SMΩRF provides two cursors (CURSOR 1 and CURSOR 2) for
measurements on computed spectrum image. They work in two modes: Tracking and Free mode.
In Tracking mode, indicated by CT icon, Y position of the cursor is stuck to the waveform while X position
can be adjusted. In Free mode, indicated by CF icon, both X and Y positions of the cursor can be
adjusted. On screen,cursors are indicated by small square labeled 1 or 2.
CURSORS
4.
Cursors can be controlled by placing selection to cursor 1 or 2 field. Their position in amplitude and
frequency is numerically presented in in table on the right side of display. Bottom line of the table with Δ
sign shows difference between CURSOR 1 and CURSOR 2 for both amplitude and frequency.
Cursors have slightly different control according to their mode. In Tracking mode turning the knob on
selected cursor changes its horizontal frequency position. When pushed and turned, the other cursor
changes its frequency position. It simplifies manipulation with both cursors.
In Free mode both cursors must be controlled separately. Turning the knob on selected cursor changes
its horizontal position, when pushed and turned it changes its vertical position.
TONE
5.
TONE field is shortcut to built-in tone generator START/STOP function. When icon is lit, tone generator
generates defined output. Its output is defined in MAIN MENU | TONE GENERATOR and settings are
unique for the Spectrum screen.
Spectrum screen has a special SCREEN MENU item - DISPLAY TYPE which defines how peak hold values are
represented on display. Peak value is kept individually for each frequency considering time of its appearance.
LINE selection draws peak value as line
•
AREA selection draws peak value as faded area
•
Please note, SPECTRUM screen uses RF envelope data obtained from the peak detector (similar to diode
detection). Therefore do not expect to see the spectrum image of SSB signals as you know them from your
digital modes program, SDR or panadapter. Phase information of the peak detected SSB signal is lost and
cannot be accurately reconstructed for unknown modulation signal. However, it still shows proper spectrum
image of AM signals, as well as occupied bandwidth in CW mode.
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SPECTRUM SCREEN
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