BNC 630 - Manual (Page 32)

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5.13 External SSB Mode
Introduction
The External SSB mode generates a Single SideBand (SSB) modulated signal of fixed carrier frequency. An externally supplied
signal on the Ext Mod In connector is used to modulate either the upper or lower sideband of a carrier sinusoid. The modulation
waveform is suppressed carrier, i.e. little carrier energy is present in the modulated signal.
External SSB Mode Parameters
The External SSB mode has the following front panel display:
Figure 5.13-1: External SSB mode display
1. Upper/Lower Sideband selection
This parameter selects which sideband will be generated. Single sideband modulation specifies that all energy in the modulated
waveform should be either above the carrier frequency or below it. Upper sideband places all signal energy above the carrier
frequency, and Lower sideband places all signal energy below the carrier frequency.
To select Lower sideband, press 0 . To select Upper sideband, press 1 . Pressing any arrow key or rotating the wheel will toggle the
sideband selection between Upper and Lower.
2. Carrier Frequency
In this field enter the frequency of the carrier. You may enter from 0 Hz (DC) to 21.5000000 MHz in .01 Hz steps.
Note: It is possible to enter values for the carrier frequency such that the upper sideband can exceed 21.5 MHz or the lower
sideband can go below 0 Hz. Care should be taken not to do this since distortion of the output waveform may result.
3. Level
In this field enter the output level, from 4 mVp-p to 10 Vp-p in 1 mV steps or from -44.0 dBm to +21.0 dBm in .1 dBm steps.
NOTE: The level specified is a 50 ohm LOADED level. This is the level of the signal which will appear across a 50 ohm load
connected to the SIG Out connector. Into an open circuit, the output swing will be twice the value entered.
Offset
You can enter an offset voltage for the output waveform. For more information on output offsets refer to section 4.4.
Ext Gating Input
(rear panel connector)
This TTL compatible input can be used to gate the output signal on or off. A logic high voltage turns off the output.
For further information on the Ext Gating Input, refer to section 2.0.
Ext SSB Upper Sideband
20,000,000.00 Hz -10.0 dBm
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