Vislink Strata RX, Техническое справочное руководство

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Theory of Operation 9-4
Strata RX
Technical Reference Manual
output frequency to be varied.
This output frequency is then passed it through a multiplier to
raise its frequency to one that is exactly 900 MHz away from the
incoming signal. Depending on the Band, this frequency may be
either 900 MHz lower or 900 MHz higher than the incoming
signal. This signal is filtered to reduce spurious signals before
being applied to the Mixer.
Mixer
In the Mixer, the incoming signal is mixed with the LO
signal, resulting in two mixer outputs: the sum of the input
signals, and the difference between them. The difference signal
will be the desired 900 MHz.
Finally the 900 MHz signal is Low Pass Filtered to remove the
signal representing the sum of the two MIxer signals.
2 GHz LNC
One specific version of the LNC is the 2GHz LNC.
The 2 GHz LNC differs in that it has two inputs - one for incoming
2 GHz RF, and an “AUX” input for accepting 2 GHz from a Low
Noise Block Down Converter (LNB). The inputs are selectable,
and are amplified or filtered as needed depending on the signal
source.
The block diagram is shown in Figure 9-9.
9.3.3 Band-Specific RF Architecture
The LNB is used alone, or together with the LNC, depending on
which Band is to be received.
Lower Bands
For the lower frequency bands, the incoming RF
is applied directly to the Low Noise Converter (LNC), which
converts the signal to 900 MHz as described in Section 9.3.2.
No other modules are needed in the Front End. See Figure 9-2.
Figure 9-2: Lower Bands Configuration
2 GHz Band
For the 2 GHz Band, the two-input version of the
LNC is used. When receiving 2 GHz, the RF is applied to the RF
Input of the LNC. The AUX input is not used.
No other modules are needed in the Front End. See Figure 9-3.
Figure 9-3: 2 GHz Configuration
Higher Bands
For the higher frequency bands, the RF signal is
applied to a Low Noise Block Down Converter (LNB), which
converts the signal to 2 GHz and passes it to the 2 GHz LNC.
The 2 GHz LNC converts the signal to 900 MHz. For some
bands there may be a special LNB that incorporates its own
LNC. These special LNBs therefore would accept the RF signal
and convert it directly to 900 MHz.
See Figure 9-4.
LNC
RF In 900 MHz Out
LNC
2 GHz In
900 MHz Out
RF In
AUX In