1 RECEPTION
1.4 RX Auxiliary Circuits
Typical
On the
Noise is typically
Within the DSP, the processing block of the noise blanker is placed in a stage earlier than the filter block that determines the final pass bandwidth. Thus, even if the final pass bandwidth is narrowed, the blanking operation can work properly, free of the influence of the narrowed bandwidth.
However, roofing filters are located far earlier than the DSP, in the later stage of the first mixer. As a result, in the event the bandwidth of the roofing filter becomes as narrow as 500 Hz, the pulse width becomes wider and a conventional digital noise blanker would not deliver a sufficient blanking effect.
This is the exact case while down conversion is active on the
During the up conversion, the noise signal is derived from the second IF stage and delivered to the noise blanker circuit as in previous models.
Hints and Tips
“What are NB1 and NB2?”
NB1and NB2 are the name of the functions that have been used in
As explained above, while the narrow bandwidth of the roofing filter is employed, the noise blanker of the DSP cannot have a sufficient effect. However, the NB2 realized with the DSP on the
NB2 of the
Hints and Tips
“Improvement of sensitivity in the BC band and alteration in ATT attenuation”
On the
CONTENTS
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