Chapter 3 _______________________________________________________ Hardware Installation
VAISALA_______________________________________________________________________ 75
0916-023
Figure 19 Calibration Plot for a Stand-Alone 16-Bit IFDR
3.2.11 IF Gain and System Performance
The previous discussion was concerned with measuring the dynamic range
of a stand-alone IFD. We will now examine how the unit performs in the
context of a complete radar receiver. We assume that an LNA/Mixer has
already been selected that offers an appropriate balance between price and
noise figure. Having chosen these front-end components, the only
parameter that remains to be determined is the total RF/IF gain between the
antenna waveguide and the IFDR.
Assume that the thermal noise (kT) of the system is -114 dBm/MHz, and
that the noise figure of the LNA/Mixer is 2 dB. We want to bring this
-112 dBm/MHz noise level up into the working range of the IFDR, so that
the received echoes can be optimally processed. However, in trying to
select the required gain, we realize that we must make a trade-off between
preserving the receiver sensitivity that has been established by the LNA,
and preserving the overall dynamic range of the IFDR. This is the exact
same trade-off that is made in traditional multi-stage analog receiver
systems that include a WDR LOG receiver.
To Next Page
Loading...
Need help?
General