By verifying whether each output word is correct, you can isolate malfunctioning bits in the
interface data bus.
This test is less stringent than the input/output test IOTEST since the input data paths to
the processor are not being checked. Typically, the OTEST is performed only when the
IOTEST fails to determine whether the fault was on input or output.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
---------------------------------------------------------------
| | | | | | | | | | | | | | | | |
| | 0 0 1 0 1 | Command
|-------------------------------------------|-------------------|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
---------------------------------------------------------------
| | | | | | | | | | | | | | | | |
| 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 | Output 1
|---------------------------------------------------------------|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
---------------------------------------------------------------
| | | | | | | | | | | | | | | | |
|1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | Output 16
|---------------------------------------------------------------|
8.7
Sample Noise Level (SNOISE)
Use SNOISE to estimate the current noise level from the receiver, so that the noise can be
subtracted from subsequent measurements.
Data are sampled for 256 pulses at 256 bins, beginning at a selectable range and spaced by
the range resolution at that pulse width. The internal trigger generator is temporarily set to a
special noise rate (usually much lower than the operating rate) during the process. It is the
user's responsibility to make sure that no returned power is present within the
approximately 32 km sampling interval. In some cases, it may be necessary to raise the
antenna during the noise measurement to avoid thermal noise pickup from the ground, or
from weather targets.
SNOISE has the option of setting up a new sampling range and trigger generator rate each
time it is called. Two bits in the command word determine which, if any, of the new values
overrides the current values stored in RVP900. The power-up sampling range is 250 km
(input value of 250), and the power-up trigger rate is 200 Hz (input value of 30000). These
initial values persist until such time as they are altered here. Both input words must always
be supplied after the command, even if the command calls for ignoring one or both of them.
RVP900 User Guide M211322EN-J
252
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