USER’S MANUAL__________________________________________________________________
96 __________________________________________________________________ M211322EN-D
Interpreting the Serial 16-bit Data Word
The serial 16-bit data word has several different interpretations according
to how the RVP900 has been configured, and whether Bit #22 of the uplink
stream is set or clear. The evolution of these different formats has been in
response to new features being added to the IFDR (Section 3.2 RVP901
IFDR Installation on page 62), and the production of the DAFC module
(Section 3.4 Digital AFC Module (DAFC) on page 84).
The original use of the uplink data word was simply to convey a 16-bit
AFC level, generally for use with a magnetron system. Bit #22 is clear in
this case, and the word is interpreted as a linear signed binary value. The
use of this format is discouraged for new hardware designs, but it remains
available to guarantee compatibility with older equipment.
0916-036
When the IFDR is jumpered for phase locking to an external reference
clock, then Bit #22 is clear and the data word conveys the PLL clock ratio,
and the Positive/Negative deviation sign of the Voltage Controlled Crystal
Oscillator (VCXO). This format is commonly used with klystron systems,
especially when the RVP900 is locking to an external trigger.
0916-037
The AFC-16 and PLL-16 formats can never be interleaved for use at the
same time, since there would be no way to distinguish them at the receiving
end.
Finally, an expanded format has been defined to handle all future
requirements of the serial uplink. Bit #22 is set in this case, and the data
word is interpreted as a 4-bit command and 12-bit data value. A total of
16x12=192 auxiliary data bits thus become available via sequential
transmission of one or more of these words. The CMD/DATA words can
Level 01111111111111111 (most positive AFC voltage)
0000000000000000 (center AFC voltage)
1000000000000000 (most negative AFC voltage)
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