Operation 23
CG635 Synthesized Clock Generator
R
RF synthesizer R parameter
N
RF synthesizer N parameter
D Divider
=
2
D
FT3
Bits 48-63 of the frequency tuning word
FT2
Bits 32-47 of the frequency tuning word
FT1
Bits 16-31 of the frequency tuning word
FT0
Bits 0-15 of the frequency tuning word
PRBS
PRBS on/off/disabled status (if installed)
RB
Rb stability (if installed)
The STATUS parameter displays the current value of the CG635 serial poll status byte.
This is the same value that is returned by the *STB? command. See the CG635 Remote
Programming chapter for information on how to interpret the status byte.
The SYNTH parameter displays the current lock status of CG635. The interpretation of
each lock status bit is summarized in Table 14. The red UNLK LED will be on when any
of these bits is set. If the SYNTH parameter is 3, for example, then the RF and 19 MHz
PLLs are currently unlocked.
Table 14: Synthesizer Lock Status
Bit Name
Meaning
0
RF_UNLOCK
RF PLL is unlocked.
1
19MHZ_UNLOCK
19 MHz PLL is unlocked
2
10MHZ_UNLOCK
10 MHz PLL is unlocked
3
RB_UNLOCK
Optional Rb oscillator is unlocked
4
OUTPUT_DISABLED
The output is disabled
5
PHASE_SHIFT
The output is scheduled to shift phase.
6 Reserved
7 Reserved
The interpretation of the SYNTH parameter is similar to that of the lock status register
(LCKR? command). The difference is that the SYNTH parameter bits indicate the current
state of each bit, while the lock status register bits indicate whether the bits have been set
since the register was last read.
The ERRORS parameter displays the number of errors currently stored in the error
buffer. The errors may be retrieved one by one over the remote interface by repeatedly
sending the LERR? command. See the CG635 Remote Programming chapter for
information about the meaning of errors returned by the LERR? command.
The parameters R, N, D define the current state of the RF synthesizer. They satisfy the
equation,
OUT
D
DDS
f
N
R
f
2
=
,
