Specifications - Novatech 409B Instruction Manual

are dependent upon your supplied clock. See specifi-
cations for signal levels required and acceptable fre-
quency range. If you wish to maintain this setting,
use the save command "S".
3.10 The external clock can also be used with Kp=1
for direct connection to the DDS generator. With
Kp=1, the PLL multiplier is disabled. Use this direct
input, up to 500 MHz, for optimum phase noise per-
formance.
When using an external clock, frequency scaling of
the "F" command may be required. Please see
Operation, Section 4, for details. If your unit has the
/R option installed, see Appendix B.
3.11 Signal Outputs. There are four signal outputs
on the 409B labelled 0 to 3 on the front panel BNCs.
These correspond to channels F0 through F3, and
other commands. Simply connect your 50Ω applica-
tion cable to appropriate output.
3.12 Mounting. An optional 1U rack adapter is
available for mounting up to four 409B into a rack
panel. Please consult factory.
4.0 Operation
4.1 Power on reset. After power is applied, the
409B takes approximately 500ms to initialize. Com-
mands sent during this time will be ignored or may
cause erroneous operation.
4.2 Specifications are met within approximately 15
minutes of power up.
4.3 After the 409B has been installed in the cus-
tomer application system, all that is required for
operation is to send the appropriate serial commands
per Table 2.
4.4 The user host computer software must properly
format the serial commands. Incorrect formatting
will result in an error code being returned. See Table
1 for a list of error codes.
4.5 For maximum interface speed, it is suggested
that Echoing be disabled by the "E d" command.
This will allow the host to send characters at a faster
NOVATECH INSTRUMENTS
NOTE:
rate. Note that no flow control is provided. Depend-
ing upon your host, the 409B may not be able to
keep up with serial characters. The 409B will
respond with an "OK" for a correctly received data
command. You will have to verify correct operation
at your host rate.
4.6 A special baud rate command is available if you
wish to set a different baud rate. The value set by
this command is volatile and not saved in EEPROM.
Upon power up, reset or clear, the 409B defaults to
19.2kBaud.
Kb 78
Kb 3c
Kb 1e
Kb 14
Kb 0a
4.7 If you are using an external clock, the value sent
to the 409B in the "Fn" command must be scaled.
The output frequency of the 409B when used with
an external clock is given by:
F = (F
out command
Where K
pe
customer, and K
(0x0f).
4.8 The nominal Internal Clock has a value of
28,633,115.306666666 Hz (2
mance is obtained when the External Clock input
times the Reference PLL multiplier (Kp) is close to
the default value (429.4967296 MHz, max: 500
MHz), as the on-board filters are optimized for that
range.
4.9 For an example of scaling, suppose an external
clock of 10.000 MHz is used and an output of 1.544
MHz is desired (Kp=15):
F = (1.544)*(15*28,633,115.306666667)
command
(15*10,000,000)
= 4.4209530
4.10 The command then sent to the 409B for the
1.544 MHz output, with a 10 MHz external clock,
will be (assuming Kp is unchanged):
5
;9.6kBaud
;19.2kBaud
;38.4kBaud
;57.6kBaud
;115.2kBaud
/
)*(K *F ) (K
pe ext clk
is the value of Kp set by the
is the internal default Kp
pi
32
/150). Best perfor-
409B Manual, 17-Apr-2015
*F )
pi int clk
/