( 2 milliseconds of drift per hour).
VARIABLE
DEFAULT
DESCRIPTION
mode
0
TFP operational mode
timecode
IRIGB
reference timecode expected
format
modulated
modulated timecode expected
gencode
IRIGB
TFP generates IRIGB
path
1
path selection variable (see 'P' packet)
local
0
.
local time offset (GPS modes only)
accum
32000
_
VCXO DAC value (nominally centered)
leapsec
0
GPS to UTC leap second correction (only used in GPS modes)
MODE 1 F R E E RUNNING MODE
This mode is virtually the same as mode 2. Without a 1PPS input the TFP runs at the last known
oscillator frequency. Major time can be set with the 'B' packet. The TFP timebase can be adjusted
with packet 'D'.
MODE 2 E X T E R N A L 1 PPS MODE
The TFP synchronizes to the signal on the 1PPS input. Major time can be loaded with the 'B' packet.
The acquisition range is the same as described in mode 0.
- MODE 3 R E A L TIME CLOCK MODE
The TFP synchronizes to the onboard real time clock (RTC) IC, and the major time is also derived
from the clock IC. The RTC is battery backed. This mode is not recommended when using the oven
oscillator because the accuracy of the RTC is not high enough to ensure that the oven will be able
to track it with slippages. See Mode 0 description.
MODE 4 D I G I T A L SYNC MODE
This mode is not implemented.
MODE 5 G P S MODE WITH GPS RECEIVER ONBOARD
The TFP only supports this mode in the bc735VME / bc357VXI configuration. It currently available
in only a double wide 6U form factor.
MODE 6 G P S MODE WITH GPS RECEIVER LOCATED IN THE ANTENNA
This is an optional mode available with the bc637VME / bc357VXI configuration. It is described
in a separate manual.
MODE 7 D I A G N O S T I C AND DEFAULT SETTING MODE
Initially this mode was provided to allow the TFP to be photographed. The LED display is loaded
with static time
12:34:56.
As more battery backed parameters were added it became useful to use
this mode as a means of setting all battery backed data to standard defaults. This data and the default
values established by mode 7 are as follows.
1
1
1
4-2
bc635VME/bc350VXI Manual
Datum Inc., Bancomm Div.