* * * WARNING ***
If offsets larger than +/- 990 microseconds are used, then the TFP jamsynch feature must be
turned off using packet 'P'. The reason for this requirement is that under normal operation i f a
difference between the reference time and the TFP time is detected to be greater than +/- 1
millisecond the TFP timebase is "jammed" to the reference time so that a lengthy steering process
is avoided.
4.1.7 PACKET 'H' SET TIMECODE FORMAT FOR MODE 0
Packet
'H'
allows the host to select the timecode format and modulation type. The packet format
is as follows. T h e timecode format and modulation values are maintained in battery backed
RAM.
byte 1 S O H
byte 2
' H '
byte 3 f o r m a t
byte 4 m o d u l a t i o n
byte 4 E T B
format choices
'A' I R I G A
'B' I R I G B
'C' 2 1 3 7 (XR3 with 100Hz symbol rate)
NASA36
'X' X R 3 (25Hz symbol rate)
modulation choices
'M' a m p l i t u d e modulated sinewave
'D' p u l s e code modulation (DC level shift)
DC level shift not is supported for 2137 and XR3 codes.
4.1.8 PACKET 'I' CLOCK SOURCE SELECT
Packet
'I'
is used to select the clock source for the TFP. The TFP uses a frequency of 10MHz for all
timing functions. The 10 MHZ be may derived from the TFP VCXO or it may be supplied from an
external oscillator via J1 pin#1 or P2 pin#C22. The packet format is as follows.
byte 1 S O H
byte 2 ' I '
byte 3 ' E ' or 'I' External or Internal
byte 4 E T B
On power on the TFP always defaults to the internal oscillator selection.
4-6 b c 6 3 5 V M E / b c 3 5 0 V X 1 Manual
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Inc., Bancomm Div.
