FIFO DATA PACKETS
Symmetricom, Inc.
bc620/627AT Time and Frequency Processor
4-9
Modulation Choices
“M”
Amplitude modulated sinewave.
“D”
Pulse 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 10MHz be may derived from the TFP VCXO or it may be supplied
from an external oscillator via J1 pin#1. The packet format is as follows:
byte
1
SOH.
byte
2
“I.”
byte
3
“E” or “I” External or Internal.
byte
4
ETB.
On power on the TFP always defaults to the internal oscillator selection.
4.1.9 PACKET “J” - SEND DATA TO THE GPS RECEIVER (bc627AT only)
The format and content variations are discussed in a separate User's Guide.
4.1.10 PACKET “K” - SELECT GENERATOR CODE
The time code generated by the TFP is selected by packet “K.” Only two options are available
as described below. The generator code type is maintained in battery backed RAM.
byte
1
SOH.
byte
2
“K.”
byte
3
Code.
byte
4
ETB.
Code Options
“B”
Generate IRIG B amplitude modulated and DC level shift.
“H”
Generate IRIG H DC level shift only.
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