OPTION
DESCRIPTIONS
TM Option 18
Slow Code
Assembly 19400
1.0 INTRODUCTION
This assembly is used to provide the serial Five-Rate Slow Code time output for the user.
1.1
SLOW CODE DESCRIPTION
The serial code (see Figure 1) is a 33-bit, amplitude and pulse-width modulated DC level-shift code.
The code is composed of a reference marker, four code words, or seconds, minutes, hours, and days,
followed by index markers to complete the time frame. Each code word contains sub-words as
necessary to represent the units, tens, and hundreds of units. Each sub-code is weighted in a binary
coded decimal (BCD) manner.
Codes 1, 2, and 3 have a frame length of 50 precise intervals. Codes 4 and 5 have a frame length of
60 precise intervals. Leading edges of all pulses are coincident with the leading edges of the time
code frame intervals.
One pulse is deleted at the beginning and the end of each code word between each sub-code word.
Index markers complete the time frame after the time-of-year word has been read.
The amplitude and pulse-widths of the time frame information are as follows:
AMPLITUDE
Binary
1
+5V
DC
nominal
Binary
2
+2V
DC
nominal
PULSE WIDTH
Reference Marker
100% of bit interval
Binary 1
50% of bit interval
Binary 0
20% of bit interval
1.2 INSTALLATION
This assembly may be plugged into any available option position. Remove power from the
TM7000. Plug this assembly into the PTS, being careful that components are on the top side.
Interconnect to the desired destination equipment. Apply power.
1.3 OPERATION
Operation of this option is normally transparent to the user. Selection of the output automatically
follows the operating mode so that the time displayed on the TM7000 LED display, whether
translator or generator, is output in the serial word. The user may optionally defeat this automatic
selection by the installation of a jumper. To force continuous output of generated time, jumper E1
to E2. To force continuous output of translated time, jumper E2 to E3.
Symmetricom, Inc.
TM7000 TymMachine TCG/T (Rev D)
A-41