OPTION DESCRIPTIONS
GPS OPTION 07A 5 MHZ SINE WAVE SHAPER
ASSEMBLY 20457-25
1.0 INTRODUCTION
This option description provides Phase Noise and Harmonic specifications, an explanation of the
Sine Wave Shaper logic used to develop the Sine Wave output and adjustment of the output
amplitude.
This Shaper/Assembly can be plugged into the J7/J9, J8/J10, J18/J22, or J19/J23 option areas of
the GPS Motherboard Assembly. The 5 MHz Sine Wave output will be present on rear panel
BNCs J3B, J3C, J3E, or J3F respectively.
1.1 SPECIFICATIONS
The following specifications apply at 13dbm output level using an oven oscillator. These
specifications are worst case.
Harmonics -35 dBc
Spurious Noise -35 dBc
Phase Noise
1Hz -76 dBc/Hz
10Hz -103 dBc/Hz
100Hz -112 dBc/Hz
1KHz -114 dBc/Hz
10KHz -116 dBc/Hz
100KHz -119 dBc/Hz
1.2 FUNCTIONAL EXPLANATION
A 5 MHz square wave derived from the 10MHz internal oscillator is input to J1 pin 7 of the Sine
Wave Shaper Assembly. The signal is filtered and shaped to generate the 5 MHz Sine Wave
output at P1 pin 2 of the same assembly.
This signal is then routed to a rear panel BNC. Refer to the GPS Option/Connector
Configuration sheet at the beginning of the ExacTime User’s Guide for the output connector
designation. Refer to the Top Assembly Drawing for connector location. This signal is
adjustable from zero to six volts peak-to-peak and has been factory adjusted to three volts peak-
to-peak into a 50Ω load.
1.3 OUTPUT AMPLITUDE ADJUSTMENT
The output amplitude of this signal can be adjusted to the desired amplitude using LEVEL
potentiometer R13, on the Sine Wave Shaper assembly.
Symmetricom Inc ET6 ExacTime GPS TC & FG (Rev C) C-17
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