Tektronix Tektronix SPG8000, Technical Reference

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Speci fi cations
Option GPS speci fi cations
The following tables list the electrical and environmental characteristics of the
GPS Synchronization and Timecode option.
Table 26: GPS or GLONASS antenna input
Characteristic Performance requirements Reference information
Input type 50 Ω BNC; internally terminated
Input signal level minimum (typical) > 18 dB above ambient level Nominal gain of antenna minus cable loss,
so a 35 dB antenna can have 17 dB cable
loss at 1.575 GHz.
Return Loss (typical)
8 dB at 1575 MHz
Input has a narrow RF fi lter so it re fl ects
most energy not near the GPS or GLONASS
signal frequency.
DC Antenna power output voltage
(typical) 3.3 or 5 V at nominal load Sourced on Antenna input. May be enabled
or disable. Approximately 12
Ω internal
resistance so open circuit voltage is greater.
Open circuit voltage is typically 3.8 V and
5.4 V.
DC Antenna power output current
(typical) 55 mA.
Antenna fault thresholds (typical) “OPEN” if <10 mA, “SHORT” if >100 mA.
Else “Nominal” Antenna power state is displayed on UI in
GPS status screen. Rear LED shows green
fl ashing if open, green steady if nominal, red
if shorted, and off if the power is not enabled.
Table 27: GPS timebase
Characteristic Performance requirements Reference information
Reference modes User may select Internal or External lock to
GPS Reference or to Video Reference. “Internal” sets the frequency to nominal.
“External” sets the timebase relative to the
GPS or GLONASS input and aligns the
frames to extrapolate back to the SMPTE
Epoch.
Video genlock sets timebase relative to
incoming timebase.
Operation when loses lock User may select Internal or holdover called
“Stay Current Frequency”. “Internal” reverts
to the nominal frequency as calibrated. “Stay
Current Frequency ” holds the last valid
frequency from before the input was lost.
Location modes
(GPS mode only) User may select “Fixed” or “Mobile”. “Fixed” stores a well-averaged position and
then uses that until set to reacquire. “Mobile”
recalculates the position continuously and
thus has a higher timebase variation.
16 SPG8000 Speci fi cations and Performance Veri fi cation