[time-nuts] Factors other Than Antenna Splitters

johncroos at aol.com johncroos at aol.com
Fri Oct 12 11:02:24 EDT 2012


Hello All -

The recent discussion on the use / not use of splitters affecting GPS
timing performance may be further informed by this table. It was 
extracted from
page 5-8 of the

"Thunderbolt Disciplined Clock User Guide"
Version 5.0
Part Number: 35326-30
November 2003

Table 5-1 GPS Error Sources

Error Source 1 Standard Deviation 5 - 50 ns
Atmospheric Models (Ionosphere) 5 - 50 ns
Receiver noise (Multipath) 1 - 20 ns
Satellite Clock Model 10 ns
Satellite Orbit Model 5 ns
Antenna Survey 1 ns

Paragraph 5.2 on the same page indicates the timing between two
sites to be +/-15 ns 3 sigma for the T-bolt

My take on this as an old microwave guy and non-timing expert is that
there are problems greater than splitter cross-talk and variations in 
cable
propagation delay at least for simple systems using only L1.

The more learned in these matters may be able to refine the above.

For those interested in measuring splitter effects,please remember that 
no
splitter will perform correctly unless terminated on ALL ports in its 
design
impedance. This is especially true for isolation.

- best regards john roos k6iql







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