Sentinel: GNSS Cable and Antenna Group Delays

Sentinel is sold with a 20m length cable and a TW3442 Multi-Constellation Antenna.

Electrical cables will introduce a delay of 5ns per metre, the 20m cable equates to a delay of 100ns.

The group delay values for the antenna are

• 33.5nS @ 1575.42MHz

• 31.4nS @ 1590MHz

• 44.7nS @ 1606MHz

GPS and Galileo are centred at about 1575MHz and Glonass at about 1606MHz.

Therefore, in addition to cable delay customers may wish to add 34ns antenna delay if GPS or Galileo are used and 45ns for Glonass.

This is a relatively insignificant amount when measuring a full network but may be useful to improve measurement accuracy for smaller sections, e.g. moving closer to the PRTC.