Antenna Cable
All GNSS station cabling is vulnerable to vandalism, weather, pests and fire. Externally running cables can be protected by using buried or secured conduits. Dedicated cableways are recommended within buildings. Cable connectors are potential points of failure when stressed, corroded, or infiltrated by water, dust and pests. The use of a self-amalgamating ultra-violet stabilised tape to protect cable connections is recommended. Tension in the cable at the receiver and antenna connection may place stress on the connection causing failure or intermittent connection. At the antenna this tension may also cause the antenna to rotate. A short loop of excess cable at the antenna and receiver connections is recommended. The quality of antenna cables is categorised by its rated signal loss per metre. Higher grade cables have less signal loss per linear metre at the expense of increased cost and decreased cable flexibility. Each connection along a cable increases the signal loss and adds a potential point of failure. Where inflexible high-grade cables are used for the main cable run, a short flexible lead of lower grade cable may reduce stress on the antenna or receiver connection. An unstressed cable of minimum length with minimal connectors provides an optimal solution.
An in-line amplifier reduces signal loss to the receiver, but adds another point of failure. Use higher rated low-loss cable in preference to lower rated cables with in-line amplifiers. Antenna splitters should only be used when the GNSS site includes multiple GNSS receivers, or for test purposes.
Cable Type¶
The cable type must be sufficient for the intended length of the cable run. It is recommended to use high-quality low-loss cables with a loss < 0.2 dB/m at the L1 frequency. The usage of cable connectors as well as total cable length should be minimised.
Cable Protection¶
Protect cables from weather, pests and other factors that could damage the cable. The use a suitable conduit is recommended. The antenna cable connectors should be sealed with self-amalgamating ultraviolet stable tape for protection against water infiltration and ultraviolet radiation.
Cable Tension¶
The tension in the antenna cable should be minimised, particularly at the receiver and antenna interface.
In-Line Amplifiers¶
The use of in-line amplifiers should be avoided where possible. If in use, details must be stated in the station metadata.
Cable Splitters¶
Antenna splitters should only be used if other receivers are connected to the antenna. If in use, details must be stated in the station metadata.
Lightning Protection¶
Include a grounded lightning protector to the antenna cable. In lightning prone areas, reduce the horizontal cable-run length to minimise the risk of signal induction from nearby lightning strikes.