Siemens RUGGEDCOM RX1400 Installation Manual

Also see for RUGGEDCOM RX1400: Reference guide Installation guide Installation manual

RUGGEDCOM RX1400Installation GuideChapter 2Installing the DeviceConnecting a GPS Antenna 17IMPORTANT!A site survey is recommended prior to any installation to help determine the best location for the GPSantenna. For assistance, contact a Siemens Sales representative.IMPORTANT!Although it is impossible to protect the antenna from a direct lightning strike, the antenna andconnected components can be protected from secondary effects through site selection and by installingprotection devices.Install the antenna at least 15 m (49 ft) away from and lower than any structures that attractlightning. GPS antenna damage is usually not the result of a direct lightning strike, but due to highcurrents induced by the effects of a lightning strike on a nearby structure. Lightning arrestors shouldalso be installed in the antenna line to protect the receiver and connected devices. If a lightningarrestor is installed, it is important to make sure it has a low impedance path to ground.To promote signal reception and avoid signal saturation at the receiver input, the overall GPS system requires arelative gain between 5 and 18 dBi.Use only low loss, 50 Ω coaxial cabling when connecting the GPS and any other optional components to theRX1400.NOTEUsing any length of coaxial cable will add some time delay to the GPS signal, which degrades theaccuracy of the calculated time and position. The time delay is dependent on the type of dielectricmaterial in the cable and ranges from 1 to 2 ns/ft. The table below gives some examples of the delaythat can be expected based on the dielectric type.Dielectric Type Time Delay (ns/ft) Propagation Velocity (% of c)Solid Polyethylene (PE) 1.54 65.9Foam Polyethylene (FE) 1.27 80.0Foam Polystyrene (FS) 1.12 91.0Air Space Polyethylene (ASP) 1.15 to 1.21 84 to 88Solid Teflon (ST) 1.46 69.4Air Space Teflon (AST) 1.13 to 1.20 85 to 90To connect a GPS antenna, do the following:1. Mount the antenna to a pole or wall in an area that provides good signal coverage and is away from anysignal noise emanating from other communications equipment. Make sure 90° of the sky is visible to theantenna.2. If required, connect the optional lightning arrestor, line amplifier or bandpass filter to the antenna.