GNSS-equipmentSP has equipment for GNSS (Global Navigation Satellite Systems) for applications in Time and Frequency, Positioning and Atmospheric Studies.
The time and frequency laboratory has about seven GPS-receivers in operation continuously. One of them is a combined GPS/GLONASS-receiver. Four of the receivers are code-receivers that are used for time and frequency applications only. Three of the receivers are of geodetic-type that also have the possibility to measure changes of the phase of the carrier signal from the satellites. These observations provide much more precise measurements and are used for both time and frequency and positioning.
All receivers are located inside the laboratory and receive signals from one single antenna through a 70-m temperature regulated cable and power splitters. The antenna is located on top of a 3-m high reinforced and temperature regulated concrete pillar. To protect the antenna from the environment it is located inside a plastic radome (see the pictures). The pillar is anchored to the primary rock with reinforcing bars. The cable which is partly visible inside the radome is going through a pipe inside the pillar and under ground to the buildings.
Another surrounding pipe contains cold water used for temperature regulation of the antenna cable and the pillar. Several temperature sensors are installed for a continuous registration of the temperature of the outside environment, the pillar, the radome and the water in the pipe.
A stable temperature environment is very important, especially for time and frequency applications.
SP has also developed a method for temperature regulation of the air inside the radome for a temperature regulation of the antenna with its preamplifier. The method is also preventing snow and ice from accumulating on the radome which may effect the accuracy of the measurements.