Iranian Permanent GPS Network: Strategy and ProcessingRegional networks are in tehran,tabrize and mashhad areas and the distance between the stations is about 25-30 km. Tehran as the capital with 12million population located in the southern mountain foots of central alborz in a highly active zone. In order to monitor tectonic deformation in this area 25 stations are established in different part according to geological and geodetical parameters. Fig 3  Fig 3- Tehran Network In the western and eastern Azerbaijan and ardabil areas there are many active faults such as Tassouj and north Tabrize faults. Tabriz city is located at 100km distance from this fault and historical earthquakes with 6 to 7 Richter have occurred in this area. So in order to monitor this part 20 stations are established. Fig 4  Fig 4- Tabriz Network The 3 cities of mashhad and neishaboor and sabzevar had also historically shaken by many earthquakes which destroyed the areas and killed many people due to neishaboor dasht-bayaz and kopet-dag faults. So 21 stations are established in order to monitor the active tectonic of this area. Fig 5  Fig 5- Mashhad Network Fig 3 to Fig 5 Consist also base network stations. 3) Observation Station: The function of observational station is to receive signal from GPS satellite, to accumulate them and to communicate with data center. For this purposes each station is provided with a GPS antenna, GPS receiver, communication device and backup battery. The GPS antenna is fixed on a station pillar. The receiver and other equipment are stored in the rack near Pillar. A reinforce concrete pillar is 1.5m highs standing on the reinforced concrete base (1.20m * 1.20m)and 2m cube.The base of the pillar is reinforce concrete too. A rack near the pillar keeps the GPS receive, the modem and other instrument. A fan attach to the top of the rack is controlled to keep air condition suitable for instruments and also heather for temperature control. Cables and electric power supply and telephone line are buried underground in order to preserve diminish vibration effect by wind. Since it is expected that uneven subsidence of a pillar might occur a tilt meter installed in order to check any inclination from the initial state. 93 of the station also equipped with meteorological sensor for GPS meteorology. Fig 6  Fig 6- GPS receiver and equipment GPS receivers installed in the rack are dual frequency from Ashtech uz12(ICGRS)and CGRS with 128 MB internal memory. All receivers are scheduled to receive dual band carrier phase data and code data every 30 seconds in daily mode(24h). Fig 7  Fig 7- GPS Station Antenna is set on the top of the pillar coverd with a radom. 85% of remote stations are equipped with modems and commercial telephone lines and 15% was setup with GSM modem. A transmission of 9600 bps is available for the connection to the data centre. |