A. Seif Pour Abolhassani1 , V. Gholami1
1GeoPersian Company, Tehran, Iran
In the world of seismology there are situations that we need to use a recording system in a place that has no access to open sky, or in a place with high electronic noise from cell phones or satellites. The question is what should be done in these situations in order to have clean data from the time point of view? Available GPS antennas are usually produced with a length of 5metres in the market. There are very few GPSs that support longer cables. The high frequency of GPS signals results the high precision of positioning. Most GPS antennas are an amplifier, and because they receive their 3.3V power from the source they cannot make high amplification, and the 5 meter cable limit came from this problem. With a small external noise source the GPS cannot act normally and GPS cannot lock data quickly and easily. This paper presents a GPS system which digitizes the data at the source, then transfers to the recording media. This protocol gives high performance cables with lengths more than 30-50 metres, and theoretically up to 200 metres.