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Global Navigation Satellite Systems (GNSS), presently a USD 20 billion industry, has steadily growing applications in all possible spheres with some new high precision applications like indoor navigation etc. are at the cutting edge of the technology, thus requiring sophisticated FECs. In lieu of these facts and more, in this paper we undertake thorough analysis and comparison of Advanced FEC (such as LDPC Convolutional Code) versus Traditional FEC for finite length GNSS data frames on parameters such as computational complexity, processor complexity, delay, memory requirement and BER performance (depending on block length, memory ) etc . Based on the above analysis, finally we shall be proposing the best fit FEC for present and future generation GNSS.

This letter describes a serial output sign and magnitude successive approximation A/D converter. After deciding the sign bit at the first clock pulse the signal is applied in one polarity to an A/D which uses minimum hardware. Off the shelf TTL IC's have been used. Parallel output can be obtained with minor modifications.