A.N. Karutin, S.N. Karutin, V.N. Kharisov
System of differentional correction and monitoring demands high data rate up to 3330 bits/s from GEO satellite. This occurs because the amount of data from satellite and the total number of the GNSS satellites have increased and in addition integrity must be updated each second. Traditional combination of BPSK and convolutional code leads to reduction of PR sequence length and makes worse its correlation properties.
It is suggested to replace BPSK with orthogonal signals while convolutional code is replaced by Reed-Solomon code. Such combination form concatenated code which inner code is orthogonal signal modulator (512, 9) and outer code is Reed-Solomon (511, 383). In represented structure each orthogonal signal transmits nine bits. User data frame is 4500 bits where informational are 3366 bits and the rest 1134 are checking bits. Consequently data rate is 4500 bits/s and informational symbol duration is 2 ms.
Sigal-to-noise ratio difference between proposed concatenated code and Shannon limit where code rate r = ¾ is 0,74 dB for bit error rate 10-5.
Implementation of such structure will not meet any problems because we can reuse correlators from fast locking-in block which is not utilized after signal detection from any navigation satellite.