Two LFSRs are constructed per the GPS ICD, and the first is added to selected taps of the second to produce the selected final PRN sequence.
With io_in[2:7] set to 2 to select PRN2, reset and then drive the clock; the output sequence on io_out[2] will start with 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1.
# | Input | Output |
---|---|---|
0 | clock | G1 |
1 | reset | G2 |
2 | prn[0] | Selected PRN |
3 | prn[1] | none |
4 | prn[2] | none |
5 | prn[3] | none |
6 | prn[4] | none |
7 | none | none |