FFT Splitting for Improved FPGA-Based Acquisition of GNSS Signals

Table 4

Details of the resources for the different algorithms using the Altera FFT for the L5, E5a, E5b, and E1 signals, considering time multiplexing.

Implementation	Function	Logic usage	Memory usage	Multipliers usage
		(ALM)	(M20K)	(DSP blocks)
3-FFT solution; (Figure 5(a))	3 FFTs (65 536 points)	3 × 2920	3 × 608	3 × 12
	1 multiplier	0	0	2
	Total	8760	1824	38
5-FFT solution; (Figure 6)	3 FFTs (32 768 points)	3 × 2758	3 × 264	3 × 12
	1 multiplier	0	0	2
	Total	8274	792	38
Proposed 9-FFT solution; (Figure 7)	3 FFTs (16 384 points)	3 × 2883	3 × 140	3 × 12
	4 multipliers	0	0	4 × 2
	Combinations for	28	0	0
	Combinations for	64	0	1
	Combinations for	64	0	1
	2 memories (32 768 points)	0	2 32	0
	Total	8805	484	46
Proposed 15-FFT solution	3 FFTs (8192 points)	3 × 2695	3 × 74	3 × 12
	4 multipliers	0	0	4 × 2
	Combinations for	112	0	0
	Combinations for	224	0	4
	Combinations for	224	0	4
	4 memories (16 384 points)	0	4 16	0
	Total	8645	286	52