3 // USRP - Universal Software Radio Peripheral
5 // Copyright (C) 2007 Corgan Enterprises LLC
7 // This program is free software; you can redistribute it and/or modify
8 // it under the terms of the GNU General Public License as published by
9 // the Free Software Foundation; either version 2 of the License, or
10 // (at your option) any later version.
12 // This program is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 51 Franklin Street, Boston, MA 02110-1301 USA
22 module sounder_rx(clk_i,rst_i,ena_i,sum_strobe_i,ref_strobe_i,
23 mask_i,degree_i,rx_in_i_i,rx_in_q_i,rx_i_o,rx_q_o);
25 input clk_i; // Master clock
26 input rst_i; // Subsystem reset
27 input ena_i; // Subsystem enable
28 input sum_strobe_i; // Strobe on last sample per period
29 input ref_strobe_i; // PN code reference retarded one sample per period
31 input [15:0] mask_i; // PN code LFSR mask
32 input [4:0] degree_i; // PN code LFSR sequency degree
34 input [15:0] rx_in_i_i; // I channel on receive
35 input [15:0] rx_in_q_i; // Q channel on receive
37 output [15:0] rx_i_o; // I channel of impulse response
38 output [15:0] rx_q_o; // Q channel of impulse response
40 reg [31:0] sum_i, sum_q;
41 reg [31:0] total_i, total_q;
42 wire [31:0] i_ext, q_ext;
44 sign_extend #(16,32) i_extender(rx_in_i_i, i_ext);
45 sign_extend #(16,32) q_extender(rx_in_q_i, q_ext);
49 ( .clk_i(clk_i),.rst_i(rst_i),.ena_i(ena_i),.strobe_i(ref_strobe_i),.mask_i(mask_i),.pn_o(pn_ref) );
51 wire [31:0] prod_i = pn_ref ? i_ext : -i_ext;
52 wire [31:0] prod_q = pn_ref ? q_ext : -q_ext;
54 always @(posedge clk_i)
72 sum_i <= #5 sum_i + prod_i;
73 sum_q <= #5 sum_q + prod_q;
76 wire [5:0] offset = (5'd16-degree_i);
77 wire [31:0] scaled_i = total_i << offset;
78 wire [31:0] scaled_q = total_q << offset;
79 assign rx_i_o = scaled_i[31:16];
80 assign rx_q_o = scaled_q[31:16];
82 endmodule // sounder_rx