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,rx_strobe_i,tx_strobe_i,mask_i,degree_i,len_i,
23 rx_in_i_i,rx_in_q_i,rx_i_o,rx_q_o,rx_strobe_o,
26 input clk_i; // Master clock
27 input rst_i; // Subsystem reset
28 input ena_i; // Subsystem enable
29 input rx_strobe_i; // Strobe every received sample
30 input tx_strobe_i; // Strobe every transmitted sample
32 input [15:0] mask_i; // PN code LFSR mask
33 input [4:0] degree_i; // PN code LFSR sequency degree
34 input [15:0] len_i; // PN code LFSR sequence length
35 input [15:0] rx_in_i_i; // I channel on receive
36 input [15:0] rx_in_q_i; // Q channel on receive
38 output [15:0] rx_i_o; // I channel of impulse response
39 output [15:0] rx_q_o; // Q channel of impulse response
40 output rx_strobe_o; // Impulse response value ready
42 input loop_i; // Implement loopback
44 wire strobe_in = loop_i ? tx_strobe_i : rx_strobe_i;
45 wire [16:0] len = loop_i ? (len_i - 1) : ((len_i << 1) - 2);
47 strobe #(17) phase_strobe(.clk_i(clk_i),.rst_i(rst_i),.ena_i(ena_i),
48 .rate_i(len),.strobe_i(strobe_in),.strobe_o(rx_strobe_o),
52 wire ref_strobe = tx_strobe_i & ~rx_strobe_o; // Retard reference phase once per period
54 ( .clk_i(clk_i),.rst_i(rst_i),.ena_i(ena_i),.strobe_i(ref_strobe),.mask_i(mask_i),.pn_o(pn_ref) );
56 wire [5:0] offset = (5'd16-degree_i);
58 reg [31:0] sum_i, sum_q;
59 reg [31:0] total_i, total_q;
60 wire [31:0] scaled_i = total_i << offset;
61 wire [31:0] scaled_q = total_q << offset;
62 wire [31:0] i_ext, q_ext;
64 sign_extend #(16,32) i_extender(rx_in_i_i, i_ext);
65 sign_extend #(16,32) q_extender(rx_in_q_i, q_ext);
67 wire [31:0] prod_i = pn_ref ? i_ext : -i_ext;
68 wire [31:0] prod_q = pn_ref ? q_ext : -q_ext;
70 always @(posedge clk_i)
80 total_i <= sum_i + prod_i;
81 total_q <= sum_q + prod_q;
87 sum_i = sum_i + prod_i;
88 sum_q = sum_q + prod_q;
91 assign rx_i_o = scaled_i[31:16];
92 assign rx_q_o = scaled_q[31:16];
94 endmodule // sounder_rx