diff options
Diffstat (limited to 'gr-sounder/src/fpga/lib/sounder_rx.v')
| -rw-r--r-- | gr-sounder/src/fpga/lib/sounder_rx.v | 87 |
1 files changed, 49 insertions, 38 deletions
diff --git a/gr-sounder/src/fpga/lib/sounder_rx.v b/gr-sounder/src/fpga/lib/sounder_rx.v index b7c5f4878..338afd55e 100644 --- a/gr-sounder/src/fpga/lib/sounder_rx.v +++ b/gr-sounder/src/fpga/lib/sounder_rx.v @@ -19,8 +19,9 @@ // Foundation, Inc., 51 Franklin Street, Boston, MA 02110-1301 USA // -module sounder_rx(clk_i,rst_i,ena_i,rx_strobe_i,tx_strobe_i,mask_i,len_i, - rx_in_i_i,rx_in_q_i,rx_i_o,rx_q_o,rx_strobe_o); +module sounder_rx(clk_i,rst_i,ena_i,rx_strobe_i,tx_strobe_i,mask_i,degree_i,len_i, + rx_in_i_i,rx_in_q_i,rx_i_o,rx_q_o,rx_strobe_o, + loop_i); input clk_i; // Master clock input rst_i; // Subsystem reset @@ -29,6 +30,7 @@ module sounder_rx(clk_i,rst_i,ena_i,rx_strobe_i,tx_strobe_i,mask_i,len_i, input tx_strobe_i; // Strobe every transmitted sample input [15:0] mask_i; // PN code LFSR mask + input [4:0] degree_i; // PN code LFSR sequency degree input [15:0] len_i; // PN code LFSR sequence length input [15:0] rx_in_i_i; // I channel on receive input [15:0] rx_in_q_i; // Q channel on receive @@ -37,48 +39,57 @@ module sounder_rx(clk_i,rst_i,ena_i,rx_strobe_i,tx_strobe_i,mask_i,len_i, output [15:0] rx_q_o; // Q channel of impulse response output rx_strobe_o; // Impulse response value ready - // LFSR phase counter - reg [15:0] count; - wire cycle = (count == (len_i - 1)); + input loop_i; // Implement loopback + + wire strobe_in = loop_i ? tx_strobe_i : rx_strobe_i; + wire [16:0] len = loop_i ? (len_i - 1) : ((len_i << 1) - 2); + + strobe #(17) phase_strobe(.clk_i(clk_i),.rst_i(rst_i),.ena_i(ena_i), + .rate_i(len),.strobe_i(strobe_in),.strobe_o(rx_strobe_o), + .count_o()); - always @(posedge clk_i) - if (rst_i | ~ena_i) - count <= 16'b0; - else - if (cycle) - count <= 16'b0; - else - count <= count + 16'b1; - - // Retard LFSR phase once per cycle - wire lfsr_strobe = (tx_strobe_i & ~cycle); + wire pn_ref; + wire ref_strobe = tx_strobe_i & ~rx_strobe_o; // Retard reference phase once per period + lfsr ref_code + ( .clk_i(clk_i),.rst_i(rst_i),.ena_i(ena_i),.strobe_i(ref_strobe),.mask_i(mask_i),.pn_o(pn_ref) ); - // Recreate local reference of transmitted PN code - wire pn; - lfsr reference - ( .clk_i(clk_i),.rst_i(rst_i),.ena_i(ena_i),.strobe_i(lfsr_strobe),.mask_i(mask_i),.pn_o(pn) ); + wire [5:0] offset = (5'd16-degree_i); + + reg [31:0] sum_i, sum_q; + reg [31:0] total_i, total_q; + wire [31:0] scaled_i = total_i << offset; + wire [31:0] scaled_q = total_q << offset; + wire [31:0] i_ext, q_ext; - wire [31:0] rx_i_ext, rx_q_ext; - sign_extend #(16,32) i_extend(rx_in_i_i, rx_i_ext); - sign_extend #(16,32) q_extend(rx_in_q_i, rx_q_ext); + sign_extend #(16,32) i_extender(rx_in_i_i, i_ext); + sign_extend #(16,32) q_extender(rx_in_q_i, q_ext); - reg [31:0] accum; + wire [31:0] prod_i = pn_ref ? i_ext : -i_ext; + wire [31:0] prod_q = pn_ref ? q_ext : -q_ext; + always @(posedge clk_i) if (rst_i | ~ena_i) - accum <= 32'b0; - else - if (rx_strobe_i) - if (cycle) - accum <= 32'b0; - else - if (pn) - accum <= accum + rx_i_ext; - else - accum <= accum - rx_i_ext; + begin + sum_i <= 0; + sum_q <= 0; + total_i <= 0; + total_q <= 0; + end + else if (rx_strobe_o) + begin + total_i <= sum_i + prod_i; + total_q <= sum_q + prod_q; + sum_i <= 0; + sum_q <= 0; + end + else if (strobe_in) + begin + sum_i = sum_i + prod_i; + sum_q = sum_q + prod_q; + end + + assign rx_i_o = scaled_i[31:16]; + assign rx_q_o = scaled_q[31:16]; - assign rx_i_o = accum[31:16]; - assign rx_q_o = accum[15:0]; - assign rx_strobe_o = rx_strobe_i & cycle; - endmodule // sounder_rx |