Verilog学习笔记（四）QPSK调制实现 Verilog的QPSK调制实现

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概述

Verilog的QPSK调制实现

QPSK调制一般采用两种方式：（1）调相法（2）四相位选择法

一、调相法

利用三段式状态机，实现由输入信号输出两路正交相位调制输出

`timescale 1ns / 1ps
//
// Company: 
// Engineer: 
// 
// Create Date: 2019/07/27 13:23:19
// Design Name: 
// Module Name: QPSK
// Project Name: 
// Target Devices: 
// Tool Versions: 
// Description: 
// 
// Dependencies: 
// 
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
// 
//


module QPSK(clk,rst_n,din,valid_in,out_real,out_imag,valid_out);

 input clk;
 input rst_n;
 input valid_in;     //控制信号输入
 input din;          //输入信号
 output out_real;    // 实部输出
 output out_imag;    //虚部输出
 output valid_out;   //已调制后信号输出的标志

 reg[15:0] out_real;
 reg[15:0] out_imag; 
 reg       valid_out;
  
 reg[1:0]  temp;
 reg[1:0]  state;
 reg[1:0]  nextstate;
 
 parameter IDLE=2'b00,state1=2'b01,state2=2'b10,
           ONE=16'h0fff;
 
 always@(posedge clk)  
   begin
     if(!rst_n)
       state <= IDLE;
     else
       state <= nextstate;
   end
   
  always@(* )
    begin
      if(!rst_n)
        nextstate <= IDLE;
      else
        begin
              case(state)     	 
              	 IDLE:
              	   begin
              	     if(valid_in == 1'b1)
                      nextstate <= state1;
                     else                     
              	  	   nextstate <= state; 
                   end
              	   	   
              	 state1:
              	  begin                    
              	  	 if(valid_in == 1'b1)          
              	 	   nextstate <= state2;
              	 		 else                     
              	  	   nextstate <= state;  	   
              	  end                       	   
              
                state2:
              	  begin                    
              	  	 if(valid_in == 1'b1)          
              	 	   nextstate <= state1;
              	     else                     
              	  	   nextstate <= state;  	   
              	  end                     
                default:nextstate <= IDLE;
              endcase
            end
        end
      
    
    
 always@(posedge clk)
   begin
     if(!rst_n)
       temp <= 2'b00;
     else
       begin
         if(valid_in)
            temp <= {temp[0],din};
         else
             temp <= temp;
       end
   end
   
  always@(posedge clk)
   begin
     if(!rst_n)
       begin
         out_real <= 16'b0000_0000_0000_0000;
         out_imag <= 16'b0000_0000_0000_0000;
       end
     else
       begin
       	 if(state==state2)
       	   case(temp)
       	   	 
           2'b00:
             begin
                 out_real <= ONE;
                 out_imag <= ONE;
             end
             
           2'b01:
             begin
                 out_real <= ~ONE;
                 out_imag <= ONE;
             end
             
           2'b11:
             begin
                 out_real <= ~ONE;
                 out_imag <= ~ONE;
             end
           
           2'b10:
             begin
                 out_real <= ONE;
                 out_imag <= ~ONE;
             end
           
           default:
             begin
                 out_real <= 16'h0000;
                 out_imag <= 16'h0000;
             end
           endcase
         else
           begin
             out_real <= 16'b0000_0000_0000_0000;
             out_imag <= 16'b0000_0000_0000_0000;
           end
       end
     end
       
 always@(posedge clk)
   begin
     if(!rst_n)
       begin
         valid_out <= 1'b0;
       end
     else
       begin
       	 if(state==state2)
           valid_out <= 1'b1;
         else
           begin
             valid_out <= 1'b0;
           end
       end   
    end   
endmodule

二、四相位选择法


module qpsk(clk,rst,x,y)
input clk,rst;
input x;   //系统输入信号:每4个∞1k周期输入一个x的值
output y;  /QPSK调制输出信号:在8个ck周期内按bit输出
 
reg [2: 0]count   //计数器
reg [1: 0] xreg;  //输入信号的中间寄存器
reg [1: 0] yreg;
reg[3:0] carriers;//4路载波信号

/实现QPSκ解调
assign y =(yreg == 2'b00)? carriers [3]:
(yreg == 2'b01)? carriers [2]:
(yreg == 2' b10)? carriers [1]:
(yreg == 2 b11)? carriers [0] :0;

//完成计数器,从而对模块时钟分频
always @(posedge clk or negedge rst)
if(!rst)
	count <= 3'b000;
else
	count <= count +1
//寄存输入:每4个c1k周期,将输入x寄存到xreg中


always @(posedge clk or negedge rst)
if(!rst)
	xreg <= 2'b00;
else
	if(count[1:0]==2'b11)
		xreg <= {xreg[0],x};
	else
		xreg <= xreg;

//产生载波信号并且每8个周期将奇存器xeg的值送到yreg中,供后面判断输出
always @(posedge clk or negedge rst)
if(!rst)
	begin
		carriers <= 4'b000;
		yreg <= 2'b00;
	end
else
	begin
		case(count)
			3'b000:begin
						yreg <= xreg;
						carriers <= 4'b1100;
						end
			3'b010:carriers <= 4'b1001;
			3'b100:carriers <= 4'b0011;
			3'b110:carriers <= 4'b0110;
			default:carriers <= carriers;
		endcase
	end
endmodule