fsk_demod.vhd

通信系统的FSK调制程序

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity FSK_Demod is
port(
	clk : in std_logic;
	FSK_in : in std_logic;
	Demod : out std_logic
	);
end FSK_Demod;

architecture behave of FSK_Demod is
signal cnt : std_logic_vector(7 downto 0);
begin
	process(clk)
	begin
		if rising_edge(clk) then
			cnt <= cnt + 1;
		end if;
	end process;
	
	process(FSK_in)
	variable m : integer range 0 to 6;
	begin
		if cnt > "11000000" then
			if m >= 2 then
				Demod <= '1';
			else
				Demod <= '0';
			end if;
		elsif rising_edge(FSK_in) then
			m := m + 1;
		end if;
	end process;
end behave;