1
涓�銆佹槸闈為
1
銆?/p>
鍦ㄥ崟杈瑰甫淇″彿涓彃鍏ュ己杞芥尝锛屽彲鐢ㄥ寘缁滄娉㈡硶瑙ｈ皟鍑哄熀甯︿俊鍙枫�?/p>
锛堝锛?/p>
2
銆?/p>
瀵逛簬璋冮淇″彿锛屼篃鍙互鐢ㄥ叾涓婅竟甯︽垨涓嬭竟甯︿紶杈撲俊鎭�?/p>
锛堥敊锛?/p>
3
銆?/p>
涓嶇
m(t)
鏄粈涔堜俊鍙凤紝鍦?/p>
m(t)cos
蠅
ct
鐨勯璋变腑閮芥病鏈夌鏁ｈ氨
fc.
锛堥敊锛?/p>
4
銆?/p>
鍦ㄦ暟瀛楅�氫俊涓紝鑻ユ棤鐮侀棿涓叉壈锛屽垯璇爜鐜囦负
0
銆?/p>
锛堥敊锛?/p>
5
銆?/p>
鑻ュ甯﹁皟棰戜俊鍙风殑鍩哄甫淇″彿鏈�楂橀鐜囧澶т竴鍊嶏紝鍒欒皟棰戜俊鍙峰甫瀹戒篃澧炲ぇ涓�鍊嶃�?/p>
锛堥敊锛?/p>
6
銆?/p>
鍗曟瀬鎬ф暟瀛椾俊鍙风殑杩?/p>
0
鐮佹椂闂磋秺闀匡紝瑕佹眰浣嶅悓姝ュ櫒鐨勫悓姝ヤ繚鎸佹椂闂翠篃瓒婇暱銆?/p>
锛堝锛?/p>
7
銆佸彧瑕佹棤璇爜锛屽垯
PCM
鎺ユ敹鏈鸿緭鍑烘ā鎷熶俊鍙蜂腑灏辨棤鍣０锛堥敊锛?/p>
鈥?/p>
8
銆佹暟瀛楀熀甯︾郴缁熺殑棰戝甫鍒╃敤鐜囦笉鍙兘澶т簬
2bit/(s.Hz)(
閿?/p>
)
9
銆佸湪棰戝甫鍒╃敤鐜囨柟闈?/p>
QPSK
閫氫俊绯荤粺浼樹簬
2PSK
閫氫俊绯荤粺锛堝锛?/p>
浜屻�佸～绌洪
1
銆?/p>
妯℃嫙閫氫俊绯荤粺涓紝鍙潬鎬ф渶濂界殑鏄紙
FM
锛?/p>
锛屾湁鏁堟�ф渶濂界殑鏄紙
SSB
锛?/p>
銆?/p>
2
銆?/p>
鍦?/p>
FM
閫氫俊绯荤粺涓紝閲囩敤棰勫姞閲嶅拰鍘诲姞閲嶆妧鏈殑鐩殑鏄紙鎻愰珮瑙ｈ皟鍣ㄨ緭鍑轰俊鍣瘮锛?/p>
銆?/p>
3
銆?/p>
鏃跺垎澶嶇敤鐨勮瘽璺暟瓒婂锛屼俊鎭�熺巼锛堣秺澶э級
銆?/p>
4
銆?/p>
鍦?/p>
2ASK
銆?/p>
2FSK
銆?/p>
2PSK
銆?/p>
2DPSK
閫氫俊绯荤粺涓紝
鍙潬鎬ф渶濂界殑鏄?/p>
锛?/p>
2PSK
锛?/p>
锛?/p>
鏈夋晥鎬ф渶濂界殑鏄?/p>
锛?/p>
2ASK
銆?/p>
2PSK
锛?/p>
5
銆?/p>
鍧囧寑閲忓寲鍣ㄧ殑閲忓寲淇″櫔姣斾笌缂栫爜浣嶆暟鐨勫叧绯绘槸
锛堢紪鐮佷綅鏁板鍔?/p>
1
浣嶏紝
閲忓寲淇″櫔姣斿澶?/p>
6dB
锛?/p>
锛?/p>
闈炲潎鍖�閲忓寲鍣ㄥ彲浠ユ彁楂橈紙灏忥級淇″彿鐨勯噺鍖栦俊鍣瘮銆?/p>
(
寮?/p>
9.4.10)
淇″彿閲忓櫔姣旓細
锛?/p>
S/N
锛?/p>
dB
=20lg
M
=20lg2
N
(N
涓虹紪鐮佷綅鏁?/p>
)
缂栫爜浣嶆暟澧炲姞涓�浣嶏紝
锛?/p>
S/N
锛?/p>
dB
=20lg
M
=20lg2
锛?/p>
N+1
锛?/p>
-20lg2
N
=20lg2=6dB
6
銆佹敼鍠?/p>
FM
绯荤粺鎶楀櫔澹版�ц兘鐨勬湁鏁堟帾鏂芥槸锛堥噰鐢ㄩ鍔犻噸鎶�鏈拰鍘诲姞閲嶆妧鏈級
7
銆佽嫢淇℃伅閫熺巼涓?/p>
Wbit/s,
鍒?/p>
2PSK
銆?/p>
4PSK
淇″彿鐨勮氨闆剁偣甯﹀
鍒嗗埆涓猴紙锛夊拰锛堬級
Hz
PSK
淇″彿涓哄弻鏋佹�т笉褰掗浂鐮侊紝瀵瑰熀甯︿俊鍙?/p>
R
B
=1/Ts=fs=R
b
/log2
M
, B=fs= R
b
/log2
M
瀵硅皟鍒朵俊鍙凤細甯﹀涓?/p>
B
璋?/p>
=2B=2 R
b
/log2
M
=2W/ log2
M
瀵?/p>
2PSK
锛氬甫瀹戒负锛?/p>
2W
瀵?/p>
4PSK
锛氬甫瀹戒负锛?/p>
2W/ log2
M
=2W/2=W
8
銆佽鍩哄甫绯荤粺浣跨敤浜嗕簲鎶藉ご鐨勯缃紡鑷姩鍧囪 鍣紝鍒欐绯荤粺鍐叉縺鍝嶅簲鐨勬娊鏍峰�肩瓑浜?/p>
0
鐨勪釜
鏁版渶灏戜负锛?/p>
4
锛?/p>
锛屼笉绛変簬
0
鐨勪釜鏁版渶灏戜负锛?/p>
1
锛?/p>
8
銆侀�氳繃鐪煎浘锛屽彲浠ヨ瀵熷埌锛堢爜闂翠覆鎵帮級鍜岋紙鍣０锛夌殑澶у皬
9
銆佽皟棰戜俊鍙?/p>
20cos(2*10
8
蟺
+8cos400
蟺
t)
鐨勬渶澶ч鍋忎负锛?/p>
1600
锛?/p>
Hz
锛屽甫瀹戒负锛?/p>
3600
锛?/p>
Hz
P1 05
锛?/p>
m
f
涓烘渶澶х浉浣嶅亸绉伙紝鐢辫皟棰戜俊鍙峰彲鐭ュ叾鏈�澶х浉浣嶅亸绉讳负
8
锛?/p>
m
f
=8,
璋冨埗淇″彿鐨勯鐜囷細
f
m
=400
蟺
/2
蟺
=200
鎵�浠ユ渶鍦ㄩ鍋徫?/p>
f=m
f
脳
f
m
=8200=1600.
B=2
锛?/p>
m
f
+1
锛?/p>
f
m
=3600Hz
10
銆佸綋鏃犱俊鍙锋椂锛屽姞鎬у櫔澹版槸鍚﹀瓨鍦紵锛堝瓨鍦級
锛屼箻鎬у櫔澹版槸鍚﹁繕瀛樺湪锛燂紙涓嶅瓨鍦級
11
銆佽鍩哄甫淇″彿鐨勬渶楂橀鐜囦负
3.4kHz
鐨勮闊充俊鍙凤紝鍒?/p>
AM
淇″彿甯﹀涓猴紙
6.8kHz
锛?/p>
锛?/p>
SSB
淇″彿
甯﹀涓猴紙
3.4kHz
锛?/p>
锛?/p>
DSB
淇″彿甯﹀涓猴紙
6.8kHz
锛?/p>
銆?/p>
12
銆佽淇℃伅閫熺巼涓?/p>
1.2kbit/s
锛屽垯
2ASK
淇″彿鍜?/p>
4DPSK
淇″彿鐨勯璋辫繃闆剁偣甯﹀鍒嗗埆涓猴紙锛夊拰
锛堬級
銆?/p>
PSK
淇″彿涓哄弻鏋佹�т笉褰掗浂鐮侊紝瀵瑰熀甯︿俊鍙?/p>
R
B
=1/Ts=fs=R
b
/log2
M
, B=fs= R
b
/log2
M
瀵硅皟鍒朵俊鍙凤細甯﹀涓?/p>
B
璋?/p>
=2B=2 R
b
/log2
M
=2W/ log2
M
瀵?/p>
2PSK
锛氬甫瀹戒负锛?/p>
2W
瀵?/p>
4PSK
锛氬甫瀹戒负锛?/p>
2W/ log2
M
=2W/2=W