基带

基带信号的频谱，单位频率的能量 E 作为频率 f 的函数。总能量是线下的面积。

此條目介紹的是信号处理的概念。关于无线数字通讯的信号处理器，请见「基带处理器」。

基带（英語：baseband）是频率范围非常窄的信号，也就是说幅度谱仅在原点（f = 0）附近才是非零的，其他频率几乎可以忽略。[1] 在电信与信号处理中，基带信号是未经载波调制的信号，即该信号的频率范围没有任何移位，[2] 而且频率很低 - 包含频带从接近 0 Hz到更高截止頻率或最大带宽。

由于基带信号是未经载波调制的信号，在GPS接收机和移动电话等无线数字通讯领域，基带信号有时也泛指已经过射频前端（英语：Radio Frontend）处理后的信号。[3][4]在无线通讯设备中，来自天线的信号先经射频前端（英语：Radio Frontend）的模拟电路接收，然后再转交给后续的数字电路进一步处理，而后者就是基带处理器。[3][4]在当前中文语境中，手机基带处理器所带的固件也简称“基带”[5]。

参见

• 解析信号
• 寬頻
• 窄带（英语：Narrowband）
• 宽带 (通信)（英语：Wideband）

参考文献

1. Leon W. Couch II. Digital and Analog Communication Systems. Prentice Hall. 1993. 
2. B.P. Lathi. Modern Digital and Analog Communication Systems. Holt, Rinehart and Winston. 1983. 
3. Christian Piguet. 6: Low-Power Bandband Processors for Communications. Low-Power Processors and Systems on Chips. CRC Press. [2020-01-10]. （原始内容存档于2020-04-26）. Baseband Signals are all signals in a radio system, which are not modulated onto the carrier wave. In a cellular phone, this means all signals except those in the radio frequency (RF) part of the phone. 
4. U.S. International Trade Commission. In the Matter of Certain GPS Chips, Associated Software and Systems, and Products Containing Same, Investigation No. 337-TA-596 (报告). DIANE Publishing: 6. A GPS receiver typically includes an analog signal processing portion in a radio-frequency circuit (an "RF Front End") and a digital signal processing portion in a baseband circuit (a "Baseband Processor"). In a GPS receiver, the RF Front End receivers the GPS signal, filters and amplifies the signal, and converts the resulting signal into a digital formbat. The resulting digital signal, which is sometimes referred to as the "baseband signal," is sent to the Baseband Processor. 
5. 基带是什么. 太平洋IT百科. [2016-02-07]. （原始内容存档于2016-02-07）.