题目/Title：带频偏校准的GMSK解调器设计与实现
                        A GMSK demodulator with frequency offset estimation and calibration

作者/Author：郑婧怡,高绍全,姜汉钧,张春,王志华,贾雯
                        Jingyi Zheng,Shaoquan Gao,Hanjun Jiang,Chun Zhang,Zhihua Wang,Wen Jia

期刊/Journal：电子技术应用 Application of Electronic Technique

年份/Issue Date：2016

卷（期）及页码/Volume（No.）&pages：Vol.42, No.6, pp. 101 - 104

摘要/Abstract：
本文提出了一种在零中频低功耗蓝牙接收机中使用的GMSK解调器。GMSK是一种恒包络调制方式，针对其解调最重要的判决依据是相位变化，而接收机的本振频率与发射机的载波频率误差，会对相位产生干扰。因此这里提出了一种频偏校准算法，来解决频偏对解调性能的影响。该算法由改进的一比特差分解调与CORDIC（Coordinate rotation digital computer）算法结合实现，与传统的频偏校准算法相比复杂度大大降低。在150kHz以内的频偏条件下，要达到10-3误码率要求，需要的信噪比与无频偏时相比差距
In this paper, we propose a Gaussian minimum shift keying (GMSK) demodulator structure used in a zero-IF Bluetooth low energy (BLE) transceiver. GMSK is one of the continuous phase modulation (CPM), the primary basis for demodulation is the change of phase. The carrier frequency offset between the transmitter and the receiver affects the phase changes, so a frequency offset estimation and calibration algorithm is presented. The algorithm combines improved one bit differential operation for demodulation and coordinate rotation digital computer (CORDIC) algorithm, which is less complex than the conventional frequency offset estimation algorithm. With a frequency offset within 150 kHz, the signal noise radio (SNR) difference for 0.1 percent bit error rate (BER) demand is 1 dB to the most. This GMSK demodulator is realized in Verilog and validated using FPGA.