Noise Reduction for Digital Communications—The Masterpiece, a Modified Costas Loop

• 作者: János Ladvánszky
• 来源期刊: 电路与系统(英文)
• 学科: 工学
• 关键词: Noise Symbol Error Rate QAM Costas Loop Hilbert Filter Folding Algorithm
• 年，卷（期）: 2020,（6）
• 页码范围: 57-64
• 页数: 8页
• 分类号: TN9

摘要

An efficient way of noise reduction has been presented: A modified Costas loop called as Masterpiece. The basic version of the Costas loop has been developed for SSB SC demodulation, but the same circuit can be applied for QAM (quadrature amplitude modulation) demodulation as well. Noise sensitivity of the basic version has been decreased. One trick is the transformation of the real channel input into complex signal, the other one is the application of our folding algorithm. The result is that the Masterpiece provides a 4QAM symbol error rate (SER) of 6 × 10^{<span style="white-space:nowrap;">&#8722;</span>4} for input signal to noise ratio (SNR) of <span style="white-space:nowrap;">&#8722;</span>1 dB. In this paper, an improved version of the original Masterpiece is introduced. The complex channel input signal is normalized, and rotational average is applied. The 4QAM result is SER of 3 × 10^{<span style="white-space:nowrap;">&#8722;</span>4} for SNR of <span style="white-space:nowrap;">&#8722;</span>1 dB. At SNR of 0 dB, the improved version produces 100 times better SER than that the original Costas loop does. In our times, this topic has a special importance because by application of our Masterpiece, all dangerous field strengths from 5G and WiFi, could be decreased by orders of magnitude. The Masterpiece can break the Shannon formula.