DCF77 解码器与噪声信号 [英] DCF77 decoder vs. noisy signal
问题描述
我几乎完成了我的开源 DCF77 解码器项目.当我注意到标准 (Arduino) DCF77 库在嘈杂信号上的表现非常糟糕时，一切就开始了.尤其是当天线靠近电脑或洗衣机运行时，我永远无法从解码器中获得时间.
I have almost completed my open source DCF77 decoder project. It all started out when I noticed that the standard (Arduino) DCF77 libraries perform very poorly on noisy signals. Especially I was never able to get the time out of the decoders when the antenna was close to the computer or when my washing machine was running.
我的第一种方法是为传入信号添加一个(数字)指数滤波器 + 触发器.
My first approach was to add a (digital) exponential filter + trigger to the incoming signal.
虽然这显着改善了情况，但仍然不是很好.然后我开始阅读一些关于数字信号处理的标准书籍，尤其是 Claude Elwood Shannon 的原创作品.我的结论是，正确的方法是根本不解码"信号，因为它(闰秒除外)完全是先验已知的.相反，将接收到的数据与本地合成信号匹配并仅确定适当的相位会更合适.这反过来又会将有效带宽降低几个数量级，从而显着降低噪声.
Although this improved the situation significantly, it was still not really good. Then I started to read some standard books on digital signal processing and especially the original works of Claude Elwood Shannon. My conclusion was that the proper approach would be to not "decode" the signal at all because it is (except for leap seconds) completely known a priori. Instead it would be more appropriate to match the received data to a locally synthesized signal and just determine the proper phase. This in turn would reduce the effective bandwidth by some orders of magnitude and thus reduce the noise significantly.
相位检测意味着需要快速卷积.高效卷积的标准方法当然是快速傅立叶变换.但是我正在为 Arduino/Atmega 328 实现.因此我只有 2k RAM.因此，我没有使用 FFT 的直接方法，而是开始堆叠匹配的锁相环滤波器.我在这里记录了不同的项目阶段:
Phase detection implies the need for fast convolution. The standard approach for efficient convolution is of course the fast Fourier transform. However I am implementing for the Arduino / Atmega 328. Thus I have only 2k RAM. So instead of the straightforward approach with FFT, I started stacking matched phase locked loop filters. I documented the different project stages here:
我在互联网上进行了相当广泛的搜索，但没有找到类似的方法.我仍然想知道是否有类似(也许更好)的实现.或者是否有关于这种信号重构的研究.
I searched the internet quite extensively and found no similar approach. Still I wonder if there are similar (and maybe better) implementations. Or if there exist research on this kind of signal reconstruction.
我不是在寻找什么:设计优化代码以接近香农极限.我也没有在 DCF77 上搜索有关叠加 PRNG 代码的信息.我也不需要关于匹配过滤器"的提示，因为我当前的实现是匹配过滤器的近似.关于维特比解码器或网格方法的具体提示不是我正在寻找的 - 除非它们解决了 CPU 和 RAM 限制的问题.
What I am not searching for: designing optimized codes for getting close to the Shannon limit. I am also not searching for information on the superimposed PRNG code on DCF77. I also do not need hints on "matched filters" as my current implementation is an approximation of a matched filter. Specific hints on Viterbi Decoders or Trellis approaches are not what I am searching for - unless they address the issue of tight CPU and RAM constraints.
我正在搜索的内容:是否有其他非平凡算法的描述/实现，可用于在存在明显噪声的情况下使用有限的 CPU 和 RAM 来解码信号，例如 DCF77?也许在前互联网时代的一些书籍或论文中?
What I am searching for: are there any descriptions / implementations of other non-trivial algorithms for decoding signals like DCF77, with limited CPU and RAM in the presence of significant noise? Maybe in some books or papers from the pre internet era?
推荐答案
Ollie B. 对匹配过滤器的引用不是我想要的.我之前已经在我的博客中介绍过了.
The reference to matched filters by Ollie B. is not what I was asking for. I already covered this before in my blog.
但是现在我通过私人邮件收到了一个很好的提示.有一篇论文 "性能分析和DCF77 无线电控制时钟的接收器架构 Daniel Engeler.这就是我正在寻找的东西.
However by now I received a very good hint by private mail. There exists a paper "Performance Analysis and Receiver Architectures of DCF77 Radio-Controlled Clocks" by Daniel Engeler. This is the kind of stuff I am searching for.
从 Engeler 论文开始进一步搜索，我发现以下德国专利 DE3733966A1 -Anordnung zum Empfang stark gestoerter Signale des Senders dcf-77 和 DE4219417C2 - Schmalbandemp提供日期信号.
With further searches starting from the Engeler paper I found the following German patents DE3733966A1 - Anordnung zum Empfang stark gestoerter Signale des Senders dcf-77 and DE4219417C2 - Schmalbandempfänger für Datensignale.
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