DCF77解码器与噪声信号 [英] DCF77 decoder vs. noisy signal
问题描述
我几乎已经完成了开源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差时，一切就开始了.尤其是当天线靠近计算机或洗衣机正在运行时，我再也无法从解码器中抽出时间了.
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.
我的第一种方法是向输入信号添加一个(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.
尽管这大大改善了情况，但仍然不是很好.然后，我开始阅读一些有关数字信号处理的标准书籍，尤其是克劳德·艾尔伍德·香农(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，因为先验完全知道()秒除外).取而代之的是将接收到的数据与本地合成的信号进行匹配并仅确定适当的相位会更合适.反过来，这将使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.有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，我开始使用匹配的锁相环滤波器，而不是使用FFT的简单方法.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:
- First try: exponential filter
- Start of the better apprach: phase lock to the signal / seconds ticks
- Phase lock to the minutes
- Decoding minute and hour data
- Decoding the whole signal
- Adding a local clock to deal with signal loss
- Using local synthesized signal for faster lock reacquisition after signal loss
我在互联网上进行了广泛的搜索，没有找到类似的方法.我仍然想知道是否有类似的(也许更好的)实现.或者是否有关于这种信号重建的研究.
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.
我不想要的是:设计优化代码以接近Shannon限制.我也没有在DCF77上搜索有关叠加PRNG代码的信息.我也不需要有关匹配过滤器"的提示，因为我当前的实现是匹配过滤器的近似值.我不是要寻找有关Viterbi解码器或Trellis方法的具体提示-除非它们解决了CPU和RAM严格限制的问题.
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.
我要搜索的内容:在存在严重噪声的情况下，使用有限的CPU和RAM 解码DCF77等信号的其他非平凡算法是否有任何描述/实现?也许在互联网时代之前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
我所要求的不是Ollie B.对匹配过滤器的引用.我已经在我的博客中介绍了此内容.
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，到目前为止，我已经通过私人邮件收到了很好的提示.有一篇论文性能分析和 DCF77无线电时钟的接收器体系结构" ，这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.
通过从Engeler论文开始的进一步搜索，我发现了以下德国专利 DE3733966A1- Anordnung zum Empfang信号发送器dcf-77 和 DE4219417C2-Schmalbandempfänger fürDatensignale .
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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