昨晚跟BI4PYM研究了BPM。发现BPM有类似BPC的时间码授时，是在5Mhz AM信号左右两边125hz的位置。我们进行了人工解码，结果没多大问题。未来可以通过软件进行解码为计算机进行授时以后用FT8等软件就多一条时间校准的路子。现在就是需要编写软件用软件解码。但是我的编程技术顶多就写个算账程序。我想用JAVA进行编写现在我遇到了难题如下： 1. JAVA如何将计算机声卡的音频信号进行实时读取 2. 读取的音频如何只分析125hz的时间码信号剩下的逻辑判断部分我自己的能力应该可以完成。如果有相关经验的大佬能不能指一条路子，我可以慢慢研究

我可以提供一点儿思路，你可以问问ChatGPT或者通义千问之类的AI，他能给你提供意想不到的帮助

JDK有内置的音频采样API，允许你讲声卡输入进行采样和处理：https://docs.oracle.com/javase/tutorial/sound/capturing.html 频谱分析可以考虑将采样在某个时间窗口下做FFT：http://www.developer.com/java/other/article.php/3380031/Spectrum-Analysis-using-Java-Sampling-Frequency-Folding-Frequency-and-the-FFT-Algorithm.htm

@"BI1OTX"#p23665 我已经狠狠的调教了gpt4O 有点思路了

@"BI1UHW"#p23675 好我仔细看看

大佬做出来了吗，10MHz和15MHz的授时信号不知道能不能用

为啥用BPM，现成的GPS授时不香吗，USB转串口+GPS模块也就25块钱，可以插win直接用软件对时（btk时间同步器），也可以插linux上做docker的ntp服务器直接提供ntp服务，可用性更强点

@"BG5JKZ"#p101450 因为相对于gps而言，bpm的无线电属性更强吧，并且在有电台的情况下无需再购入其他额外设备

接后续，BI4PYM所接收到的信号非BPM，最终被证实来自韩国HLA，因BPM在125Hz没有时码（接收不到），再加上他选择的是韩国的Kiwisdr，所以确定不是BPM

如果硬要搞，可以尝试68.5KHz的BPC，100KHz的BPL目前从技术上不可用，BPM目前只能做到毫秒级，而且因为快到闰秒了，时间疑似有偏差（体现在即将播发莫尔斯电码时前一秒的短滴声）

另外，这几种时码（BPL，HLA，好像还有GPS等？）好像都是一样的格式，用CW很容易解出时码

Please advise on how to synchronize a computer system using a BPM 125Hz subcarrier.

BH6ABO

Last night, I investigated BPM using BI4PYM. I found that BPM has a timing signal similar to BPC, located around the 125Hz positions on either side of the 5MHz AM signal.
We performed manual decoding, and the results were not significantly problematic.

In the future, software decoding will be used to synchronize computers. Later, using software like FT8 will provide additional time synchronization options.

Currently, I need to write software that can be decoded by other software. However, my programming skills are limited to writing simple calculation programs. I would like to use Java for this purpose.

Currently, I am facing the following problem:

How can Java read audio signals from a computer's sound card in real-time?
How to analyze the timecode signal from the audio that has been read?

I believe I should be able to handle the remaining logical reasoning part myself.
If there are any senior experts with relevant experience, could you please provide some guidance? I would like to study this further at my own pace.

BI1OTX

I can offer some ideas, and you can ask ChatGPT or similar AI models like Tongyi Qianwen for help. They might provide unexpected assistance.

BH6ABO

BI1OTX I have thoroughly trained GPT-4O and I'm starting to get some ideas.

BI1UHW

The JDK has built-in audio sampling APIs that allow you to sample and process audio input from a sound card:https://docs.oracle.com/javase/tutorial/sound/capturing.html
Spectrum analysis can consider performing FFT on samples taken within a specific time window:http://www.developer.com/java/other/article.php/3380031/Spectrum-Analysis-using-Java-Sampling-Frequency-Folding-Frequency-and-the-FFT-Algorithm.htm

BH6ABO

BI1UHW Okay, I will take a close look.

MZYDJ

Did you manage to implement it? Are the 10 MHz and 15 MHz time signals usable?

BG5JKZ

Why use BPM when readily available GPS time synchronization is so cheap? A USB-to-serial adapter plus a GPS module costs only around 25 yuan, which can be connected directly to Windows and used with software like the Btk Time Synchronizer. Alternatively, you can connect it to a Linux system to run an NTP server using Docker, providing more reliable NTP service.

BG5BUW

BG5JKZ Because, compared to GPS, BPM has stronger radio properties, and it doesn't require purchasing additional equipment when a radio is available.

BI9BUM

Subsequently, the signal received by BI4PYM was not a BPM, and it was eventually confirmed to originate from South Korea's HLA. This is because the BPM signal did not have a time code (could not be received) at 125Hz, and he had chosen to use a Kiwidsr receiver from South Korea, which further confirmed that it was not a BPM.

BH6ABO

BI9BUM 是的最后的文章也提到了是韩国大田的HLA 搞笑的是当时我就在大田

BI9BUM

If you absolutely must do it, you could try using a 68.5 kHz BPC (Baseband Pulse Code Modulation), but the 100 kHz BPL (Baseband Pulse Layer) is currently not feasible from a technical standpoint. BPM (Baseband Pulse Modulation) can only achieve millisecond-level accuracy at present, and due to its speed, it may exhibit timing discrepancies (such as a short beep before transmitting Morse code).

BI9BUM

Furthermore, it seems that these time codes (BPL, HLA, and possibly GPS, among others) all use the same format, making them relatively easy to decode using CW.

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