BPC 电波授时信号 Python 转 js 实现一半 求助 - V2EX
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guxin0123
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BPC 电波授时信号 Python 转 js 实现一半 求助

  •  
  •   guxin0123 2017-03-14 15:39:06 +08:00 3126 次点击
    这是一个创建于 3135 天前的主题,其中的信息可能已经有所发展或是发生改变。

    来源 http://www.hackrf.net

    有个六局电波的西铁城,由于地理位置偏僻收不到波

    网上看到了这个 《 BPC 电波授时信号的“零成本”伪造》 用 Python+耳机发射授时信号

    上网查了查 在苹果商店发现一个 app 售价 12 但是没有苹果手机

    觉得要是把他的代码改到 js 里面就可以在浏览器里面运行对时就非常方便了

    目前只完成了时间转 base4 部分 但是 js 音频发声转换部分没有思路 对音频和波形没有研究过

    看了两个库 timbre.js 和 lame.js 不知是否可行

    python 代码

    # -*- coding: utf-8 -*- """ Created on Tue Jan 19 15:26:45 2016 @author: zhengbowang """ import pyaudio import struct import datetime import math def dropandfill(l,s):return '0'*(l - len(s[2:])) + s[2:]#用 0 补位 def time2code(date_time, dt = datetime.timedelta(0)): #将时间转换成 BPC 编码。 date_time -= dt date = [date_time.day, date_time.month, date_time.year] timet = [date_time.hour,date_time.minute,date_time.weekday()+1] date[2] = date[2]%100#year timet[0] = timet[0]%12#am.pm p1 = dropandfill(2,bin(date_time.second/20))#seconds p2 = '00'#reserved sec1 = (p1+p2)+''.join(map(dropandfill,[4,6,4],map(bin,timet))) p31 = str(int(date_time.hour>=12)) p32 = str((sec1.count('1'))%2) p3 = p31 + p32 sec2 = ''.join(map(dropandfill,[6,4,6],map(bin,date))) p41 = str(int(date_time.year%1000>100)) p42 = str(((sec2.count('1'))%2)) p4 = p41 + p42 code2 = sec1 + p3 +sec2 + p4 bin2four = {'00':'1','01':'2','10':'3','11':'4'}#to base4 return '0'+''.join([bin2four[code2[2*i:2*i+2]] for i in range(len(code2)/2)]) dt = datetime.timedelta(hours = 1)#fake time shift samp_rate = 68500 freq = 6850 * 2 #in Hertz ttime =20 #in Sec SAMPLE_LEN = samp_rate * ttime # 20 seconds of cosine value = ampl = 32725 div = samp_rate/freq/2 data = 32725 # 打开声音输出流 p = pyaudio.PyAudio() stream = p.open(format = 8, channels = 1, rate = samp_rate, output = True) while True: date_time = datetime.datetime.now()+dt print date_time sec = (date_time.second+1)%20 code_str = time2code(date_time) start = sec * samp_rate for i in xrange((start), SAMPLE_LEN): #if i % div == 0:value = -value#carrier generate value = ampl * int(math.cos(math.pi / float(div) * float(i))) pulse = (i - sec * samp_rate)/(samp_rate / 10) packed_value = struct.pack('h', int(pulse >= int(code_str[sec]))*value) stream.write(packed_value) if i % samp_rate == 0 and i != start: sec = sec + 1 

    转到一半的 js 代码

    function time2code(date_time) { var date = [date_time.getDate(), date_time.getMonth() + 1, date_time.getFullYear()]; var timet = [date_time.getHours(), date_time.getMinutes(), date_time.getUTCDay()]; date[2] = date[2] % 100; //year timet[0] = timet[0] % 12; //am,pm var p1 = dropandfill(2, parseInt(date_time.getSeconds() / 20).toString(2)); //seconds var p2 = '00'; //reserved var sec1 = (p1 + p2) + '' + join(map(dropandfill, [4, 6, 4], map(bin, timet))) var p31 = Number(date_time.getHours() >= 12).toString(); var re = new RegExp("1", "g"); var p32 = str((sec1.match(re).length) % 2) var p3 = p31 + p32; var sec2 = '' + join(map(dropandfill, [6, 4, 6], map(bin, date))); var p41 = str(Number(date_time.getFullYear() % 1000 > 100)) var p42 = str(((sec2.match(re).length) % 2)) var p4 = p41 + p42 var code2 = sec1 + p3 + sec2 + p4 var bin2four = { '00': '1', '01': '2', '10': '3', '11': '4' } //to base4 var ret = []; ret.push('0') for (var i = 0; i < code2.length / 2; i++) { ret.push(bin2four[code2.substring(i * 2, i * 2 + 2)]); } return join(ret); } //用 0 补位 function dropandfill(size, num) { var s = "000000000" + num; return s.substr(s.length - size); } function map(a, b) { if (arguments.length == 2) { for (var i = 0; i < arguments[1].length; i++) { arguments[1][i] = arguments[0](arguments[1][i]); } return arguments[1]; } if (arguments.length == 3) { for (var i = 0; i < arguments[1].length; i++) { arguments[1][i] = arguments[0](arguments[1][i], arguments[2][i]); } return arguments[1]; } } function bin(e) { return e.toString(2); } function join(e) { var ret = ""; for (var i = 0; i < e.length; i++) { ret += e[i]; } return ret; } function str(e) { return e.toString(); } 
    2 条回复    2017-08-08 19:27:05 +08:00
    GPU
        1
    GPU  
       2017-08-08 18:39:21 +08:00 via iPhone
    好像还有一个 68.5kHz 的 5 倍频要处理
    guxin0123
        2
    guxin0123  
    OP
       2017-08-08 19:27:05 +08:00
    发现一个别人做好的了

    https://shogo82148.github.io/web-jjy/
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