Month: April 2017

You can click on a trace on the waterfall image to tune into that frequency.

index.html

var cwmarker1 = Math.floor(  cwpitch        / (32000 / 4096) );
var cwmarker2 = Math.floor( (cwpitch - 100) / (32000 / 4096) );
var cwmarker3 = Math.floor( (cwpitch + 100) / (32000 / 4096) );

function onClick(e) {
  var rect = e.target.getBoundingClientRect();
  var mx   = e.clientX - rect.left;
  var my   = e.clientY - rect.top;
  socket.emit('message7', mx);
}
canvas1.addEventListener('click', onClick, false);

index.js

  socket.on('message7', function(mx) {
    var newfreq = freqHz - (32000/4096 * mx - cwpitch);
    setfreq(newfreq);
  });

Of course, you must consider which sideband you are listening to in calculating your new frequency.

You can change the VFO frequency of your remote IC-7410 by clicking the buttons on the browser.

index.js

const bufa = new Buffer('fefe80e017', 'hex');              // preamble
const bufz = new Buffer('fd', 'hex');                      // postamble
const buf1 = new Buffer('fefe80e0174351fd', 'hex');        // CQ
const buf2 = new Buffer('fefe80e01751525a3ffd', 'hex');    // QRZ?
const buf3 = new Buffer('fefe80e003fd', 'hex');            // read freq
var buf4   = new Buffer('fefe80e0050000000000fd', 'hex');  // send freq

var SerialPort = require('serialport');
var serial     = new SerialPort(
    '/dev/ttyUSB0',
    {baudrate : 19200, parser : SerialPort.parsers.byteDelimiter([ 0xfd ])});

var http  = require('http');
var fs    = require('fs');
var index = fs.readFileSync(__dirname + '/index.html');
var app   = http.createServer(function(req, res) {
                res.writeHead(200, {'Content-Type' : 'text/html'});
                res.end(index);
              })
              .listen(3000);

var io     = require('socket.io').listen(app);
var freqHz = 7026000;

var ndata   = 512;  // data[512] + 0x0a
var pos     = 0;
var myarray = new Array();

// -- water fall --

var count = 0;
process.stdin.on('readable', function() {
  var buf = process.stdin.read();
  if (buf !== null) {
    for (var i = 0; i < buf.length; i++) {
      if (buf[i] == 0x0a) {
        if (pos >= 512) {
          io.emit('waterfall', myarray);
        }
        pos = 0;
      } else {
        myarray[pos++] = buf[i];
      }
    }
  }
});

// -- serial for IC-7410 --

serial.on('open',
          function() { console.log('serial port /dev/ttyUSB0 is opened.'); });

var count2 = 0;
serial.on('data', function(data) {
  //    console.log('received data: ', data.length, data);
  if (!(data[0] == 0xfe & data[1] == 0xfe)) {
    console.log('------------- received serial data error');
    }
  if (data[2] == 0xe0 & data[3] == 0x80 & data[4] == 0x03) {
    var f10   = data[5] >> 4 & 0x0f;
    var f1    = data[5] & 0x0f;
    var f1k   = data[6] >> 4 & 0x0f;
    var f100  = data[6] & 0x0f;
    var f100k = data[7] >> 4 & 0x0f;
    var f10k  = data[7] & 0x0f;
    var f10m  = data[8] >> 4 & 0x0f;
    var f1m   = data[8] & 0x0f;
    var freq  = f10m.toString() + f1m.toString() + "," + f100k.toString() +
               f10k.toString() + f1k.toString() + "." + f100.toString() +
               f10.toString() + f1 + " kHz";
    freqHz = f10m * 10000000 + f1m * 1000000 + f100k * 100000 + f10k * 10000 +
             f1k * 1000 + f100 * 100 + f10 * 10 + f1;
    //        console.log('count2 = ', count2++, 'freq: ' + freq, freqHz);
    io.emit('freqmsg', 'VFO A: ' + freq);
  }

});

serial
    .on('error', function(err) { console.log('Error: ', err.message); })

    // -- set frequency --

    function setfreq(f) {
      var f10m  = Math.floor(f / 10000000); f -= f10m  * 10000000;
      var f1m   = Math.floor(f / 1000000);  f -= f1m   * 1000000;
      var f100k = Math.floor(f / 100000);   f -= f100k * 100000;
      var f10k  = Math.floor(f / 10000);    f -= f10k  * 10000;
      var f1k   = Math.floor(f / 1000);     f -= f1k   * 1000;
      var f100  = Math.floor(f / 100);      f -= f100  * 100;
      var f10   = Math.floor(f / 10);       f -= f10   * 10;
      var f1    = Math.floor(f / 1);

      var data = new Array(
          [ 0xfe, 0xfe, 0x80, 0xe0, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfd ]);
      buf4[5] = f10   << 4 | f1;
      buf4[6] = f1k   << 4 | f100;
      buf4[7] = f100k << 4 | f10k;
      buf4[8] = f10m  << 4 | f1m;
      buf4[9] = 0;
      serial.write(buf4);
    }

// -- socket --

io.on('connection', function(socket) {

  socket.on('message1', function() { serial.write(buf1); });
  socket.on('message2', function() { serial.write(buf2); });

  socket.on('message3', function() {
    var newfreq = freqHz + 1000;
    setfreq(newfreq);
  });

  socket.on('message4', function() {
    var newfreq = freqHz + 100;
    setfreq(newfreq);
  });

  socket.on('message5', function() {
    var newfreq = freqHz - 100;
    setfreq(newfreq);
  });

  socket.on('message6', function() {
    var newfreq = freqHz - 1000;
    setfreq(newfreq);
  });

  socket.on('your message', function(msg) {
    serial.write(bufa);
    serial.write(msg);
    serial.write(bufz);
    io.emit('your message', msg);
  });

});

// -- request freq --

function sendTime() {
  serial.write(buf3);
  // console.log('Freq asked..');
}

setInterval(sendTime, 100);

// -- EOF --

index.html

<!doctype html>
<html>
<head>

<style>
* { margin: 0; padding: 0; box - sizing : border - box; }
body { font: 13px Helvetica, Arial; }
form { background: # 000; padding: 3px; position: fixed; bottom: 0; width: 100 % ; }
form input { border: 0; padding: 10px; width: 80 % ; margin - right : .5 % ; }
form button { width: 15 % ; background: rgb(130, 224, 255); border: none; padding: 10px; }
#messages{list - style - type : none; margin : 0; padding : 0; }
#messages li{padding : 5px 10px; }
#messages li : nth - child(odd){background : #eee; }
#messages {margin - bottom : 40px }
#messages {font - size : 2em }
#btn1 {position : fixed; top : 10px; left :  10px; font - size : 2em }
#btn2 {position : fixed; top : 10px; left :  70px; font - size : 2em }
#btn3 {position : fixed; top : 10px; left : 150px; font - size : 2em; width : 30px }
#btn4 {position : fixed; top : 10px; left : 190px; font - size : 2em; width : 30px }
#btn5 {position : fixed; top : 10px; left : 230px; font - size : 2em; width : 30px }
#btn6 {position : fixed; top : 10px; left : 270px; font - size : 2em; width : 30px }
#frequency {position : fixed; top :  10px; left : 310px; font - size : 2em }
#mycanvas  {position : fixed; top :  60px; left :  10px; font - size : 2em }
#mycanvas2 {position : fixed; top : 600px; left :  10px; font - size : 2em }
</style>

<script>
  window.addEventListener("load", init);
  function init(){}
</script>
</head>

 <body>
    <script src="https://code.jquery.com/jquery-1.11.1.js"></script>
    <script src='/socket.io/socket.io.js'></script>
    <script src="https://code.createjs.com/createjs-2015.11.26.min.js"></script>

    <button id="btn1"><font size="5">CQ</font></button>
    <button id="btn2"><font size="5">QRZ?</font></button>
    <button id="btn3"><font size="5">++</ font></button>
    <button id="btn4"><font size="5">+</font></button>
    <button id="btn5"><font size="5">-</font></button>
    <button id="btn6"><font size="5">--</font></button>

    <div id="frequency"></div>
    <div id="messages"></div>
    <form action="">
      <input id="m" autocomplete="off"/><button>Send</button>
    </form>
    <canvas id="mycanvas"  width="512" height="512" style="background:white;"></canvas>
    <canvas id="mycanvas2" width="512" height= "90" style="background:white;"></canvas>

<script>
var myarray = new Array();
var socket  = io();
var canvas;
var ctx;
var imgData;
var rgb = new Array(3);

var stage = new createjs.Stage("mycanvas2");
var t     = new createjs.Text("IC-7410", "26px serif", "DarkRed");
t.x       = 10;
t.y       = 10;
stage.addChild(t);
stage.update();

function colormap(charcode) {         // 0~9 or 0x30~0x39
  var tmp = (charcode - 0x30) * 0.1;  // 0.0~0.9
  var val;
  var r, g, b;
  if (tmp < 0.50) {
    r = 0.0;
  } else if (tmp > 0.75) {
    r = 1.0;
  } else {
    r = 4.0 * tmp - 2.0;
  }

  if (tmp < 0.25) {
    g = 4.0 * tmp;
  } else if (tmp > 0.75) {
    g = -4.0 * tmp + 4.0;
  } else {
    g = 1.0;
  }

  if (tmp < 0.25) {
    b = 1.0;
  } else if (tmp > 0.50) {
    b = 0.0;
  } else {
    b = -4.0 * tmp + 2.0;
  }

  rgb[1] = 255.0 * g;
  rgb[0] = 255.0 * r;
  rgb[2] = 255.0 * b;
}

function waterFall(myarray) {
  ctx.putImageData(imgData, 0, 1);
  imgData = ctx.getImageData(0, 0, 512, 512);
  for (j = 0; j < 512; j++) {
    colormap(myarray[j]);
    imgData.data[0 + j * 4] = rgb[0];
    imgData.data[1 + j * 4] = rgb[1];
    imgData.data[2 + j * 4] = rgb[2];
    imgData.data[3 + j * 4] = 255;
  }
}

canvas = document.getElementById('mycanvas');
ctx    = canvas.getContext('2d');

var mx, my;
function onClick(e) {
  var rect = e.target.getBoundingClientRect();
  mx       = e.clientX - rect.left;
  my       = e.clientY - rect.top;
  console.log('mouse clicked: ', mx, my);
}
canvas.addEventListener('click', onClick, false);

imgData = ctx.createImageData(512, 512);
for (i = 0; i < 512; i++) {
  for (j = 0; j < 512; j++) {
    imgData.data[0 + j * 4 + i * imgData.width * 4] = j % 256;
    imgData.data[1 + j * 4 + i * imgData.width * 4] = i % 256;
    imgData.data[2 + j * 4 + i * imgData.width * 4] = 128;
    imgData.data[3 + j * 4 + i * imgData.width * 4] = 255;
  }
}
ctx.putImageData(imgData, 0, 0);

var socket = io();

$('#btn1').click(function() { socket.emit('message1'); });
$('#btn2').click(function() { socket.emit('message2'); });
$('#btn3').click(function() { socket.emit('message3'); });
$('#btn4').click(function() { socket.emit('message4'); });
$('#btn5').click(function() { socket.emit('message5'); });
$('#btn6').click(function() { socket.emit('message6'); });

$('form').submit(function() {
  socket.emit('your message', $('#m').val());
  $('#m').val('');
  return false;
});

socket.on('your message', function(msg) {
  $('#messages').append($('<div>').text(msg));
  window.scrollTo(0, document.body.scrollHeight);
});

socket.on('waterfall', function(data) { waterFall(data); });

socket.on('freqmsg', function(msg) {
  t.text = msg;
  stage.update();
  document.getElementById("frequency").innerHTML = msg;
});

</script>

</body>
</html>

This is a real waterfall.

By the way, if you get an error message, undefined reference to ‘alloca’, with your gcc, the following line may help.

#include <alloca.h>

If you are using “stdout” instead of “stderr”, you may need to specify the mode for file buffering.

% sprig_audio_only /dev/ttyUSB0 hw:2,0 |& node index.js
% sprig_audio_only /dev/ttyUSB0 hw:2,0 |  node index.js

sprig_audio_only.c

#include <stdio.h>
int main () {
 setvbuf(stdout, NULL, _IOLBF, 0); // line buffering mode
//
 for(int i=0;i<512<i++) {
  fprintf(stdout, "%1d", audio_signal_ffted[i]);
 }
 fprintf(stdout,"\n");
 fflush(stdout); // this will also do with full buffering mode
//
}

If we put the different parts together, you will have something like this. Note that the waterfall data is a computer generated one.

index.js

// file name = index20.js, reads index20.html

const bufa = new Buffer('fefe80e017'          , 'hex'); // preamble
const bufz = new Buffer('fd'                  , 'hex'); // postamble
const buf1 = new Buffer('fefe80e0174351fd'    , 'hex'); // CQ
const buf2 = new Buffer('fefe80e01751525a3ffd', 'hex'); // QRZ?
const buf3 = new Buffer('fefe80e003fd'        , 'hex'); // read freq

var SerialPort = require('serialport');
var serial = new SerialPort('/dev/ttyUSB0',{
    baudrate: 19200,
    parser: SerialPort.parsers.byteDelimiter([0xfd])
});

var http  = require('http');
var fs    = require('fs');
var index = fs.readFileSync(__dirname + '/index20.html');
var app = http.createServer(function(req, res) {
                res.writeHead(200, {'Content-Type' : 'text/html'});
                res.end(index);
              })
              .listen(3000);

var io = require('socket.io').listen(app);

var ndata   = 512;  // data[512] + 0x0a
var pos     = 0;
var myarray = new Array();

// -- water fall --

process.stdin.on('readable', function() {
  var buf = process.stdin.read();
  if (buf !== null) {
    for (var i = 0; i < buf.length; i++) {
      if (buf[i] == 0x0a) {
        pos = 0;
        io.emit('waterfall', myarray);
      } else {
        myarray[pos++] = buf[i];
      }
    }
  }
});

// -- serial for IC-7410 --

serial.on('open',function(){
    console.log('serial port /dev/ttyUSB0 is opened.');
});

serial.on('data',function(data){
    console.log('received data: ', data.length, data);
    if ( !(data[0] == 0xfe & data[1] == 0xfe) ) {
      console.log('** received serial data error **');
    }
    if (data[2] == 0xe0 & data[3] == 0x80 & data[4] == 0x03) {
        var f10   = data[5]>>4 & 0x0f;
        var f1    = data[5]    & 0x0f;
        var f1k   = data[6]>>4 & 0x0f;
        var f100  = data[6]    & 0x0f;
        var f100k = data[7]>>4 & 0x0f;
        var f10k  = data[7]    & 0x0f;
        var f10m  = data[8]>>4 & 0x0f;
        var f1m   = data[8]    & 0x0f;
        var freq  =  f10m.toString()+ f1m.toString()+","
                   +f100k.toString()+f10k.toString()+f1k.toString()+"."
                   + f100.toString()+ f10.toString()+f1+" kHz";
        console.log('freq: ' + freq);
        io.emit('freqmsg', 'VFO A: ' + freq);
    }

});

serial.on('error', function(err) {
  console.log('Error: ', err.message);
})

// -- socket --

io.on('connection', function(socket){

    socket.on('message1', function(){
    serial.write(buf1);
  });

    socket.on('message2', function(){
    serial.write(buf2);
  });

  socket.on('your message', function(msg){
    serial.write(bufa);
    serial.write(msg);
    serial.write(bufz);
    io.emit('your message', msg);
  });

});

// -- request freq --

function sendTime() {
    serial.write(buf3);
}

setInterval(sendTime, 100);

// -- EOF --

Changed the color mapping and some parts of the code.

index.js

var http  = require('http');
var fs    = require('fs');
var index = fs.readFileSync(__dirname + '/index.html');

var app = http.createServer(function(req, res) {
                res.writeHead(200, {'Content-Type' : 'text/html'});
                res.end(index);
              })
              .listen(3000);

var io = require('socket.io').listen(app);

var ndata   = 512;  // data[512] + 0x0a
var pos     = 0;
var myarray = new Array();

process.stdin.on('readable', function() {
  var buf = process.stdin.read();
  if (buf !== null) {
    for (var i = 0; i < buf.length; i++) {
      if (buf[i] == 0x0a) {
        pos = 0;
        io.emit('waterfall', myarray);
      } else {
        myarray[pos++] = buf[i];
      }
    }
  }
});

process.stdin.on('end', function() {
});

index.html

<!doctype html>
<html>
<head>
<script src='/socket.io/socket.io.js'></script>
<script src="https://code.createjs.com/createjs-2015.11.26.min.js"></script>

<script>
var myarray = new Array();
var socket  = io();
var canvas;
var ctx;
var imgData;

window.addEventListener("load", init);

function init() {
  canvas = document.getElementById('myCanvas');
  ctx    = canvas.getContext('2d');

  imgData = ctx.createImageData(512, 512);
  for (i = 0; i < 512; i++) {
    for (j = 0; j < 512; j++) {
      imgData.data[0 + j * 4 + i * imgData.width * 4] = j % 256;
      imgData.data[1 + j * 4 + i * imgData.width * 4] = i % 256;
      imgData.data[2 + j * 4 + i * imgData.width * 4] = 128;
      imgData.data[3 + j * 4 + i * imgData.width * 4] = 255;
    }
  }
  ctx.putImageData(imgData, 0, 0);
}

function waterFall(myarray) {
  ctx.putImageData(imgData, 0, 1);
  imgData = ctx.getImageData(0, 0, 512, 512);
  for (j = 0; j < 512; j++) {
    var tmp                 = ((myarray[j] - 48) * 25 % 256) / 256.0;
    imgData.data[0 + j * 4] = colormap_r(tmp);
    imgData.data[1 + j * 4] = colormap_g(tmp);
    imgData.data[2 + j * 4] = colormap_b(tmp);
    imgData.data[3 + j * 4] = 255;
  }
}

socket.on('waterfall', function(data) { waterFall(data); });

function colormap_r(tmp) {
  var val;
  if (tmp < 0.50) {
    val = 0.0;
  } else if (tmp > 0.75) {
    val = 1.0;
  } else {
    val = 4.0 * tmp - 2.0;
  }
  return 255.0 * val;
}

function colormap_g(tmp) {
  var val;
  if (tmp < 0.25) {
    val = 4.0 * tmp;
  } else if (tmp > 0.75) {
    val = -4.0 * tmp + 4.0;
  } else {
    val = 1.0;
  }
  return 255.0 * val;
}

function colormap_b(tmp) {
  var val;
  if (tmp < 0.25) {
    val = 1.0;
  } else if (tmp > 0.50) {
    val = 0.0;
  } else {
    val = -4.0 * tmp + 2.0;
  }
  return 255.0 * val;
}

</script>
</head>

<body>
    <canvas id="myCanvas" width="512" height="512" style="background:white;"></canvas>
</body>
</html>

The window on the right is with sprig, a C program running on a remote host to which IC-7410 is attached via an USB I/F.

The window on the left is a browser showing the same waterfall image.

You see four different browsers on a local host. They are Chrome, Firefox, Opera, and Safari. Can you tell which is which?

Remote host:

% sprig /dev/ttyUSB0 HW:2,0 |& node index.js

sprig.c

  for(int j=0;j<WATERFALL_XSIZE;j++) {
       double tmp  =  audio_signal_ffted[j];
       int    iii  = 10.0*tmp; fprintf(stderr, "%1d", iii);
       *p++ = *q++ = colormap_r(tmp);
       *p++ = *q++ = colormap_g(tmp);
       *p++ = *q++ = colormap_b(tmp);
  }

index.js

var http  = require('http');
var fs    = require('fs');
var index = fs.readFileSync(__dirname + '/index.html');
var count = 0;

var app = http.createServer(function(req, res) {
  res.writeHead(200, {'Content-Type' : 'text/html'});
  res.end(index);
});

var io = require('socket.io').listen(app);
app.listen(3000);

var ndata = 512;
var pos   = 0;
var myarray = new Array(ndata);

process.stdin.on('readable', function() {
  var buf = process.stdin.read();
  for (var i = 0; i < buf.length; i++) {
    myarray[pos++] = buf[i];
    if(pos == ndata) {
      pos = 0;
      console.log(myarray[0], myarray[1], myarray[2]);
      io.emit('time', {buffer : myarray});
    }
  }
});

index.html

<!doctype html>
<html>
<head>
<script src='/socket.io/socket.io.js'></script>
<script src="https://code.createjs.com/createjs-2015.11.26.min.js"></script>
<script>
var myarray = Array();
var socket  = io();
var canvas;
var ctx;
var imgData;
function init() {
  canvas = document.getElementById('myCanvas');
  ctx    = canvas.getContext('2d');

    imgData = ctx.createImageData(512, 512);
    for (i = 0; i < 512; i++) {
      for (j = 0; j < 512; j++) {
        imgData.data[0 + j * 4 + i * imgData.width * 4] = j % 256;
        imgData.data[1 + j * 4 + i * imgData.width * 4] = i % 256;
        imgData.data[2 + j * 4 + i * imgData.width * 4] = 0;
        imgData.data[3 + j * 4 + i * imgData.width * 4] = 255;
      }
    }
    ctx.putImageData(imgData, 0, 0);
}

function emitParticles(myarray) {
  ctx.putImageData(imgData, 0, 1);
  imgData = ctx.getImageData(0, 0, 512, 512);
  for (j = 0; j < 512; j++) {
    var index = (myarray[j] - 48) * 32 % 256;
    imgData.data[0 + j * 4] = index;
    imgData.data[1 + j * 4] = 256 - index;
    imgData.data[2 + j * 4] = 0;
    imgData.data[3 + j * 4] = 255;
  }
}

socket.on('time', function(data) {
  myarray = data.buffer;
  emitParticles(myarray);
console.log(count);
});
</script>
</head>

<body>
    <canvas id="myCanvas" width="512" height="512" style="background:white;"></canvas>
    <p id='messages'></p>
</body>
</html>

By using getImageData and putImageData with an appropriate offset value, you do not have to explicitly shift the data in imgData.

index.html

<!doctype html>
<html>
<head>
<script src='/socket.io/socket.io.js'></script>
<script src="https://code.createjs.com/createjs-2015.11.26.min.js"></script>
<script>
var nxdata  = 32;
var nydata  = 32;
var myarray = Array(nxdata);
var mytable = Array(nxdata * nydata);
var socket  = io();
var canvas;
var ctx;
var imgData;

window.addEventListener("load", init);

function init() {
  canvas = document.getElementById('myCanvas');
  ctx    = canvas.getContext('2d');
    imgData = ctx.createImageData(512, 512);
    for (i = 0; i < 512; i++) {
      for (j = 0; j < 512; j++) {
        imgData.data[0 + j * 4 + i * imgData.width * 4] = j % 256;
        imgData.data[1 + j * 4 + i * imgData.width * 4] = (255 - (i % 256));
        imgData.data[2 + j * 4 + i * imgData.width * 4] =
            ((i / 2 + j / 2) % 256);
        imgData.data[3 + j * 4 + i * imgData.width * 4] = 255;
      }
    }
    ctx.putImageData(imgData, 0, 0);
}

function emitParticles(myarray) {
  ctx.putImageData(imgData, 0, 1);
  imgData = ctx.getImageData(0, 0, 512, 512);
  for (j = 0; j < 512; j++) {
    imgData.data[0 + j * 4] = (myarray[(j>>4)%8] - 48) * 32 % 256;
    imgData.data[1 + j * 4] = j % 256;
    imgData.data[2 + j * 4] = 0;
    imgData.data[3 + j * 4] = 255;
  }
}

socket.on('time', function(data) {
  myarray = data.buffer;
  emitParticles(myarray);
});
</script>
</head>

<body>
    <canvas id="myCanvas" width="512" height="512" style="background:white;"></canvas>
    <p id='messages'></p>
</body>
</html>

A more natural way to draw waterfall pictures is to use the methods, createImageData, getImageData, and putImageData.

index.html

<!doctype html>
<html>
<head>
<script src='/socket.io/socket.io.js'></script>
<script src="https://code.createjs.com/createjs-2015.11.26.min.js"></script>
<script>
var nxdata  = 32;
var nydata  = 32;
var myarray = Array(nxdata);
var mytable = Array(nxdata * nydata);
var socket  = io();
var canvas;
var ctx;
var imgData;

window.addEventListener("load", init);

function init() {
  console.log('init..');
  canvas = document.getElementById('myCanvas');
  ctx    = canvas.getContext('2d');

  if (canvas.getContext && canvas.getContext('2d').createImageData) {
    imgData = ctx.createImageData(512, 512);
    for (i = 0; i < 512; i++) {
      for (j = 0; j < 512; j++) {
        imgData.data[0 + j * 4 + i * imgData.width * 4] = j % 256;
        imgData.data[1 + j * 4 + i * imgData.width * 4] = (255 - (i % 256));
        imgData.data[2 + j * 4 + i * imgData.width * 4] =
            ((i / 2 + j / 2) % 256);
        imgData.data[3 + j * 4 + i * imgData.width * 4] = 255;
      }
    }
    ctx.putImageData(imgData, 0, 0);
  }
}

var count  = 0;
var marker = 0;
function emitParticles(myarray) {
  count++;
  if (count % 128 == 0) {
    marker = 255;
    count  = 0;
  } else {
    marker = 0;
  }
  for (j = 0; j < 512; j++) {
    imgData.data[0 + j * 4 + (512 - 1) * imgData.width * 4] = marker;
    imgData.data[1 + j * 4 + (512 - 1) * imgData.width * 4] = 0;
    imgData.data[2 + j * 4 + (512 - 1) * imgData.width * 4] =
        (32 * myarray[(j >> 3) % 10]) % 256;
    imgData.data[3 + j * 4 + (512 - 1) * imgData.width * 4] = 255;
  }

  for (i = 0; i < 512 - 1; i++) {
    for (j = 0; j < 512; j++) {
      for (k = 0; k < 4; k++) {
        imgData.data[k + j * 4 + i * imgData.width * 4] =
            imgData.data[k + j * 4 + (i + 1) * imgData.width * 4];
      }
    }
  }

  ctx.putImageData(imgData, 0, 0);
}

socket.on('time', function(data) {
  myarray = data.buffer;
  emitParticles(myarray);
});
</script>
</head>

<body>
    <canvas id="myCanvas" width="512" height="512" style="background:white;">
    </canvas>
    <p id='messages'></p>
</body>
</html>