Bloated Software Makes Me Sick

Improving ECG Reliability

⚠️ Check out my newer ECG designs:

• Sound Card ECG with AD8232
• Single op-amp ECG

Although I made a functional ECG circuit, it was extremely finicky. If you attached the electrodes too weakly (not a good enough connection), you would get no signal. If you attached the electrodes too tightly (too good of a connection), you wouldn’t get a signal either. You had to have just the right resistance between the electrodes and the body for them to work. I tried some things and finally discovered that a resistor between the circuit and me (on the ground lead) significantly improved the situation, but requires a really good body connection. My leads (2) were made from wires (non-shielded) with gator clips at the end clamping onto pennies. I added a dab of moisturizer to the pennies to get a really good connection and used electrical tape to attach them to my chest (+) and leg (GND). I recorded heart data in 10 minute blocks, and it worked amazingly well! Here is a video if me recording my ECG while playing Counter-Strike.

If you look closely you can see my heartbeat as the two leftmost bars on the display of the laptop. I’m continuing to work on this circuit, and will release details when it’s a little more complete. My plan is to write it up formally, provide a ton of examples/documentation, and really dive into the analysis aspect of it (RRI calculations, variability analysis, etc) and post it to Hackaday. DIY ECGs are nothing new, but no one who’s made one has really gone deep into its interpretation. My goal is to have this complete by next week! For now, enjoy the pretty videos.

Fringe Culture Seared Into My Brain

Generate Apache-Style HTTP Access Logs via SQL and PHP

Does your web hosting company block access to access.log, the text file containing raw website log files? If so, you’re like me, and it sucks. There’s a plethora of gorgeous and extremely insightful website traffic analyzers, but all of them require access to raw HTTP access logs. Today I propose a semi-efficient way to generate such logs utilizing PHP to determine page load data (time, user IP, requested page, referring page, user client, etc) and SQL to save such data for easy retrieval later. Note that this method is a HUGE improvement of my previous project which used PHP scripts to store HTTP access logs as flat files. Although it worked in theory, in all practicality the process of opening, writing to, and closing a text file (which grew a few MB a week) was too cumbersome for my server to comfortable handle. The method described on this page utilizes SQL, a database engine well-suited to meet these exact demands. When we’re done, you’ll be able to use a web interface to view your access log (pictured, converting long, complicated search queries to web search and image search strings automatically), or have the option to export it directly to an access.log text file in a standard Apache-style format.

First, make sure your database is structured appropriately. This page is written for those with a working knowledge of PHP and SQL, but if you’re new to the field I encourage you to learn! W3Schools.com is an awesome resource to rapidly learn new languages. Also, when starting-out with SQL (like me), phpMyAdmin is a awesome. The code, as it’s currently written (below) is designed to store data in the “nibjb” database under the “logs” table. Briefly, it uses PHP to determine user data (time, ip, requested page, etc.) and injects this information into the SQL database. In fact, it’s doing it to you right now! Don’t believe me? View the source of this web page and scroll to the bottom. BAM! There you are.

// logme.php
<?php

if ( !isset($wp_did_header) ) {
    $wp_did_header = true;
    require_once( '/home/content/n/i/b/nibjb/html/blog/wp-load.php' );
    //wp();
    //require_once( '/home/content/n/i/b/nibjb/html/blog/wp-includes/template-loader.php' );
}

function logwriter_handlevar($varname,$defaultvalue){
    $tempvar = getenv($varname);
    if(!empty($tempvar)) {
        return $tempvar;
    } else {
        return $defaultvalue;
    }
}

if (!empty($REMOTE_HOST)) {
$logwriter_remote_vistor = $REMOTE_HOST;
}else{
$logwriter_remote_vistor = logwriter_handlevar("REMOTE_ADDR","-");
}

$logwriter_remote_ident = logwriter_handlevar("REMOTE_IDENT","-");
$logwriter_remote_user = logwriter_handlevar("REMOTE_USER","-");
$logwriter_date = date("d/M/Y:H:i:s");
$logwriter_request_method = logwriter_handlevar("REQUEST_METHOD","GET");
$logwriter_request_uri = logwriter_handlevar("REQUEST_URI","");
$logwriter_server_protocol = logwriter_handlevar("SERVER_PROTOCOL","HTTP/1.1");
$logwriter_http_referer = logwriter_handlevar("HTTP_REFERER","-");
$logwriter_http_user_agent = logwriter_handlevar("HTTP_USER_AGENT","");
$logwriter_logstring = "$logwriter_remote_vistor $logwriter_remote_ident $logwriter_remote_user [$logwriter_date $logwriter_timezone] "$logwriter_request_method $logwriter_request_uri $logwriter_server_protocol" 200 - "$logwriter_http_referer" "$logwriter_http_user_agent"n";
?>

<?php
$username="YOUR_USERNAME";
$password="YOUR_PASSWORD";
$database="nibjb";
mysql_connect('mysql157.secureserver.net',$username,$password);
//mysql_connect(localhost,$username,$password);

$query = "INSERT INTO logs VALUES ('','$logwriter_date','$logwriter_remote_vistor','$logwriter_request_method','$logwriter_request_uri','$logwriter_server_protocol','$logwriter_http_referer','$logwriter_http_user_agent')";
mysql_query($query);
mysql_close();
?>

<!--
LOG DETAILS:
time: <?php echo($logwriter_date); ?>
vistor: <?php echo($logwriter_remote_vistor); ?>
method: <?php echo($logwriter_request_method); ?>
request: <?php echo($logwriter_request_uri); ?>
protocol: <?php echo($logwriter_server_protocol); ?>
referrer: <?php echo($logwriter_http_referer); ?>
agent: <?php echo($logwriter_http_user_agent); ?>
HTML LOG LINE:
<?php echo($logwriter_logstring); ?>
-->

All right, that was easy. Every time we load logme.php, it adds the data to the SQL database. To add data every time you go to a particular web page, you could use a PHP include() statement in each webpage, or you could take advantage of the PHP’s auto_append_file feature! Simply insert the following line into your php.ini file if you have access to yours:

auto_append_file = "/path/to/html/logme.php"

How do we access this data once it’s been loaded into the database? There are many different ways, but I’ve chosen to get a little creative with a sleek, yet minimalistic web-based fronted. It basically just shows the last [x] number of entries in the access log. You can adjust the number of entries displayed by slapping on some arguments to the URL, transforming viewLast.php into viewLast.php?limit=123 or something (see the screenshot above). I won’t discuss the details of this script. It’s self-explanatory.

// viewLast.php
<html>
<head>
<style type="text/css">
td {
font-family: verdana, arial;
font-size:10px;
}
</style>
</head>
<body>
<?php

$limit = (int)$_GET['limit'];
if ($limit===0) {$limit=25;}

$username="YOUR_USERNAME";
$password="YOUR_PASSWORD";
$database="nibjb";
mysql_connect('mysql157.secureserver.net',$username,$password);
mysql_select_db($database) or die( "Unable to select database");
$query="
SELECT * FROM logs WHERE
request NOT LIKE "%testlog.php%"
AND request NOT LIKE  "%/logs/%"
AND request NOT LIKE "%/wp-admin/%"
ORDER BY ID DESC LIMIT 0,$limit
";
//$query="SELECT * FROM logs WHERE referrer LIKE "%&q=%" or referrer LIKE "%&prev=%" ";
$result=mysql_query($query);
$num=mysql_numrows($result);
mysql_close();
?>

<b><?php echo($query); ?></b>
<table border="1">
<tr>
<td>id</td>
<td>time</td>
<td>visitor</td>
<td>request</td>
<td>referrer</td>
</tr>

<?php
$i=1;
while ($i<$num) {
$id=mysql_result($result,$i,"id");
$time=mysql_result($result,$i,"time");
$visitor=mysql_result($result,$i,"visitor");
$method=mysql_result($result,$i,"method");
$request=mysql_result($result,$i,"request");
$protocol=mysql_result($result,$i,"protocol");
$referrer=mysql_result($result,$i,"referrer");
$referrer2=str_replace("&", "& ", $referrer);
$agent=mysql_result($result,$i,"agent");
$searchWords="";
$searchEngine="";
if (strpos($referrer, "q=")>0 and strpos($referrer, "google")>0) {$searchEngine="Google Web Search: ";}
if (strpos($referrer, "prev=/images")>0 and strpos($referrer, "google")>0) {$searchEngine="Google Image Search: ";}

// SEARCH EXTRACTION //
$j=0;
$rTemp=str_replace("prev=/images%3Fq%3D", "q=", $referrer);
$rTemp=str_replace("?q=","&q=", $rTemp);
$rTemp=str_replace("%2B"," ", $rTemp);
$rTemp=str_replace("%26"," ", $rTemp);
$rTemp=str_replace("%3D"," ", $rTemp);
$rTemp=str_replace("+"," ", $rTemp);
$wvars=split("&",$rTemp);
while ($j<count($wvars)){
    if (substr($wvars[$j],0,2) === "q=") {
        $searchWords = $searchWords . $wvars[$j] . " ";
        }
    $j++;
}

$searchWords=substr($searchWords,strpos($searchWords, "q=")+2);
if (strlen($searchWords)<3) {$searchWords=$referrer;}

echo "
<tr>
<td>$id</td>
<td>$time</td>
<td>$visitor</td>
<td><a href='$request'>$request</a></td>
<td>$searchEngine <a href='$referrer'>$searchWords</a></td>
</td>
";
$i++;
}
?>
</table>
</body>
</html>

And you’re done! This example is a simplified, bare bones example. You can take this a long way if you’d like. My goal is lite & flexible. A quick query from Python and Matplotlib (for example) yields gorgeous visual representations of otherwise-convoluted data!

If you have any questions, or end-up developing something awesome with this code, shoot me an email! It’s not luxurious, but this code works for me, and I share it with the best of intentions.

PySquelch: A Python-Based Frequency Audio Activity Monitor

I’m pretty much done with this project so it’s time to formally document it. This project is a collaboration between Fred, KJ4LFJ who supplied the hardware and myself, Scott, KJ4LDF who supplied the software. Briefly, a scanner is set to a single frequency (147.120 MHz, the output of an active repeater in Orlando, FL) and the audio output is fed into the microphone hole of a PC sound card. The scripts below (run in the order they appear) detect audio activity, log the data, and display such data graphically.

Here is some sample output:

Live-running software is current available at: Fred’s Site. The most current code can be found in its working directory. For archival purposes, I’ll provide the code for pySquelch in ZIP format. Now, onto other things…