Question

I receive 12 hour time format from GPS tracker .
example , GPS time : 8:25:40 in GMT0 (in 12hour format)
GPS sent this time with a delay may be in range of 1~20 minute

receive time from GPS with 00:2:15 delay on 2012-07-27 23:27:55 with Europe/Moscow timezone

P.S: on above data , result of my GPS time must be 2012-07-27 23:25:40

Question:
How can I specify GPS time in my Timezone (Europe/Moscow) ?

Answer 1

$gps_time      = "9:43:52";
$time_received = "01:45:04 2012-07-28";

$utc    = new DateTimeZone("UTC");
$moscow = new DateTimeZone("Europe/Moscow");

//Instantiate both AM and PM versions of your time
$gps_time_am = new DateTime("$gps_time AM", $utc);
$gps_time_pm = new DateTime("$gps_time PM", $utc);

//Received time
$time_received = new DateTime($time_received, $moscow);

//Change timezone to Moscow
$gps_time_am->setTimezone($moscow);
$gps_time_pm->setTimezone($moscow);

//Check the difference in hours. If it's less than 1 hour difference, it's the correct one.
if ($time_received->diff($gps_time_pm)->h < 1) {
    echo $gps_time_pm->format("H:i:s Y-m-d");
}
else {
    echo $gps_time_am->format("H:i:s Y-m-d");
}

Make sure to specify the exact date of the received time to prevent oddities.

P.S. Moscow is in Europe.