$re = '/(\$INGGA.*\n\$INHDT.*\n)/';
$str = '$INGGA,091124.00,5249.8336,N,00120.9619,W,1,20,0.6,95.0,M,49.4,M,,*50
$INHDT,31.9,T*1E $INZDA,091124.0055,06,05,2016,,*7F
$INVTG,22.0,T,,M,4.4,N,8.1,K,A*24
$PRDID,2.13,-0.06,34.09*6C
$INGGA,091124.20,5249.8338,N,00120.9618,W,1,20,0.6,95.0,M,49.4,M,,*5D
$INHDT,34.1,T*13 $INZDA,091124.2055,06,05,2016,,*7D
$INVTG,24.9,T,,M,4.4,N,8.1,K,A*2B
$PRDID,2.16,-0.03,36.24*61
$INGGA,091124.40,5249.8340,N,00120.9616,W,1,20,0.6,95.0,M,49.4,M,,*5A
$INHDT,36.3,T*13 $INZDA,091124.4055,06,05,2016,,*7B
$INVTG,27.3,T,,M,4.4,N,8.1,K,A*22
$PRDID,2.11,-0.05,38.33*68
$INGGA,091124.60,5249.8343,N,00120.9614,W,1,20,0.6,95.1,M,49.4,M,,*58
$INHDT,38.4,T*1A $INZDA,091124.6055,06,05,2016,,*79
$INVTG,29.5,T,,M,4.4,N,8.1,K,A*2A
$PRDID,2.09,-0.02,40.37*6D
$INGGA,091124.80,5249.8345,N,00120.9612,W,1,20,0.6,95.1,M,49.4,M,,*56
$INHDT,40.4,T*15 $INZDA,091124.8055,06,05,2016,,*77
$INVTG,31.7,T,,M,4.4,N,8.1,K,A*21
$PRDID,2.09,0.02,42.42*40
$INGGA,091125.00,5249.8347,N,00120.9610,W,1,20,0.6,95.1,M,49.4,M,,*5F
$INHDT,42.4,T*17
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php