$re = '/B(?<Seconds>[\d\w]{34})\s/';
$str = 'Start File
AXCT XCTrack 0.6.0 - translations: 2017-03-14 17:49:58 on HUAWEI GEM-702L 6.0
HPPLTPILOT:Kay Starkermann
HOSITSite:Schwängimatt
HPCCLCOMPETITION CLASS:FAI-3 (PG)
HPGTYGLIDERTYPE:SKYWALK Spice
HODTM100GPSDATUM:WGS-84
HFALG:GEO
HFDTE060417
LXCTDEVICE eyJjYXBhYmlsaXRpZXMiOnsibWVtQ2xhc3MiOjI1NiwibWVtTGFyZ2VDbGFzcyI6M
LXCTDEVICE jU2LCJuYW4iOnRydWV9LCJkZXZpY2UiOnsiYW5kcm9pZElkIjoiMzRhM2Q1MzBhZm
LXCTDEVICE I4YmViYyIsImJvYXJkIjoiR0VNLTcwMkwiLCJidWlsZElkIjoiSFVBV0VJR0VNLTc
LXCTDEVICE wMkwiLCJjcHVBQkkiOiJhcm02NC12OGEiLCJjcHVBQkkyIjoiIiwiZGV2aWNlU3Ry
LXCTDEVICE aW5nIjoiSFVBV0VJIEdFTS03MDJMIDYuMCIsImRpc3BsYXkiOnsiaCI6MTg0OCwib
LXCTDEVICE W0iOjE1Ljc0ODAzMiwidyI6MTIwMH0sImZpbmdlcnByaW50IjoiSFVBV0VJL0dFTS
LXCTDEVICE 03MDJML0hXR2VtaW5pOjYuMC9IVUFXRUlHRU0tNzAyTC9DMjA5QjIwMzp1c2VyL3J
LXCTDEVICE lbGVhc2Uta2V5cyIsImhhcmR3YXJlIjoiaGkzNjM1IiwibWFudWZhY3R1cmVyIjoi
LXCTDEVICE SFVBV0VJIiwicHJvZHVjdCI6IkdFTS03MDJMIiwic2RrIjoyM30sInhjdHJhY2siO
LXCTDEVICE nsidmVyc2lvbkNvZGUiOjYzLCJ2ZXJzaW9uTmFtZSI6IjAuNi4wIC0gdHJhbnNsYX
LXCTDEVICE Rpb25zOiAyMDE3LTAzLTE0IDE3OjQ5OjU4In19
LXCTSENSOR Sensors: SENSOR_BT, external GPS:true, external baro:true, intern
LXCTSENSOR al baro:false
LXCTEARTHMODEL FAI_SPHERE
B1505404717336N00740471EA0101001091
B1505414717336N00740472EA0101001091
B1505424717335N00740472EA0101001091
B1505434717336N00740472EA0101001090
B1505444717336N00740472EA0100901090
B1505454717336N00740471EA0100901091
B1505464717336N00740471EA0101001091
B1505474717336N00740471EA0101001091
B1505484717336N00740471EA0101001091
B1505494717336N00740471EA0101001091
B1505504717336N00740471EA0101001091
B1505514717336N00740471EA0101001091
End File';
preg_match_all($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