Lost Sync With Device

[Hateley123]

I am trying to use a Teensy 4.1 as a clock when connecting lidar, cameras and IMUs. However, whenever I tried to send an nmea message through my serial 1 port, it takes too long and as a result my system desyncs. my code is copied below

Definitions:
#define GPSERIAL Serial1 // $GPRMC

Code:
if (sendNMEA == true) {
char time_now[7], date_now[7];
time_t t = nh.now().sec;
sprintf(time_now, "%02i%02i%02i", hour(t), minute(t), second(t));
sprintf(date_now, "%02i%02i%02i", day(t), month(t), year(t) % 100);
String nmea_string = F("GPRMC,") + String(time_now) +
F(",A,4365.107,N,79347.702,E,022.4,084.4,") +
String(date_now) + ",003.1,W";
String chk = checksum(nmea_string);
nmea_string = "$" + nmea_string + "*" + chk + "\n";
GPSERIAL.print(nmea_string);
sendNMEA = false;
digitalWriteFast(PPS_PIN, LOW); // minimum pulse duration required by LiDAR is 10 us
//nh.loginfo(nmea_string.c_str());
}

The code works as I am able to obtain a nmea_string. I have tested this through outputting the string, but I am unable to pass through the lidar.

I am using:
VLP-16 Puck Connecting the PPS to the GPS Sync Pulse and connecting GPSERIAL to GPS Serial Reciever (manual:https://velodynelidar.com/wp-content/uploads/2019/12/63-9243-Rev-E-VLP-16-User-Manual.pdf)

Any assistance would be appreciated.

[Hateley123]

using noetic btw