EG915N-EU GNSS: Invalid UTC and Coordinates after First Fix

IoT Modules LTE Standard Module
1

Hi Quectel Team,

I am encountering an issue with the GNSS performance on the EG915N-EU module. After the first valid fix is obtained, the module outputs several records with corrupted timestamps and incorrect coordinates before stabilizing again.

Module Details:

  • Model: EG915N-EU
  • Fix Type: The records show Fix Mode 3 (3D Fix) despite the data being incorrect.

The Problem: As shown in the table below, the first record (19346) is correct. However, immediately after, the GNSS time jumps to 1984 and 2079, and the coordinates drift to near (0,0). By the fourth record, the coordinates return to the correct location, but the year remains stuck in 1999.

Data Log:
id|toradex_serial_number|lat|lng|speed|gnss_time|log_time|sattelites|hdop|pdop|gps_signal|quality|fix_mode|sog|cogt
19351|15176805|42.7205|23.312|0.772|2026-02-09 02:57:44.000000|2026-02-09 02:57:44.804291|7|1.24|2.22|0|0|3|0.487|0
19350|15176805|42.7206|23.312|0.179|2026-02-09 02:57:42.000000|2026-02-09 02:57:42.695394|7|1.24|2.22|0|0|3|0.487|0
19349|15176805|42.7205|23.312|0.317|1999-11-30 02:57:40.000000|2026-02-09 02:57:40.708301|7|1.24|2.22|0|0|3|0.487|0
19348|15176805|0.0118668|0.00647555|0.487|2079-02-23 07:17:30.000000|2026-02-09 02:57:18.695376|6|1.26|3.05|0|0|3|0.487|0
19347|15176805|0.71201|0.388533|0.487|1984-07-30 01:53:14.000000|2026-02-09 02:57:16.688177|6|1.26|3.05|0|0|3|0.487|0
19346|15176805|42.7206|23.312|0.487|2026-02-09 02:57:14.000000|2026-02-09 02:57:14.695429|6|1.26|3.05|0|0|3|0.487|0

Observations:

  • The log_time (local system time) shows that these records occur in sequence.
  • The error happens immediately after the GNSS engine starts/gets a fix.
  • The module reports 6-7 satellites and a valid 3D fix during these corrupted periods.
2

Dear @Martin_Manolov ,

Good Day,

The behavior you are observing with your EG915N-EU (which functions similarly to the EG915U/G series in these sources) indicates a synchronization failure between the GNSS engine and the module’s Real-Time Clock (RTC) during the initial fix acquisition.

Recommended steps as below:
RTC Configuration: Use the command AT+QCFG="rtc/cfg",<NV_enable>,<RTC_enable>,<NWT_enable>,<TZ_cfg> to manage how the module handles time.

• Recommended Setting: AT+QCFG="rtc/cfg",1,1,1,1 .

◦ This ensures the module takes time from NV (Non-Volatile memory) as the initial value.

◦ It synchronizes the RTC with the base station time once connected to the network

Thank You and Have a Great Day!