Embodiments described herein may generally pertain to a crystal oscillator (XO) in a device configured for GNSS or GPS applications. More particularly, an exemplary XO is “uncompensated,” which refers herein to an XO which lacks built-in temperature or voltage compensation (or in other words, an XO which comprises a lack of built-in compensation) to account for frequency variation, in contrast to the aforementioned TCXO and VCTCXO, which have temperature and/or voltage compensation on the TCXO and/or VCTCXO device. The description of embodiments may simply make reference to an XO, and it will be understood hereinafter that such a reference will pertain to an uncompensated XO, unless otherwise specified. Therefore, exemplary embodiments may be configured to overcome the problem associated with large frequency variation in the XO by temperature-calibrating the XO prior to launch of GNSS applications, or in other words, without waiting for explicit initiation field calibration following the launch of the first GNSS session. As used herein, GNSS sessions can include applications such as positioning, tracking, mapping, or other location/position based applications using wireless signals received from satellite sources or sometimes, calibrated terrestrial sources such as wireless wide area networks (WWAN), code division multiple access (CDMA), long term evolution (LTE) networks. In some embodiments, temperature-calibration of the XO prior to launch of GNSS sessions may also mean temperature-calibration of an exemplary XO as early as possible after the device comprising the XO is taken out of the box and made ready for use (e.g., by powering on the device for the first time). As will be explained below, some embodiments are also configured to perform this temperature-calibration based on exemplary triggering conditions, mechanisms, or events and in a background mode.