SIDLOC (Spacecraft Identification and Localization) is a proposed standard for satellite and spacecraft identification and localization. It is developed as an ESA funded ARTES activity by Libre Space Foundation. The goal of the SIDLOC system is to provide reliable spacecraft identification and orbit determination, especially early after the deployment.

The SIDLOC system relies on a reduced size autonomous transmitter that requires minimal integration and area on the carrier spacecraft. The ground segment of the SIDLOC system utilizes the existing SatNOGS network and the UHF band to perform the signal demodulation and identification. The SIDLOC system uses DSSS (Direct Sequence Spread Spectrum) PSK modulated signals with an effective bitrate of ~50 bits/s. Through an accurate Doppler frequency shift estimation mechanism, the SIDLOC system provides orbit determination capabilities, enabling open and independent SSA (Space Situational Awareness) activities.