Experiences with the GPS in Unstabilized CubeSat

Abstract

The paper summarizes the experiences with the operation of the piNAV GPS receiver in a 1U unstabilized CubeSat operated on LEO orbit. piNAV L1 is a GPS receiver developed by an author for small satellite missions. The receiver is equipped with the 15 GPS L1 C/A channels and acquisition accelerator that shortens the cold start of the receiver on LEO to 65 s. The typical power consumption is 120 mW. Lucky-7 is a private 1U technological CubeSat with power budget 1 W that operates on the quasisynchronous polar orbit at altitude 520 km. One of its scientific missions is to test the operation of GPS. The space experiments proved the successful operation of the GPS receiver. The position information was available for approximately 80% of the time, where the position outage was caused by a satellite rotation and relatively long navigation signal reacquisition. The experimental data proved that the position availability can be improved by a higher-performance signal acquisition engine.

Demonstration of the Capability of 1U CubeSat for Measurement of the Energy Spectrum on LEO

“…This paper aims to verify the capability of the 1U CubeSat to realize the measurement of the radiation spectra. This is in contrast to our previous paper in which we tested the functionality of the GPS receiver [19] and performed less complex dosimetry measurement with low volume of the used data without deeper evaluation [20,21].…”

CubeSat Observation of the Radiation Field of the South Atlantic Anomaly

“…Protons within the SAA with lower energy tend to drift towards the north, whereas the most energetic protons of the SAA move towards the south. In [34], piDOSE was estimated to be sensitive to protons with energies larger than 30 MeV due to the shielding of sensitive volume. Moreover, the latitudinal movement of the SAA depends on the solar cycle [21].…”

“…The main component of the satellite is an onboard computer that integrates two independent computers and UHF modems that control the satellite, collect scientific data, and communicate with ground stations. The scientific module (Figure 4) is equipped with the GPS receiver piNAV 2 [32][33][34], the radiation detector piDOSE [35,36], a spectrometer and a low-resolution camera. The energy for satellite operation is generated by gallium arsenide solar cells that are mounted on the five satellite panels.…”

“…The rotation rate is determined from the current of individual solar panels or from the periodic variation in the carrier to noise (C/N0) indicator of the GPS receiver. The rotation rate is not constant; the typical value is one turn per minute [34]. This rotation causes the GPS position to be unavailable some of the time [34].…”

“…The rotation rate is not constant; the typical value is one turn per minute [34]. This rotation causes the GPS position to be unavailable some of the time [34]. The typical availability of PNT (position, navigation, and timing) solutions is 80% of the time.…”