# GNSS Jamming Observed on Sounding Rocket Flights from Northern Scandinavia +
Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))). [PERSON]  
1 German Space Operations Center (GSOC), German Aerospace Center (DLR), Munchener Str. 20, D-8234 Westling, Germany; [EMAIL_ADDRESS] (O.M. ); [EMAIL_ADDRESS] (M.M.) [PERSON]  
1 German Space Operations Center (GSOC), German Aerospace Center (DLR), Munchener Str. 20, D-8234 Westling, Germany; [EMAIL_ADDRESS] (O.M. ); [EMAIL_ADDRESS] (M.M.) [PERSON]  
1 German Space Operations Center (GSOC), German Aerospace Center (DLR), Munchener Str. 20, D-8234 Westling, Germany; [EMAIL_ADDRESS] (O.M. ); [EMAIL_ADDRESS] (M.M.) [PERSON]  
2 Mobile Rocket Base (MORABA), German Aerospace Center (DLR), Munchener Str. 20, D-8234 Westling, Germany; marcus.hoerschen@[EMAIL_ADDRESS] (M.H.-E.)  
2 Mobile Rocket Base (MORABA), German Aerospace Center (DLR), Munchener Str. 20, D-8234 Westling, Germany; marcus. The tracking filters of the GNSS receivers used were specially adapted to the high acceleration and jerk, especially at lift-off and at motor burnout. Until now, single-frequency, L1-band GNSS receivers have been utilized. The DLR Phoenix-HD GPS receiver is a GPS constellation-only receiver with twelve tracking channels. It was specifically developed at DLR for use on board sounding rockets and bases upon the Orion-HD GPS receiver. It was introduced to the MORABA sounding rockets in 2001 and has since proven to be very robust in countless sounding rocket flights [1]. The Novatel OEM719 receiver is a state-of-the-art geodetic-grade receiver which can track the signals of all current GNSS constellations. It is regarded as one of the successors to the discontinued DLR Phoenix-HD GPS receiver for navigation on sounding rockets. Sounding rockets with active attitude control or guided sounding rockets also have an inertial navigation system on board, which provides not only the position and velocity but also the orientation of the sounding rocket. Several different GNSS antenna options are available depending on the specific configuration and mission type of the sounding rocket. The most suitable are so-called wraparound antennas. These antenna rings consist of several patch antenna elements whose feeds are connected in groups via signal combiners to form a single antenna output and, as the name suggests, are wrapped around the cylindric body of the sounding rocket payload. The network of patch antenna elements enables the continuous tracking of GNSS signals, especially during the spinning phase. From the end of 2022, MORABA observed that the reception of GNSS signals on sounding rocket vehicles was disturbed. Table 1 lists all sounding rocket missions of MORABA since the end of 2021. The first phenomena of interfered GNSS signals were detected on the TEXUS-57 mission. Similar phenomena were observed on the following sounding rocket flights. In the beginning, the interference was small but became dominant on more recent missions. The interference was strong enough to decrease the signal quality of the GNSS signals such that the GNSS receivers could not continuously track these signals anymore. Since the launch of REXUS-27, interference has regularly occurred, leading to a temporary or even complete loss of the navigation solution. During the MAPHEUS-13 mission, the reception of GNSS signals was prevented by a technical issue, so that an assessment of the interference was not possible.