© ASTRON

These images show measurements from the first operating Ethernet receiver, tested with a low band antenna (LBA) at the ASTRON test field, as part of the MID4Automotive project.

The Ethernet receiver places the ADC close to the antenna, minimising analogue cable length and directly connecting the antenna to the Ethernet network.

The digitised data is transported over a fiber Ethernet link, with the clock sent towards the antenna using the White Rabbit protocol and the data stream returned from the antenna. The Ethernet receiver not only reduces copper costs but also enables flexible processing on GPUs.

The first plot shows frequency versus time. The structure visible across the band around 60 MHz is consistent with sky-dominated emission rather than local interference. The second plot shows the summed power between 58 and 59 MHz, which clearly increases as strong sources in the Milky Way move through the antenna beam. In red, the power of subband 300 (58.5 MHz) over the same time interval is shown for an LBA antenna at station CS002. This agreement confirms that the observed signal is dominated by astronomical sources rather than instrumental effects.

This confirms that the Ethernet receiver chain preserves weak sky signals and that the system noise is low enough to observe galactic emission.

For this demonstration, a small coaxial cable is used between the antenna and Huisje West; in the next step, the Ethernet receiver will be integrated into the antenna pole.