Feature: RF and microwave
Satellite monitoring systems for
real-time RF intelligence By the technical team of Teledyne SP Devices
S
atellite monitoring is important for many tasks, including the continuous observation of satellite communications and navigation signals for link
quality, to detect interference and verify compliance with spectrum regulations. Tese systems provide global and consistent visibility of uplink and downlink behaviour, which is critical for applications ranging from GNSS integrity and spectrum surveillance to interference hunting and system validation.
System architecture Te primary objective of satellite monitoring is to maintain the integrity of space-to-ground and ground-to-space links. Tis includes verifying uplink and downlink quality, detecting unintentional or malicious interference and supporting regulatory enforcement. Architecturally, monitoring systems are typically structured around three elements: the space segment, consisting of satellites with transponders and antennas operating in defined frequency bands; the ground segment, which includes monitoring stations equipped with large antennas, RF front ends
30 April 2026
www.electronicsworld.co.uk
and digitisers; and the user segment, where specialised soſtware and hardware analyse and visualise the captured data.
Sampling considerations Satellite services operate across designated RF bands (Figure 1), each divided into uplink and downlink sub-bands in bi- directional systems, in order to minimise mutual interference. Downlinks are usually allocated to the lower portion of a band due to lower atmospheric attenuation, whilst uplinks occupy higher frequencies to support higher data rates. Sub-band definitions vary by system;
for example, Galileo uses “E” designations within the L-band rather than the “L” nomenclature used by other GNSS constellations. From a monitoring perspective, this
diversity makes frequency planning and sampling strategy critical. Te sampling rate must ensure that the signal of interest occupies a single Nyquist zone, with out- of-band components suppressed through analogue filtering. For direct sampling, this typically translates to minimum rates of approximately 2GSPS for L-band, 4GSPS for S-band, and 8 GSPS for C-band, assuming appropriate bandpass filters are applied.
Front-end signal capture Modern monitoring stations rely on wideband digitisers to convert analogue RF signals into digital data streams. Devices such as the ADQ35-WB (Figures 2 and 3) from Teledyne SP Devices support direct sampling of L- and S-band signals without frequency mixers, reducing system complexity and calibration effort. With 12-bit resolution and up to 9GHz usable input bandwidth, such digitisers enable flexible deployment across multiple satellite bands. External low-noise amplifiers and anti-alias filters remain essential to preserve signal fidelity and prevent spectral folding during analogue-to- digital conversion. The selection of sampling rate
directly impacts both data integrity and downstream processing efficiency. For example, sampling the L-band at 5GSPS places the signal entirely within the first Nyquist zone, while S-band under- sampling at GSPS confines the signal to the second Nyquist zone with sufficient guard bands. In contrast, poorly chosen rates can split the signal across Nyquist boundaries, introducing unavoidable aliasing.
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