White Paper: Test & Measurement
Radio Astronomy Measurements Using a GaGe RazorMax Digitizer
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This application note describes how direct RF digitization enables precise measurement of extremely weak radio astronomy signals centered near 100 MHz. Traditional down-conversion architectures add noise, phase distortion, and calibration complexity, while direct digitization preserves signal integrity. Using a 16-bit, 500 MS/s GaGe RazorMax PCIe digitizer with wide analog bandwidth, the system captures low-power cosmic emissions with high dynamic range and frequency resolution. Continuous high-throughput streaming supports multi-day acquisition, while GPU-accelerated FFT processing enables real-time spectral analysis and long-term averaging. The result is a scalable, cost-effective platform for radio astronomy and other weak-signal, high-data-rate scientific measurement applications.
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Overview
This application note from Vitrek details the use of their GaGe RazorMax high-speed digitizer for advanced radio astronomy measurements, focusing on capturing weak cosmic signals around 100 MHz. Radio astronomy requires highly sensitive data acquisition systems capable of handling extremely low-power electromagnetic emissions amidst broadband noise. The document highlights an application where a customer monitors astronomical RF emissions near 100 MHz, typical of distant cosmic sources, and discusses how the RazorMax digitizer meets stringent demands for dynamic range, noise performance, frequency resolution, and long-term stability.
Unlike higher-frequency systems that use complex down-conversion stages, this application benefits from direct RF digitization, enabled by the modest frequency band well below 300 MHz. Direct digitization avoids extra noise, phase distortion, and calibration issues caused by mixers, preserving signal integrity. The RazorMax CompuScope 16502 PCIe digitizer offers a maximum 500 MS/s sampling rate, 16-bit vertical resolution, and a 300 MHz analog input bandwidth, comfortably capturing signals with minimal attenuation and excellent amplitude fidelity.
The 16-bit ADC provides a theoretical signal-to-quantization-noise ratio of ~98 dB, enabling detection of very weak spectral features without clipping stronger signals, crucial for accurate long-term spectral integration and averaging. Anti-aliasing filters in the front-end reduce out-of-band noise and prevent aliasing, ensuring data quality and system linearity.
The acquired data streams at up to 1 GB/s per channel (two channels produce up to 2 GB/s) via a PCIe Gen3 x8 interface capable of >4 GB/s sustained throughput. Continuous, loss-free data streaming enables multi-day uninterrupted acquisition, essential for meaningful astronomical studies. Real-time digital signal processing (DSP) leverages high-performance CPUs and multiple GPU accelerators to perform dense, microsecond-scale FFT spectral analysis in real time. This yields thousands of spectral frames per second, which are averaged and analyzed to extract peak frequencies, characterize broadband backgrounds, and track temporal spectral variability.
This approach delivers a scalable, cost-effective radio astronomy platform with excellent dynamic range, spectral resolution, and continuous operation without data gaps. The principles of direct digitization, high dynamic range, deterministic data transfer, and GPU-accelerated DSP are extendable to other scientific fields requiring weak-signal detection at high data rates. As digitizer and computing technologies evolve, such direct RF acquisition architectures are poised to form the foundation of next-generation measurement systems.
For more details, visit Vitrek’s website.