Cost-Effective Allan Deviation Measurement in SDRs Using Integrated ADC

This paper presents a novel technique for measuring the Allan deviation of the internal oscillator within a software-defined radio (SDR). This modified version of the standard double mixer time difference (DMTD) method utilizes the SDR’s analog-to-digital converter (ADC) to eliminate the need for expensive and specialized equipment. By analyzing the phase of the sampled signal through the ADC, the Allan deviation can be determined, providing insight into the stability of the oscillator. The paper demonstrates the effectiveness of this method through experiments conducted on five SDR platforms. The Pluto SDR and Wombat showed low and consistent Allan Deviation measurements, with the RTL-SDR performing better than expected.