Measurements of IP3 and P1dB for Spectrum Monitoring with Software Defined Radios

Published

March 30, 2022

Author(s)

Mike McNulty, Dazhen Gu, Dan Kuester, Payam Nayeri

Abstract

This paper discusses methodology for characterizing linearity summary parameters of software-defined radio receivers. First, we introduce a highly automated testbed for 1-dB compression point (P1dB) and third-order input intercept point (IIP3). With this system, we have observed some surprising deviations from the expected slope of 3 dB/dB in the power response of the third-order intermodulation distortion (IMD3). In response to this, we developed a measurement technique based on linear regression that accounts for the actual slope. A methodology study considers this technique in comparison with existing techniques for IIP3 measurements of spectrum monitoring receivers. In consideration for the increase in IM3 model complexity, we also propose an alternative parameter to simplify the quantitative evaluation of spectral regrowth near the receiver noise floor. We argue that this equivalence point provides a designer with more valuable information than an IIP3 point for spectrum monitoring applications.

Proceedings Title

Proceedings of the 16th European Conference on Antennas and Propagation

Conference Dates

March 27-April 1, 2022

Conference Location

Madrid, ES

Conference Title

16th European Conference on Antennas and Propagation

Pub Type

Conferences

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Keywords

software-defined radios, 1-dB compression point, IP3, measurements, spectrum monitoring

Citation

McNulty, M. , Gu, D. , Kuester, D. and Nayeri, P. (2022), Measurements of IP3 and P1dB for Spectrum Monitoring with Software Defined Radios, Proceedings of the 16th European Conference on Antennas and Propagation, Madrid, ES, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=934065 (Accessed October 9, 2025)