Frequency stability of software-defined radios - part I. Measurements
DOI:
https://doi.org/10.24425/mms.2023.155803Abstract
The popularity and high efficiency of the software-defined radio (SDR) architecture led to its export to other areas of technology, 𝑒.𝑔., software-defined networks, vehicles, infrastructure, etc. These devices, as commercials off-the-shelfs (COTS), are the basis for numerous implementations and prototyping of new solutions. SDR allows for easy adoption of existing or development and testing of new communication standards, protocols, etc., also thanks to the support of open and free applications. SDR frequency stability is important in numerous applications, especially in techniques based on frequency measurement. This paper presents the methodology for frequency stability measurements for several popular COTS SDR platforms. Measurement was conducted in two variants, with and without an external rubidium frequency standard (RFS). We generally analyse two groups of frequency stability metrics, 𝑖.𝑒., the fundamental parameters and the Allan deviation that provide a comparison of measurement and manufacturer datasheet. These parameters are analysed as a function of time depending on the selected measurement intervals. We determine the distribution of the parameters tested, which is the basis for assessing and classifying SDRs. The results obtained can serve as a basis for modelling the SDR instability phenomenon in future simulation studies, including our own planned work as well as broader research conducted by the scientific community.References
[1] Goeller, L., & Tate, D. (2014). A technical review of software defined radios: vision, reality, and current status. In 2014 IEEE Military Communications Conference (pp. 1466-1470). https://doi.org/10.1109/milcom.2014.242
[2] Machado-Fernández, J.R. (2014). Software Defined Radio: Basic principles and applications. Revista Facultad de Ingeniería, 24(38), 79. https://doi.org/10.19053/01211129.3160
[3] Krishnan, R., Babu, R.G., Kaviya, S., Kumar, N.P., Rahul, C., & Raman, S.S. (2017). Software defined radio (SDR) foundations, technology tradeoffs: A survey. 2017 IEEE International Conference on Power, Control, Signals and Instrumentation Engineering (ICPCSI), 2677-2682. https://doi.org/10.1109/icpcsi.2017.8392204
[4] Michailidis, E.T., Maliatsos, K., & Vouyioukas, D. (2024). Software-defined radio deployments in UAV-driven applications: A comprehensive review. IEEE Open Journal of Vehicular Technology, 1-43. https://doi.org/10.1109/ojvt.2024.3477937
[5] Hussain, W., Isoaho, J., & Nurmi, J. (2016). The Future of Software-Defined Radio: Recommendations. In Springer eBooks (pp. 237-238). https://doi.org/10.1007/978-3-319-49679-5_12
[6] Jdid, B., Hassan, K., Dayoub, I., Lim, W.H., & Mokayef, M. (2021). Machine Learning Based Automatic Modulation Recognition for Wireless Communications: A Comprehensive Survey. IEEE Access, 9, 57851-57873. https://doi.org/10.1109/access.2021.3071801
[7] De La Rosa, J. M. (2022). AI-Assisted Sigma-Delta Converters - Application to Cognitive Radio. IEEE Transactions on Circuits & Systems II: Express Briefs, 69(6), 2557-2563. https://doi.org/10.1109/tcsii.2022.3161717
[8] Skokowski, P., Malon, K., & Łopatka, J. (2022). Building the Electromagnetic Situation Awareness in MANET Cognitive Radio Networks for Urban Areas. Sensors, 22(3), 716. https://doi.org/10.3390/s22030716
[9] Manco, J., Dayoub, I., Nafkha, A., Alibakhshikenari, M., & Thameur, H.B. (2022). Spectrum Sensing Using Software Defined Radio for Cognitive Radio Networks: A Survey. IEEE Access, 10, 131887-131908. https://doi.org/10.1109/access.2022.3229739
[10] Lahoud, C., Ehsanfar, S., Gabriel, M., Kuffner, P., & Mosner, K. (2022). Experimental Testbed Results on LTE/5G-V2I Communication Using Software Defined Radio. ICC 2022 - IEEE International Conference on Communications, 2894-2899. https://doi.org/10.1109/icc45855.2022.9838411
[11] Zhang, J., Lu, K., Wan, Y., Xie, J., & Fu, S. (2024). Empowering UAV-Based Airborne Computing Platform with SDR: Building an LTE Base Station for Enhanced Aerial Connectivity. IEEE Transactions on Vehicular Technology, 1-14. https://doi.org/10.1109/tvt.2024.3406339
[12] Bergstrom, C., Chuprun, S., Gifford, S., & Maalouli, G. (2002). Software Defined Radio (SDR) Special Military Applications. In Military Communications Conference MILCOM (pp. 383-388). https://doi.org/10.1109/milcom.2002.1180472
[13] Mobile Experts LLC (2011) Software Defined Radio (SDR): Market Shipments and Adoption Review. Report Commissioned by Wireless Innovation Forum. Sep. 09, 2025. [Online]. Available: https://www.wirelessinnovation.org/assets/documents/mexp-sdr-11%20final.pdf
[14] Malatest B. (2023). Software defined radios (SDR) for electronic warfare. Apr. 24, 2023. [Online]. Available: https://www.everythingrf.com/community/software-defined-radios-sdr-for-electronic-warfare
[15] Rukaiya, R., Khan, S.A., Farooq, M.U., & Matloob, I. (2024). Communication architecture and operations for SDR-enabled UAVs network in disaster-stressed areas. Ad Hoc Networks, 160, 103506. https://doi.org/10.1016/j.adhoc.2024.103506
[16] Szczepanik, R., & Kelner, J.M. (2025). Filtering and overlapping data for accuracy enhancement of Doppler-based location method. Sensors, 25(5), 1465. https://doi.org/10.3390/s25051465
[17] Bednarz, K., Wojtuń, J., Kelner, J.M., & Różyc, K. (2024). Frequency Instability Impact of Low-Cost SDRs on Doppler-Based Localization Accuracy. Sensors, 24(4), 1053. https://doi.org/10.3390/s24041053
[18] Matuszewski, J., & Kraszewski, T. (2021). Evaluation of emitter location accuracy with the modified triangulation method by means of maximum likelihood estimators. Metrology and Measurement Systems, 28(4), 781-802. https://doi.org/10.24425/mms.2021.138537
[19] Mochizuki, K., Uchino, M., & Morikawa, T. (2007). Frequency-Stability measurement system using high-speed ADCs and digital signal processing. IEEE Transactions on Instrumentation and Measurement, 56(5), 1887-1893. https://doi.org/10.1109/tim.2007.895588
[20] De La Rosa, J.J.G., Moreno, A., Lloret, I., Pallarés, V., & Liñán, M. (2006). Characterisation of frequency instability and frequency offset using instruments with incomplete data sheets. Measurement, 39(7), 664-673. https://doi.org/10.1016/j.measurement.2006.01.001
[21] Marszalec, M., Lusawa, M., & Osuch, T. (2020b). Efficient frequency jumps detection algorithm for atomic clock comparisons. Metrology and Measurement Systems, 28(1), 107-121. https://doi.org/10.24425/mms.2021.135996
[22] Bednarz K., Wojtuń J., Kelner J.M., Ziółkowski C., & Leśnik C. (2025). Frequency stability of software-defined radios - Part II. Modelling for simulation studies. (in review), Metrology and Measurement Systems, 32(4), 2025.
[23] “ADALM-PLUTO SDR hack: Tune 70 MHz to 6 GHz and GQRX install,” rtl-sdr.com. Accessed: May 19, 2025. [Online]. Available: https://www.rtl-sdr.com/adalm-pluto-sdr-hack-tune-70-mhz-to-6-ghz-and-gqrx-install
[24] Analog Devices, “ADALM-PLUTO SDR active learning module.” 2017. [Online]. Available: https://www.analog.com/media/en/news-marketing-collateral/product-highlight/adalm-pluto-product-highlight.pdf
[25] Ettus Research, “USRP B200mini-i.” 2024. [Online]. Available: https://www.ettus.com/all-products/usrp-b200mini-i-2
[26] Nuand, “bladeRF 2.0 micro xA4.” 2024. [Online]. Available: https://www.nuand.com/product/bladerf-xa4
[27] Ettus Research, “USRP networked series.” 2024. [Online]. Available: https://www.ettus.com/product-categories/usrp-networked-series
[28] Ettus Research, “TX and RX daughterboards for the USRP software radio system,” Olifantasia. [Online]. Available: https://www.olifantasia.com/gnuradio/usrp/files/datasheets/datasheet_daughterboards.pdf
[29] EMIN, “NI USRP-2930 USRP software defined radio device (50 MHz 2.2 GHz, 1-channel, GPSDO).” 2024. [Online]. Available: https://emin.com.mm/niusrp-2930781910-01-ni-usrp-2930-usrp-software-defined-radio-device-50-mhz-2-2-ghz-1-channel-gpsdo-100661/pr.html
[30] National Instruments, “USRP-2950 specifications.” 2024. [Online]. Available: https://www.ni.com/docs/en-US/bundle/usrp-2950-specs/page/specs.html
[31] Przystupa, K., Kolodiy, Z., Yatsyshyn, S., Majewski, J., Khoma, Y., Petrovska, I., Lasarenko, S., & Hut, T. (2022). Standard deviation in the simulation of statistical measurements. Metrology and Measurement Systems, 30(1), 17-30. https://doi.org/10.24425/mms.2023.144403
[32] Greenhall, C., Howe, D., & Percival, D. (1999). Total variance, an estimator of long-term frequency stability [standards]. IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 46(5), 1183-1191. https://doi.org/10.1109/58.796124
[33] Howe D.A. (1976). Frequency domain stability measurements: a tutorial introduction, U.S. Department of Commerce, National Bureau of Standards, Institute for Basic Standards, Time and Frequency Division, Washington, DC, NBS Technical Note 679, Mar. 1976. [Online]. Available: https://www.govinfo.gov/content/pkg/GOVPUB-C13-8becaeba7356ac60e56d89f36043ff7e/pdf/GOVPUB-C13-8becaeba7356ac60e56d89f36043ff7e.pdf
[34] Křen, P. (2012). Laser frequency counting and frequency modulation width measurement from an FFT signal. Metrology and Measurement Systems, 19(3), 565-572. https://doi.org/10.2478/v10178-012-0049-0
[35] Kelner, J.M., Ziółkowski, C., & Marszałek, P. (2016). Influence of the frequency stability on the emitter position in SDF method. In International Conference on Military Communications and Information Systems (ICMCIS) (pp. 1-6). https://doi.org/10.1109/icmcis.2016.7496554
[36] Fernández, E., Calero, D., & Parés, M. (2017). CSAC characterization and its impact on GNSS clock augmentation performance. Sensors, 17(2), 370. https://doi.org/10.3390/s17020370
[37] Dawkins, S.T., McFerran, J.J., & Luiten, A.N. (2007). Considerations on the measurement of the stability of oscillators with frequency counters. IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 54(5), 918-925. https://doi.org/10.1109/tuffc.2007.337
[38] Gu, X., Zheng, C., Li, Z., Zhou, G., Zhou, H., & Zhao, L. (2023). Cooperative localization for UAV systems from the perspective of physical clock synchronization. IEEE Journal on Selected Areas in Communications, 42(1), 21-33. https://doi.org/10.1109/jsac.2023.3322797
[39] Wang, G., Yao, Y., Yan, T., Bian, L., & Meng, Y. (2019). A new optical frequency transfer method via fibre based on active phase noise compensation with single acousto-optic modulator. Metrology and Measurement Systems, 26(1), 115-124. https://doi.org/10.24425/mms.2019.126334
[40] Berber, Z., Kameche, S., & Benkhelifa, E. (2019). High tolerance of charge pump leakage current in Integer-N PLL frequency synthesizer for 5G networks. Simulation Modelling Practice and Theory, 95, 134-147. https://doi.org/10.1016/j.simpat.2019.04.010
