Transfer Function Measurements When the Reference Signal is Known but not Accessible

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Publisher: SMPTE
Doc Type: Journal Article
Content Type: Original Research
Abbreviated Title: SMPTE Motion Imaging Jour.
Volume: 134, No. 3, pp. 16–21
Abstract: Transfer function measurements offer significant benefits over historical band spectrum measurements for calibrating loudspeakers by additionally calculating phase and coherence in the frequency domain and identifying the arrival time of reflections in the time domain. However, this requires two channels: the reference signal input to the speaker and a microphone in the sound field. In cinema systems, it is often difficult to duplicate the reference signal to an analyzer. There may be no spare inputs or outputs, limited routing options, and/or digital connectors not conducive to a Y-cable. A virtual reference method is presented, which, given a copy of the reference signal, can be reconstituted in real-time. Virtual reference can also detect, measure, and compensate for sample rate differences between the playback device and the analyzer. This allows the analyzer to show a stable trace while virtual reference separately displays clocking differences such as jitter and wander.
Publication Date: 2025-05-01
DOI: 10.5594/JMI.2025/PGRJ7276
ISSN: Print: 1545-0279 | Electronic: 2160-2492
Link: https://doi.org/10.5594/JMI.2025/PGRJ7276
Author(s): Juan Sierra Lozanzo
Swapan Gandhi
Jay Wyatt
Roger Schwenke
Keyword(s): Transfer Function, Reference Signal, Virtual Reference, Band Spectrum
Copyright: © 2025 SMPTE

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Juan Sierra Lozanzo, Swapan Gandhi, Jay Wyatt, and Roger Schwenke; Transfer Function Measurements When the Reference Signal is Known but not Accessible, MIJ 2025, Volume 134, Number 3 (pp. 16 to 21); SMPTE, 2025. Available at https://doi.org/10.5594/JMI.2025/PGRJ7276

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Juan Sierra Lozanzo, Swapan Gandhi, Jay Wyatt, and Roger Schwenke; Transfer Function Measurements When the Reference Signal is Known but not Accessible, MIJ 2025, Volume 134, Number 3 (pp. 16 to 21); SMPTE, 2025. Available at https://doi.org/10.5594/JMI.2025/PGRJ7276

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<span class="citation">Juan Sierra Lozanzo, Swapan Gandhi, Jay Wyatt, and Roger Schwenke; <cite>Transfer Function Measurements When the Reference Signal is Known but not Accessible</cite>, MIJ 2025, Volume 134, Number 3 (pp. 16 to 21); SMPTE, 2025. Available at <a href="https://doi.org/10.5594/JMI.2025/PGRJ7276" target="_blank" rel="noopener">https://doi.org/10.5594/JMI.2025/PGRJ7276</a></span>

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Juan Sierra Lozanzo, Swapan Gandhi, Jay Wyatt, and Roger Schwenke; Transfer Function Measurements When the Reference Signal is Known but not Accessible, MIJ 2025, Volume 134, Number 3 (pp. 16 to 21); SMPTE, 2025
doi: 10.5594/JMI.2025/PGRJ7276
url: https://doi.org/10.5594/JMI.2025/PGRJ7276

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<li>
Juan Sierra Lozanzo, Swapan Gandhi, Jay Wyatt, and Roger Schwenke; <cite id="bib-10-5594-jmi-2025-pgrj7276">Transfer Function Measurements When the Reference Signal is Known but not Accessible</cite>, MIJ 2025, Volume 134, Number 3 (pp. 16 to 21); SMPTE, 2025
<span class="doi">10.5594/JMI.2025/PGRJ7276</span>
</li>