Signal Processing for Digital Vinyl Latency Reduction
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Solution Overview
Problem
Conventional digital vinyl systems (DVS) experience latency in determining the speed and position of a rotating recording medium due to the need for noise reduction and smoothing of the carrier wave, which introduces delay in the audible response, making it difficult to accurately emulate the manipulation of traditional vinyl records.
Innovation Solution
A method and apparatus that filter a time code signal to recover a sinusoidal pilot signal and a binary signal, allowing for the determination of the recording medium's speed and position without modulation, thereby minimizing the need for latency-inducing smoothing, using a high pass/low pass filter to separate the pilot and binary signals, which are combined without modulation, allowing for accurate and fast determination of frequency and playback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If heavy noise reduction or smoothing is applied to the PLL output signal to accurately determine carrier wave frequency, then measurement precision is improved, but latency increases due to the weighted moving average calculation over multiple samples
Solution Approach 1:
The time code signal is segmented into two separate components: a pilot signal for frequency determination and a binary signal for position determination. This segmentation allows the pilot signal to be processed with minimal smoothing (reducing latency) while the binary signal provides the necessary position information, resolving the contradiction between measurement precision and latency.
Solution Approach 2:
A pilot signal is introduced as an intermediary carrier wave that is not modulated by the binary signal. This pilot signal serves as a mediator that provides a clean, unmodulated reference for frequency determination, eliminating the need for aggressive smoothing of the modulated carrier wave and thereby reducing latency while maintaining measurement precision.
2Loss of information
If a modulated carrier wave is used to encode binary position information, then information capacity is improved, but the complexity of frequency detection increases requiring aggressive smoothing that introduces latency
Solution Approach 1:
The signal is divided into two separate functional components: an unmodulated pilot carrier wave for frequency detection and a modulated binary signal for position information. This segmentation simplifies the overall processing complexity by allowing independent optimization of each component - the pilot signal requires minimal processing while the binary signal carries the position data.
Solution Approach 2:
The pilot signal acts as an intermediary that carries frequency information without being modulated by position data. This intermediary signal simplifies the detection process by providing a clean reference wave that does not require complex demodulation or aggressive filtering, thereby reducing processing complexity and latency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables highly accurate and rapid determination of record speed and position, reducing latency and improving the responsiveness of the audio playback to the manipulation of the recording medium, thus enhancing the emulation of traditional vinyl record manipulation.
Implementation Method 1
a filter to filter a time code signal retrieved from a rotating recording medium to recover a sinusoidal pilot signal and a binary signal summed in the time code signal
Data Source
AI summary
Method and apparatus for signal processing for controlling a digital audio source may include retrieving a time code signal from a rotating recording medium. The time code signal may be a sum of a binary signal and a sinusoidal pilot signal in the audible range, and the binary signal has a symbol frequency less than a frequency of the pilot signal. The time code signal may be filtered to recover the pilot signal and the binary signal. An estimated speed of rotation of the recording medium may be determined from a recovered pilot signal, and an estimated position may be determined from a recovered binary signal, for controlling the digital audio source.