Optical Link Audio Transmission with Temporal Offset
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing communication systems for audible sound over optical links face challenges in effectively transmitting low-frequency sounds due to frequency roll-off, particularly when the temporal offset between signal copies is not sufficient, leading to inadequate reproduction of speech and other audio signals.
Innovation Solution
The method involves generating pairs of signal copies with a temporal offset of at least 100 µs, which is greater than the time of flight from the first location to a third location, allowing for effective modulation and transmission of audible sounds over optical links, enabling better communication of low-frequency sounds by adjusting the delay to prevent low-frequency roll-off within the audible bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a small temporal offset is used between signal copies, then the transmission speed is faster, but low-frequency roll-off occurs causing poor reproduction of audible sounds
Solution Approach 1:
The patent changes the temporal offset parameter from a small value to at least 100 μs, which is at least four times greater than the time of flight from the first location to the third location. This parameter change shifts the low-frequency roll-off to below the audible range, enabling faithful reproduction of audible sounds while maintaining efficient transmission.
2Reliability
If a large temporal offset is used between signal copies, then low-frequency sounds are reproduced better, but the transmission delay increases
Solution Approach 1:
The patent applies partial action by setting the temporal offset to exactly what is needed (at least 100 μs and four times the time of flight) to push the roll-off below audible frequencies, rather than using an excessively large offset. This provides sufficient delay to improve low-frequency reproduction while minimizing unnecessary transmission delay.
3Device complexity
If the temporal offset is less than 100 μs, then the system is more compact and faster, but audible bandwidth communication is compromised
Solution Approach 1:
The patent establishes a minimum temporal offset parameter of 100 μs (four times the time of flight) that ensures the low-frequency roll-off occurs below the audible range. This parameter setting enables the system to communicate full audible bandwidth sounds effectively while maintaining reasonable system compactness.
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 allows for the reliable transmission and reproduction of audible sounds, including speech and musical noises, by ensuring that the temporal offset is sufficient to prevent low-frequency roll-off, thereby improving the communication of audio signals over optical links.
Implementation Method 1
with an interferometric means generating pairs of signal copies such that there is a temporal offset between the signal copies of each pair
Implementation Method 2
transmitting the pairs of signal copies over the optical link from the second location such that the pairs of signal copies are modulated by a speech sound present at the first location
Implementation Method 3
reflecting the pairs of signal copies at a third location
Implementation Method 4
causing one signal copy of a given pair to mix with the other signal copy of that pair to produce a signal representative of that speech sound
Data Source
Figure 1~5
Figure 2a~2b
Figure 3~4
AI summary
The present invention relates to the communication or reproduction of sound, in particular audible sound. There is provided a method of communicating a sound, including the steps of: transmitting, onto an optical link, pairs of signal copies, the signal copies of a given pair having a time offset relative to one another; applying the audible sound to the optical link, such that the audible sound causes a phase modulation to the transmitted signal copies; receiving modulated signal copies previously transmitted onto the link; and, for received pairs of signal copies, causing one signal copy of a pair to mix with the other signal copy of that pair so as to produce a signal representative of the sound. The sound is an audible sound. It has been found that a delay of at least 75 micro seconds allows for a better reproduction of audio sounds, since these have a relatively low frequency content.