Avoiding Frequency Cancellation Using Multiple Microphones in a Surveillance Camera
(2021) EITM01 20211Department of Electrical and Information Technology
- Abstract
- In surveillance it is important that the recordings are accurate and in as high
quality as possible. The surveillance surroundings and equipment can alter and
change the audio and needs to be compensated for.
This master thesis project investigates whether using multiple microphones
could improve the audio quality. The project was limited to only use analog
electronics and constricted itself to the audible frequency range of 20 Hz to 20
kHz.
The projects started with a theoretical study of different concepts of multiple
microphones, then one concept was implemented and evaluated. The chosen
concept was how to avoid destructive interference using multiple microphones
achieving a frequency response without cancelled frequencies.
... (More) - In surveillance it is important that the recordings are accurate and in as high
quality as possible. The surveillance surroundings and equipment can alter and
change the audio and needs to be compensated for.
This master thesis project investigates whether using multiple microphones
could improve the audio quality. The project was limited to only use analog
electronics and constricted itself to the audible frequency range of 20 Hz to 20
kHz.
The projects started with a theoretical study of different concepts of multiple
microphones, then one concept was implemented and evaluated. The chosen
concept was how to avoid destructive interference using multiple microphones
achieving a frequency response without cancelled frequencies.
After the prestudy, the concept was realised by filtering the signals from two
microphones that were exposed to destructive interference in different frequency
ranges. The filter was based on the Linkwitz-Riley crossover filter.
Simulations were used to evaluate the filter, witch was then realised in a prototype
that was tested in an audio lab.
The test result showed that the concept functioned successfully. The filter
produced a signal without the frequency losses that each of the microphones experienced. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9043399
- author
- Ringsmose, Victoria LU
- supervisor
- organization
- course
- EITM01 20211
- year
- 2021
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Audio, analog electronics, acoustics, interferense, cancelled frequencies, surveillance, multiple microphones, frequency analysis, crossover filter, analog filter
- report number
- LU/LTH-EIT 2021-808
- language
- English
- id
- 9043399
- date added to LUP
- 2021-05-05 10:33:45
- date last changed
- 2021-05-05 10:33:45
@misc{9043399, abstract = {{In surveillance it is important that the recordings are accurate and in as high quality as possible. The surveillance surroundings and equipment can alter and change the audio and needs to be compensated for. This master thesis project investigates whether using multiple microphones could improve the audio quality. The project was limited to only use analog electronics and constricted itself to the audible frequency range of 20 Hz to 20 kHz. The projects started with a theoretical study of different concepts of multiple microphones, then one concept was implemented and evaluated. The chosen concept was how to avoid destructive interference using multiple microphones achieving a frequency response without cancelled frequencies. After the prestudy, the concept was realised by filtering the signals from two microphones that were exposed to destructive interference in different frequency ranges. The filter was based on the Linkwitz-Riley crossover filter. Simulations were used to evaluate the filter, witch was then realised in a prototype that was tested in an audio lab. The test result showed that the concept functioned successfully. The filter produced a signal without the frequency losses that each of the microphones experienced.}}, author = {{Ringsmose, Victoria}}, language = {{eng}}, note = {{Student Paper}}, title = {{Avoiding Frequency Cancellation Using Multiple Microphones in a Surveillance Camera}}, year = {{2021}}, }