Patent Review
Patent No: US 3668542
Publication date: June 6,1972 Inventors: Daniel W. Stoffer C.
Title : Audio Compression Circuit Using OpAmp and
JFET
Summary :
Audio Compression reduces the dynamic range of the
any recording by bringing down the level of the loudest parts, meaning the loud
and quiet parts are now closer together in volume and the natural volume
variations are less obvious. This generally helps in mixing of musical tracks
without a significant fight. The audio compression circuit mentioned in this
patent promises a good frequency response and fast attack. The mentioned
technique makes use of a p-channel JFET connected to an Op-amp input. The FET
acts as a voltage controlled amplifier in the Operational amplifier feedback
loop. This invention thereby aims to provide gain
control not affecting the dc bias and also free of settling time limitations
which otherwise poses to be a major
problem in most audio compression circuits.
Patent Link : https://www.google.com/patents/US3668542
Paper Review
Journal : International Journal of Advanced Research in Computer and
Communication Engineering
Title : Analysis and Comparison of Audio Compression Using Discrete Wavelet Transform
Volume 86 – No 13, January 2014
Summary :
Speech compression is a technique of converting human speech into an efficiently encoded signal which can later
be decoded to produce the approximate original back again. Compression not only
reduces storage space but also bandwidth transmission power and energy. The
implemented technique Discrete wavelet Transform (DWT) decomposes original
signal into wavelet coefficients at different scales and positions which are
later truncated to perform encoding or decoding. It was also found that this
technique works best for recorded signals compared to the real time ones.
Paper Link : https://www.researchgate.net/publication/272384288_Analysis_and_Comparison_of_Audio_Compression_Using_Discrete_Wavelet_Transform
Plagiarism Check Link : https://drive.google.com/drive/folders/0BxzVWYbaSXFrMUtVRzNZWXpLeTQ
Good to know new techniques for speech compression!
ReplyDeleteUse of JFET and OPAMP in speech compression circuit is something new that your blog talks about.
ReplyDeleteYes it was something new for me to learn as well.
DeleteYes it was something new for me to learn as well.
DeleteGood to learn new techniques such as DWT
ReplyDeleteA key advantage it has over Fourier transforms is temporal resolution meaning it can capture both frequency and location information.
DeleteNice topic
ReplyDeleteJFET based opamp is preferred for audio signal to avoid input impedance problem of TTL logic.
ReplyDeleteCompression of audio reduces storage space.
ReplyDeleteAbsolutely and at the same time reduces the average energy requirement for transmission, moreover the compression should be such that there is acceptable loss of quality.
DeleteAbsolutely and at the same time reduces the average energy requirement for transmission, moreover the compression should be such that there is acceptable loss of quality.
DeleteNice application. Well explained
ReplyDeletesomething new
ReplyDeleteWell written
ReplyDelete