jackg@tekirl.LABS.TEK.COM (Jack Gjovaag) (09/08/89)
I don't follow the latest in integrated circuit offerings but based upon some products I have seen lately, I think there must be a reasonably priced chipset for converting voice to digital form, storing it, and retreiving it and restoring it to its analog form. Does anyone have a pointer to such an integrated circuit? Reply to jackg@tekirl.labs.tek.com. Thanks in advance. Jack Gjovaag Tek Labs
bill@videovax.tv.Tek.com (William K. McFadden) (09/08/89)
One of the cheapest ways to digitize and compress speech is with a codec. These chips are used by the phone company. They take an audio input and filter it, digitize it, and compress it into 8-bit samples at an 8 KHz sample rate. In addition, there is circuitry to convert the digits back to audio. The digital I/O is serial. The parts cost around $5 to $10 in hundreds; I don't know the single piece price. There are two standards, mu-law and A-law. The difference refers to the data compression algorithm, mu-law being the U.S. phone standard and A-law being the European standard. It doesn't matter which one you use-- they both work well. Codecs are made by many companies, including AT&T, Intel, Motorola, National, Oki, Fujitsu, and others. As for storage and retrieval, a cheap microcontroller (e.g., 8051 type) and a bunch of slow RAM should work fine. If you want to do any digital signal processing (e.g., extra data compression), TI's 1st generation DSP, the TMS 32010, can be had for less than $5 (not sure about single piece prices). -- Bill McFadden Tektronix, Inc. P.O. Box 500 MS 58-639 Beaverton, OR 97077 UUCP: bill@videovax.Tek.com, {hplabs,uw-beaver,decvax}!tektronix!videovax!bill GTE: (503) 627-6920 "The biggest difference between developing a missle component and a toy is the 'cost constraint.'" -- John Anderson, Engineer, TI