mazda@killer.Dallas.TX.US (John Wilson) (03/16/89)
I'm searching for information on MTS stereo decoders to add to my VCR/TV system. I have a Canon HF-600 Stereo VHS VCR that is capable of recording dual channel audio. This unit has a MPX OUT plug that was to be connected to a MS-10 Stereo Decoder option that is no longer in production. Are any such (any brand) MTS Decoders still in production? Is the MPX OUT signal a composite FM signal of both audio channels? The manual simply says this connection is for the MS-10 option but doesn't explain what the actual out-signal is. If this is a composite stereo (multiplexed) signal, what's the possibility of my building a decoder using the ECG1655 TV STEREO DECODER Integrated circuit or equivalent? Any information on converting a TV system to Stereo would be appreciated. Thanx in advance, -- ------------------------------------------------------------------------------- Moral principles can never be compromised; | J.P.Wilson - ...!killer!mazda they can only be abandoned. J.G.H. | mazda@killer.UUCP -------------------------------------------------------------------------------
mazda@rtmvax.UUCP (John Wilson) (03/17/89)
I'm searching for information on MTS stereo decoders to add to my VCR/TV system. I have a Canon HF-600 Stereo VHS VCR that is capable of recording dual channel audio. This unit has a MPX OUT plug that was to be connected to a MS-10 Stereo Decoder option that is no longer in production. Are any such (any brand) MTS Decoders still in production? Is the MPX OUT signal a composite FM signal of both audio channels? The manual simply says this connection is for the MS-10 option but doesn't explain what the actual out-signal is. If this is a composite stereo (multiplexed) signal, what's the possibility of my building a decoder using the ECG1655 TV STEREO DECODER Integrated circuit or equivalent? Any information on converting a TV system to Stereo would be appreciated. Thanx in advance, -- -------------------------------------------------------------------------------- ...the greatest sensation of existence, | J.P.Wilson - ...!rtmvax!mazda not to trust, but to know. a.r. | mazda@rtmvax.UUCP --------------------------------------------------------------------------------
tkopp@carroll1.UUCP (Tom Kopp) (03/20/89)
In article <2943@rtmvax.UUCP> mazda@rtmvax.UUCP (John Wilson) writes: > > Are any such (any brand) MTS Decoders still in production? > Is the MPX OUT signal a composite FM signal of both audio >my building a decoder using the ECG1655 TV STEREO DECODER Integrated >circuit or equivalent? Well, having been working on just such a project, I can pass the info on to you. The proper chip to use is the LM1884 (I believe, but I cannot seem to find my documentation). The box I've got is in Radio Electronics c. 2/87 I believe. Might have been 2/88, but... It was a 2 part article, so Feb and March at any rate. There are plans for building an MTS decoder in various methods, including straight MPX output, modifications to a non-stereo VCR as well as building a 'probe' (antenna tuned to 4.5 and attached to TV) which will pass the appropriate information to the decoder box which has a left and right line level output on it, as well as a headphone jack. You will probably want to do some tweaking w/ the box once you get it built, as when you actually order some of the parts from a person here in Milwaukee, you get what amounts to an 'upgrade' kit. The original (article) used an FM stereo decoder... the LM1884 is a fairly new (less than a year?) chip specifically designed, like the 1655, for TV stereo. Good luck! -- "Patience is a virtue, and I'm virtually bankrupt!" - Me tkopp@carroll1.UUCP or uunet!marque!carroll1!tkopp Thomas J. Kopp @ Carroll College 3B2 - Waukesha, WI
johng@trwind.UUCP (John Greene) (03/23/89)
In article <329@carroll1.UUCP> tkopp@carroll1.UUCP (Tom Kopp) writes: >In article <2943@rtmvax.UUCP> mazda@rtmvax.UUCP (John Wilson) writes: >> >> Are any such (any brand) MTS Decoders still in production? >> Is the MPX OUT signal a composite FM signal of both audio >>my building a decoder using the ECG1655 TV STEREO DECODER Integrated >>circuit or equivalent? > > >to an 'upgrade' kit. The original (article) used an FM stereo decoder... >the LM1884 is a fairly new (less than a year?) chip specifically designed, like >the 1655, for TV stereo. Good luck! > > Actually the part is not all *that* new as I have a 1984 data book that has that chip in it. I would not hold all that much confidence in the article printed in Radio Electronics. I was so disappointed in the errors and mistakes in their designs that I won't even look at the magazine anymore. -- John E. Greene "People are just like frankfurters....You have to decide if you're going to be a hot dog or just another wiener" DLR TRW Information Networks Division 23800 Hawthorne Blvd, Torrance CA 90505 ARPA: johng@trwind.ind.TRW.COM USENET: ..trwrb!trwind!johng
cptvideo@cbnewsc.ATT.COM (david.vlack) (03/24/89)
I built the RE stereo decoder and found that it indeed can work well, but NOT AS PUBLISHED. Some minor matrixing errors are easily corrected in the circuit, but the biggest flaw is the lack of high frequency expansion circuitry. The article points out the omission and states that the missing circuitry will not have a serious effect on the performance. In fact, the lack of dynamic HF expansion completely destroys the stereo image. I made a considerable modification to the circuit to use the unused half of the NE570 compander chip to provide for the missing expansion function. That plus numerous changes to time constants in both the signal and control paths yielded a reasonably good performing MTS decoder. By using quad op-amp chips the whole thing can be built on a board area of 1.5 x 2.5 inches and can be tucked away in an unused space in a VCR. I did that and now enjoy stereo recording of TV programs on my non MTS equipped HIFI VCR. The NE570 can not exactly duplicate the function of a DBX chip, but it is suprising how close it can come. I have the modified schematic but posting it is well beyond the capacity of the ASCII character set. Regards: Dave Vlack ...att!iexist!cptvideo