Hi Folks, I was wondering if someone could point me to some auxiliary information on the BTSC/MTS specification. I already have the FCC OET60 document, but it is very shy on diagrams and I'm finding it hard to interpret. I'm especially interested in the specifics of the dynamic range compandor that is utilized in the difference and SAP channels. I also am wondering whether or not the preemphasis/deemphasis filtering is the same for the sum channel and difference channels. Any pointers would be appreciated. For those who may be curious, BTSC/MTS is the specification for the old analog TV audio, the key point of which is to accept two channels, a stereo main channel and a second audio program (SAP) channel at the transmitter, encode it into the NTSC signal, and recover it at the receiver. -- % Randy Yates % "Maybe one day I'll feel her cold embrace, %% Fuquay-Varina, NC % and kiss her interface, %%% 919-577-9882 % til then, I'll leave her alone." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
BTSC/MTS Specification Clarifications
Started by ●May 2, 2007
Reply by ●May 2, 20072007-05-02
Randy Yates wrote:> Hi Folks, > > I was wondering if someone could point me to some auxiliary > information on the BTSC/MTS specification. I already have the FCC > OET60 document, but it is very shy on diagrams and I'm finding it hard > to interpret. > > I'm especially interested in the specifics of the dynamic range > compandor that is utilized in the difference and SAP channels. I also > am wondering whether or not the preemphasis/deemphasis filtering is > the same for the sum channel and difference channels. > > Any pointers would be appreciated.Randy, It looks like you are working on the BTSC project for quite a while. Is it a decoder or encoder? I can help you with it, however this is going to be business. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
Reply by ●May 2, 20072007-05-02
Vladimir Vassilevsky <antispam_bogus@hotmail.com> writes:> [...] > I can help you with it, however this is going to be business.That is so kind of you, Vladimir. Thank you, but that's not the kind of "help" I was looking for. -- % Randy Yates % "She tells me that she likes me very much, %% Fuquay-Varina, NC % but when I try to touch, she makes it %%% 919-577-9882 % all too clear." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr
Reply by ●May 2, 20072007-05-02
On May 2, 9:15 am, Randy Yates <y...@ieee.org> wrote:> Hi Folks, > > I was wondering if someone could point me to some auxiliary > information on the BTSC/MTS specification. I already have the FCC > OET60 document, but it is very shy on diagrams and I'm finding it hard > to interpret. >Hi Randy,, did you try over at sci.engineering.television.broadcast.... etc.? Mark
Reply by ●May 2, 20072007-05-02
Mark <makolber@yahoo.com> writes:> On May 2, 9:15 am, Randy Yates <y...@ieee.org> wrote: >> Hi Folks, >> >> I was wondering if someone could point me to some auxiliary >> information on the BTSC/MTS specification. I already have the FCC >> OET60 document, but it is very shy on diagrams and I'm finding it hard >> to interpret. >> > Hi Randy,, > > did you try over at sci.engineering.television.broadcast.... etc.?No, I did not. Thanks for the pointer, Mark! -- % Randy Yates % "Midnight, on the water... %% Fuquay-Varina, NC % I saw... the ocean's daughter." %%% 919-577-9882 % 'Can't Get It Out Of My Head' %%%% <yates@ieee.org> % *El Dorado*, Electric Light Orchestra http://home.earthlink.net/~yatescr
Reply by ●May 2, 20072007-05-02
For the folks on sci.engr.television.broadcast. --Randy Randy Yates <yates@ieee.org> writes:> Hi Folks, > > I was wondering if someone could point me to some auxiliary > information on the BTSC/MTS specification. I already have the FCC > OET60 document, but it is very shy on diagrams and I'm finding it hard > to interpret. > > I'm especially interested in the specifics of the dynamic range > compandor that is utilized in the difference and SAP channels. I also > am wondering whether or not the preemphasis/deemphasis filtering is > the same for the sum channel and difference channels. > > Any pointers would be appreciated. > > For those who may be curious, BTSC/MTS is the specification for the > old analog TV audio, the key point of which is to accept two channels, > a stereo main channel and a second audio program (SAP) channel at the > transmitter, encode it into the NTSC signal, and recover it at the > receiver. > -- > % Randy Yates % "Maybe one day I'll feel her cold embrace, > %% Fuquay-Varina, NC % and kiss her interface, > %%% 919-577-9882 % til then, I'll leave her alone." > %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO > http://home.earthlink.net/~yatescr-- % Randy Yates % "Remember the good old 1980's, when %% Fuquay-Varina, NC % things were so uncomplicated?" %%% 919-577-9882 % 'Ticket To The Moon' %%%% <yates@ieee.org> % *Time*, Electric Light Orchestra http://home.earthlink.net/~yatescr
Reply by ●May 2, 20072007-05-02
Randy Yates wrote:> Vladimir Vassilevsky <antispam_bogus@hotmail.com> writes: > >>[...] >>I can help you with it, however this is going to be business. > > > That is so kind of you, Vladimir. Thank you, but that's not the > kind of "help" I was looking for.Always welcome. It is a joy to find a solution by oneself, however is seems like someone snapped off more than he can chew. Just curious how many other comp.dsp folks did they try to contract on this project. Apparently your bid was the lowest, but you have underestimated the effort... Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
Reply by ●May 2, 20072007-05-02
Randy Yates wrote: (snip)> For those who may be curious, BTSC/MTS is the specification for the > old analog TV audio, the key point of which is to accept two channels, > a stereo main channel and a second audio program (SAP) channel at the > transmitter, encode it into the NTSC signal, and recover it at the > receiver.As well as I know it, the stereo signal is very similar to FM stereo, except with the subcarrier at two times the line rate, which is about 15734kHz. The pre-emphasis is probably also different, I don't know the time constants for it. SAP is a dbx (2:1 full band) compressed FM subcarrier with center, I believe, at five times the line rate. The dbx compression allows for reasonable quality in what would otherwise be a noisy signal. Other than the compression and frequency it should be similar to the FM broadcast SCA subcarrier. It might be that the FCC references the existing standards instead of writing new ones, with only the changes needed documented. -- glen
Reply by ●May 3, 20072007-05-03
On May 2, 6:15 am, Randy Yates <y...@ieee.org> wrote:> Hi Folks, > > I was wondering if someone could point me to some auxiliary > information on the BTSC/MTS specification. I already have the FCC > OET60 document, but it is very shy on diagrams and I'm finding it hard > to interpret. > > I'm especially interested in the specifics of the dynamic range > compandor that is utilized in the difference and SAP channels. I also > am wondering whether or not the preemphasis/deemphasis filtering is > the same for the sum channel and difference channels. > > Any pointers would be appreciated. > > For those who may be curious, BTSC/MTS is the specification for the > old analog TV audio, the key point of which is to accept two channels, > a stereo main channel and a second audio program (SAP) channel at the > transmitter, encode it into the NTSC signal, and recover it at the > receiver. > -- > % Randy Yates % "Maybe one day I'll feel her cold embrace, > %% Fuquay-Varina, NC % and kiss her interface, > %%% 919-577-9882 % til then, I'll leave her alone." > %%%% <y...@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescrThere is a several hundred page document that you can purchase that goes into a lot of detail on BTSC (I can remember from which standards body/organisation it comes from). It was written (like the specification itself) with analog design in mind and goes into detail about how to calibrate, measure various parameters as well as having many pages of numeric tables. Everything you need is in the OET60 document, it is just not obvious how to interpret it all. As far as the pre/de emphasis, it is not the same on the sum and difference channels. Are you doing a Encoder or Decoder?
Reply by ●May 3, 20072007-05-03
glen herrmannsfeldt wrote:> Randy Yates wrote: > > (snip) > >> For those who may be curious, BTSC/MTS is the specification for the >> old analog TV audio, the key point of which is to accept two channels, >> a stereo main channel and a second audio program (SAP) channel at the >> transmitter, encode it into the NTSC signal, and recover it at the >> receiver. > > As well as I know it, the stereo signal is very similar to FM stereo, > except with the subcarrier at two times the line rate, which is about > 15734kHz. The pre-emphasis is probably also different, I don't > know the time constants for it. > > SAP is a dbx (2:1 full band) compressed FM subcarrier > with center, I believe, at five times the line rate. The dbx > compression allows for reasonable quality in what would otherwise > be a noisy signal. Other than the compression and frequency it > should be similar to the FM broadcast SCA subcarrier. > > It might be that the FCC references the existing standards instead > of writing new ones, with only the changes needed documented.Isn't the deviation 75 KHz instead of broadcast FM's 150? Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
