[Randy Yates]

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."
%%%% % 'Yours Truly, 2095', *Time*, ELO
http://home.earthlink.net/~yatescr

[Vladimir Vassilevsky]

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

[Randy Yates]

Vladimir Vassilevsky 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."
%%%% % 'Yours Truly, 2095', *Time*, ELO
http://home.earthlink.net/~yatescr

[Mark]

On May 2, 9:15 am, 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.

Hi Randy,,

did you try over at sci.engineering.television.broadcast.... etc.?

Mark

[Randy Yates]

Mark writes:

On May 2, 9:15 am, 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.

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'
%%%% % *El Dorado*, Electric Light Orchestra
http://home.earthlink.net/~yatescr

[Randy Yates]

For the folks on sci.engr.television.broadcast.

--Randy

Randy Yates 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."
%%%% % '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'
%%%% % *Time*, Electric Light Orchestra
http://home.earthlink.net/~yatescr

[Vladimir Vassilevsky]

Randy Yates wrote:
Vladimir Vassilevsky 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

[glen herrmannsfeldt]

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

[[email protected]]

On May 2, 6:15 am, 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.

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."
%%%% % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr

There 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?

[Jerry Avins]

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.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

[tony kirke]

On May 2, 4:50 pm, 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.

-- glen

The stereo signal is not very close to FM stereo. It is similar in
that it splits the signal into L+R and L-R components that are
modulated. However, L-R is dbx compressed and AM modulated first.

[Randy Yates]

glen herrmannsfeldt writes:

tony kirke wrote:

(snip about television sound)

The stereo signal is not very close to FM stereo. It is similar in
that it splits the signal into L+R and L-R components that are
modulated. However, L-R is dbx compressed and AM modulated first.

I had remembered that SAP was dbx compressed, but forgot the
stereo subcarrier was. It makes sense, though, since you have
to have the chip in there, anyway.

But what do you mean by AM modulated first? In addition to the
AM suppressed carrier usually used for the stereo subcarrier?

No. You were right the first time, Glen. It is very similar to FM. The
L+R sum signal is transmitted on the old mono main channel, and the
L-R difference signal is "encoded" and then DSB-SC modulated on a
subcarrier at 2 times the pilot subcarrier. The pilot subcarrier is the
horizontal scan rate (15734 Hz or so).
--
% Randy Yates % "Rollin' and riding and slippin' and
%% Fuquay-Varina, NC % sliding, it's magic."
%%% 919-577-9882 %
%%%% % 'Living' Thing', *A New World Record*, ELO
http://home.earthlink.net/~yatescr

[glen herrmannsfeldt]

tony kirke wrote:

(snip about television sound)

The stereo signal is not very close to FM stereo. It is similar in
that it splits the signal into L+R and L-R components that are
modulated. However, L-R is dbx compressed and AM modulated first.

I had remembered that SAP was dbx compressed, but forgot the
stereo subcarrier was. It makes sense, though, since you have
to have the chip in there, anyway.

But what do you mean by AM modulated first? In addition to the
AM suppressed carrier usually used for the stereo subcarrier?

-- glen

[glen herrmannsfeldt]

Jerry Avins wrote:

glen herrmannsfeldt wrote:

(snip)

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.

(snip)

Isn't the deviation 75 KHz instead of broadcast FM's 150?

I believe 25kHz instead of broadcast FM's 75kHz.
(That is, +/- 75kHz for a total width of 150kHz.)

Analog FM tuners will usually reach the sound carrier
of TV channel 6.

But I consider that as a separate question from the content
of the audio signal, with its own subcarriers.

-- glen

[Randy Yates]

glen herrmannsfeldt writes:

Jerry Avins wrote:

glen herrmannsfeldt wrote:

(snip)

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.

(snip)

Isn't the deviation 75 KHz instead of broadcast FM's 150?

I believe 25kHz instead of broadcast FM's 75kHz.
(That is, +/- 75kHz for a total width of 150kHz.)

The deviation depends on the mode. For mono-only signal, the peak
deviation is 25 kHz. For MTS (Multichannel Television Sound), the peak
deviation should not exceed 73 kHz.
--
% Randy Yates % "So now it's getting late,
%% Fuquay-Varina, NC % and those who hesitate
%%% 919-577-9882 % got no one..."
%%%% % 'Waterfall', *Face The Music*, ELO
http://home.earthlink.net/~yatescr

[tony kirke]

On May 3, 2:46 pm, Randy Yates wrote:
glen herrmannsfeldt writes:
tony kirke wrote:

(snip about television sound)

The stereo signal is not very close to FM stereo. It is similar in
that it splits the signal into L+R and L-R components that are
modulated. However, L-R is dbx compressed and AM modulated first.

I had remembered that SAP was dbx compressed, but forgot the
stereo subcarrier was. It makes sense, though, since you have
to have the chip in there, anyway.

But what do you mean by AM modulated first? In addition to the
AM suppressed carrier usually used for the stereo subcarrier?

No. You were right the first time, Glen. It is very similar to FM. The
L+R sum signal is transmitted on the old mono main channel, and the
L-R difference signal is "encoded" and then DSB-SC modulated on a
subcarrier at 2 times the pilot subcarrier. The pilot subcarrier is the
horizontal scan rate (15734 Hz or so).
--
% Randy Yates % "Rollin' and riding and slippin' and
%% Fuquay-Varina, NC % sliding, it's magic."
%%% 919-577-9882 %
%%%% % 'Living' Thing', *A New World Record*, ELOhttp://home.earthlink.net/~yatescr


Yes. I should have simply said that L-R is DBX compressed. I wasn't
aware that FM stereo had a pilot though.

[Randy Yates]

tony kirke writes:

On May 3, 2:46 pm, Randy Yates wrote:
glen herrmannsfeldt writes:
tony kirke wrote:

(snip about television sound)

The stereo signal is not very close to FM stereo. It is similar in
that it splits the signal into L+R and L-R components that are
modulated. However, L-R is dbx compressed and AM modulated first.

I had remembered that SAP was dbx compressed, but forgot the
stereo subcarrier was. It makes sense, though, since you have
to have the chip in there, anyway.

But what do you mean by AM modulated first? In addition to the
AM suppressed carrier usually used for the stereo subcarrier?

No. You were right the first time, Glen. It is very similar to FM. The
L+R sum signal is transmitted on the old mono main channel, and the
L-R difference signal is "encoded" and then DSB-SC modulated on a
subcarrier at 2 times the pilot subcarrier. The pilot subcarrier is the
horizontal scan rate (15734 Hz or so).
--
% Randy Yates % "Rollin' and riding and slippin' and
%% Fuquay-Varina, NC % sliding, it's magic."
%%% 919-577-9882 %
%%%% % 'Living' Thing', *A New World Record*, ELOhttp://home.earthlink.net/~yatescr


Yes. I should have simply said that L-R is DBX compressed. I wasn't
aware that FM stereo had a pilot though.

Yes - it's at 19 kHz instead of 16.75 kHz.
--
% Randy Yates % "Rollin' and riding and slippin' and
%% Fuquay-Varina, NC % sliding, it's magic."
%%% 919-577-9882 %
%%%% % 'Living' Thing', *A New World Record*, ELO
http://home.earthlink.net/~yatescr

[Randy Yates]

Randy Yates writes:

Yes - it's at 19 kHz instead of 16.75 kHz.

I meant 15.75 kHz.
--
% Randy Yates % "How's life on earth?
%% Fuquay-Varina, NC % ... What is it worth?"
%%% 919-577-9882 % 'Mission (A World Record)',
%%%% % *A New World Record*, ELO
http://home.earthlink.net/~yatescr

[Randy Yates]

glen herrmannsfeldt writes:

Randy Yates wrote:

Randy Yates writes:

Yes - it's at 19 kHz instead of 16.75 kHz.

I meant 15.75 kHz.

Except that it is closer to 15.734 kHz, unless you can find
a black and white show with stereo sound.

I was rounding to the nearest 50 kHz.
--
% Randy Yates % "She has an IQ of 1001, she has a jumpsuit
%% Fuquay-Varina, NC % on, and she's also a telephone."
%%% 919-577-9882 %
%%%% % 'Yours Truly, 2095', *Time*, ELO
http://home.earthlink.net/~yatescr

[glen herrmannsfeldt]

Randy Yates wrote:

Randy Yates writes:

Yes - it's at 19 kHz instead of 16.75 kHz.

I meant 15.75 kHz.

Except that it is closer to 15.734 kHz, unless you can find
a black and white show with stereo sound.

-- glen

[Robert Orban]

In article , says...


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.

http://www.thatcorp.com/dbxtv-home.html

[glen herrmannsfeldt]

Robert Orban wrote:
(snip)

Any pointers would be appreciated.

http://www.thatcorp.com/dbxtv-home.html

A digital implementation of the analog system,
including the dbx compression!

Or, since the previous patent had expired, a way to
keep patent protection for the system.

It seems to even include verilog source (presumably
for patent licensees only).

-- glen