TV Second Audio Programming (SAP) on radio?
 

Some tv stations broadcast audio programming on their second audio
channel (SAP). For example, some channels play the news in Spanish.

Is there any way to listen to these second audio programs on the
radio?
If I have a cheap digital tuning (or analog tuning) AM / FM radio,
is there a way to let it pick up the SAP frequencies?

Step by step instructions would be greatly appreciated.

In article ,
tech guy wrote:
Some tv stations broadcast audio programming on their second audio
channel (SAP). For example, some channels play the news in Spanish.

Is there any way to listen to these second audio programs on the
radio?
If I have a cheap digital tuning (or analog tuning) AM / FM radio,
is there a way to let it pick up the SAP frequencies?

Step by step instructions would be greatly appreciated.

This is for US analog TV.

SAP is a narrowband FM subcarrier on the TV Audio Signal. 75 Khz,
I think. So if you tap the detector output of a TV set [Note: Extreme
shock hazard on most TV Sets] or a VCR, and feed that into a receiver
or VLF converter, you can pick it up (poorly) using slope detection
on an AM receiver. It's very narrowband FM, and uses one of the noise
reduction systems (dbx? dolby?). There's also a "studio to remote"
subcarrier at, I think, 95 kHz. (I never got around to monitoring it).

This is the same as a SCA signal on a FM Audio Broadcast, where
67, 75, and 92 kHz are used for "Elevator Music", talking newspapers
for the blind, and various subscription ethnic radio services.

Easiest way would be to hit the thrift stores or repair shops for
a half-broken top of the line VCR that has that bell and whistle.

Mark Zenier Washington State resident

Mark Zenier wrote:
SAP is a narrowband FM subcarrier on the TV Audio Signal. 75 Khz,
I think.

78.67KHz, 5 times horizontal sweep. It's DBX companded.

The other subcarrier ("pro channel") is at 102.27KHz. It has no fixed
purpose but many stations indeed use it for studio=remote purposes.

This is the same as a SCA signal on a FM Audio Broadcast, where
67, 75, and 92 kHz are used for "Elevator Music", talking newspapers
for the blind, and various subscription ethnic radio services.

There's no 75KHz subcarrier for FM but there is a data carrier at 57KHz
on some stations, used for RDS. (which allows some newer car radios to
display the name of the station you're tuned to - and sometimes, the
song being played)

It is theoretically illegal (under the ECPA) to monitor FM SCAs or the
"pro channel" without the station's permission. No, I don't think
there's much chance of getting caught.

--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

In article ,
Doug Smith W9WI wrote:
Mark Zenier wrote:
SAP is a narrowband FM subcarrier on the TV Audio Signal. 75 Khz,
I think.

78.67KHz, 5 times horizontal sweep. It's DBX companded.

The other subcarrier ("pro channel") is at 102.27KHz. It has no fixed
purpose but many stations indeed use it for studio=remote purposes.

This is the same as a SCA signal on a FM Audio Broadcast, where
67, 75, and 92 kHz are used for "Elevator Music", talking newspapers
for the blind, and various subscription ethnic radio services.

There's no 75KHz subcarrier for FM but there is a data carrier at 57KHz
on some stations, used for RDS. (which allows some newer car radios to
display the name of the station you're tuned to - and sometimes, the
song being played)

No, I've monitored some of the local SCA services here, and (as of a dozen
years ago, when I built an SCA demodulator) they did use 75 kHz. If they
bothered to have one, they usually had all three in use. There's no
regulation beyond how much modulation and bandwidth of their signal is
devoted to SCA. There's also a whole zoo full of digital services.

Mark Zenier Washington State resident

On Wed, 6 Oct 2004 11:45:27 -0500, Mark Zenier wrote
(in article ):

In article ,
tech guy wrote:
Some tv stations broadcast audio programming on their second audio
channel (SAP). For example, some channels play the news in Spanish.

Is there any way to listen to these second audio programs on the
radio?
If I have a cheap digital tuning (or analog tuning) AM / FM radio,
is there a way to let it pick up the SAP frequencies?

Step by step instructions would be greatly appreciated.

This is for US analog TV.

SAP is a narrowband FM subcarrier on the TV Audio Signal. 75 Khz,
I think. So if you tap the detector output of a TV set [Note: Extreme
shock hazard on most TV Sets] or a VCR, and feed that into a receiver
or VLF converter, you can pick it up (poorly) using slope detection
on an AM receiver. It's very narrowband FM, and uses one of the noise
reduction systems (dbx? dolby?). There's also a "studio to remote"
subcarrier at, I think, 95 kHz. (I never got around to monitoring it).

This is the same as a SCA signal on a FM Audio Broadcast, where
67, 75, and 92 kHz are used for "Elevator Music", talking newspapers
for the blind, and various subscription ethnic radio services.

Easiest way would be to hit the thrift stores or repair shops for
a half-broken top of the line VCR that has that bell and whistle.

Mark Zenier Washington State resident


--------------------------------------------------------

Actually, before going on a rampage through all the thrift shops (et
cetera) within a 179.52 mile radius, it's a really good idea to see if
your teevee has it built in.

Fer instance, on mine (Sony), go to the teevee menu, go to audio and
select "SAP".



Gray Shockley
--------------------------------------------------------
Looks Good/Lasts a Long Time