Tv signals..Trasmitter??

[Anders N. Vinje]

Hello.
I have been wondering about this thing with tv ratings work. How do they
know witch channel you are watching.

Another question is. Here in Norway we have to pay a lisence every year to
our public tv-station. I have seen this car with a big antenna on it. It was
to see if people had their tv on. How is this possible? Does send out som
kind of signal telling its on? And witch frequensy you are watching. And i
thought the tv just was a reciver....


Anders

 

[michael turner]

On Sun, 14 Mar 2004 22:57:56 +0000, Anders N. Vinje wrote:

Hello.
I have been wondering about this thing with tv ratings work. How do they
know witch channel you are watching.

A small number of *selected*, *nonimated* households have a small box,
linked to the TV which records which channel is being being watched, and
for how long for. Also these people record how many people in the
household, are watching that particular channel, by pressing buttons on a
remote-control connected to the monitoring-hardware. A similar thing is
done for radio listener ratings. The idea is do give an overall
representation of viewing/listening figures.

Also which households have the monitoring equipment, is kept a closely
guarded secret for obvious reasons.

Another question is. Here in Norway we have to pay a lisence every year
to our public tv-station.

It's the same here in Britain to fund the BBC, and AFAIK most of
Western-Europe has a similar arrangement.

I have seen this car with a big antenna on it.

They don't always need that 'car with a big antenna', they often use small
handheld detectors for detecting individual TVs, STBs and videos in
blocks-of-flats, multiple household buildings, etc.

It was to see if people had their tv on. How is this possible? Does send
out som kind of signal telling its on? And witch frequensy you are
watching. And i thought the tv just was a reciver....

Yup a TV is just a receiver, but it radiates a small portion of its IF
signal, this is what the detectors use, and so can tell which channel your
watching.

Also they don't have to check every household, only the ones registered as
NOT having a license.

--
Michael Turner
Email (ROT13)
zvxr.gheare1963@ivetva.arg

 

[Tim Auton]

"Anders N. Vinje" <thedumpster@hotmail.com> wrote:

Hello.
I have been wondering about this thing with tv ratings work. How do they
know witch channel you are watching.

They don't. They have a sample of people (a few thousand) which
statistics say is enough to predict the behaviour of the population to
within a percent or two (very much like election polls). It's these
people that they monitor - they have special boxes in their homes.


Tim
--
Love is a travelator.

 

[michael turner]

On Sun, 14 Mar 2004 23:17:56 +0000, michael turner wrote:

On Sun, 14 Mar 2004 22:57:56 +0000, Anders N. Vinje wrote:

It was to see if people had their tv on. How is this possible? Does
send out som kind of signal telling its on? And witch frequensy you are
watching. And i thought the tv just was a reciver....

Yup a TV is just a receiver, but it radiates a small portion of its IF
signal, this is what the detectors use, and so can tell which channel
your watching.

PS.

From http://www.tv-l.co.uk:

How our detector vans can catch out licence evaders? We can detect a TV in
use, in any area. That's because every TV contains a component called the
'local oscillator', which emits a signal when the television is switched
on. It's this signal that the equipment on our vans picks up.

But, what if you live in a block of flats or a house without road access?
Well if this is the case our enquiry officer can simply use one of our
hand-held scanners. Measuring both direction and strength of signal, they
make it easy for us to locate television sets in hard to reach places.

--
Michael Turner
Email (ROT13)
zvxr.gheare1963@ivetva.arg

 

[Glenn Ashmore]

Anders N. Vinje wrote:

Another question is. Here in Norway we have to pay a lisence every year to
our public tv-station. I have seen this car with a big antenna on it. It was
to see if people had their tv on. How is this possible? Does send out som
kind of signal telling its on? And witch frequensy you are watching. And i
thought the tv just was a reciver....

We don't have that over on this side of the pond. We just have to sit
through 3 or 4 weeks a year of begging and pleading.

There are several little oscillator circuits inside every TV set. One
called the Intermediate Frequency Oscillator separates the picture
signal from the carrier frequency. Another is in the tuner section and
others control the vertical and horozontal sweep. They don't radiate
very far but they are detectable by the proper receiver at several
hundred feet.

Somehow the idea of trucks driving around detecting TV sets reminds me
of Fahrenheit 451. I think I better recheck all my books critical of
the administration for those anti-theft chips.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

 

[gothika]

On Sun, 14 Mar 2004 21:10:43 -0500, Glenn Ashmore <gashmore3@cox.net>
wrote:

Anders N. Vinje wrote:

Another question is. Here in Norway we have to pay a lisence every year to
our public tv-station. I have seen this car with a big antenna on it. It was
to see if people had their tv on. How is this possible? Does send out som
kind of signal telling its on? And witch frequensy you are watching. And i
thought the tv just was a reciver....

We don't have that over on this side of the pond. We just have to sit
through 3 or 4 weeks a year of begging and pleading.

There are several little oscillator circuits inside every TV set. One
called the Intermediate Frequency Oscillator separates the picture
signal from the carrier frequency. Another is in the tuner section and
others control the vertical and horozontal sweep. They don't radiate
very far but they are detectable by the proper receiver at several
hundred feet.

Somehow the idea of trucks driving around detecting TV sets reminds me
of Fahrenheit 451. I think I better recheck all my books critical of
the administration for those anti-theft chips.

You'd be better off checking with someone who worked in the Federal
government who's in the know.
Our government did the same thing for many years and worse.
You seem to be knowledgeable in electronics. Can you say passive
intrusion?
The technology to listen in on us in our homes has been around for
many decades.

 

[gothika]

On Mon, 15 Mar 2004 01:38:03 +0000, michael turner
<zvxr.gheare1963@ivetva.arg> wrote:

On Sun, 14 Mar 2004 23:17:56 +0000, michael turner wrote:

On Sun, 14 Mar 2004 22:57:56 +0000, Anders N. Vinje wrote:

It was to see if people had their tv on. How is this possible? Does
send out som kind of signal telling its on? And witch frequensy you are
watching. And i thought the tv just was a reciver....

Yup a TV is just a receiver, but it radiates a small portion of its IF
signal, this is what the detectors use, and so can tell which channel
your watching.

Would it be possible to shield the set? Maybe using MU metal or some
such?

PS.

From http://www.tv-l.co.uk:

How our detector vans can catch out licence evaders? We can detect a TV in
use, in any area. That's because every TV contains a component called the
'local oscillator', which emits a signal when the television is switched
on. It's this signal that the equipment on our vans picks up.

But, what if you live in a block of flats or a house without road access?
Well if this is the case our enquiry officer can simply use one of our
hand-held scanners. Measuring both direction and strength of signal, they
make it easy for us to locate television sets in hard to reach places.

 

[gothika]

On Mon, 15 Mar 2004 01:38:03 +0000, michael turner
<zvxr.gheare1963@ivetva.arg> wrote:

On Sun, 14 Mar 2004 23:17:56 +0000, michael turner wrote:

On Sun, 14 Mar 2004 22:57:56 +0000, Anders N. Vinje wrote:

It was to see if people had their tv on. How is this possible? Does
send out som kind of signal telling its on? And witch frequensy you are
watching. And i thought the tv just was a reciver....

Yup a TV is just a receiver, but it radiates a small portion of its IF
signal, this is what the detectors use, and so can tell which channel
your watching.

Wait, I just remembered there is made a copper mesh cloth that is

supposed to shield all intrusive technology.
There are a couple of firms in the US that make and sell it. One or
two overseas(England I think.)
I can't remember what it's called though. Saw it on Tech TV last
month.
Can anyone here remember what this mesh is called?

PS.

From http://www.tv-l.co.uk:

How our detector vans can catch out licence evaders? We can detect a TV in
use, in any area. That's because every TV contains a component called the
'local oscillator', which emits a signal when the television is switched
on. It's this signal that the equipment on our vans picks up.

But, what if you live in a block of flats or a house without road access?
Well if this is the case our enquiry officer can simply use one of our
hand-held scanners. Measuring both direction and strength of signal, they
make it easy for us to locate television sets in hard to reach places.

 

[michael turner]

On Sun, 14 Mar 2004 22:49:54 -0600, gothika wrote:

On Mon, 15 Mar 2004 01:38:03 +0000, michael turner
zvxr.gheare1963@ivetva.arg> wrote:

On Sun, 14 Mar 2004 23:17:56 +0000, michael turner wrote:

On Sun, 14 Mar 2004 22:57:56 +0000, Anders N. Vinje wrote:

It was to see if people had their tv on. How is this possible? Does
send out som kind of signal telling its on? And witch frequensy you are
watching. And i thought the tv just was a reciver....

Yup a TV is just a receiver, but it radiates a small portion of its IF
signal, this is what the detectors use, and so can tell which channel
your watching.

Would it be possible to shield the set? Maybe using MU metal or some
such?

AFAIK the signal from the TV is radiated via the antenna thru the
downlead. The local-oscillator and IF are within the TV's tuner-head,
which is normally a grounded screened metal box already.

I suppose one could devise some kind of filtering/duplexing arrangement to
block the sets radiated signal, while still allowing the TV signal to
pass-thru. But in the end it's probably safer just to buy a
TV-License.

--
Michael Turner
Email (ROT13)
zvxr.gheare1963@ivetva.arg

 

[michael turner]

On Sun, 14 Mar 2004 22:54:23 -0600, gothika wrote:

On Mon, 15 Mar 2004 01:38:03 +0000, michael turner
zvxr.gheare1963@ivetva.arg> wrote:

On Sun, 14 Mar 2004 23:17:56 +0000, michael turner wrote:

On Sun, 14 Mar 2004 22:57:56 +0000, Anders N. Vinje wrote:

It was to see if people had their tv on. How is this possible? Does
send out som kind of signal telling its on? And witch frequensy you are
watching. And i thought the tv just was a reciver....

Yup a TV is just a receiver, but it radiates a small portion of its IF
signal, this is what the detectors use, and so can tell which channel
your watching.

Wait, I just remembered there is made a copper mesh cloth that is
supposed to shield all intrusive technology.

You been watching that Gene Hackman/Will Smith movie 'Enemy of the State' ?

There are a couple of firms in the US that make and sell it. One or
two overseas(England I think.)
I can't remember what it's called though. Saw it on Tech TV last
month.
Can anyone here remember what this mesh is called?

A Faraday-cage ?

--
Michael Turner
Email (ROT13)
zvxr.gheare1963@ivetva.arg

 

[Stephen J. Rush]

On Mon, 15 Mar 2004 10:21:47 +0000, michael turner wrote:

Would it be possible to shield the set? Maybe using MU metal or some
such?

AFAIK the signal from the TV is radiated via the antenna thru the
downlead. The local-oscillator and IF are within the TV's tuner-head,
which is normally a grounded screened metal box already.

I suppose one could devise some kind of filtering/duplexing arrangement to
block the sets radiated signal, while still allowing the TV signal to
pass-thru. But in the end it's probably safer just to buy a
TV-License.

This problem has already been solved by designers of military radio
equipment, but the solution has to be engineered into each receiver. In
short, it is possible to design a receiver that doesn't radiate enough to
be detectable, but it isn't easy or cheap to do it right.