Quad shield coax & dielectric?
 

In message , Jerry Stuckle
writes
On 3/17/2014 3:15 PM, Rob wrote:
Jerry Stuckle wrote:
Most likely the company reduced the transmitted power by a factor
of 10 at the time of the switchover, to put the added link margin
in their own pockets.
(transmitting a megawatt of ERP as was regular in the analog days
puts a serious dent in your electricity bill, even when you have
a lot of antenna gain)


Not at all. If anything, they raised their power.

Here they went from 1 megawatt to about 50 kilowatt (ERP).
And then there are several programmes on one transponder, instead
of one analog programme. This gives significant savings in power.


OK, you mean absolute power. Yes, they can lower the ERP - but that
does not necessarily lower the power for the signal. Remember at 1MW
the power was spread over 4.25 Mhz (assuming video only, of course).
Digital requires much less bandwidth, so they don't need as much power
to get the same effective signal. However, digital still requires a
stronger signal than analog, in the bandwidth provided. You need quite
a bit of noise before it becomes visible in analog. Digital, a single
noise pulse can cause the loss of several bits of information. Because
of the compression involved, this is more than one or two pixels.

I think not much of that is correct.
The systems differ a bit between US and elsewhere, but over here the
channel spacing of digital and analog is the same, and the bandwidth
is similar (a bit more for digital if anything).

Also there is no discission of "spreading", we are just discussing
peak envelope ERP.
You could argue that a single digital stream sending 5 programmes
means that 1 programme is transmitted at 1/5 the power, but that is
not what I mean. The total ERP for 1 transmitter has been lowered,
and it transmits multiple programmes to boot.

Digital requires less power because it requires less signal-to-noise
ratio at the receiver.


There are major differences between Europe's PAL and the U.S.'s NTSC.

Where do you get these strange ideas? Yes, there are differences (the
major one being the subcarrier phase alternation of PAL), but otherwise
the systems are very similar - and none of the differences really affect
the basics of RF system measurements.

But the digital signal has much LESS bandwidth than the old analog one.

No it doesn't. It's the same. In the UK the 8MHz wide analogue channels
have been replaced with an 8MHz wide digital QAM signal, and this
occupies the same channel frequency. Unless I'm very much mistaken, the
US has done the same (except that the channels are 6MHz wide).

That was the major impetus over here to switch to digital - to free
up major bandspace in the VHF and UHF spectrums.

The 'freeing-up' is because each QAM multiplexed transport stream
carries typically up to 6 TV channels and 6 high-quality stereo radio
channels.

We now have as many (or, in some areas, more) stations in a much
smaller band than before.

Digital requires less power because the bandwidth is much lower.

Only insofar as the digital decoder can successfully extract accurate
data from the 6 or 8MHz wide multiplexed transport stream at
signal-to-noise ratios which, for analogue, would produce barely
watchable pictures.
--
Ian

Quad shield coax & dielectric?
 

On 3/17/2014 5:03 PM, Ian Jackson wrote:
In message , Jerry Stuckle
writes
On 3/17/2014 3:15 PM, Rob wrote:
Jerry Stuckle wrote:
Most likely the company reduced the transmitted power by a factor
of 10 at the time of the switchover, to put the added link margin
in their own pockets.
(transmitting a megawatt of ERP as was regular in the analog days
puts a serious dent in your electricity bill, even when you have
a lot of antenna gain)


Not at all. If anything, they raised their power.

Here they went from 1 megawatt to about 50 kilowatt (ERP).
And then there are several programmes on one transponder, instead
of one analog programme. This gives significant savings in power.


OK, you mean absolute power. Yes, they can lower the ERP - but that
does not necessarily lower the power for the signal. Remember at 1MW
the power was spread over 4.25 Mhz (assuming video only, of course).
Digital requires much less bandwidth, so they don't need as much power
to get the same effective signal. However, digital still requires a
stronger signal than analog, in the bandwidth provided. You need quite
a bit of noise before it becomes visible in analog. Digital, a single
noise pulse can cause the loss of several bits of information. Because
of the compression involved, this is more than one or two pixels.

I think not much of that is correct.
The systems differ a bit between US and elsewhere, but over here the
channel spacing of digital and analog is the same, and the bandwidth
is similar (a bit more for digital if anything).

Also there is no discission of "spreading", we are just discussing
peak envelope ERP.
You could argue that a single digital stream sending 5 programmes
means that 1 programme is transmitted at 1/5 the power, but that is
not what I mean. The total ERP for 1 transmitter has been lowered,
and it transmits multiple programmes to boot.

Digital requires less power because it requires less signal-to-noise
ratio at the receiver.


There are major differences between Europe's PAL and the U.S.'s NTSC.

Where do you get these strange ideas? Yes, there are differences (the
major one being the subcarrier phase alternation of PAL), but otherwise
the systems are very similar - and none of the differences really affect
the basics of RF system measurements.


From facts.

But the digital signal has much LESS bandwidth than the old analog one.

No it doesn't. It's the same. In the UK the 8MHz wide analogue channels
have been replaced with an 8MHz wide digital QAM signal, and this
occupies the same channel frequency. Unless I'm very much mistaken, the
US has done the same (except that the channels are 6MHz wide).


Wrong again.

That was the major impetus over here to switch to digital - to free
up major bandspace in the VHF and UHF spectrums.

The 'freeing-up' is because each QAM multiplexed transport stream
carries typically up to 6 TV channels and 6 high-quality stereo radio
channels.


Ah, so the channel is effectively only 1Mhz wide then.

We now have as many (or, in some areas, more) stations in a much
smaller band than before.

Digital requires less power because the bandwidth is much lower.

Only insofar as the digital decoder can successfully extract accurate
data from the 6 or 8MHz wide multiplexed transport stream at
signal-to-noise ratios which, for analogue, would produce barely
watchable pictures.

You really don't understand digital, do you?

I hate it when someone tries to tell me my job which I've been doing for
years... But some people just think they know it all...

--
==================
Remove the "x" from my email address
Jerry Stuckle

==================

Quad shield coax & dielectric?
 

In message , Jerry Stuckle
writes
On 3/17/2014 5:03 PM, Ian Jackson wrote:
In message , Jerry Stuckle
writes
On 3/17/2014 3:15 PM, Rob wrote:
Jerry Stuckle wrote:
Most likely the company reduced the transmitted power by a factor
of 10 at the time of the switchover, to put the added link margin
in their own pockets.
(transmitting a megawatt of ERP as was regular in the analog days
puts a serious dent in your electricity bill, even when you have
a lot of antenna gain)


Not at all. If anything, they raised their power.

Here they went from 1 megawatt to about 50 kilowatt (ERP).
And then there are several programmes on one transponder, instead
of one analog programme. This gives significant savings in power.


OK, you mean absolute power. Yes, they can lower the ERP - but that
does not necessarily lower the power for the signal. Remember at 1MW
the power was spread over 4.25 Mhz (assuming video only, of course).
Digital requires much less bandwidth, so they don't need as much power
to get the same effective signal. However, digital still requires a
stronger signal than analog, in the bandwidth provided. You need quite
a bit of noise before it becomes visible in analog. Digital, a single
noise pulse can cause the loss of several bits of information. Because
of the compression involved, this is more than one or two pixels.

I think not much of that is correct.
The systems differ a bit between US and elsewhere, but over here the
channel spacing of digital and analog is the same, and the bandwidth
is similar (a bit more for digital if anything).

Also there is no discission of "spreading", we are just discussing
peak envelope ERP.
You could argue that a single digital stream sending 5 programmes
means that 1 programme is transmitted at 1/5 the power, but that is
not what I mean. The total ERP for 1 transmitter has been lowered,
and it transmits multiple programmes to boot.

Digital requires less power because it requires less signal-to-noise
ratio at the receiver.


There are major differences between Europe's PAL and the U.S.'s NTSC.

Where do you get these strange ideas? Yes, there are differences (the
major one being the subcarrier phase alternation of PAL), but otherwise
the systems are very similar - and none of the differences really affect
the basics of RF system measurements.


From facts.

Care to share a few of your 'facts'? How do the relatively minor
differences between analogue PAL and NTSC affect how you do RF (and most
video) performance measurements?

But the digital signal has much LESS bandwidth than the old analog one.

No it doesn't. It's the same. In the UK the 8MHz wide analogue channels
have been replaced with an 8MHz wide digital QAM signal, and this
occupies the same channel frequency. Unless I'm very much mistaken, the
US has done the same (except that the channels are 6MHz wide).


Wrong again.

I assure you that what I said about the UK situation is 100% correct.
However, I've lost touch with what you do in the USA - so as I'm wrong,
how do you transmit digital TV. In particular, how do cable TV systems
organise the RF spectrum?

That was the major impetus over here to switch to digital - to free
up major bandspace in the VHF and UHF spectrums.

The 'freeing-up' is because each QAM multiplexed transport stream
carries typically up to 6 TV channels and 6 high-quality stereo radio
channels.


Ah, so the channel is effectively only 1Mhz wide then.

No. In the UK, the 'channel' is 8MHz wide, and occupies the same
frequency slot as the old single analogue channel. It is a QAM (or
sometimes QPSK) multiplex of all the programmes it contains. Yes, if you
have six TV channels in a 6MHz wide QAM mux you could consider that each
channel occupies 1MHz, but they are not six adjacent individual digital
signals. They are all jumbled up in the single 6MHz digital signal. The
decoder sorts them out automagically, and puts the required picture on
your TV screen.

We now have as many (or, in some areas, more) stations in a much
smaller band than before.

Digital requires less power because the bandwidth is much lower.

Only insofar as the digital decoder can successfully extract accurate
data from the 6 or 8MHz wide multiplexed transport stream at
signal-to-noise ratios which, for analogue, would produce barely
watchable pictures.

You really don't understand digital, do you?

I have to admit that I used to be intimately familiar with many aspects
of analogue, but there's a lot about digital that I don't know.
Fortunately, these days I don't really have to!

I hate it when someone tries to tell me my job which I've been doing
for years... But some people just think they know it all...

Se above.
--
Ian

Quad shield coax & dielectric?
 

Jerry Stuckle wrote:
That was the major impetus over here to switch to digital - to free
up major bandspace in the VHF and UHF spectrums.

The 'freeing-up' is because each QAM multiplexed transport stream
carries typically up to 6 TV channels and 6 high-quality stereo radio
channels.


Ah, so the channel is effectively only 1Mhz wide then.

That is only an "average" that you get when you divide the total bandwidth
by the number of TV programmes transmitted.
As multiple TV programmes are transmitted on a single channel,
that occupies the width of a classical analog channel that could
transmit only a single programme, more programmes can be put in
the same bandwidth.

However, to receive one of them you really need to receive the
entire channel (several MHz wide), so all link budget calculations
should be based on the full bandwidth. Later, the receiver throws
away most of the bits it has received and decodes only the information
for one of the TV programmes.

Quad shield coax & dielectric?
 

On 17/03/2014 15:45, Jeff wrote:


I also dispute that televisions are made to handle +20dBm; that is 100mW
far in excess of what a tv tuner can handle without overload!!!!

+20dbmV may be but not +20dbm.

Jeff

I know little about TV broadcasting, but in my (audio) field, 0 dBm is
taken as a level of 1 milliwatt into 600 ohms (0.775 V).

Funny how all these "standards" arise!

Incidentally, during the early development of 10cm radar kit, the "dB"
was banished from the lab. the chaps preferring to express their results
in linear units.

Les.

Quad shield coax & dielectric?
 

On 18/03/2014 10:10, Lordgnome wrote:
On 17/03/2014 15:45, Jeff wrote:


I also dispute that televisions are made to handle +20dBm; that is 100mW
far in excess of what a tv tuner can handle without overload!!!!

+20dbmV may be but not +20dbm.

Jeff

I know little about TV broadcasting, but in my (audio) field, 0 dBm is
taken as a level of 1 milliwatt into 600 ohms (0.775 V).

Funny how all these "standards" arise!

Indeed, 0dBm is 1 milliwatt, a measure of power, so it is 1mW into
whatever your system impedance happens to be, the actual voltage (&
current) will depend on your system impedance, 50, 75, 600 ohms or whatever.

Jeff

Quad shield coax & dielectric?
 

In message , Jeff writes
On 18/03/2014 10:10, Lordgnome wrote:
On 17/03/2014 15:45, Jeff wrote:


I also dispute that televisions are made to handle +20dBm; that is 100mW
far in excess of what a tv tuner can handle without overload!!!!

+20dbmV may be but not +20dbm.

Jeff

I know little about TV broadcasting, but in my (audio) field, 0 dBm is
taken as a level of 1 milliwatt into 600 ohms (0.775 V).

Funny how all these "standards" arise!

Indeed, 0dBm is 1 milliwatt, a measure of power, so it is 1mW into
whatever your system impedance happens to be, the actual voltage (&
current) will depend on your system impedance, 50, 75, 600 ohms or
whatever.

Quite. However, it's unfortunate that the 'W' seems to have got dropped
off the end - thus allowing dBm to be used carelessly and incorrectly
(as Jerry seems to have been doing).
--
Ian

Quad shield coax & dielectric?
 

Indeed, 0dBm is 1 milliwatt, a measure of power, so it is 1mW into
whatever your system impedance happens to be, the actual voltage (&
current) will depend on your system impedance, 50, 75, 600 ohms or
whatever.

Quite. However, it's unfortunate that the 'W' seems to have got dropped
off the end - thus allowing dBm to be used carelessly and incorrectly
(as Jerry seems to have been doing).

But it always has been so, and I don't think it is a case of the 'W'
being forgotten, it was never there in the first place since the 40's
when dBm started to come into use.

Jeff

Quad shield coax & dielectric?
 

On 3/18/2014 4:56 AM, Ian Jackson wrote:
In message , Jerry Stuckle
writes
On 3/17/2014 5:03 PM, Ian Jackson wrote:
In message , Jerry Stuckle
writes
On 3/17/2014 3:15 PM, Rob wrote:
Jerry Stuckle wrote:
Most likely the company reduced the transmitted power by a factor
of 10 at the time of the switchover, to put the added link margin
in their own pockets.
(transmitting a megawatt of ERP as was regular in the analog days
puts a serious dent in your electricity bill, even when you have
a lot of antenna gain)


Not at all. If anything, they raised their power.

Here they went from 1 megawatt to about 50 kilowatt (ERP).
And then there are several programmes on one transponder, instead
of one analog programme. This gives significant savings in power.


OK, you mean absolute power. Yes, they can lower the ERP - but that
does not necessarily lower the power for the signal. Remember at 1MW
the power was spread over 4.25 Mhz (assuming video only, of course).
Digital requires much less bandwidth, so they don't need as much
power
to get the same effective signal. However, digital still requires a
stronger signal than analog, in the bandwidth provided. You need
quite
a bit of noise before it becomes visible in analog. Digital, a
single
noise pulse can cause the loss of several bits of information.
Because
of the compression involved, this is more than one or two pixels.

I think not much of that is correct.
The systems differ a bit between US and elsewhere, but over here the
channel spacing of digital and analog is the same, and the bandwidth
is similar (a bit more for digital if anything).

Also there is no discission of "spreading", we are just discussing
peak envelope ERP.
You could argue that a single digital stream sending 5 programmes
means that 1 programme is transmitted at 1/5 the power, but that is
not what I mean. The total ERP for 1 transmitter has been lowered,
and it transmits multiple programmes to boot.

Digital requires less power because it requires less signal-to-noise
ratio at the receiver.


There are major differences between Europe's PAL and the U.S.'s NTSC.

Where do you get these strange ideas? Yes, there are differences (the
major one being the subcarrier phase alternation of PAL), but otherwise
the systems are very similar - and none of the differences really affect
the basics of RF system measurements.


From facts.

Care to share a few of your 'facts'? How do the relatively minor
differences between analogue PAL and NTSC affect how you do RF (and most
video) performance measurements?

But the digital signal has much LESS bandwidth than the old analog one.

No it doesn't. It's the same. In the UK the 8MHz wide analogue channels
have been replaced with an 8MHz wide digital QAM signal, and this
occupies the same channel frequency. Unless I'm very much mistaken, the
US has done the same (except that the channels are 6MHz wide).


Wrong again.

I assure you that what I said about the UK situation is 100% correct.
However, I've lost touch with what you do in the USA - so as I'm wrong,
how do you transmit digital TV. In particular, how do cable TV systems
organise the RF spectrum?

That was the major impetus over here to switch to digital - to free
up major bandspace in the VHF and UHF spectrums.

The 'freeing-up' is because each QAM multiplexed transport stream
carries typically up to 6 TV channels and 6 high-quality stereo radio
channels.


Ah, so the channel is effectively only 1Mhz wide then.

No. In the UK, the 'channel' is 8MHz wide, and occupies the same
frequency slot as the old single analogue channel. It is a QAM (or
sometimes QPSK) multiplex of all the programmes it contains. Yes, if you
have six TV channels in a 6MHz wide QAM mux you could consider that each
channel occupies 1MHz, but they are not six adjacent individual digital
signals. They are all jumbled up in the single 6MHz digital signal. The
decoder sorts them out automagically, and puts the required picture on
your TV screen.

We now have as many (or, in some areas, more) stations in a much
smaller band than before.

Digital requires less power because the bandwidth is much lower.

Only insofar as the digital decoder can successfully extract accurate
data from the 6 or 8MHz wide multiplexed transport stream at
signal-to-noise ratios which, for analogue, would produce barely
watchable pictures.

You really don't understand digital, do you?

I have to admit that I used to be intimately familiar with many aspects
of analogue, but there's a lot about digital that I don't know.
Fortunately, these days I don't really have to!

I hate it when someone tries to tell me my job which I've been doing
for years... But some people just think they know it all...

Se above.

You've lost track of a lot. And I'm tired of teaching a pig to sing.

You know nothing about what I do, who I work with, or what's going on in
the United States. Yet you think you know more than I do about my job,
the people in my industry, and the equipment I use.

I tell you what. You come over and do my job for about ten years.
Then, MAYBE, you'll be qualified enough to know something about it.

Until then, you're just a troll.


--
==================
Remove the "x" from my email address
Jerry Stuckle

==================

Quad shield coax & dielectric?
 

On 3/18/2014 5:11 AM, Rob wrote:
Jerry Stuckle wrote:
That was the major impetus over here to switch to digital - to free
up major bandspace in the VHF and UHF spectrums.

The 'freeing-up' is because each QAM multiplexed transport stream
carries typically up to 6 TV channels and 6 high-quality stereo radio
channels.


Ah, so the channel is effectively only 1Mhz wide then.

That is only an "average" that you get when you divide the total bandwidth
by the number of TV programmes transmitted.
As multiple TV programmes are transmitted on a single channel,
that occupies the width of a classical analog channel that could
transmit only a single programme, more programmes can be put in
the same bandwidth.

However, to receive one of them you really need to receive the
entire channel (several MHz wide), so all link budget calculations
should be based on the full bandwidth. Later, the receiver throws
away most of the bits it has received and decodes only the information
for one of the TV programmes.


You need to check on how the signals are transmitted. You seem claim to
know a lot about how U.S. TV works, even though you're thousands of
miles away. But then you know a lot more about my job, the people I
work with, and the tools I use than I do.

Come on over and do my job for about ten years. Then maybe, just maybe,
you'll be qualified to comment on it.

Otherwise, I just consider you a troll.


--
==================
Remove the "x" from my email address
Jerry, AI0K

==================