"Free space attenuation has no frequency dependency."

You must be joking! Free space attenuation is dependant on frequency and can be
written as:

Attenuation in dB = 36.6 + 20 log F + 20 log d, where F is frequency in MHz and d is
distance in miles.

Believe me, I really would like free speace attenuation to be frequency independant,
(I work with radio planning of 2GHz WCDMA mobile systems) but unfortunately the
dependancy is there, when increasing the frequency 10 times the attenuation
increases 20dB for the same distance.

Regards Hans

Don Pearce wrote:

On Sun, 22 Feb 2004 17:35:28 +0100, Peter Völpel
wrote:

Don Pearce schrieb:

2. I have been told by TV engineers that the higher frequencies don't have
near the coverage per watt that the low ones do. With this changeover in the
US to digital the FCC is assigning new digital channels by lottery. There
was a local TV station that had a VHF channel on analog and got assigned a
UHF for the digital. They now are using twice the KWs and are spending twice
the money on electricity running their new transmitter to get the same
coverage area they had with the VHF.

Can you clarify?

Mike Metzger

Although coverage per watt is not really an issue, the problem comes
with no line-of-sight coverage, particularly beyond the horizon. As
you go higher in frequency you need more power to penetrate shadow
areas. Certainly in cities that means really high frequencies need a
lot of power. Satellite TV works because the elevation of the
satellite is so high that just about anybody can get line-of-sight
from somewhere on their house.

the issue are not shadow aereas, that is a question of the satellites
transmitantenna beamwith.

I was talking about shadow areas from terrestrial transmissions, not
satellite.

The problem is caused by the higher siganlpath attenuation which raises
with the frequency.

Free space attenuation has no frequency dependency.

Beside, attenuation on dustparticles over big cities, reindrops, fog
etc.
is higher on higher frequencies

This is true, but easily allowed for.

regards

Peter

d

_____________________________

http://www.pearce.uk.com

On Wed, 25 Feb 2004 14:33:53 +0900, Tube wrote:

"Free space attenuation has no frequency dependency."

You must be joking! Free space attenuation is dependant on frequency and can be
written as:

Attenuation in dB = 36.6 + 20 log F + 20 log d, where F is frequency in MHz and d is
distance in miles.

Believe me, I really would like free speace attenuation to be frequency independant,
(I work with radio planning of 2GHz WCDMA mobile systems) but unfortunately the
dependancy is there, when increasing the frequency 10 times the attenuation
increases 20dB for the same distance.

Regards Hans

Free space attenuation has no frequency dependency. How many times do
I need to say it? The 20logF term in your equation describes the size
of the receiving antenna, which is assumed to be frequency-dependent -
it is unrelated to attenuation in free space.

The power flux density at any distance is equal to the transmitted
power divided by the area of a sphere of radius equal to the distance.
There is no frequency term.

Try this on-paper experiment . Assume a perfect dish receiving antenna
of a size of your choice. Now work out the signal power you get from
it at various frequencies, using the same transmitted power.
Interesting result? There is no change in received power with
frequency.

You want less power at the higher frequency? You have to make the
antenna smaller.

d

_____________________________

http://www.pearce.uk.com

On Wed, 25 Feb 2004 14:33:53 +0900, Tube wrote:

"Free space attenuation has no frequency dependency."

You must be joking! Free space attenuation is dependant on frequency and can be
written as:

Attenuation in dB = 36.6 + 20 log F + 20 log d, where F is frequency in MHz and d is
distance in miles.

Believe me, I really would like free speace attenuation to be frequency independant,
(I work with radio planning of 2GHz WCDMA mobile systems) but unfortunately the
dependancy is there, when increasing the frequency 10 times the attenuation
increases 20dB for the same distance.

Regards Hans

Free space attenuation has no frequency dependency. How many times do
I need to say it? The 20logF term in your equation describes the size
of the receiving antenna, which is assumed to be frequency-dependent -
it is unrelated to attenuation in free space.

The power flux density at any distance is equal to the transmitted
power divided by the area of a sphere of radius equal to the distance.
There is no frequency term.

Try this on-paper experiment . Assume a perfect dish receiving antenna
of a size of your choice. Now work out the signal power you get from
it at various frequencies, using the same transmitted power.
Interesting result? There is no change in received power with
frequency.

You want less power at the higher frequency? You have to make the
antenna smaller.

d

_____________________________

http://www.pearce.uk.com

On Wed, 25 Feb 2004 14:33:53 +0900, Tube wrote:

"Free space attenuation has no frequency dependency."

You must be joking! Free space attenuation is dependant on frequency and can be
written as:

Attenuation in dB = 36.6 + 20 log F + 20 log d, where F is frequency in MHz and d is
distance in miles.

Believe me, I really would like free speace attenuation to be frequency independant,
(I work with radio planning of 2GHz WCDMA mobile systems) but unfortunately the
dependancy is there, when increasing the frequency 10 times the attenuation
increases 20dB for the same distance.

Regards Hans

Free space attenuation has no frequency dependency. How many times do
I need to say it? The 20logF term in your equation describes the size
of the receiving antenna, which is assumed to be frequency-dependent -
it is unrelated to attenuation in free space.

The power flux density at any distance is equal to the transmitted
power divided by the area of a sphere of radius equal to the distance.
There is no frequency term.

Try this on-paper experiment . Assume a perfect dish receiving antenna
of a size of your choice. Now work out the signal power you get from
it at various frequencies, using the same transmitted power.
Interesting result? There is no change in received power with
frequency.

You want less power at the higher frequency? You have to make the
antenna smaller.

d

_____________________________

http://www.pearce.uk.com

On Wed, 25 Feb 2004 14:33:53 +0900, Tube wrote:

"Free space attenuation has no frequency dependency."

You must be joking! Free space attenuation is dependant on frequency and can be
written as:

Attenuation in dB = 36.6 + 20 log F + 20 log d, where F is frequency in MHz and d is
distance in miles.

Believe me, I really would like free speace attenuation to be frequency independant,
(I work with radio planning of 2GHz WCDMA mobile systems) but unfortunately the
dependancy is there, when increasing the frequency 10 times the attenuation
increases 20dB for the same distance.

Regards Hans

Free space attenuation has no frequency dependency. How many times do
I need to say it? The 20logF term in your equation describes the size
of the receiving antenna, which is assumed to be frequency-dependent -
it is unrelated to attenuation in free space.

The power flux density at any distance is equal to the transmitted
power divided by the area of a sphere of radius equal to the distance.
There is no frequency term.

Try this on-paper experiment . Assume a perfect dish receiving antenna
of a size of your choice. Now work out the signal power you get from
it at various frequencies, using the same transmitted power.
Interesting result? There is no change in received power with
frequency.

You want less power at the higher frequency? You have to make the
antenna smaller.

d

_____________________________

http://www.pearce.uk.com

(Curious) wrote in message . com...
Why aren't there amplitude modulated stations in the high megahertz/gigahertz range?

What artifacts would arise?

At least in the satellite GHz bands (L, Ku, Ka, etc), the type of
amplifiers commonly used (klystrons, TWTs and SSPAs) are very
non-linear. SSPAs are better, but you should see the typical AM-AM
transfer curve of a TWT, which is what you normally find on-board
satellites and in big earth stations: ugly.

For single carrier operation, you want to be able to operate them at
saturation for eficiency reasons, so you can't use amplitude
modulation: around the saturation point you have a very flat curve
where BOTH an increase AND a decrease in input power results in a
comparatively very small decrease in output power. Now go demodulate
that! That's why all satellite transmissions are either analogue FM
(yes there's still quite a few of those around) or constant amplitude
digital modulation schemes (BPSK, QPSK and 8-PSK: strictly speaking
they are not constant amplitude once they have been suitably filtered,
but the resulting amplitude variations contain no information, these
are phase modulation schemes). There have been experiments with some
more bandwidth-efficient modulation schemes that do have some AM (like
16-QAM) but then you have to run the amplifier with large backoffs (up
to 10 dB) to stay within the linear region, wasting a lot of power and
requiring much bigger antennas for a decent carrier to noise ratio.

For multi-carrier operation it would be a total nightmare. I mean,
even the small long term amplitude variations of each carrier (due to
satellite tracking, rain fades, etc) are a nightmare to deal with,
basically because they change the carefully chosen operation point of
the amplifier and hence the intermodulation distortion level, which in
this mode of operation is the main noise (well, noise-like)
contribution to the link budget; let alone if you had AM modulated
carriers. Then there's also crosstalk when you have one big carrier
and smaller ones. Basically you would have to allow for huge margins
to make sure you always stay within the linear region which, again,
would throw your efficiency out of the window and would require much
bigger antennas.

Hope this helps,

Carlos (in a previous life, Transmission Planning Manager for
Eutelsat)

(Curious) wrote in message . com...
Why aren't there amplitude modulated stations in the high megahertz/gigahertz range?

What artifacts would arise?

At least in the satellite GHz bands (L, Ku, Ka, etc), the type of
amplifiers commonly used (klystrons, TWTs and SSPAs) are very
non-linear. SSPAs are better, but you should see the typical AM-AM
transfer curve of a TWT, which is what you normally find on-board
satellites and in big earth stations: ugly.

For single carrier operation, you want to be able to operate them at
saturation for eficiency reasons, so you can't use amplitude
modulation: around the saturation point you have a very flat curve
where BOTH an increase AND a decrease in input power results in a
comparatively very small decrease in output power. Now go demodulate
that! That's why all satellite transmissions are either analogue FM
(yes there's still quite a few of those around) or constant amplitude
digital modulation schemes (BPSK, QPSK and 8-PSK: strictly speaking
they are not constant amplitude once they have been suitably filtered,
but the resulting amplitude variations contain no information, these
are phase modulation schemes). There have been experiments with some
more bandwidth-efficient modulation schemes that do have some AM (like
16-QAM) but then you have to run the amplifier with large backoffs (up
to 10 dB) to stay within the linear region, wasting a lot of power and
requiring much bigger antennas for a decent carrier to noise ratio.

For multi-carrier operation it would be a total nightmare. I mean,
even the small long term amplitude variations of each carrier (due to
satellite tracking, rain fades, etc) are a nightmare to deal with,
basically because they change the carefully chosen operation point of
the amplifier and hence the intermodulation distortion level, which in
this mode of operation is the main noise (well, noise-like)
contribution to the link budget; let alone if you had AM modulated
carriers. Then there's also crosstalk when you have one big carrier
and smaller ones. Basically you would have to allow for huge margins
to make sure you always stay within the linear region which, again,
would throw your efficiency out of the window and would require much
bigger antennas.

Hope this helps,

Carlos (in a previous life, Transmission Planning Manager for
Eutelsat)

(Curious) wrote in message . com...
Why aren't there amplitude modulated stations in the high megahertz/gigahertz range?

What artifacts would arise?

At least in the satellite GHz bands (L, Ku, Ka, etc), the type of
amplifiers commonly used (klystrons, TWTs and SSPAs) are very
non-linear. SSPAs are better, but you should see the typical AM-AM
transfer curve of a TWT, which is what you normally find on-board
satellites and in big earth stations: ugly.

For single carrier operation, you want to be able to operate them at
saturation for eficiency reasons, so you can't use amplitude
modulation: around the saturation point you have a very flat curve
where BOTH an increase AND a decrease in input power results in a
comparatively very small decrease in output power. Now go demodulate
that! That's why all satellite transmissions are either analogue FM
(yes there's still quite a few of those around) or constant amplitude
digital modulation schemes (BPSK, QPSK and 8-PSK: strictly speaking
they are not constant amplitude once they have been suitably filtered,
but the resulting amplitude variations contain no information, these
are phase modulation schemes). There have been experiments with some
more bandwidth-efficient modulation schemes that do have some AM (like
16-QAM) but then you have to run the amplifier with large backoffs (up
to 10 dB) to stay within the linear region, wasting a lot of power and
requiring much bigger antennas for a decent carrier to noise ratio.

For multi-carrier operation it would be a total nightmare. I mean,
even the small long term amplitude variations of each carrier (due to
satellite tracking, rain fades, etc) are a nightmare to deal with,
basically because they change the carefully chosen operation point of
the amplifier and hence the intermodulation distortion level, which in
this mode of operation is the main noise (well, noise-like)
contribution to the link budget; let alone if you had AM modulated
carriers. Then there's also crosstalk when you have one big carrier
and smaller ones. Basically you would have to allow for huge margins
to make sure you always stay within the linear region which, again,
would throw your efficiency out of the window and would require much
bigger antennas.

Hope this helps,

Carlos (in a previous life, Transmission Planning Manager for
Eutelsat)

(Curious) wrote in message . com...
Why aren't there amplitude modulated stations in the high megahertz/gigahertz range?

What artifacts would arise?

At least in the satellite GHz bands (L, Ku, Ka, etc), the type of
amplifiers commonly used (klystrons, TWTs and SSPAs) are very
non-linear. SSPAs are better, but you should see the typical AM-AM
transfer curve of a TWT, which is what you normally find on-board
satellites and in big earth stations: ugly.

For single carrier operation, you want to be able to operate them at
saturation for eficiency reasons, so you can't use amplitude
modulation: around the saturation point you have a very flat curve
where BOTH an increase AND a decrease in input power results in a
comparatively very small decrease in output power. Now go demodulate
that! That's why all satellite transmissions are either analogue FM
(yes there's still quite a few of those around) or constant amplitude
digital modulation schemes (BPSK, QPSK and 8-PSK: strictly speaking
they are not constant amplitude once they have been suitably filtered,
but the resulting amplitude variations contain no information, these
are phase modulation schemes). There have been experiments with some
more bandwidth-efficient modulation schemes that do have some AM (like
16-QAM) but then you have to run the amplifier with large backoffs (up
to 10 dB) to stay within the linear region, wasting a lot of power and
requiring much bigger antennas for a decent carrier to noise ratio.

For multi-carrier operation it would be a total nightmare. I mean,
even the small long term amplitude variations of each carrier (due to
satellite tracking, rain fades, etc) are a nightmare to deal with,
basically because they change the carefully chosen operation point of
the amplifier and hence the intermodulation distortion level, which in
this mode of operation is the main noise (well, noise-like)
contribution to the link budget; let alone if you had AM modulated
carriers. Then there's also crosstalk when you have one big carrier
and smaller ones. Basically you would have to allow for huge margins
to make sure you always stay within the linear region which, again,
would throw your efficiency out of the window and would require much
bigger antennas.

Hope this helps,

Carlos (in a previous life, Transmission Planning Manager for
Eutelsat)

Tube wrote:

"Free space attenuation has no frequency dependency."

You must be joking!

I don't think he was. Are you?

Free space attenuation is dependant on frequency and can be
written as:

Attenuation in dB = 36.6 + 20 log F + 20 log d, where F is frequency in MHz and d is
distance in miles.

Believe me, I really would like free speace attenuation to be frequency independant,
(I work with radio planning of 2GHz WCDMA mobile systems) but unfortunately the
dependancy is there, when increasing the frequency 10 times the attenuation
increases 20dB for the same distance.

Oh dear. How many times has smaller receiver antenna aperture size been
confused with some actual loss in free space or a vacuum? (It is as hard to
defeat the energy conservation law in a vacuum -- or basically lossless air --
as it is anywhere else.) I wish "they" wouldn't call this effect "free space
loss," because that is not what it is.

Tube wrote:

"Free space attenuation has no frequency dependency."

You must be joking!

I don't think he was. Are you?

Free space attenuation is dependant on frequency and can be
written as:

Attenuation in dB = 36.6 + 20 log F + 20 log d, where F is frequency in MHz and d is
distance in miles.

Believe me, I really would like free speace attenuation to be frequency independant,
(I work with radio planning of 2GHz WCDMA mobile systems) but unfortunately the
dependancy is there, when increasing the frequency 10 times the attenuation
increases 20dB for the same distance.

Oh dear. How many times has smaller receiver antenna aperture size been
confused with some actual loss in free space or a vacuum? (It is as hard to
defeat the energy conservation law in a vacuum -- or basically lossless air --
as it is anywhere else.) I wish "they" wouldn't call this effect "free space
loss," because that is not what it is.

Tube wrote:

"Free space attenuation has no frequency dependency."

You must be joking!

I don't think he was. Are you?

Free space attenuation is dependant on frequency and can be
written as:

Attenuation in dB = 36.6 + 20 log F + 20 log d, where F is frequency in MHz and d is
distance in miles.

Believe me, I really would like free speace attenuation to be frequency independant,
(I work with radio planning of 2GHz WCDMA mobile systems) but unfortunately the
dependancy is there, when increasing the frequency 10 times the attenuation
increases 20dB for the same distance.

Oh dear. How many times has smaller receiver antenna aperture size been
confused with some actual loss in free space or a vacuum? (It is as hard to
defeat the energy conservation law in a vacuum -- or basically lossless air --
as it is anywhere else.) I wish "they" wouldn't call this effect "free space
loss," because that is not what it is.

Tube wrote:

"Free space attenuation has no frequency dependency."

You must be joking!

I don't think he was. Are you?

Free space attenuation is dependant on frequency and can be
written as:

Attenuation in dB = 36.6 + 20 log F + 20 log d, where F is frequency in MHz and d is
distance in miles.

Believe me, I really would like free speace attenuation to be frequency independant,
(I work with radio planning of 2GHz WCDMA mobile systems) but unfortunately the
dependancy is there, when increasing the frequency 10 times the attenuation
increases 20dB for the same distance.

Oh dear. How many times has smaller receiver antenna aperture size been
confused with some actual loss in free space or a vacuum? (It is as hard to
defeat the energy conservation law in a vacuum -- or basically lossless air --
as it is anywhere else.) I wish "they" wouldn't call this effect "free space
loss," because that is not what it is.

Curious wrote:

Why aren't there amplitude modulated stations in the high megahertz/gigahertz range?


I don't know what specific "stations" you are refering to. In the US, the
"standard" radio services have been the familiar AM band (@ around 1 MHz) and FM
band (@ around 100 MHz). This restriction is simply due to the sequence of
history and governmental decree. FM was not invented until the 1930's, so as an
accident of history it simply ended up at a higher frequency than the AM band;
not because of some of the technological issues some have claimed in this
thread. Google Edwin Armstrong for some interesting old radio history. He was
a giant.

There are multitudinous "stations" that use AM well into the GHz range. For
example, our cheezy little 802.11a WLAN 5 GHz stuff uses OFDM in which each
subcarrier is both AM an PM modulated. Taking advantage of both degrees of
freedom (amplitude *and* phase) seems to allow higher bit rates. That means you
could get your hi-fi across the cheezy OFDM link with no troubles. AM
transmitters are a tough challenge though. FM transmitters are bone head simple
and power efficient, but you won't get the same data rates as a system that
takes advantage of both phase and amplitude.


What artifacts would arise?

None really. Of course, amplitude sensitive detection is sensitive to amplitude
noise, as is phase/freq detection to phase noise.

Curious wrote:

Why aren't there amplitude modulated stations in the high megahertz/gigahertz range?


I don't know what specific "stations" you are refering to. In the US, the
"standard" radio services have been the familiar AM band (@ around 1 MHz) and FM
band (@ around 100 MHz). This restriction is simply due to the sequence of
history and governmental decree. FM was not invented until the 1930's, so as an
accident of history it simply ended up at a higher frequency than the AM band;
not because of some of the technological issues some have claimed in this
thread. Google Edwin Armstrong for some interesting old radio history. He was
a giant.

There are multitudinous "stations" that use AM well into the GHz range. For
example, our cheezy little 802.11a WLAN 5 GHz stuff uses OFDM in which each
subcarrier is both AM an PM modulated. Taking advantage of both degrees of
freedom (amplitude *and* phase) seems to allow higher bit rates. That means you
could get your hi-fi across the cheezy OFDM link with no troubles. AM
transmitters are a tough challenge though. FM transmitters are bone head simple
and power efficient, but you won't get the same data rates as a system that
takes advantage of both phase and amplitude.


What artifacts would arise?

None really. Of course, amplitude sensitive detection is sensitive to amplitude
noise, as is phase/freq detection to phase noise.

Curious wrote:

Why aren't there amplitude modulated stations in the high megahertz/gigahertz range?


I don't know what specific "stations" you are refering to. In the US, the
"standard" radio services have been the familiar AM band (@ around 1 MHz) and FM
band (@ around 100 MHz). This restriction is simply due to the sequence of
history and governmental decree. FM was not invented until the 1930's, so as an
accident of history it simply ended up at a higher frequency than the AM band;
not because of some of the technological issues some have claimed in this
thread. Google Edwin Armstrong for some interesting old radio history. He was
a giant.

There are multitudinous "stations" that use AM well into the GHz range. For
example, our cheezy little 802.11a WLAN 5 GHz stuff uses OFDM in which each
subcarrier is both AM an PM modulated. Taking advantage of both degrees of
freedom (amplitude *and* phase) seems to allow higher bit rates. That means you
could get your hi-fi across the cheezy OFDM link with no troubles. AM
transmitters are a tough challenge though. FM transmitters are bone head simple
and power efficient, but you won't get the same data rates as a system that
takes advantage of both phase and amplitude.


What artifacts would arise?

None really. Of course, amplitude sensitive detection is sensitive to amplitude
noise, as is phase/freq detection to phase noise.

Curious wrote:

Why aren't there amplitude modulated stations in the high megahertz/gigahertz range?


I don't know what specific "stations" you are refering to. In the US, the
"standard" radio services have been the familiar AM band (@ around 1 MHz) and FM
band (@ around 100 MHz). This restriction is simply due to the sequence of
history and governmental decree. FM was not invented until the 1930's, so as an
accident of history it simply ended up at a higher frequency than the AM band;
not because of some of the technological issues some have claimed in this
thread. Google Edwin Armstrong for some interesting old radio history. He was
a giant.

There are multitudinous "stations" that use AM well into the GHz range. For
example, our cheezy little 802.11a WLAN 5 GHz stuff uses OFDM in which each
subcarrier is both AM an PM modulated. Taking advantage of both degrees of
freedom (amplitude *and* phase) seems to allow higher bit rates. That means you
could get your hi-fi across the cheezy OFDM link with no troubles. AM
transmitters are a tough challenge though. FM transmitters are bone head simple
and power efficient, but you won't get the same data rates as a system that
takes advantage of both phase and amplitude.


What artifacts would arise?

None really. Of course, amplitude sensitive detection is sensitive to amplitude
noise, as is phase/freq detection to phase noise.

I work in the AM; FM; Analog and Digital TV industry in Australia.

The answer the the burning question, why not AM in higher Freq.

Well it comes down to power and the size of the TX mast.

For example we have a site transmitting on 747 kHZ with a 600 foot
mast running at 10 kW.

And another Tx at 1548 kHZ with a 150 foot mast and 50 kW.

So the smaller the mast the more power you require to punch out the
same radiation pattern.

More power = more money.

And also in the age of concept of AM I'm sure the engineers didn't
know about Giga hertz or it would have been Giga cycles back then.

Blame it on Marconi for not pushing the boundaries.

I work in the AM; FM; Analog and Digital TV industry in Australia.

The answer the the burning question, why not AM in higher Freq.

Well it comes down to power and the size of the TX mast.

For example we have a site transmitting on 747 kHZ with a 600 foot
mast running at 10 kW.

And another Tx at 1548 kHZ with a 150 foot mast and 50 kW.

So the smaller the mast the more power you require to punch out the
same radiation pattern.

More power = more money.

And also in the age of concept of AM I'm sure the engineers didn't
know about Giga hertz or it would have been Giga cycles back then.

Blame it on Marconi for not pushing the boundaries.

I work in the AM; FM; Analog and Digital TV industry in Australia.

The answer the the burning question, why not AM in higher Freq.

Well it comes down to power and the size of the TX mast.

For example we have a site transmitting on 747 kHZ with a 600 foot
mast running at 10 kW.

And another Tx at 1548 kHZ with a 150 foot mast and 50 kW.

So the smaller the mast the more power you require to punch out the
same radiation pattern.

More power = more money.

And also in the age of concept of AM I'm sure the engineers didn't
know about Giga hertz or it would have been Giga cycles back then.

Blame it on Marconi for not pushing the boundaries.

I work in the AM; FM; Analog and Digital TV industry in Australia.

The answer the the burning question, why not AM in higher Freq.

Well it comes down to power and the size of the TX mast.

For example we have a site transmitting on 747 kHZ with a 600 foot
mast running at 10 kW.

And another Tx at 1548 kHZ with a 150 foot mast and 50 kW.

So the smaller the mast the more power you require to punch out the
same radiation pattern.

More power = more money.

And also in the age of concept of AM I'm sure the engineers didn't
know about Giga hertz or it would have been Giga cycles back then.

Blame it on Marconi for not pushing the boundaries.

Emphatic wrote:

I work in the AM; FM; Analog and Digital TV industry in Australia.

The answer the the burning question, why not AM in higher Freq.

Well it comes down to power and the size of the TX mast.

For example we have a site transmitting on 747 kHZ with a 600 foot
mast running at 10 kW.

And another Tx at 1548 kHZ with a 150 foot mast and 50 kW.

So the smaller the mast the more power you require to punch out the
same radiation pattern.

Utter nonsense.

More power = more money.

And also in the age of concept of AM I'm sure the engineers didn't
know about Giga hertz or it would have been Giga cycles back then.

Utter nonsense.

Blame it on Marconi for not pushing the boundaries.

Utter nonsense. He did push the boundaries _for the time_; that is why he is
remembered.

Emphatic wrote:

I work in the AM; FM; Analog and Digital TV industry in Australia.

The answer the the burning question, why not AM in higher Freq.

Well it comes down to power and the size of the TX mast.

For example we have a site transmitting on 747 kHZ with a 600 foot
mast running at 10 kW.

And another Tx at 1548 kHZ with a 150 foot mast and 50 kW.

So the smaller the mast the more power you require to punch out the
same radiation pattern.

Utter nonsense.

More power = more money.

And also in the age of concept of AM I'm sure the engineers didn't
know about Giga hertz or it would have been Giga cycles back then.

Utter nonsense.

Blame it on Marconi for not pushing the boundaries.

Utter nonsense. He did push the boundaries _for the time_; that is why he is
remembered.

Emphatic wrote:

I work in the AM; FM; Analog and Digital TV industry in Australia.

The answer the the burning question, why not AM in higher Freq.

Well it comes down to power and the size of the TX mast.

For example we have a site transmitting on 747 kHZ with a 600 foot
mast running at 10 kW.

And another Tx at 1548 kHZ with a 150 foot mast and 50 kW.

So the smaller the mast the more power you require to punch out the
same radiation pattern.

Utter nonsense.

More power = more money.

And also in the age of concept of AM I'm sure the engineers didn't
know about Giga hertz or it would have been Giga cycles back then.

Utter nonsense.

Blame it on Marconi for not pushing the boundaries.

Utter nonsense. He did push the boundaries _for the time_; that is why he is
remembered.

Emphatic wrote:

I work in the AM; FM; Analog and Digital TV industry in Australia.

The answer the the burning question, why not AM in higher Freq.

Well it comes down to power and the size of the TX mast.

For example we have a site transmitting on 747 kHZ with a 600 foot
mast running at 10 kW.

And another Tx at 1548 kHZ with a 150 foot mast and 50 kW.

So the smaller the mast the more power you require to punch out the
same radiation pattern.

Utter nonsense.

More power = more money.

And also in the age of concept of AM I'm sure the engineers didn't
know about Giga hertz or it would have been Giga cycles back then.

Utter nonsense.

Blame it on Marconi for not pushing the boundaries.

Utter nonsense. He did push the boundaries _for the time_; that is why he is
remembered.

I stand corrected, at least partially. HighDef appears to be a subset of the
new DTV (Digital TV) standard, and the FCC is allowing broadcasters to
choose how to use their alloted channel space. Either a single HDTV
broadcast or multiple low-res programs.

Anyway, here's a link: http://www.fcc.gov/cgb/consumerfacts/digitaltv.html

Mike

Don't know if this matters on the propagation subject, but I wasn't
referring to high def. I know that is a completely different animal. I
was
talking about the same old NTSC resolution but transmitted in digital
format. The FCC is apparently trying to free up some spectrum for other
stuff (can't remember what) and figures they can cram more TV channels
into
less space by going digital. As I said, they're assigning the new
digital
channels by lottery and this poor station I'm aware of got a UHF channel
where their analog is on VHF.

I'd be interested to know what other digital format the FCC is behind. If
have a web pointer or even just a keyword I could search on, I'd be
interested.

--Randy

I stand corrected, at least partially. HighDef appears to be a subset of the
new DTV (Digital TV) standard, and the FCC is allowing broadcasters to
choose how to use their alloted channel space. Either a single HDTV
broadcast or multiple low-res programs.

Anyway, here's a link: http://www.fcc.gov/cgb/consumerfacts/digitaltv.html

Mike

Don't know if this matters on the propagation subject, but I wasn't
referring to high def. I know that is a completely different animal. I
was
talking about the same old NTSC resolution but transmitted in digital
format. The FCC is apparently trying to free up some spectrum for other
stuff (can't remember what) and figures they can cram more TV channels
into
less space by going digital. As I said, they're assigning the new
digital
channels by lottery and this poor station I'm aware of got a UHF channel
where their analog is on VHF.

I'd be interested to know what other digital format the FCC is behind. If
have a web pointer or even just a keyword I could search on, I'd be
interested.

--Randy

I stand corrected, at least partially. HighDef appears to be a subset of the
new DTV (Digital TV) standard, and the FCC is allowing broadcasters to
choose how to use their alloted channel space. Either a single HDTV
broadcast or multiple low-res programs.

Anyway, here's a link: http://www.fcc.gov/cgb/consumerfacts/digitaltv.html

Mike

Don't know if this matters on the propagation subject, but I wasn't
referring to high def. I know that is a completely different animal. I
was
talking about the same old NTSC resolution but transmitted in digital
format. The FCC is apparently trying to free up some spectrum for other
stuff (can't remember what) and figures they can cram more TV channels
into
less space by going digital. As I said, they're assigning the new
digital
channels by lottery and this poor station I'm aware of got a UHF channel
where their analog is on VHF.

I'd be interested to know what other digital format the FCC is behind. If
have a web pointer or even just a keyword I could search on, I'd be
interested.

--Randy

I stand corrected, at least partially. HighDef appears to be a subset of the
new DTV (Digital TV) standard, and the FCC is allowing broadcasters to
choose how to use their alloted channel space. Either a single HDTV
broadcast or multiple low-res programs.

Anyway, here's a link: http://www.fcc.gov/cgb/consumerfacts/digitaltv.html

Mike

Don't know if this matters on the propagation subject, but I wasn't
referring to high def. I know that is a completely different animal. I
was
talking about the same old NTSC resolution but transmitted in digital
format. The FCC is apparently trying to free up some spectrum for other
stuff (can't remember what) and figures they can cram more TV channels
into
less space by going digital. As I said, they're assigning the new
digital
channels by lottery and this poor station I'm aware of got a UHF channel
where their analog is on VHF.

I'd be interested to know what other digital format the FCC is behind. If
have a web pointer or even just a keyword I could search on, I'd be
interested.

--Randy