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

What artifacts would arise?

This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode, a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room on
the spectrum. In fact, the entire AM radio band could only carry maybe 2 FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple, static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode, a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room on
the spectrum. In fact, the entire AM radio band could only carry maybe 2 FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple, static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode, a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room on
the spectrum. In fact, the entire AM radio band could only carry maybe 2 FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple, static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode, a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room on
the spectrum. In fact, the entire AM radio band could only carry maybe 2 FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple, static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Mike Metzger" wrote in
message .com...
This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode, a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room on
the spectrum. In fact, the entire AM radio band could only carry maybe 2 FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple, static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Mike Metzger" wrote in
message .com...
This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode, a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room on
the spectrum. In fact, the entire AM radio band could only carry maybe 2 FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple, static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Mike Metzger" wrote in
message .com...
This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode, a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room on
the spectrum. In fact, the entire AM radio band could only carry maybe 2 FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple, static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Mike Metzger" wrote in
message .com...
This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode, a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room on
the spectrum. In fact, the entire AM radio band could only carry maybe 2 FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple, static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

"Mike Metzger" wrote in message y.com...
This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

FM stations are not in the lower-frequuency bands because FM require
more bandwidth than AM and lower-frequencies don't have the bandwidth
to handle FM.

Now the reverse...

What artifacts would affect AM stations in the FM band?

Considering that most electric/electronic equipment work in the
lower-frequency range (e.g. 50-60Hz), wouldn't higher frequencies be
less vulnerable to static?

"Mike Metzger" wrote in message y.com...
This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

FM stations are not in the lower-frequuency bands because FM require
more bandwidth than AM and lower-frequencies don't have the bandwidth
to handle FM.

Now the reverse...

What artifacts would affect AM stations in the FM band?

Considering that most electric/electronic equipment work in the
lower-frequency range (e.g. 50-60Hz), wouldn't higher frequencies be
less vulnerable to static?

"Mike Metzger" wrote in message y.com...
This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

FM stations are not in the lower-frequuency bands because FM require
more bandwidth than AM and lower-frequencies don't have the bandwidth
to handle FM.

Now the reverse...

What artifacts would affect AM stations in the FM band?

Considering that most electric/electronic equipment work in the
lower-frequency range (e.g. 50-60Hz), wouldn't higher frequencies be
less vulnerable to static?

"Mike Metzger" wrote in message y.com...
This isn't really an audio.tech question, but I'll give it a try anyway. Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower frequency
bands?"

FM stations are not in the lower-frequuency bands because FM require
more bandwidth than AM and lower-frequencies don't have the bandwidth
to handle FM.

Now the reverse...

What artifacts would affect AM stations in the FM band?

Considering that most electric/electronic equipment work in the
lower-frequency range (e.g. 50-60Hz), wouldn't higher frequencies be
less vulnerable to static?

On Sat, 21 Feb 2004 03:17:13 -0500, "Jerry G."
wrote:

The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

These are the numbers for AM. The bandwidth of the modulation simply
requires the double of the bandwidth for transmission. If the carrier
frequency is 1.000 MHz and the maximum audio frequency to be trans-
mitted is 5 kHz, the broadcast signal extends from 995 kHz through
1005 kHz. The dynamic range of the received signal is just the ratio
between the received power of the signal and the received power of
noise.

FM is quite different: The bandwidth of the broadcast signal is
determined by the amplitude of the signal, not by its frequency.
Usually the bandwidth is 100 kHz, both for mono and for stereo
broadcast. For a mono broadcast the upper frequency limit is
about 15 kHz, for a stereo broadcast the highest frequency is
53 kHz. In theory the bandwith of a FM signal is infinite. The more
you limit it the more distortion is introduced *and* the signal to
noise ration is degraded.

Thus, the 100 kHz signal width of FM is a compromise between
the number of channels that fit into a given band and the signal to
noise ration and distortion. S/N is about 70 dB, distortion is about
0.05% (these are practical numbers, not theoretical numbers).

HTH
Norbert

On Sat, 21 Feb 2004 03:17:13 -0500, "Jerry G."
wrote:

The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

These are the numbers for AM. The bandwidth of the modulation simply
requires the double of the bandwidth for transmission. If the carrier
frequency is 1.000 MHz and the maximum audio frequency to be trans-
mitted is 5 kHz, the broadcast signal extends from 995 kHz through
1005 kHz. The dynamic range of the received signal is just the ratio
between the received power of the signal and the received power of
noise.

FM is quite different: The bandwidth of the broadcast signal is
determined by the amplitude of the signal, not by its frequency.
Usually the bandwidth is 100 kHz, both for mono and for stereo
broadcast. For a mono broadcast the upper frequency limit is
about 15 kHz, for a stereo broadcast the highest frequency is
53 kHz. In theory the bandwith of a FM signal is infinite. The more
you limit it the more distortion is introduced *and* the signal to
noise ration is degraded.

Thus, the 100 kHz signal width of FM is a compromise between
the number of channels that fit into a given band and the signal to
noise ration and distortion. S/N is about 70 dB, distortion is about
0.05% (these are practical numbers, not theoretical numbers).

HTH
Norbert

On Sat, 21 Feb 2004 03:17:13 -0500, "Jerry G."
wrote:

The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

These are the numbers for AM. The bandwidth of the modulation simply
requires the double of the bandwidth for transmission. If the carrier
frequency is 1.000 MHz and the maximum audio frequency to be trans-
mitted is 5 kHz, the broadcast signal extends from 995 kHz through
1005 kHz. The dynamic range of the received signal is just the ratio
between the received power of the signal and the received power of
noise.

FM is quite different: The bandwidth of the broadcast signal is
determined by the amplitude of the signal, not by its frequency.
Usually the bandwidth is 100 kHz, both for mono and for stereo
broadcast. For a mono broadcast the upper frequency limit is
about 15 kHz, for a stereo broadcast the highest frequency is
53 kHz. In theory the bandwith of a FM signal is infinite. The more
you limit it the more distortion is introduced *and* the signal to
noise ration is degraded.

Thus, the 100 kHz signal width of FM is a compromise between
the number of channels that fit into a given band and the signal to
noise ration and distortion. S/N is about 70 dB, distortion is about
0.05% (these are practical numbers, not theoretical numbers).

HTH
Norbert

On Sat, 21 Feb 2004 03:17:13 -0500, "Jerry G."
wrote:

The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

These are the numbers for AM. The bandwidth of the modulation simply
requires the double of the bandwidth for transmission. If the carrier
frequency is 1.000 MHz and the maximum audio frequency to be trans-
mitted is 5 kHz, the broadcast signal extends from 995 kHz through
1005 kHz. The dynamic range of the received signal is just the ratio
between the received power of the signal and the received power of
noise.

FM is quite different: The bandwidth of the broadcast signal is
determined by the amplitude of the signal, not by its frequency.
Usually the bandwidth is 100 kHz, both for mono and for stereo
broadcast. For a mono broadcast the upper frequency limit is
about 15 kHz, for a stereo broadcast the highest frequency is
53 kHz. In theory the bandwith of a FM signal is infinite. The more
you limit it the more distortion is introduced *and* the signal to
noise ration is degraded.

Thus, the 100 kHz signal width of FM is a compromise between
the number of channels that fit into a given band and the signal to
noise ration and distortion. S/N is about 70 dB, distortion is about
0.05% (these are practical numbers, not theoretical numbers).

HTH
Norbert

In the US commercial AM band, frequencies are allocated on 10kHz intervals,
but the transmitters themselves are allowed to modulate with audio
frequencies up to 10kHz. That means the sidebands of adjacent channels will
overlap, resulting in so-called "monkey chatter" that occurs when listening
at night. You're hearing the inverted spectrum from stations on the adjacent
channels. Furthermore, the carrier from the adjacent channels will "look"
like 10kHz sidebands, which creates the familiar 10kHz whistle you hear on
AM at night.

There is no overlap between alternate channels, which are separated by
20kHz. The FCC tries to allocate frequencies on alternate channels between
locally situated transmitters. During the day, when there is no "skip" from
distant transmitters, you don't hear adjacent channel interference.

"Jerry G." wrote in message
...
The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Mike Metzger" wrote in
message .com...
This isn't really an audio.tech question, but I'll give it a try anyway.
Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower
frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode,
a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more
pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz
max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room
on
the spectrum. In fact, the entire AM radio band could only carry maybe 2
FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple,
static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their
old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

In the US commercial AM band, frequencies are allocated on 10kHz intervals,
but the transmitters themselves are allowed to modulate with audio
frequencies up to 10kHz. That means the sidebands of adjacent channels will
overlap, resulting in so-called "monkey chatter" that occurs when listening
at night. You're hearing the inverted spectrum from stations on the adjacent
channels. Furthermore, the carrier from the adjacent channels will "look"
like 10kHz sidebands, which creates the familiar 10kHz whistle you hear on
AM at night.

There is no overlap between alternate channels, which are separated by
20kHz. The FCC tries to allocate frequencies on alternate channels between
locally situated transmitters. During the day, when there is no "skip" from
distant transmitters, you don't hear adjacent channel interference.

"Jerry G." wrote in message
...
The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Mike Metzger" wrote in
message .com...
This isn't really an audio.tech question, but I'll give it a try anyway.
Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower
frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode,
a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more
pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz
max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room
on
the spectrum. In fact, the entire AM radio band could only carry maybe 2
FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple,
static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their
old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

In the US commercial AM band, frequencies are allocated on 10kHz intervals,
but the transmitters themselves are allowed to modulate with audio
frequencies up to 10kHz. That means the sidebands of adjacent channels will
overlap, resulting in so-called "monkey chatter" that occurs when listening
at night. You're hearing the inverted spectrum from stations on the adjacent
channels. Furthermore, the carrier from the adjacent channels will "look"
like 10kHz sidebands, which creates the familiar 10kHz whistle you hear on
AM at night.

There is no overlap between alternate channels, which are separated by
20kHz. The FCC tries to allocate frequencies on alternate channels between
locally situated transmitters. During the day, when there is no "skip" from
distant transmitters, you don't hear adjacent channel interference.

"Jerry G." wrote in message
...
The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Mike Metzger" wrote in
message .com...
This isn't really an audio.tech question, but I'll give it a try anyway.
Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower
frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode,
a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more
pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz
max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room
on
the spectrum. In fact, the entire AM radio band could only carry maybe 2
FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple,
static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their
old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

In the US commercial AM band, frequencies are allocated on 10kHz intervals,
but the transmitters themselves are allowed to modulate with audio
frequencies up to 10kHz. That means the sidebands of adjacent channels will
overlap, resulting in so-called "monkey chatter" that occurs when listening
at night. You're hearing the inverted spectrum from stations on the adjacent
channels. Furthermore, the carrier from the adjacent channels will "look"
like 10kHz sidebands, which creates the familiar 10kHz whistle you hear on
AM at night.

There is no overlap between alternate channels, which are separated by
20kHz. The FCC tries to allocate frequencies on alternate channels between
locally situated transmitters. During the day, when there is no "skip" from
distant transmitters, you don't hear adjacent channel interference.

"Jerry G." wrote in message
...
The standard broadcast AM stations in the broadcast band are a total of 10
kHz wide (+- 5 kHz referenced to centre band of received broadcast
station). The international short-wave broadcast stations are a total of 5
kHz wide (+-2.5 kHz referenced to centre band of received short-wave
broadcast station). At the -3 Db point in reference to the centre of the
carrier would be the determination of the bandwidth.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Mike Metzger" wrote in
message .com...
This isn't really an audio.tech question, but I'll give it a try anyway.
Any
experts out there jump in and correct me.

The better question is "why aren't there FM stations in the lower
frequency
bands?"

Here's a brief history as best I can piece it together.

AM transmitters are very simple designs. Ditto on the receivers. A diode,
a
small resistor and capacitor, a good antenna, a pair of headphones and
you've got an AM receiver. Early vacuum tubes limited oscillators and
amplifiers to low frequencies, so that's how the AM band got started. With
better technology in all areas came the more sophisticated and complicated
FM transmitters and receivers. FM also has the nice feature of rejecting
static from man made and natural sources, resulting in a much more
pleasing
listening experience. Naturally, there was the drive for higher fidelity
with the full audio frequency response (I think AM is limited to 5 Khz
max,
FM is 15 Khz). To broadcast this higher fidelity takes up a lot more room
on
the spectrum. In fact, the entire AM radio band could only carry maybe 2
FM
stations. However, in the higher broadcast frequencies, say 100 Mhz, the
15Khz addition from the audio is a much less significant number.

The technology to oscillate and amplify signals at the UHF and microwave
spectrum is much more complicated and expensive than the low frequency
stuff. What would then be the point of broadcasting the simple,
static-prone
AM over these more sophisticated systems? Having said that, television
broadcast (at about 50 Mhz) is a hybrid with the picture sent AM and the
sound sent FM. That's all changing now with all TV stations required to go
digital (not high definition) by I think 2007.

What about FM at the low frequencies? Yes, it is possible. But can you
imagine every radio station and every consumer having to throw out their
old
equipment and get all new. For no real benefit (since the audio response
would still be limited to the 5 Khz).

Hope this answers your question...

Mike


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

What artifacts would arise?

Hey Don, now *I'm* curious.

I designed a TV transmitter for a middle eastern operator. It worked at
12GHz and covered to the horizon in all directions with a power of
only 3 watts. This was angle modulated.


1. Was this 12 Ghz a microwave uplink or what? Obviously your standard TV
set isn't going to receive a 12 Ghz signal.

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

Hey Don, now *I'm* curious.

I designed a TV transmitter for a middle eastern operator. It worked at
12GHz and covered to the horizon in all directions with a power of
only 3 watts. This was angle modulated.


1. Was this 12 Ghz a microwave uplink or what? Obviously your standard TV
set isn't going to receive a 12 Ghz signal.

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

Hey Don, now *I'm* curious.

I designed a TV transmitter for a middle eastern operator. It worked at
12GHz and covered to the horizon in all directions with a power of
only 3 watts. This was angle modulated.


1. Was this 12 Ghz a microwave uplink or what? Obviously your standard TV
set isn't going to receive a 12 Ghz signal.

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

Hey Don, now *I'm* curious.

I designed a TV transmitter for a middle eastern operator. It worked at
12GHz and covered to the horizon in all directions with a power of
only 3 watts. This was angle modulated.


1. Was this 12 Ghz a microwave uplink or what? Obviously your standard TV
set isn't going to receive a 12 Ghz signal.

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

"Creative Music Synth [220]" wrote in
message om...

Considering that most electric/electronic equipment work in the
lower-frequency range (e.g. 50-60Hz), wouldn't higher frequencies be
less vulnerable to static?

Not at all. Normally running equipment drawing even substantial amounts of
power at the 50/60 Hz is no problem at all for radio reception. But when
that current gets interrupted or reconnected substatial amounts of RF energy
can be generated over a very wide spectrum. This was in fact the earliest
radio transmitter, sending Morse code by a spark gap. All you needed was a
battery and the ignition coil from a model T Ford and you could transmit.
Even X-Rays are generated this way: electrons are accelerated to high speed
then suddenly decelerated. In their deceleration they have to give up their
energy and it comes out as X radiation.

So, you can have a space heater in your room drawing 2000 Watts with your
radio next to it and never hear a thing. But the little shop across the
street with the blinking neon sign (drawing maybe 50 watts) will drive you
absolutely insane with the buzz buzz buzz all the time. And it will cover
the entire radio spectrum you're trying to listen to.

The advantage of higher frequencies is the use of FM, which has a built in
circuit (called a discriminator) that rejects AM signals, and that's what
most noise is.

HTH

Mike Metzger

"Creative Music Synth [220]" wrote in
message om...

Considering that most electric/electronic equipment work in the
lower-frequency range (e.g. 50-60Hz), wouldn't higher frequencies be
less vulnerable to static?

Not at all. Normally running equipment drawing even substantial amounts of
power at the 50/60 Hz is no problem at all for radio reception. But when
that current gets interrupted or reconnected substatial amounts of RF energy
can be generated over a very wide spectrum. This was in fact the earliest
radio transmitter, sending Morse code by a spark gap. All you needed was a
battery and the ignition coil from a model T Ford and you could transmit.
Even X-Rays are generated this way: electrons are accelerated to high speed
then suddenly decelerated. In their deceleration they have to give up their
energy and it comes out as X radiation.

So, you can have a space heater in your room drawing 2000 Watts with your
radio next to it and never hear a thing. But the little shop across the
street with the blinking neon sign (drawing maybe 50 watts) will drive you
absolutely insane with the buzz buzz buzz all the time. And it will cover
the entire radio spectrum you're trying to listen to.

The advantage of higher frequencies is the use of FM, which has a built in
circuit (called a discriminator) that rejects AM signals, and that's what
most noise is.

HTH

Mike Metzger

"Creative Music Synth [220]" wrote in
message om...

Considering that most electric/electronic equipment work in the
lower-frequency range (e.g. 50-60Hz), wouldn't higher frequencies be
less vulnerable to static?

Not at all. Normally running equipment drawing even substantial amounts of
power at the 50/60 Hz is no problem at all for radio reception. But when
that current gets interrupted or reconnected substatial amounts of RF energy
can be generated over a very wide spectrum. This was in fact the earliest
radio transmitter, sending Morse code by a spark gap. All you needed was a
battery and the ignition coil from a model T Ford and you could transmit.
Even X-Rays are generated this way: electrons are accelerated to high speed
then suddenly decelerated. In their deceleration they have to give up their
energy and it comes out as X radiation.

So, you can have a space heater in your room drawing 2000 Watts with your
radio next to it and never hear a thing. But the little shop across the
street with the blinking neon sign (drawing maybe 50 watts) will drive you
absolutely insane with the buzz buzz buzz all the time. And it will cover
the entire radio spectrum you're trying to listen to.

The advantage of higher frequencies is the use of FM, which has a built in
circuit (called a discriminator) that rejects AM signals, and that's what
most noise is.

HTH

Mike Metzger

"Creative Music Synth [220]" wrote in
message om...

Considering that most electric/electronic equipment work in the
lower-frequency range (e.g. 50-60Hz), wouldn't higher frequencies be
less vulnerable to static?

Not at all. Normally running equipment drawing even substantial amounts of
power at the 50/60 Hz is no problem at all for radio reception. But when
that current gets interrupted or reconnected substatial amounts of RF energy
can be generated over a very wide spectrum. This was in fact the earliest
radio transmitter, sending Morse code by a spark gap. All you needed was a
battery and the ignition coil from a model T Ford and you could transmit.
Even X-Rays are generated this way: electrons are accelerated to high speed
then suddenly decelerated. In their deceleration they have to give up their
energy and it comes out as X radiation.

So, you can have a space heater in your room drawing 2000 Watts with your
radio next to it and never hear a thing. But the little shop across the
street with the blinking neon sign (drawing maybe 50 watts) will drive you
absolutely insane with the buzz buzz buzz all the time. And it will cover
the entire radio spectrum you're trying to listen to.

The advantage of higher frequencies is the use of FM, which has a built in
circuit (called a discriminator) that rejects AM signals, and that's what
most noise is.

HTH

Mike Metzger

(Creative Music Synth [220]) wrote in message . com...
snip

STFU kook!

You have no business entering other's topics. So get the hell out
before a complaint strikes your ISP and you are thrown off the net for
good!

(Creative Music Synth [220]) wrote in message . com...
snip

STFU kook!

You have no business entering other's topics. So get the hell out
before a complaint strikes your ISP and you are thrown off the net for
good!

(Creative Music Synth [220]) wrote in message . com...
snip

STFU kook!

You have no business entering other's topics. So get the hell out
before a complaint strikes your ISP and you are thrown off the net for
good!

(Creative Music Synth [220]) wrote in message . com...
snip

STFU kook!

You have no business entering other's topics. So get the hell out
before a complaint strikes your ISP and you are thrown off the net for
good!

On Sun, 22 Feb 2004 01:20:49 GMT, "Mike Metzger"
wrote:

Hey Don, now *I'm* curious.

I designed a TV transmitter for a middle eastern operator. It worked at
12GHz and covered to the horizon in all directions with a power of
only 3 watts. This was angle modulated.


1. Was this 12 Ghz a microwave uplink or what? Obviously your standard TV
set isn't going to receive a 12 Ghz signal.

No, this was the broadcast link, and it was received by the customers
with an analogue satellite box and special dish and LNB.

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.

d

_____________________________

http://www.pearce.uk.com

On Sun, 22 Feb 2004 01:20:49 GMT, "Mike Metzger"
wrote:

Hey Don, now *I'm* curious.

I designed a TV transmitter for a middle eastern operator. It worked at
12GHz and covered to the horizon in all directions with a power of
only 3 watts. This was angle modulated.


1. Was this 12 Ghz a microwave uplink or what? Obviously your standard TV
set isn't going to receive a 12 Ghz signal.

No, this was the broadcast link, and it was received by the customers
with an analogue satellite box and special dish and LNB.

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.

d

_____________________________

http://www.pearce.uk.com

On Sun, 22 Feb 2004 01:20:49 GMT, "Mike Metzger"
wrote:

Hey Don, now *I'm* curious.

I designed a TV transmitter for a middle eastern operator. It worked at
12GHz and covered to the horizon in all directions with a power of
only 3 watts. This was angle modulated.


1. Was this 12 Ghz a microwave uplink or what? Obviously your standard TV
set isn't going to receive a 12 Ghz signal.

No, this was the broadcast link, and it was received by the customers
with an analogue satellite box and special dish and LNB.

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.

d

_____________________________

http://www.pearce.uk.com

On Sun, 22 Feb 2004 01:20:49 GMT, "Mike Metzger"
wrote:

Hey Don, now *I'm* curious.

I designed a TV transmitter for a middle eastern operator. It worked at
12GHz and covered to the horizon in all directions with a power of
only 3 watts. This was angle modulated.


1. Was this 12 Ghz a microwave uplink or what? Obviously your standard TV
set isn't going to receive a 12 Ghz signal.

No, this was the broadcast link, and it was received by the customers
with an analogue satellite box and special dish and LNB.

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.

d

_____________________________

http://www.pearce.uk.com

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.
The problem is caused by the higher siganlpath attenuation which raises
with the frequency.
Beside, attenuation on dustparticles over big cities, reindrops, fog
etc.
is higher on higher frequencies

regards

Peter

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.
The problem is caused by the higher siganlpath attenuation which raises
with the frequency.
Beside, attenuation on dustparticles over big cities, reindrops, fog
etc.
is higher on higher frequencies

regards

Peter

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.
The problem is caused by the higher siganlpath attenuation which raises
with the frequency.
Beside, attenuation on dustparticles over big cities, reindrops, fog
etc.
is higher on higher frequencies

regards

Peter