I have a question in regards to the theory of ATV.

If I were to run a video signal straight into, say, a 70cm transmitter
(staying within the linear range of the transmitter's input, i.e. not
clipping) and had a receiver that had a video out / TV connected to
the reciever's output (and could adjust the amplitude of the output
signal), would that work?

Or do most "standard" (audio) transmitters/receivers have limitations
about the maximum frequency they can modulate/de-modulate? It seems
to me that the latter would be the only reason that ATV equipment
would be nessesary. Or is there some other reason this scenario would
not work?

On a side note, what's the lowest carrier frequency ATV can operate on
before the video signal degrades or begins aliasing?

Thanks in advance for any information!
Dave

TRY SEVERAL LINKS AT URL:
http://ac6v.com/opmodes.htm#A

--
Lamont Cranston

The Shadow Knows
"David Harper" wrote in message
om...
I have a question in regards to the theory of ATV.

If I were to run a video signal straight into, say, a 70cm transmitter
(staying within the linear range of the transmitter's input, i.e. not
clipping) and had a receiver that had a video out / TV connected to
the reciever's output (and could adjust the amplitude of the output
signal), would that work?

Or do most "standard" (audio) transmitters/receivers have limitations
about the maximum frequency they can modulate/de-modulate? It seems
to me that the latter would be the only reason that ATV equipment
would be nessesary. Or is there some other reason this scenario would
not work?

On a side note, what's the lowest carrier frequency ATV can operate on
before the video signal degrades or begins aliasing?

Thanks in advance for any information!
Dave

TRY SEVERAL LINKS AT URL:
http://ac6v.com/opmodes.htm#A

--
Lamont Cranston

The Shadow Knows
"David Harper" wrote in message
om...
I have a question in regards to the theory of ATV.

If I were to run a video signal straight into, say, a 70cm transmitter
(staying within the linear range of the transmitter's input, i.e. not
clipping) and had a receiver that had a video out / TV connected to
the reciever's output (and could adjust the amplitude of the output
signal), would that work?

Or do most "standard" (audio) transmitters/receivers have limitations
about the maximum frequency they can modulate/de-modulate? It seems
to me that the latter would be the only reason that ATV equipment
would be nessesary. Or is there some other reason this scenario would
not work?

On a side note, what's the lowest carrier frequency ATV can operate on
before the video signal degrades or begins aliasing?

Thanks in advance for any information!
Dave

On 21 Jun 2004 10:06:11 -0700, (David Harper)
wrote:

I have a question in regards to the theory of ATV.

If I were to run a video signal straight into, say, a 70cm transmitter
(staying within the linear range of the transmitter's input, i.e. not
clipping) and had a receiver that had a video out / TV connected to
the reciever's output (and could adjust the amplitude of the output
signal), would that work?

Or do most "standard" (audio) transmitters/receivers have limitations
about the maximum frequency they can modulate/de-modulate? It seems
to me that the latter would be the only reason that ATV equipment
would be nessesary. Or is there some other reason this scenario would
not work?

That's it: The video signal has a bandwidth of a few MHz and needs
frequency response down to DC. It's way beyond what the average
transceiver is capable of.

The average radio has frequency response from 100 Hz to 3.5 KHz or so.
Using direct discriminator/varactor connections gives wider response,
but not wide enough. Dedicated ATV equipment is needed.

On a side note, what's the lowest carrier frequency ATV can operate on
before the video signal degrades or begins aliasing?

440 is the lowest band ATV is allowed on.

Thanks in advance for any information!
Dave

ATV is a neat mode. Have fun!

On 21 Jun 2004 10:06:11 -0700, (David Harper)
wrote:

I have a question in regards to the theory of ATV.

If I were to run a video signal straight into, say, a 70cm transmitter
(staying within the linear range of the transmitter's input, i.e. not
clipping) and had a receiver that had a video out / TV connected to
the reciever's output (and could adjust the amplitude of the output
signal), would that work?

Or do most "standard" (audio) transmitters/receivers have limitations
about the maximum frequency they can modulate/de-modulate? It seems
to me that the latter would be the only reason that ATV equipment
would be nessesary. Or is there some other reason this scenario would
not work?

That's it: The video signal has a bandwidth of a few MHz and needs
frequency response down to DC. It's way beyond what the average
transceiver is capable of.

The average radio has frequency response from 100 Hz to 3.5 KHz or so.
Using direct discriminator/varactor connections gives wider response,
but not wide enough. Dedicated ATV equipment is needed.

On a side note, what's the lowest carrier frequency ATV can operate on
before the video signal degrades or begins aliasing?

440 is the lowest band ATV is allowed on.

Thanks in advance for any information!
Dave

ATV is a neat mode. Have fun!

wrote in message . ..
On 21 Jun 2004 10:06:11 -0700, (David Harper)
wrote:

I have a question in regards to the theory of ATV.

If I were to run a video signal straight into, say, a 70cm transmitter
(staying within the linear range of the transmitter's input, i.e. not
clipping) and had a receiver that had a video out / TV connected to
the reciever's output (and could adjust the amplitude of the output
signal), would that work?

Or do most "standard" (audio) transmitters/receivers have limitations
about the maximum frequency they can modulate/de-modulate? It seems
to me that the latter would be the only reason that ATV equipment
would be nessesary. Or is there some other reason this scenario would
not work?

That's it: The video signal has a bandwidth of a few MHz and needs
frequency response down to DC. It's way beyond what the average
transceiver is capable of.

The average radio has frequency response from 100 Hz to 3.5 KHz or so.
Using direct discriminator/varactor connections gives wider response,
but not wide enough. Dedicated ATV equipment is needed.

Gotcha...thanks for the response! However, based on what you've said,
"what if" I were to do what I described on AM? Technically, assuming
you were using a high enough frequency to prevent aliasing, you
"could" transmit a video signal with a simple AM transmitter and
receiver...or am I mistaken?

Thanks in advance!
Dave

wrote in message . ..
On 21 Jun 2004 10:06:11 -0700, (David Harper)
wrote:

I have a question in regards to the theory of ATV.

If I were to run a video signal straight into, say, a 70cm transmitter
(staying within the linear range of the transmitter's input, i.e. not
clipping) and had a receiver that had a video out / TV connected to
the reciever's output (and could adjust the amplitude of the output
signal), would that work?

Or do most "standard" (audio) transmitters/receivers have limitations
about the maximum frequency they can modulate/de-modulate? It seems
to me that the latter would be the only reason that ATV equipment
would be nessesary. Or is there some other reason this scenario would
not work?

That's it: The video signal has a bandwidth of a few MHz and needs
frequency response down to DC. It's way beyond what the average
transceiver is capable of.

The average radio has frequency response from 100 Hz to 3.5 KHz or so.
Using direct discriminator/varactor connections gives wider response,
but not wide enough. Dedicated ATV equipment is needed.

Gotcha...thanks for the response! However, based on what you've said,
"what if" I were to do what I described on AM? Technically, assuming
you were using a high enough frequency to prevent aliasing, you
"could" transmit a video signal with a simple AM transmitter and
receiver...or am I mistaken?

Thanks in advance!
Dave

David Harper wrote in message
om...
wrote in message
. ..
On 21 Jun 2004 10:06:11 -0700, (David Harper)
wrote:

I have a question in regards to the theory of ATV.

snip

Gotcha...thanks for the response! However, based on what you've said,
"what if" I were to do what I described on AM? Technically, assuming
you were using a high enough frequency to prevent aliasing, you
"could" transmit a video signal with a simple AM transmitter and
receiver...or am I mistaken?

Thanks in advance!
Dave

Most (all?) ATV activity on 70cm is AM. You still have the video bandwidth
requirements in your modulation circuits and getting the modulation
linearity needed for a good picture isn't trivial.

David Harper wrote in message
om...
wrote in message
. ..
On 21 Jun 2004 10:06:11 -0700, (David Harper)
wrote:

I have a question in regards to the theory of ATV.

snip

Gotcha...thanks for the response! However, based on what you've said,
"what if" I were to do what I described on AM? Technically, assuming
you were using a high enough frequency to prevent aliasing, you
"could" transmit a video signal with a simple AM transmitter and
receiver...or am I mistaken?

Thanks in advance!
Dave

Most (all?) ATV activity on 70cm is AM. You still have the video bandwidth
requirements in your modulation circuits and getting the modulation
linearity needed for a good picture isn't trivial.