ChairmanOfTheBored wrote:
> On Sat, 13 Oct 2007 10:42:01 +1000, John Monro
> <johnmonro@optusnet.removethis.com.au> wrote:
> 
>> tfosdike@gmail.com wrote:
>>> On Oct 12, 2:14 pm, IAmTheSlime
>>> <TheSlimeFromYourVi...@oozingacrossyourlivingroomfloor.org> wrote:
>>>> On Fri, 21 Sep 2007 14:30:37 -0400, Jerry Avins <j...@ieee.org> wrote:
>>>>> Don Pearce wrote:
>>>>>> On Thu, 20 Sep 2007 17:44:01 -0400, "Jerry G."
>>>>>> <jerry...@NOSPAMhotmail.com> wrote:
>>>>>>> Reverse video to give higher transmission power during black was chosen,
>>>>>>> because noise is more visible to the eye in the black levels of video.
>>>>>>> With the whites, noise is less visible to the eye. Therefore the higher
>>>>>>> transmission power levels in black levels allow for less visible noise
>>>>>>> due to any RF carrier signal loss.
>>>>>> So do you think the noise gets smaller during the higher parts of the
>>>>>> signal (the blacks)? Let me assure you it doesn't. The amplitude of
>>>>>> the noise in the black area is identical whether it is placed at the
>>>>>> top of the modulation or the bottom. Noise adds linearly to the
>>>>>> signal, it doesn't multiply. It makes not a jot of difference to the
>>>>>> noise whether black it at the top, or whit is.
>>>>>> The polarity of the signal is all about making every frame identical
>>>>>> in height so that each component of the signal can be identified
>>>>>> unambiguously.
>>>>> It's easy to see even fairly dim stars against a dark nighttime sky.
>>>>> Seeing black specks against a bright daytime sky is much harder. The
>>>>> contrast ratio may be the same, but size matters.
>>>>> Jerry
>>>>   The "farmer" that discovered Pluto after years of intensive slide
>>>> examination knows a thing or two about contrast.
>>>>
>>>>   The plates were all developed so the examiner got black "stars" or
>>>> "objects" on a white "space" background.
>>>>
>>>>  There is a reason for this.  It has to do with the human eye, and how
>>>> the brain processes visual information.
>>> I would have thought that the primary reason for using a white
>>> background was to avoid introducing extra noise from the photographic
>>> processing required to convert back to a positive image.
>>>
>> Astronomical plates were normally developed as negatives because 
>> negative processing is simpler and quicker than positive 'reversal' 
>> processing.  Ease of finding unexpected objects would not be a 
>> consideration because the plates are rarely used for this purpose, most 
>> imaging being done on known objects.
> 
>  Bullshit. That is EXACTLY what the plates the man who discovered Pluto
> was using them for!  He was hired because no scientist wanted to perform
> the painstaking and laborious task required.
>> Also, I think the alternative 'reversal' developing process would 
>> introduce additional error into the relationship between the 
>> astronomical object's actual brightness and the optical density of its 
>> image as recorded on the plate.

Think carefully about this and you may learn something.
Did the person undertake a new photographic survey or did he use the 
ovservatory's archival material?
If the latter, do you think the original purpose of the astronomers who 
produced the material may have had something to do with whether 
negatives or positives were produced?

> 
>  Brightness wasn't a factor. The plates were specifically used to FIND
> previously undiscovered moving objects.  Contrast ratio was the important
> factor.
> 
> 
>>  Precise recording of object brightness 
>> is a common requirement of astronomers.
> 
>   The task being done being the dependent factor.  In THIS case,
> brightness was NOT a factor, was NOT gauged, and the ONLY thing being
> sought was a new, previously undiscovered object.
> 
>   The discovery of Pluto was the result:
> 
> http://en.wikipedia.org/wiki/Pluto#Discovery
> 
>   The plates shown were reversed in the wiki page, but Mr. Tombaugh
> examined negatives.

On Sat, 13 Oct 2007 10:42:01 +1000, John Monro
<johnmonro@optusnet.removethis.com.au> wrote:

>tfosdike@gmail.com wrote:
>> On Oct 12, 2:14 pm, IAmTheSlime
>> <TheSlimeFromYourVi...@oozingacrossyourlivingroomfloor.org> wrote:
>>> On Fri, 21 Sep 2007 14:30:37 -0400, Jerry Avins <j...@ieee.org> wrote:
>>>> Don Pearce wrote:
>>>>> On Thu, 20 Sep 2007 17:44:01 -0400, "Jerry G."
>>>>> <jerry...@NOSPAMhotmail.com> wrote:
>>>>>> Reverse video to give higher transmission power during black was chosen,
>>>>>> because noise is more visible to the eye in the black levels of video.
>>>>>> With the whites, noise is less visible to the eye. Therefore the higher
>>>>>> transmission power levels in black levels allow for less visible noise
>>>>>> due to any RF carrier signal loss.
>>>>> So do you think the noise gets smaller during the higher parts of the
>>>>> signal (the blacks)? Let me assure you it doesn't. The amplitude of
>>>>> the noise in the black area is identical whether it is placed at the
>>>>> top of the modulation or the bottom. Noise adds linearly to the
>>>>> signal, it doesn't multiply. It makes not a jot of difference to the
>>>>> noise whether black it at the top, or whit is.
>>>>> The polarity of the signal is all about making every frame identical
>>>>> in height so that each component of the signal can be identified
>>>>> unambiguously.
>>>> It's easy to see even fairly dim stars against a dark nighttime sky.
>>>> Seeing black specks against a bright daytime sky is much harder. The
>>>> contrast ratio may be the same, but size matters.
>>>> Jerry
>>>   The "farmer" that discovered Pluto after years of intensive slide
>>> examination knows a thing or two about contrast.
>>>
>>>   The plates were all developed so the examiner got black "stars" or
>>> "objects" on a white "space" background.
>>>
>>>  There is a reason for this.  It has to do with the human eye, and how
>>> the brain processes visual information.
>> 
>> I would have thought that the primary reason for using a white
>> background was to avoid introducing extra noise from the photographic
>> processing required to convert back to a positive image.
>> 
>
>Astronomical plates were normally developed as negatives because 
>negative processing is simpler and quicker than positive 'reversal' 
>processing.  Ease of finding unexpected objects would not be a 
>consideration because the plates are rarely used for this purpose, most 
>imaging being done on known objects.

 Bullshit. That is EXACTLY what the plates the man who discovered Pluto
was using them for!  He was hired because no scientist wanted to perform
the painstaking and laborious task required.
>
>Also, I think the alternative 'reversal' developing process would 
>introduce additional error into the relationship between the 
>astronomical object's actual brightness and the optical density of its 
>image as recorded on the plate.

 Brightness wasn't a factor. The plates were specifically used to FIND
previously undiscovered moving objects.  Contrast ratio was the important
factor.


>  Precise recording of object brightness 
>is a common requirement of astronomers.

  The task being done being the dependent factor.  In THIS case,
brightness was NOT a factor, was NOT gauged, and the ONLY thing being
sought was a new, previously undiscovered object.

  The discovery of Pluto was the result:

http://en.wikipedia.org/wiki/Pluto#Discovery

  The plates shown were reversed in the wiki page, but Mr. Tombaugh
examined negatives.

tfosdike@gmail.com wrote:
> On Oct 12, 2:14 pm, IAmTheSlime
> <TheSlimeFromYourVi...@oozingacrossyourlivingroomfloor.org> wrote:
>> On Fri, 21 Sep 2007 14:30:37 -0400, Jerry Avins <j...@ieee.org> wrote:
>>> Don Pearce wrote:
>>>> On Thu, 20 Sep 2007 17:44:01 -0400, "Jerry G."
>>>> <jerry...@NOSPAMhotmail.com> wrote:
>>>>> Reverse video to give higher transmission power during black was chosen,
>>>>> because noise is more visible to the eye in the black levels of video.
>>>>> With the whites, noise is less visible to the eye. Therefore the higher
>>>>> transmission power levels in black levels allow for less visible noise
>>>>> due to any RF carrier signal loss.
>>>> So do you think the noise gets smaller during the higher parts of the
>>>> signal (the blacks)? Let me assure you it doesn't. The amplitude of
>>>> the noise in the black area is identical whether it is placed at the
>>>> top of the modulation or the bottom. Noise adds linearly to the
>>>> signal, it doesn't multiply. It makes not a jot of difference to the
>>>> noise whether black it at the top, or whit is.
>>>> The polarity of the signal is all about making every frame identical
>>>> in height so that each component of the signal can be identified
>>>> unambiguously.
>>> It's easy to see even fairly dim stars against a dark nighttime sky.
>>> Seeing black specks against a bright daytime sky is much harder. The
>>> contrast ratio may be the same, but size matters.
>>> Jerry
>>   The "farmer" that discovered Pluto after years of intensive slide
>> examination knows a thing or two about contrast.
>>
>>   The plates were all developed so the examiner got black "stars" or
>> "objects" on a white "space" background.
>>
>>  There is a reason for this.  It has to do with the human eye, and how
>> the brain processes visual information.
> 
> I would have thought that the primary reason for using a white
> background was to avoid introducing extra noise from the photographic
> processing required to convert back to a positive image.
> 

Astronomical plates were normally developed as negatives because 
negative processing is simpler and quicker than positive 'reversal' 
processing.  Ease of finding unexpected objects would not be a 
consideration because the plates are rarely used for this purpose, most 
imaging being done on known objects.

Also, I think the alternative 'reversal' developing process would 
introduce additional error into the relationship between the 
astronomical object's actual brightness and the optical density of its 
image as recorded on the plate.  Precise recording of object brightness 
is a common requirement of astronomers.


Regards,
John

glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote in 
news:OrqdnQBYdfUnjpDanZ2dnUVZ_ruqnZ2d@comcast.com:

> Gary Tait wrote:
> (snip)
> 
>> It depends on your perspective.
> 
>> Such boxes are technically tuners that output the signle tuned 
channel.
>> They are not "convertors" in the sense they do not convert all the 
>> digital channels to analog for an older TV to tune. 
> 
> I remember in the days of UHF getting more popular, and using
> a converter box that output on VHF channel 3.  This can be done
> with the appropriate mixer and LO, without converting the input
> to baseband.  It does involve tuned circuits, but does not
> convert all (70) UHF channels to be tuned on a (12 channel)
> VHF tuner.

Yes, that is a traditional cable convertor, which wen out of fasion when 
integrated descramblers came to be.  Even the tuner block in an analog 
TV is a sort of frequency convertor, it just converts the incoming RF 
channel to an IF, which the circuits detect the video baseband from.

> I believe there were/are block converters from cable channels
> to UHF which do convert all at once.  Most cable boxes don't
> do that, though.  Early (analog) ones did the down conversion
> similar to the UHF conversion described above.  Most now likely
> go to baseband and then remodulate for those without video inputs.

Yes, there were block upconvertors, which converted a block of cable 
channels to UHF frequencies. 

Modern digital cable and satellite boxes (and late era analog cable 
tuner/descramblers) output composite video/stereo audio, not baseband.
Baseband is the signal that comes off the primary video detector, and 
has the audio subcarrier (s) on it still. Those signals are filtered off 
and the signal clamped to make composite video. Digital boxes just make 
the composite or other video signal from the data from the video 
deocder.

> The distinction between 'tuner' and 'converter' is fuzzy.
A convertor just converts frequency. A tuner tunes a signal an outputs 
"line" video and audio.

> I don't believe that there is a convenient way to block convert
> the ATSC input to NTSC output.  One could build a box with
> multiple tuners, decoders, and modulators but I doubt that
> would be for the consumer market.

Not for a $40 box.

> The box needs an ATSC tuner, and the logic to convert the
> result to an NTSC analog signal.  Most likely with both video
> and RF outputs.  The output of the ATSC tuner is the digital
> signal, not suitable for an analog TV, so the box needs
> both a tuner and converter.
> 

All ATSC tuner boxes do that now. They tune the ATSC hannel and output a 
viewiable SD or HD video signal. Some may lack RF out though.

It is just they have to make one that meets the requirements for a 
voucher (which has certain stipulations an STB manufacturer could easily 
meet, and some boxes could likely technically meet today).

> -- glen
>

On Oct 12, 2:14 pm, IAmTheSlime
<TheSlimeFromYourVi...@oozingacrossyourlivingroomfloor.org> wrote:
> On Fri, 21 Sep 2007 14:30:37 -0400, Jerry Avins <j...@ieee.org> wrote:
> >Don Pearce wrote:
> >> On Thu, 20 Sep 2007 17:44:01 -0400, "Jerry G."
> >> <jerry...@NOSPAMhotmail.com> wrote:
>
> >>> Reverse video to give higher transmission power during black was chosen,
> >>> because noise is more visible to the eye in the black levels of video.
> >>> With the whites, noise is less visible to the eye. Therefore the higher
> >>> transmission power levels in black levels allow for less visible noise
> >>> due to any RF carrier signal loss.
>
> >> So do you think the noise gets smaller during the higher parts of the
> >> signal (the blacks)? Let me assure you it doesn't. The amplitude of
> >> the noise in the black area is identical whether it is placed at the
> >> top of the modulation or the bottom. Noise adds linearly to the
> >> signal, it doesn't multiply. It makes not a jot of difference to the
> >> noise whether black it at the top, or whit is.
>
> >> The polarity of the signal is all about making every frame identical
> >> in height so that each component of the signal can be identified
> >> unambiguously.
>
> >It's easy to see even fairly dim stars against a dark nighttime sky.
> >Seeing black specks against a bright daytime sky is much harder. The
> >contrast ratio may be the same, but size matters.
>
> >Jerry
>
>   The "farmer" that discovered Pluto after years of intensive slide
> examination knows a thing or two about contrast.
>
>   The plates were all developed so the examiner got black "stars" or
> "objects" on a white "space" background.
>
>  There is a reason for this.  It has to do with the human eye, and how
> the brain processes visual information.

I would have thought that the primary reason for using a white
background was to avoid introducing extra noise from the photographic
processing required to convert back to a positive image.

On Fri, 21 Sep 2007 14:30:37 -0400, Jerry Avins <jya@ieee.org> wrote:

>Don Pearce wrote:
>> On Thu, 20 Sep 2007 17:44:01 -0400, "Jerry G."
>> <jerryg50@NOSPAMhotmail.com> wrote:
>> 
>>> Reverse video to give higher transmission power during black was chosen, 
>>> because noise is more visible to the eye in the black levels of video. 
>>> With the whites, noise is less visible to the eye. Therefore the higher 
>>> transmission power levels in black levels allow for less visible noise 
>>> due to any RF carrier signal loss.
>> 
>> So do you think the noise gets smaller during the higher parts of the
>> signal (the blacks)? Let me assure you it doesn't. The amplitude of
>> the noise in the black area is identical whether it is placed at the
>> top of the modulation or the bottom. Noise adds linearly to the
>> signal, it doesn't multiply. It makes not a jot of difference to the
>> noise whether black it at the top, or whit is.
>> 
>> The polarity of the signal is all about making every frame identical
>> in height so that each component of the signal can be identified
>> unambiguously.
>
>It's easy to see even fairly dim stars against a dark nighttime sky. 
>Seeing black specks against a bright daytime sky is much harder. The 
>contrast ratio may be the same, but size matters.
>
>Jerry


  The "farmer" that discovered Pluto after years of intensive slide
examination knows a thing or two about contrast.

  The plates were all developed so the examiner got black "stars" or
"objects" on a white "space" background.

 There is a reason for this.  It has to do with the human eye, and how
the brain processes visual information.

glen herrmannsfeldt gah@ugcs.caltech.edu posted to
sci.electronics.design:

> Gary Tait wrote:
> (snip)
> 
>> It depends on your perspective.
> 
>> Such boxes are technically tuners that output the signle tuned
>> channel. They are not "convertors" in the sense they do not convert
>> all the digital channels to analog for an older TV to tune.
> 
> I remember in the days of UHF getting more popular, and using
> a converter box that output on VHF channel 3.  This can be done
> with the appropriate mixer and LO, without converting the input
> to baseband.  It does involve tuned circuits, but does not
> convert all (70) UHF channels to be tuned on a (12 channel)
> VHF tuner.
> 
> I believe there were/are block converters from cable channels
> to UHF which do convert all at once.  Most cable boxes don't
> do that, though.  Early (analog) ones did the down conversion
> similar to the UHF conversion described above.  Most now likely
> go to baseband and then remodulate for those without video inputs.
> 
> The distinction between 'tuner' and 'converter' is fuzzy.
> I don't believe that there is a convenient way to block convert
> the ATSC input to NTSC output.  One could build a box with
> multiple tuners, decoders, and modulators but I doubt that
> would be for the consumer market.

While i have not see one, there is nothing that prevents it
technologically.  I have seen receivers that can receive the entire
AM band (in stereo as broadcast) at the same time.  I have seen
receivers that receive over half of the FM band (in stereo)
simultaneously.  Only ADC, DAC, and compute power available preclude
block conversion.  Dig around  bit on software defined radios and you
can find the done devices that i have found.

> 
> The box needs an ATSC tuner, and the logic to convert the
> result to an NTSC analog signal.  Most likely with both video
> and RF outputs.  The output of the ATSC tuner is the digital
> signal, not suitable for an analog TV, so the box needs
> both a tuner and converter.
> 
> -- glen

Gary Tait wrote:
(snip)

> It depends on your perspective.

> Such boxes are technically tuners that output the signle tuned channel.
> They are not "convertors" in the sense they do not convert all the 
> digital channels to analog for an older TV to tune. 

I remember in the days of UHF getting more popular, and using
a converter box that output on VHF channel 3.  This can be done
with the appropriate mixer and LO, without converting the input
to baseband.  It does involve tuned circuits, but does not
convert all (70) UHF channels to be tuned on a (12 channel)
VHF tuner.

I believe there were/are block converters from cable channels
to UHF which do convert all at once.  Most cable boxes don't
do that, though.  Early (analog) ones did the down conversion
similar to the UHF conversion described above.  Most now likely
go to baseband and then remodulate for those without video inputs.

The distinction between 'tuner' and 'converter' is fuzzy.
I don't believe that there is a convenient way to block convert
the ATSC input to NTSC output.  One could build a box with
multiple tuners, decoders, and modulators but I doubt that
would be for the consumer market.

The box needs an ATSC tuner, and the logic to convert the
result to an NTSC analog signal.  Most likely with both video
and RF outputs.  The output of the ATSC tuner is the digital
signal, not suitable for an analog TV, so the box needs
both a tuner and converter.

-- glen

ChairmanOfTheBored <RUBored@crackasmile.org> wrote in 
news:lqllg3tts6vqvmhks1me4v46g4vivqvp4t@4ax.com:

>>
>>   A tuner is not a converter. 
> 
>   You're an idiot.  An HDTV TUNER that ALSO puts out onto 4:3 TVs IS a
> converter, you retarded fuckhead!
> 

It depends on your perspective.

Such boxes are technically tuners that output the signle tuned channel.
They are not "convertors" in the sense they do not convert all the 
digital channels to analog for an older TV to tune. 

>> According to the official HDTV websites,
>>they wouldn't go on sale till next year. The cost, after the voucher 
is
>>supposed to be in the  $20 range.
>>
>> You're wrong, as usual.
> 
>   I have owned mine for nearly three years, and you are an utter 
retard,
> as usual.

Again perspective.

Digital OTA tuners have been sold for years now. It is just the voucher 
program is not in effect yet, and I don't think that voucher eligble 
tuners are in stores yet.