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Brown dwarf numbers way down



 
 
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  #1  
Old February 1st 09, 07:26 PM posted to alt.astronomy
K. Carson
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Posts: 22
Default Brown dwarf numbers way down

In article
,
BradGuth wrote:

By now, linear response 200-dB dynamic range CMOS image sensors of 5.6-
µm are readily available, with 4.1 µm pixels that should start to
emerge this year, each ideally suited to the dual 16 bit ADC
configured camera.


I don't believe you know what a decibel is.

It is simply ten times the base-10 logarithm of a ratio.
  #2  
Old February 1st 09, 10:36 PM posted to alt.astronomy
BradGuth
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Posts: 21,544
Default Brown dwarf numbers way down

On Feb 1, 10:26*am, "K. Carson" wrote:
In article
,

BradGuth wrote:
By now, linear response 200-dB dynamic range CMOS image sensors of 5.6-
µm are readily available, with 4.1 µm pixels that should start to
emerge this year, each ideally suited to the dual 16 bit ADC
configured camera.


I don't believe you know what a decibel is.

It is simply ten times the base-10 logarithm of a ratio.


A 200 db rated cmos image sensor needs roughly a 32 bit ADC, and
anyway you'd care to cut through all the possible interpretations,
that's a lot of brightness range.

Are you saying that a 32 bit ADC is not something doable?

~ BG
  #3  
Old February 1st 09, 11:05 PM posted to alt.astronomy
K. Carson
external usenet poster
 
Posts: 22
Default Brown dwarf numbers way down

In article
,
BradGuth wrote:

On Feb 1, 10:26*am, "K. Carson" wrote:
In article
,

BradGuth wrote:
By now, linear response 200-dB dynamic range CMOS image sensors of 5.6-
µm are readily available, with 4.1 µm pixels that should start to
emerge this year, each ideally suited to the dual 16 bit ADC
configured camera.


I don't believe you know what a decibel is.

It is simply ten times the base-10 logarithm of a ratio.


A 200 db rated cmos image sensor needs roughly a 32 bit ADC,


I'd like to see how you made this calculation.

and
anyway you'd care to cut through all the possible interpretations,
that's a lot of brightness range.

Are you saying that a 32 bit ADC is not something doable?


Where did I post anything remotely related to analog-digital
conversions?
  #4  
Old February 2nd 09, 01:39 AM posted to alt.astronomy
BradGuth
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Posts: 21,544
Default Brown dwarf numbers way down

On Feb 1, 2:05*pm, "K. Carson" wrote:
In article
,



BradGuth wrote:
On Feb 1, 10:26*am, "K. Carson" wrote:
In article
,


BradGuth wrote:
By now, linear response 200-dB dynamic range CMOS image sensors of 5.6-
µm are readily available, with 4.1 µm pixels that should start to
emerge this year, each ideally suited to the dual 16 bit ADC
configured camera.


I don't believe you know what a decibel is.


It is simply ten times the base-10 logarithm of a ratio.


A 200 db rated cmos image sensor needs roughly a 32 bit ADC,


I'd like to see how you made this calculation.


Was informed that each bit of an ADC is worth 6 db. Therefore 200/6 =
33.333 ASC bits. Using a pair of 16 bit ADCs should buy us 32 bits
worth of processing for using us 192 db worth of imager dynamic
range. Half that amount of DR should actually be sufficient, but as
long as cmos imagers of 200 db are available, why not use it?


and
anyway you'd care to cut through all the possible interpretations,
that's a lot of brightness range.


Are you saying that a 32 bit ADC is not something doable?


Where did I post anything remotely related to analog-digital
conversions?


I'm just wondering what exactly it is you're driving at. Besides, who
the hell cares how many ADC bits it takes?

The point is, 192 DB or better cmos imager should have no problems in
getting us a darn good look-see at Sirius C, that is unless you intend
to either exclude the IR spectrum or not otherwise use a narrow
bandpass or spectrum cutoff optical filter that would easily exclude
everything above 750 nm. I might consider a 750 to 1500 nm or
possibly even an 800 to 1200 nm bandpass as a good enough starting
point, of which by itself would eliminate the vast bulk of most
everything Sirius A and B have to offer.

~ BG

  #5  
Old February 2nd 09, 02:59 AM posted to alt.astronomy
K. Carson
external usenet poster
 
Posts: 22
Default Brown dwarf numbers way down

In article
,
BradGuth wrote:

The point is, 192 DB or better cmos imager should have no problems in
getting us a darn good look-see at Sirius C, that is unless you intend
to either exclude the IR spectrum or not otherwise use a narrow
bandpass or spectrum cutoff optical filter that would easily exclude
everything above 750 nm. I might consider a 750 to 1500 nm or
possibly even an 800 to 1200 nm bandpass as a good enough starting
point, of which by itself would eliminate the vast bulk of most
everything Sirius A and B have to offer.


The bandgap of Si is about 1200 nm, such dim objects are invisible.
  #6  
Old February 2nd 09, 07:16 AM posted to alt.astronomy
BradGuth
external usenet poster
 
Posts: 21,544
Default Brown dwarf numbers way down

On Feb 1, 5:59*pm, "K. Carson" wrote:
In article
,

BradGuth wrote:
The point is, 192 DB or better cmos imager should have no problems in
getting us a darn good look-see at Sirius C, that is unless you intend
to either exclude the IR spectrum or not otherwise use a narrow
bandpass or spectrum cutoff optical filter that would easily exclude
everything above 750 nm. *I might consider a 750 to 1500 nm or
possibly even an 800 to 1200 nm bandpass as a good enough starting
point, of which by itself would eliminate the vast bulk of most
everything Sirius A and B have to offer.


The bandgap of Si is about 1200 nm, such dim objects are invisible.


Whatever, if you say so. Are you opposed to using CCDs?

~ BG


 




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