Zajimava zavada osciloskopu Hantek DSO5062B

[Kručinský Ladislav]

Díky za vysvětlení, takže digitalizaci fosforu jsme zvládli, teď třeba zlato... ;-)

Zdravím
Kručinský


-----Original Message-----
From: hw-list-bounces na list.hw.cz [mailto:hw-list-bounces na list.hw.cz] On Behalf Of Pavel Troller
Sent: Monday, April 22, 2013 8:44 AM
To: HW-news
Subject: Re: Zajimava zavada osciloskopu Hantek DSO5062B

Zdravím,
  myslím, že to je z toho popisu jasné.
  DPO používá 2 procesy - zřejmě čistě hardwarový zápis do paměti ("Phosphor
database") zřejmě pomocí DMA, a zobrazování této informace na běžném displeji.
Každému pixelu displeje odpovídá jedna buňka té phosphor database, což ale není prostý bit, ale nějaké obecné číslo. Zápis není jen 0/1, ale sumuje se k hodnoté již uložené. V popisu to není, ale zřejmě tam bude třetí proces, který bude pravidelně odečítat ze všech buněk konstantní hodnotu, takže nepříliš často občerstvované pixely budou slábnout, až zmizí. Tím je programově docela pěkně simulovaná dlouhodosvitová obrazovka klasického osciloskopu.
  Zdraví Pavel

> Ak som to spravne pochopil tak je to odlisny sposob spracovania. Nikdy 
> som nad tym nerozmyslal tak som si musel zobrat na pomoc wikipediu :-) 
> Uplne obycajny digitalny osciloskop len sprosto navzorkuje signal a 
> zobrazi ho. Navzorkuje dalsi a zobrazi.
>
> U phosphor pisu ze sa pouziva akasi umela zotrvacnost v zobrazovani 
> aby si tam videl aj glitche a ine iregularity signalu. Potialto som to 
> pochopil
> :-) Okrem toho pisu ze sa pouziva uplne iny sposob spracovania signalu 
> aby bol osciloskop rychlejsi a mal mensi dead time, toto som zatial nepochopil.
> Podla vsetkeho to bola nova technologia zavedena u prvych cislicovych 
> osciloskopoch a dnes sa to pouziva uz na vsetkych slusnych masinach 
> akurat to uz nezdoraznuju.
>
>
> A disadvantage of digital oscilloscopes is the limited refresh rate of 
> the screen. On an analog oscilloscope, the user can get an intuitive 
> sense of the trigger rate simply by looking at the steadiness of the 
> CRT trace. For a digital oscilloscope, the screen looks exactly the 
> same for any signal rate which exceeds the screen's refresh rate. 
> Additionally, it is sometimes hard to spot "glitches" or other rare 
> phenomena on the black-and-white screens of standard digital 
> oscilloscopes; the slight persistence of CRT phosphors on analog 
> oscilloscopes makes glitches visible even if many subsequent triggers 
> overwrite them. Both of these difficulties have been overcome recently 
> by "digital phosphor oscilloscopes," which store data at a very high 
> refresh rate and display it with variable intensity, to simulate the trace persistence of a CRT oscilloscope.
>
> Digital phosphor oscilloscopes
> Digital phosphor oscilloscopes (DPOs) were introduced by Tektronix in 
> the late 1990s. DPOs employ a parallel processing architecture rather 
> than the serial processing architecture of other types of digital oscilloscopes.
> This allows DPOs to capture transient events while maintaining a large 
> bandwidth. With the use of parallel processing, the display permits 
> intensity information to be seen in real time.
> The first stage of the parallel-processing unit is a vertical 
> amplifier, like that of digital storage oscilloscopes. The second 
> stage continues to mimic that of a DSO: the signal is sent to an ADC. 
> After the ADC, however, the processing architecture varies. A DSO 
> captures waveforms in a serial manner. This generates a "holdoff" 
> time, in which the oscilloscope can not record any activity. The speed 
> of the microprocessor thereby limits the rate at which waveforms can 
> be captured. A DPO rasterizes the digital waveform into a digital phosphor database, which is continually updated.
> Then, about every 1/30th of a second, an image of the signal is sent 
> to the display. By directly rasterizing the data and copying it to 
> display memory from the digital phosphor database, the rate 
> determining step is no longer the speed of the microprocessor.
> The "phosphor" of the DPO is purely electronic. The digital phosphor 
> database is composed of many cells which correspond to single pixels 
> within the display. Each time a cell is touched by the waveform, 
> intensity information accumulates. The DPO can display the information 
> in terms of contrasting colors.[5][6]
>
>
> On Apr/22/2013 8:00, Kručinský Ladislav wrote:
>> Ahoj, Balu,
>> zaujal mě ten název: Digital Phosphor Oscilloscope...
>> To je k čemu dobré to slůvko "Phosphor" ?
>>
>> Zdravím
>> Kručinský
>>
>>
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