Zajimava zavada osciloskopu Hantek DSO5062B

[Pavel Troller]

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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