Zajimava zavada osciloskopu Hantek DSO5062B

[balu@home]

ano, tak nejak som to pochopil. Teraz sa to zda samozrejme, ale na 
zaciatku digitalnych osciloskopov to asi nebolo 'obvious'
Som zvedavy kedy s tym pride rigol :-)


On Apr/22/2013 8:44, Pavel Troller wrote:
> 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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