Products > Test Equipment
Picoscope Hack
markone:
--- Quote from: jasonRF on December 07, 2022, 01:49:47 pm ---
--- Quote from: markone on December 05, 2022, 09:28:19 pm ---
All the models that you listed are quite peculiar/unique, this does not apply to ordinary models, especially 2000 series, that i would consider overpriced for USB2.0 devices.
--- End quote ---
Sure, they are expensive compared to budget benchtop scopes made by Rigol/Siglent/Instek/etc. But early this year I was in the market for a USB scope upgrade where I wanted 2 channels and at least 100 MHz bandwidth, along with deep memory, large FFTs, serial decoding and either high-res mode or digital low-pass filtering. I did not find any viable options besides Picoscope. Sure, you can find cheaper USB scopes with reasonable hardware specs manufactured by Owon or DreamSourceLab or others, but you just do not get the rest of the capabilities. My budget was too low for a 2208B (or even a 2207B), so I shopped ebay for a handful of months until I found something I could afford. I would have been happy with a 2000 or 3000-series, but the first good option I found was a 5244B that I picked up for $450 US.
I think a lot of the Picoscope cost is due to design and manufacturing in the UK (at least both of mine are made in the UK), relatively low sales volumes, and the superior software/firmware. If a company like Owon decided to be serious about their software, they could give Pico enough competition to force prices down, but this doesn't seem likely to happen any time soon.
jason
--- End quote ---
5244B at 450 USD seems quite a bargain, I guess that you would never have bought it at full price.
I agree to pay a plus for a professional SW support but to be honest Picoscope 6 nowadays sounds quite outdated, at that price mechanisms like serial protocol trigger and performance streaming mode should be a standard feature, on the other hand brands like Owon & Hantek, that sometimes provide decent HW for the money, are much worse, often at a level that renders their products almost useless for serious job. I do not mention Picoscope 7 because it's still almost work in progress.
Years ago, with lower prices and less competition from desktop DSO's market, Picoscope listing was much more justified, now you have to have quite peculiar/niche needing to find an acceptable balance money / features.
The fact that Picoscopes are assembled by third parts in UK it's a factor that increase cost but not at the that level, at least for that level of quantity.
You are right, if only Owon ... but i fear that sadly we never see that.
_Wim_:
--- Quote from: _Wim_ on November 26, 2022, 12:58:04 pm ---Woohoo, the bandwidth has been fixed! Opening the front end shield, there was a 75ohm resistor in series with the input. I have change this to a zero ohm resistor, and :-+ :-+ :-+
--- End quote ---
To further evaluate the frequency response at all ranges, I made the following test setup:
BG7TBL Noise source => DC-block => Stepped attenuator => 50-ohm input adaptor => Picoscope input
This gave me a relative smooth noise spectrum that I could attenuate, to test the response on all ranges. To make the comparison easier, all plots where normalized to the +-20V range (with zero ohm resistor mod). Goal was to compare the frequency response with different attenuator settings in the scope to ensure the zero ohm mod worked correctly with different attenuator settings.
The same test was performed with the unmodified input (with 75 ohm series resistor). Conclusion: both unmodified and modified had +-2dB variation over all the ranges.
markone:
--- Quote from: _Wim_ on December 11, 2022, 12:46:42 pm ---
--- Quote from: _Wim_ on November 26, 2022, 12:58:04 pm ---Woohoo, the bandwidth has been fixed! Opening the front end shield, there was a 75ohm resistor in series with the input. I have change this to a zero ohm resistor, and :-+ :-+ :-+
--- End quote ---
To further evaluate the frequency response at all ranges, I made the following test setup:
BG7TBL Noise source => DC-block => Stepped attenuator => 50-ohm input adaptor => Picoscope input
This gave me a relative smooth noise spectrum that I could attenuate, to test the response on all ranges. To make the comparison easier, all plots where normalized to the +-20V range (with zero ohm resistor mod). Goal was to compare the frequency response with different attenuator settings in the scope to ensure the zero ohm mod worked correctly with different attenuator settings.
The same test was performed with the unmodified input (with 75 ohm series resistor). Conclusion: both unmodified and modified had +-2dB variation over all the ranges.
--- End quote ---
Interesting, I would try with some other values for input resistor because with zero It would seem that aliasing could be a problem.
_Wim_:
BG7TBL Noise source => DC-block => Stepped attenuator => CMU200 vs
BG7TBL Noise source => DC-block => Stepped attenuator => 50-ohm input adaptor => Picoscope input
As the same "drop" between 60Mhz and 160Mhz is seen as when I sweeped the CMU200 generator to the picoscope input (https://www.eevblog.com/forum/testgear/picoscope-hack/msg4545359/#msg4545359), I do start to believe the Pico is a little low between 60Mhz and 160Mhz...
_Wim_:
--- Quote from: markone on December 11, 2022, 01:40:40 pm ---Interesting, I would try with some other values for input resistor because with zero It would seem that aliasing could be a problem.
--- End quote ---
Might be worth a try, but I would have expected to see those aliasing effects in the spectrums measured above.
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