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My first Digital Osciloscope help me OWON SDS7102V firmware 2.7.4

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dssence:
Hi first of all I want to introduce myself, my name is paul i'm from argentina, and I'm myself a computer engineer and I'm leaned towards reverse engineering.. hacking and modding different devices. I came up it was time to get a digital osciloscope and came across brand known as OWON, I found a direct importer in my country with good prices.
  So basically I would like you guys to help me out and see which are the goods and bads of OWON model 7102V, but mostly about "OWON" brand in general. I want to buy a scope that would be a good inversion for my research, that I won't regret later. So I will be really apreciatting all your knowledge and savvyness on the matter.
  First of all I don't know if it's best to buy a 100mhz Owon or 200mhz. I will be doing mostly everything from decoding signals from FPGA's CPLD's PIC's AVR's from different gadgets to doing reverse engineering of anything you may imagine for research and hobby. So that's something to take into account.
   Secondly I don't have a Logic Analyzer but I know I can buy one from seedstudio called Logic Sniffer here's the link

http://www.seeedstudio.com/depot/open-workbench-logic-sniffer-p-612.html?cPath=174

 I will by doing some power supplpy repair.. notebook repair .. console repair as well. So I would like to know if by using an osciloscope I can be doing testing of digital circuits as well. or it's mostly for analog signals.. maybe Im confusing myself and I should get a logic analyzer.. but I don't think that's the case. To give you an idea of the things I might be doing or actually leaning myself into ..this is one of the sites which lead to reverse engineering. which really called my attention

http://spritesmods.com/?art=diskgenie&page=5   

in that site the guy is checking how secure it's a hard drive enclosure which encrypts information.. and it's doing some decoding to see at what instant the pic mcu saves the password..

 By the way the SDS7102V i will be getting has the factory firmware 2.7.4.

 anyways I'm listening to all of you .. thanks !

AndrejaKo:
Hi there!

Well first read this https://www.eevblog.com/forum/product-reviews-photos-and-discussion/review-of-owon-sds7102/ thread, if you haven't already. It is long, but it has plenty of details as well as some common problems with the scopes such as the grinding fan problem or the channel 1 problem (which should have been solved for some time now).

As for the type of scope itself, you should spend some time and try to think how you're going to use it. What you wrote as intended use is a bit vague.  You'll need to "assign" priorities to the uses which you consider more important than other and be aware of the limitations of each version of the scope. For example the sample rate listed is for one channel use only and if you want to use both channels, the sample rate will be cut in half. The result of that is that a two 100 MHz signals viewed by each probe won't be as accurately shown as one 100 MHz signal viewed by one probe. For PICs, AVRs and some CPLDs that may not be a problem, but some FPGAs are fast and you may need more bandwidth and sample rate in order to view their signals correctly.

Next, it seems that you're thinking if you should buy a logic analyzed or a scope. If you're going to get seriously working with electronics, you'll need both!

 Why? Well the SDS7102 does have large sample memory (10 Mpoints per channel), but it's a scope and it doesn't do any protocol decoding or similar. What that means in practice is that if you have a device using say I^2C device and you're probing the data line, you'll need to count ones and zerores by hand and then decode convert them manually into hex digits and then figure out what's happening. Decent logic analyzers should be capable of doing that automatically. Good ones (in the low price range) will even be able to decode some parts of the protocol and tell you for example which parts of the message are the actual data being transmitted and which are just ACKs/NACKs and other protocol details. If you get a scope you'll have to do all that by hand and it gets tedious quickly. I know that because I decided to get an SDS7102 instead of a logic analyzer.  All is not horrible though, since if you have a working bus, you won't need much details about the shape of the digital signal itself so you'll be able make long captures by increasing the timebase.  If you're good with programming, you could import the data captured by the scope as a .csv file and then process it to do some decoding on a PC, if you want that. Still, a logic analyzer is more comfortable for debugging some parts of digital logic.


On the other hand, if you're designing or troubleshooting an analog circuit (or a digital one where you expect problems with signal integrity), you'll definitely need a scope. A logic analyzer simply can't replace a scope in such usage scenario. Scope will give you the ability so actually see the waveforms and based on that you'll be able to decide what needs to be done. If you're going to be repairing modern switch mode power supplies, you'll need a scope to solve more complex problems.


Also do note that the 200 MHz scope called SDS8102 is in some areas no better that the 100 MHz SDS7102 and that areas may be important to you. The scope has bandwidth of 200 MHz and sample rate of 2 GS/s. If you use both channels, you get 1 GS/s per channel, so each channel is as good as whole SDS7102. In that mode, each channel can store up to just 10K points of data! To get the 10 M points, you'll need to run both channels in sample rate of 500 MS/s or lower. One channel running in 1 GS/s mode can fill all 10 M points, but if you run it in 2 GS/s mode (which may be needed by some very fast FPGAs), you'll get again just 10 K points.

As far as Owon is concerned, their hardware, see what people are talking about in the thread I linked to. My impression is that their hardware is not that bad, but the software side isn't very good. The PC software is horrible and the scope could do with a bit more and a bit better implemented software features.

dssence:
Hi thanks again for such a complete reply in detail, I was trying to make up my head, and I think I will be buying the SDS8202 or the MSO8202 (which has a logic analyzer integrated) .
    I wanted to ask you a couple things, the price tag of the SDS8202 is around 1000 U$s and the MSO it's around 1300U$s . Now the question which raises , is , if it's really worth buying the MSO with everything integrated or not . Cause these kind of devices with all integrated most of the time have problems , I would like to know what you think about it , cause of not I'll be getting the SDS8202 as I said I want a good equipment that would be worht buying for everything I'll be doing.  I will be paying like around 300 U$s for the logic analyzer on the MSO 8202 T and I think the screen size it's smaller. As far as I've checked on the specs differences are the follwoing

MSO8202T with logic analyzer which has a faster rise time =1.7ns vs =3.5ns on the 7102 and also horizontal 2ns/div~100s/div step by 1~2~5 on 7102V vs 8202T 1ns/div~100s/div, step by 1~2~5 how does that actually matter.

this is a graphical comparison with some things quite I don't understand why the MSO seems not so good compared to the SDS8202

Dread:
I have a SDS-8202V and I really like it, I have had no problems with it and the construction is top notch.  I highly suggest you get the battery pack, its a feature that really makes the Owon very handy.

dssence:
Hi dread thanks so much for your answer , so you recommend me on getting the SDS8202V , I was thinking on the MSO but it lacks many features the SDS have .. I could get a separate logic analyzer. By the way what things you dislike from it ? could you tell me pros and cons ?

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