Looking for a Scope, leaning towards the GW Instek MDO-2204EG - Page 1
Forum section: electronics / testgear

author: kreyszig
author_rank: Regular Contributor
timestamp: September 07, 2017, 12:54:08 am
content: I am looking to get a 4-channel scope for general use, including looking at switching power supply ripple and noise. I also want to use it for I2C/SPI/UART/CAN decoding and for audio. I also want to use the scope for general circuit design, and to play with RPIs and Arduinos.From my understanding, I should aim for >100 MHz bandwidth if I want to analyse switching power supply output. Also my desire to have 4 channels limits my options. Based on these, the GDS-2204E, MDO-2204E* an MSO-2204E* models from GW Instek seemed interesting. Based on Dave's video about MSOs, if I really want to do more advanced digital decoding, I should go with a dedicated USB logic analyser, so this excludes the MSO-2204E*.I would be interested to know what should be the usefulness of the SA in the MDO-2204E* for what I want to do (switching PSU, audio?). My initial impression was that getting both the SA and AWG in the MDO-2204EG could be a reasonably good value for an additional ~$300 compared to the GSD-2204E, but the MDO-2204EX was less interesting since I don't care too much about the DMM and I could buy a better separate power supply in the future.So basically I wanted to know if the MDO-2204EG should be the best option at a reasonable price (let say around $2000) given what I want to do.Thanks!

author: kreyszig
author_rank: Regular Contributor
timestamp: September 07, 2017, 02:57:23 pm
content: Another option for me would be to wait for the Siglent SDS1204X-E to be released in North America. From my understanding it will be very similar to the GW Instek GDS-2204E in terms of hardware and software performance/functionalities (except for shared vertical control and the presence of a trigger out?), but for about $500 vs $1350? It would then be more difficult to justify paying $1150 extra for the AWG and the SA of the GW Instek MDO-2204EG. How much more useful could be the SA of the MDO-2204E* in practice compared to the FFT mode which is quite good based on the reviews I saw?Thanks!

author: MrW0lf
author_rank: Frequent Contributor
timestamp: September 07, 2017, 03:13:50 pm
content: I've read MDO manual and their SA thingshouldoutperform conventional FFT in the high freq range when looking for details, but never once seen them actually probing some challenging situation in demo videos. So it's unknown so far.As for Siglent one must understand that they have cut some corners to achieve low cost. Go look video just posted in X-E thread and you can see them. Main thing is doing complex processing in "best effort" method seemingly not in sync with actual ack. So while wfm rate may be high for DPO part, measurements, decoding, FFT are quite slow updating and seem to skip wfms. But they operate to high accuracy so things are not beyond measureIf you compare with GWI videos it seems to demonstrate higher processing power, especially with FFT. Accuracy is probably similar. So essentially you pay for speed and some say for more polished firmware.

author: Fungus
author_rank: Super Contributor
timestamp: September 07, 2017, 03:16:05 pm
content: Quote from: kreyszig on September 07, 2017, 12:54:08 amNope.

author: nctnico
author_rank: Super Contributor
timestamp: September 07, 2017, 03:53:37 pm
content: Quote from: MrW0lf on September 07, 2017, 03:13:50 pmI agree. If you want a scope which works as specified then go for the GW Instek. According to the specs it seems to be able to use the internal function generator as a tracking generator although it is 'limited' to 25MHz.

author: technogeeky
author_rank: Frequent Contributor
timestamp: September 08, 2017, 09:35:20 am
content: Quote from: MrW0lf on September 07, 2017, 03:13:50 pmComing from the Rigol 1054z (but having access to real spectrum analyzers), that seems really impressive to me. Not only the resolution, but man the speed of the FFT. And the way the FFT 'rolls' against the rolling input.Very nice.

author: kreyszig
author_rank: Regular Contributor
timestamp: September 08, 2017, 11:37:17 am
content: Thank you. So yes if GWI are doing a significantly better job with the firmware and their scope is more responsive, that could be worth the extra cost

author: David Hess
author_rank: Super Contributor
timestamp: September 08, 2017, 05:59:25 pm
content: Quote from: Fungus on September 07, 2017, 03:16:05 pmI agree. Unless you working with bleeding edge higher frequency switching power supplies, even 50 MHz is sufficient and the more important behaviors like transient response occur at much lower frequencies. 100 MHz yields a 3.5 nanosecond transition time and how many switching regulator waveforms are faster than that? The fastest are usually an order of magnitude slower.Further, probing above 100 MHz is not trivial and high voltage differential probes are limited by their common mode rejection even above 20 MHz.A good high bandwidth AC or AC/DC current probe would be more useful than a faster oscilloscope.

author: kreyszig
author_rank: Regular Contributor
timestamp: September 08, 2017, 08:59:26 pm
content: The maximum voltage of the integrated AWG into 50ohm is 2.5Vpp fro the MDO-2104EX, isn't it a bit low? Given the price difference between the GDS-2104E and the MDO-2104EG, the unproven usefulness of the SA and the well working FFT, I am wondering if I should get a GDS-21044 and a separate AWG such as the Rigol DG1022Z instead for about the same total cost?

author: nctnico
author_rank: Super Contributor
timestamp: September 08, 2017, 09:06:18 pm
content: IIRC every internal function generator inside an oscilloscope is limited to about 2.5Vpp into 50 Ohm. A seperate function generator will also be easier to operate anyway. OTOH being able to use an internal function generator as a tracking generator like the MDO2000E promises might be usefull if you want to measure frequency responses from filters, resonating circuits and amplifiers in an easy way.

author: kreyszig
author_rank: Regular Contributor
timestamp: September 09, 2017, 01:34:29 am
content: Quote from: nctnico on September 08, 2017, 09:06:18 pmCan the internal generator be used as a tracking one with the FFT as well (i.e. to draw the intensity of the FFT at the generated frequency as a function of that frequency)? Otherwise the SA doesn't below 1kHz, so it is of limited use for audio?

author: nctnico
author_rank: Super Contributor
timestamp: September 09, 2017, 08:06:16 am
content: Quote from: kreyszig on September 09, 2017, 01:34:29 amThe minimum frequency span seems is 1kHz but the lowest frequency is DC. After all the spectrum analysis is based on FFT.

author: SharpEars
author_rank: Unknown
timestamp: October 11, 2017, 03:01:56 pm
content: I wonder how good the noise floor on these scopes is. Isn't Instek known for its very low noise floor (i.e., SNR)?I only see specs listed for averaging for the SA at:Display Average Noise Level for the SA: 1V/div < -50dBm, Avg : 16 ; 100mV/div < -70dBm, Avg : 16 ; 10mV/div < -90dBm, Avg : 16Not sure if these are good compared to Rigol/Keysight/Tek, perhaps someone more knowledgeable in this area can chime in.I would like to know if the excellent noise floor of their previous scopes is present in these new ones.

author: slugrustle
author_rank: Frequent Contributor
timestamp: December 04, 2017, 01:46:02 am
content: This scope looks great. Can someone link to a review or post their experiences with it?

author: kreyszig
author_rank: Regular Contributor
timestamp: January 03, 2018, 03:44:41 pm
content: I ordered a MDO-2204EG on September 14th and the shipment date keeps being postponed. Now it is set for February 12th... Are these delays normal for a new product like that? I could not find one in stock anywhere, so I doubt it is an issue with the store I am buying it from... I am starting to think about looking for a different scope...Thanks!

author: nctnico
author_rank: Super Contributor
timestamp: January 03, 2018, 04:58:44 pm
content: As I wrote before: the MDO-2000E doesn't offer much over the MSO-2000E. I'd change the order and get an MSO2204E instead. The delivery delay probably indicates not many people are buying the MDO model.