Time for a new Oscilloscope & MSO5074 questions - Page 1
Forum section: electronics / testgear

author: molerat
author_rank: Newbie
timestamp: June 24, 2019, 09:56:09 pm
content: I've been rocking a Rigol DS1052E for almost 5 years now and while it's been good to me, I think I've outgrown it.I'm in the market for some thing with 4 channels and a higher sampling rate. Bandwidth is not my primary concern as I generally work in the analog domain with typical frequencies in the audio range.MSO5074 looks like quite a deal and, as I understand it, is very hackable. One of the big selling points is the optional function generator (needs to be unlocked with a serial, I know). I figured that any of the multi-function oscilloscopes with only operate in one mode at a time, but I'm noticing that other multi-function oscilloscopes advertise the ability to produce bode plots so maybe that isn't necessarily true? Perhaps some oscilloscopes are designed with this functionality in mind? Does the MSO5074 need any other expensive peripherals to work as a function generator? Is there a sync output (The manual isn't very clear about this)?Any other recommendations for something <=$1000?

author: thm_w
author_rank: Super Contributor
timestamp: June 24, 2019, 10:56:14 pm
content: If you don't care about bandwidth a lower cost scope could work too, or 10-bit+. Feel free to read the numerous threads on this forum.https://www.eevblog.com/forum/testgear/first-oscilloscope-for-third-year-ee-student/https://www.eevblog.com/forum/testgear/rigolsiglent-new-low-end-dso-platforms/etc.You don't need need any peripherals to use the function generator, but I would get some BNC cables, BNC adapters, and 50 ohm feed through adapters ($6 each). There is no sync output. The two function generators, 16ch logic analyzer, and four channels can all run at the same time.You haven't given any specific requirements for a generator, so no one can say whether or not internal or external unit is suitable.They are supposed to add bode plot function in future MSO5000 firmware versions. Right now you can write a python script to generate a bode plot which works well. There are some advantages to having PC based control as you have complete control over frequency steps, averaging, etc. Although, something like picoscope/AD2/sound card, would likely be better if you are looking for accuracy in audio ranges.

author: molerat
author_rank: Newbie
timestamp: June 24, 2019, 11:56:58 pm
content: For bode plots a sweep of 0 to ~20KHz is adequate. Sync output should be available in addition to and separately from the common waveforms. MSO5074 provides control over amplitude, offset, etc. which is all fine and good. This all with the expectation that this functionality is required in order to produce bode plots on an oscilloscope.There is a waveform called 'sinc' in the MSO5000 manual. That's not a sync output?

author: thm_w
author_rank: Super Contributor
timestamp: June 25, 2019, 12:18:38 am
content: Quote from: molerat on June 24, 2019, 11:56:58 pmYou could use AD2 or a sound card to achieve 20kHz (not to 0Hz but very close). Just throwing it out there though. If your budget is ~$1k for a scope then it is great value, just not really tailored for precision audio work at all.Sinc is a waveform that looks like this:https://en.wikipedia.org/wiki/Sinc_functionA sync output is not needed to produce a bode plot when you have control over the frequency via PC. Usually used for the sweep mode to indicate the start frequency of sweep (although I'm sure there are many other cases its useful for).DG811 is a good function generator for $280 with sync outputs:https://www.rigolna.com/products/waveform-generators/dg800/There are also the siglent units which connect to the scope, if you are looking for "dead simple" operation then I might wait to see what the Rigol bode is like and if its not good get siglent. If you don't mind writing software the Rigol will be better value (sample rate wise, but front end isn't as quiet).

author: molerat
author_rank: Newbie
timestamp: June 25, 2019, 02:07:36 am
content: You said "something like picoscope/AD2/sound card, would likely be better if you are looking for accuracy in audio ranges."and then said "You could use AD2 or a sound card to achieve 20kHz (not to 0Hz but very close). Just throwing it out there though. If your budget is ~$1k for a scope then it is great value, just not really tailored for precision audio work at all."Can you expound on that?

author: Someone
author_rank: Super Contributor
timestamp: June 25, 2019, 07:49:23 am
content: Quote from: molerat on June 24, 2019, 11:56:58 pmHaving a dual channel function generator on the Rigol 5000 you can use one channel as a sync output with a pulse waveform, the (adjustable) phase between the outputs will remain steady. Other scopes offer trigger out, or even more useful is an internal trigger source from the waveform generator (since the typical use for a sync output was to trigger a scope) so you don't need cables or occupy a channel.

author: Fungus
author_rank: Super Contributor
timestamp: June 25, 2019, 07:53:23 am
content: Quote from: molerat on June 25, 2019, 02:07:36 am14-bit DAC makes Analog Discovery much better than any 8-bit 'scope:https://www.eevblog.com/forum/projects/analog-disovery-as-audio-analyzer/The MSO5000's bode plot abilities are unknown because it's only going to appear in a future firmware update. Don't expect miracles though, it doesn't have really sensitive/low noise inputs in the mV ranges.