New Instek GDS-1052-U? - Page 1
Forum section: electronics / general

author: morphius
author_rank: Newbie
timestamp: November 23, 2011, 05:33:31 pm
content: Howdy All,I've been researching an inexpensive digital oscilloscope. I have very little experience with oscilloscopes, mainly from school many moons ago. I realize that the Rigol DS1052e has been the popular entry level choice, but I noticed what appears to be a new line of budget scopes from Instek, the GDS-1000-U serieshttp://www.gwinstek.com/en/product/productdetail.aspx?pid=3&mid=7&id=1299(not to be confused with the GDS-1000a or the GDS-1000a-U.) The 50MHz version (GDS-1052-U) is $299 at tequipment.com, a price point at which I'm essentially ready to just pull the trigger.There are three main spec differences that I notice between this Instek and the Rigol. The Instek samples at 250 MSa/s (vs 1 GSa/s for the Rigol) which I'm not particularly worried about especially with a 50 MHz scope. The Rigol has a multiplication math function which the Instek lacks but I have no idea where I would ever need that function. Finally, the Instek has only a 4kpt record length per channel compared to the minimum of 8kpt on the Rigol (dual channel, 500 MSa/S) with the potential for 1Mpt using long memory at some sample rates. This small record length has me a bit worried although I'm not altogether sure whether that would even present a problem for me in the foreseeable future.My primary uses would be debugging some hobby microcontroller projects including communications and sensor interfacing. I don't see me going over 20MHz clock frequencies anytime soon with most communications below 10kbps probably topping out at 115kbps.Can anyone offer an example of where I would likely be limited by the 4kpt record length? Is there any other reason to hold off on just picking up this scope?I can see that the Rigol is better in many ways, but I can't justify spending the extra $100 (I can barely justify spending thefirst$300). I think that a less capable scope in my workshop is probably better than a more capable one that sits in the store.Many thanks for bearing with me as a first time poster.

author: Unknown
author_rank: Unknown
timestamp: November 23, 2011, 07:48:34 pm
content: Note that 250 MS/s is a bit on the low side for 50MHz single shot (rule of thumb would be 25MHz single shot). Does it go down to 125 MS/s in dual channel mode?250 MS/s and 4 kpoints is definitely old technology (not that the Rigol is particularly new). If you sample a serial signal, and you want say 10 points per bit to get a reasonable representation of the signal, you only have memory for 400 bits, or 40 bytes (excluding space and stop bits). This is probably not enough for a single transmission. Triggering on a particular point in a serial signal is an issue since the cheap scopes don't usually feature serial triggering. But it depends on your applications. Long capture memory is less important if you use a logic analyzer in combination with a scope, for example. If you have control over both sides of the communication, you may be able to arrange trigger signals or adjust the signal to make the measurement easier.I would agree that a less capable scope in your hands is much better than a perfect scope you can't afford. I'm not familiar with the scopes you mention, so I don't know if there are any other issues like build quality, user interface, responsiveness or screen quality.

author: saturation
author_rank: Super Contributor
timestamp: November 23, 2011, 08:03:33 pm
content: It reads like you've spec'd out your intended application, and know the specs for a scope to meet the need.Try the tequipment.net chat box and see if they can match any price you can find on the net lower that theirs, say for Rigol. I used that plus something akin to a black friday discount code and got ~ $50 off the scope, free shipping, last year.

author: morphius
author_rank: Newbie
timestamp: November 26, 2011, 02:32:57 pm
content: Alm,Thank you for pointing out the drop to 125MSa/s in dual channel mode. I could not find that stated on the datasheet or in the manual (kudos to Rigol for making that explicit.) To Instek's credit, they replied to my question submitted through their online contact form within hours and it does in fact drop to 125 MSa/s per channel. I will be using a usb logic analyzer for tracking the bits and bytes once I can confirm that they are properly being sent with the scope. However, I did end up thinking of an application for long memory: verifying oscillator startup. Based on those points, I think I will suck it up and go with the Rigol.Saturation,Thanks for the tip about tequipment.net, I will check that out before ordering from Dealextreme.