School me on ms. Analog V Digital - Page 1
Forum section: electronics / beginners

author: Porch
author_rank: Contributor
timestamp: February 12, 2015, 06:58:11 am
content: I have used a Snap-on Vantage for automotive use for a few years. I though I had a good understanding of the basics, but now that I have my TekTronics 465 (100Mhz), my first "real" scope, and I am a bit confused on the differences in the settings.The Vantage will go down to 5ms range. It does not list the Mhz that this scope supports, so I was wondering what the Mhz this scope is? I tried to do the math, but I am failing.Second thing. Using the 1Khz calibrate on the TekTronics 465, I look at the waveform on both units.On the Vantage, I set it to 5ms to see about 5 full waveforms on the screen.On the TekTronics, I have to use the 0.5ms setting to see the same thing. 5ms puts too many waveforms on the screen.Both scopes show the full square wave to be 1Khz.What am I missing here?Thanks

author: miguelvp
author_rank: Super Contributor
timestamp: February 12, 2015, 07:31:44 am
content: https://www1.snapon.com/Files/Diagnostics/Platforms/VantagePROBrochure.pdf3MHz at 8 MSPS (mega samples per second)The inverse of 3MHz is 1/3 of a micro second (us) or 333.33 ns. Are you sure the range limit is not 5 us (micro seconds)?In any event, that is an automotive scope, not much to do with a bench digital scope. But you can probe ignition coils as well it seems and all that running Windows CE.Btw the inverse of 5ms is 200 Hz per division, so you will see 5 square waves per division on that 1KHz signal if the limit is indeed 5ms per division.

author: elliott
author_rank: Regular Contributor
timestamp: February 12, 2015, 07:35:38 am
content: The Vantage is doing 5ms per screen, at 1khz each cycle is 1ms, so you're seeing 5 cycles. The Tek is doing 5ms per division and there are 12 divisions on the screen so you should be seeing 60 cycles.

author: Porch
author_rank: Contributor
timestamp: February 12, 2015, 01:59:40 pm
content: I have the original Vantage.http://buy1.snapon.com/products/diagnostics/vantage.aspThe new Vantage Pro is CE based. Slow and confusing UI, bulky design, crashes a lot. All the things you want in a next generation product, I guess.It is indeed 5ms. So 200Hz it is then. Elliott hit the nail on the head. It's 5ms per screen on the Vantage since it does not have any divisions on the screen. You pause the capture and move around two bars across the waveform and it will tell you the voltage at the bards, frequency, ms, etc. I guess it's a good way to make use of it's limited bandwidth.Thanks a bunch.

author: w2aew
author_rank: Super Contributor
timestamp: February 12, 2015, 02:48:01 pm
content: Quote from: elliott on February 12, 2015, 07:35:38 amMinor correction - the 465 has 10 divisions horizontally, so a 0.5ms/div setting is the same as the 5ms setting on the Vantage.

author: elliott
author_rank: Regular Contributor
timestamp: February 12, 2015, 04:04:32 pm
content: Quote from: w2aew on February 12, 2015, 02:48:01 pmI shouldn't try to answer questions when tired, I don't know where I got the idea that any analog scope has 12 divisions.

author: AG6QR
author_rank: Frequent Contributor
timestamp: February 12, 2015, 05:33:04 pm
content: The Vantage will go down to 5ms range. It does not list the Mhz that this scope supports, so I was wondering what the Mhz this scope is? I tried to do the math, but I am failing.Just a quick note: The amount of time per division, or time per entire screen width, is a measure of the sweep speed. If you know the sweep speed and you can count how many cycles you see per division or per screen, you can figure the signal's frequency. But when you ask "what the MHz the scope supports", be aware that the maximum sweep speed of a scope is somewhat independent of the scope's bandwidth in MHz.The bandwidth is the frequency at which a signal's amplitude will be displayed 3dB lower than its true value. The scope's response will roll off further as the frequency goes higher. A scope can usually display signals somewhat higher than its rated bandwidth, but their amplitude will not be accurate.Scopes with higher bandwidths are usually capable of faster sweep speeds, but there's no hard and fast rule about exactly how many cycles of a waveform should be shown on the screen when the scope is at its maximum sweep speed and the signal is at the scope's rated bandwidth.