I’m in the market for my first oscilloscope and I was hoping to get some advice from you guys on which one to buy.
Although I’m interested generally in learning how to use a scope, the reason I’m posting in the Wireless/RF forum is because I have a particular interest in learning more about RFID and I want to start looking into the RF modulation for both 125khz (LF) and 13.65mhz (HF) cards / readers, so whatever one I buy should have the bandwidth/sampling rate to handle this.
My preference would be a digital scope with USB so I can take advantage of some of the event recording features, etc.
For hobbyists, I think a Tektronix is not very good value for the money. I have a standard TDS220 myself, but that’s mostly because I got it cheap. It is great, but it is very limited compared to newer, even cheaper scopes. Escpecially in sample memory and PC connectivity.
If I would be looking for a scope today I would consider something from Rigol. You can get a really good one for under $500 shipped.
USB scopes are fine, but don’t fool yourself that it will be any cheaper if you want a good one.
Thanks for the tips on brands, but the main thing I’m after is what I should be looking for in terms of minimum features or performance if I want to capture 125khz and 13.56mhz RF signals.
I have a Hantek DS2090 USB PC-based DSO. Very pleased with it. Most of my work is with signals that are not recurring, line a nice sine wave. So a standard 'scope rather than a DSO isn’t useful.
The DS2090 is good enough for most of what I do.
Purchased direct from distributor in China for something like $140 including shipping.
I also have a venerable Tektronix 465 'scope. Rarely used now but useful now and then.
I use Textronix TDS2014B. It was posted that the Rigol is much cheaper than textronix. Well its only just a very little cheaper. For the price difference I go with the TEK, they are very good scopes and very easy to learn and use.
Stay away from the Agilant(HP) DSO 3xxx, the trigger is very weird and the controls are VERY VERY touchy. Just turn a knob 1 degree and the trace goes off screen. It is also in the same price range $1500-2k 4 ch 100mhz color DSO
Scopes in this range are what they are. Not to be confused for a “GOOD” scope at $10-30K. But I’d guess for what you want any of the %1.5-2k scopes would be fine if you stay with a name brand.
For RF stuff you really need a Vector Network Analyzer. Used HP’s on ebay for $1-30k
Just my thoughts. We all have our favorite tools and tend to stand by them till death :mrgreen: :mrgreen:
The price range I’m looking at is up to $1000 (less is preferable). The highest priority is knowing that I’ll be able to capture a 13.56mhz RF signal with enough resolution to see the amplitude and load modulation used by the reader and card respectively for comms.
I’m now looking seriously at getting the DSO-1200 (http://www.hantek.com.cn/english/produc … sp?unid=76). It’s 200mhz with 500Msa/s real-time, so it seems enough to suit my needs although I’d really like to get a second opinion since this is my first scope
Does anyone have any general feedback on the DSO-1200? I can find reviews for their USB-only scopes but not this one!
To be very honest you would be wasting your money, I looked at the web site and there is very little info. You get what you pay for. RF is very hard to capture on a scope. I’ve been doing some RF stuff but its up at 2.4 ghz and I can see it on the TEK scope but that’s all. At 13 mhz you’ll see it but a scope is not really made for RF stuff, you really need a VNA Vector network Analyzer to do it properly. That said anything is better than nothing. Pay the extra $500 and get a good scope. Not a USB scope, Not a software scope. A good scope. Like I said I like TEK’s a 100mhz 2 channel B&W is < $1000 new and if you look around you can find them for $850 new. Its a good scope found on many many shop work benches. Not great but good and stable and easy to use. The color TEK’s start around $1500 but B&W are cheaper. The color is cool but not really needed.
I can’t answer your direct question, I’d guess at 13 mhz with a 100mhz scope you’d be more than ok
One last thing Tektronix has LIFETIME warranty on TDS models…LIFETIME think about it
I can’t really help with what model would be suitable for RF type of stuff, as I’ve never worked in that area.
But, I can suggest on a way to get a decent scope cheaper - try looking for second hand older models (from reputable places of course). I ended up getting a decent 100 MHz analogue scope for cheaper than the cheapest 20MHz digital scope. I found a local electronics surplus type place on ebay. He had a bunch of scopes the Army was getting rid of, and one had been sitting around for a few months so he dropped the price by half. I just happened to stumble across it a few days after that The scopes were all perfectly fine - the Army just decided to upgrade because they had it in their budget to replace them after a given number of years.
Also, try emailing places that sell scopes and ask if they have any refurbished scopes, and if you’re a student see if they have a student discount. I found this out by luck - when I emailed a local distributor to see if they had refurbished scopes, I mentioned I was a student, and they replied that they didn’t have anything like that, but that they did give a 10% student discount (I didn’t end up buying from them, but I will certainly contact them if I need a new scope later).
Oh, and in my limited experience, I find that to view a given fast signal, the bandwidth required on a digital scope is several times higher than the bandwidth on the analogue scopes, I guess due to the sampling nature of the digital scopes.
remember that an analog 'scope or a digital non-storage 'scope is unable to capture/display a signal or serial data or bit patterns that are non-recurring. In microprocessor and digital work, normally one sets up a trigger condition and captures a one-time signal.
Before low cost DSO’s we used to trigger and use the 'scope’s CRT phosphor persistence to “hold” the image a fraction of a second so we could “see” the pattern that happened once.
Recurring signals like a square wave are simple enough for any scope.
So a good entry level DSO is the Hantek DS2090 or better.
kosullivan:
The price range I’m looking at is up to $1000 (less is preferable). The highest priority is knowing that I’ll be able to capture a 13.56mhz RF signal with enough resolution to see the amplitude and load modulation used by the reader and card respectively for comms.
I’m now looking seriously at getting the DSO-1200 (http://www.hantek.com.cn/english/produc … sp?unid=76). It’s 200mhz with 500Msa/s real-time, so it seems enough to suit my needs although I’d really like to get a second opinion since this is my first scope
Does anyone have any general feedback on the DSO-1200? I can find reviews for their USB-only scopes but not this one!
–ko
I have a DS2090. Bought at a big discount direct from dealer in China. Works well for most of my hobby needs. Wish it had a larger sample memory, but it gets the job done if you are clever in how it's triggered. Newest PC software is a big improvement in ease of use.
Actually on the subject of sample memory, the DSO-1200 has 32k samples and it can sample at 500MS/s realtime. I’m still a little fuzzy on the subject of how you calculate the time you can sample. I understand it to be simply ‘sample memory / # samples per second’. So if I have a 13.56Mhz signal, I would need at least twice that as a sample rate, which would give me 32k/27.12m = 1.1ms I could capture. Is this correct? If so it seems awfully small for a scope boasting 200mhz bandwidth.
If you (or anyone) could shed light on whether I’m calculating this correctly it’d me much appreciated.
Cheers,
Ko
P.S. Stevech, any chance of getting the contact for who you bought yours off? Was it literally just contacting Hantek?
13.56 x 2 Msamples/s is the absolute minimum you need to reconstruct the signal with a sin(x)/x approximation.
In reality you need at least four times, up to 10 times the shannon limit. Why? because mostly you seek for non-linearities or higher band harmonics.
And yes 32k (in fact 14k for DSO from hantek) is small, but it’s enought to cover 1400 15Mhz cycles at 10x sampling. Learn how to generate triggers, even with high end agilent scope I have to generate accurate triggers to capture small event and navigate trough long events.
And hantek DSO have a crap software, better get a rigol.
I’ve taken the risk after talking to a few different people that sell that Hantek DSO-1200 and gone with it.
I have a choice of using it standalone with nice tactile buttons and screen which has so far been the biggest criticism I’ve seen for USB scopes, or I can plug it in and get all the nifty software features. Finally I’m quite a traveler, so the appeal of a handheld unit is too much to resist.
I also got it for USD$688 so I’m pretty happy with the price and there’s a 30-day 100% return (except shipping) policy so at least it gives me the option of seeing how good this baby will fly.
The biggest concerns I have are a) 32k memory; and b) It’s a new product so I’m trusting the reviews given to me by salesmen that the people who bought it so far are happy. One guy in particular gave me fairly straight-up answers about it so we’ll see how it goes once I throw a few contactless APDU’s @ 13.56mhz at it!
Thanks for all the answers/debate people, I’ll post a reply with my thoughts on it once I’ve had a good play.
