I've tried to used $10,000, 1GHz scopes for decoding, they suck at it - it's like trying to look at the Great Barrier Reef through the botom of a jam jar - far better to be able to a) check that the signals look like you expect them to with the scope and b) move to the logic analyzer.
- Analyze EMI suppression in power supply and amplifier circuits, mostly LF-UHF related projects.
- Analyze RF components: filter response, attenuation, etc.
- Troubleshoot radio equipment: figure out if oscillators are working OK, debug receiver stages, etc.
- Reverse engineering: I2C/SPI/UART and other buses, memory dumping, rewriting, glitches/side channel attacks.
- Debugging small circuits with the usual run of the mill PIC/AVR/MCU: arduino, STM32.
- Assorted experiments, like firmware stuff for hard drives, computer equipment, FPGAs
- Video signals: sync clocks, conversion....
I really appreciate your responses, it's always great to see someone putting in some effort and time. I will just list a few of the case scenarios I will likely be involved with, in my lab:
- Analyze EMI suppression in power supply and amplifier circuits, mostly LF-UHF related projects.
- Analyze RF components: filter response, attenuation, etc.
- Troubleshoot radio equipment: figure out if oscillators are working OK, debug receiver stages, etc.
- Reverse engineering: I2C/SPI/UART and other buses, memory dumping, rewriting, glitches/side channel attacks.
- Debugging small circuits with the usual run of the mill PIC/AVR/MCU: arduino, STM32.
- Assorted experiments, like firmware stuff for hard drives, computer equipment, FPGAs
- Video signals: sync clocks, conversion....
I was initially looking for spending up to 1k EUR, since I have put quite some money into things recently... Considering this, what do you honestly think would suit me best? Siglent or splurge a little and pick the Tektronix? Any decent EU seller that offers discounts? (I'm between jobs now)
I've tried to used $10,000, 1GHz scopes for decoding, they suck at it - it's like trying to look at the Great Barrier Reef through the botom of a jam jar - far better to be able to a) check that the signals look like you expect them to with the scope and b) move to the logic analyzer.
If you're a masochist, then I suppose the scope might do the job.
I've tried to used $10,000, 1GHz scopes for decoding, they suck at it - it's like trying to look at the Great Barrier Reef through the botom of a jam jar - far better to be able to a) check that the signals look like you expect them to with the scope and b) move to the logic analyzer.The trick is to save the data as CSV and analyse it on a PC. When the 'bad' message is found then go back to the scope and look at the signal. Sometimes a problem only occurs once per hour or more. Deep memory is very useful for these kind of cases.
I really appreciate your responses, it's always great to see someone putting in some effort and time. I will just list a few of the case scenarios I will likely be involved with, in my lab:
- Analyze EMI suppression in power supply and amplifier circuits, mostly LF-UHF related projects.
- Analyze RF components: filter response, attenuation, etc.
- Troubleshoot radio equipment: figure out if oscillators are working OK, debug receiver stages, etc.
- Reverse engineering: I2C/SPI/UART and other buses, memory dumping, rewriting, glitches/side channel attacks.
- Debugging small circuits with the usual run of the mill PIC/AVR/MCU: arduino, STM32.
- Assorted experiments, like firmware stuff for hard drives, computer equipment, FPGAs
- Video signals: sync clocks, conversion....
I've tried to used $10,000, 1GHz scopes for decoding, they suck at it - it's like trying to look at the Great Barrier Reef through the botom of a jam jar - far better to be able to a) check that the signals look like you expect them to with the scope and b) move to the logic analyzer.The trick is to save the data as CSV and analyse it on a PC. When the 'bad' message is found then go back to the scope and look at the signal. Sometimes a problem only occurs once per hour or more. Deep memory is very useful for these kind of cases.
The better technique is to use the right tool for the job in the first place: a logic analyser or sprintf(). Both of those are very good at selecting only the interesting information, and discarding the rest.
I've tried to used $10,000, 1GHz scopes for decoding, they suck at it - it's like trying to look at the Great Barrier Reef through the botom of a jam jar - far better to be able to a) check that the signals look like you expect them to with the scope and b) move to the logic analyzer.The trick is to save the data as CSV and analyse it on a PC. When the 'bad' message is found then go back to the scope and look at the signal. Sometimes a problem only occurs once per hour or more. Deep memory is very useful for these kind of cases.
The better technique is to use the right tool for the job in the first place: a logic analyser or sprintf(). Both of those are very good at selecting only the interesting information, and discarding the rest.As I wrote before: that way you know something is wrong but not exactly what is wrong. IOW: you learn nothing new! A lot of communication related problems are in the analog domain and a problem may not repeat itself often.
Any eye diagram won't work well for SPI, I2C, UART, etc. And then you still don't know when & what happened in relation with other signals.
As I wrote before: that way you know something is wrong but not exactly what is wrong. IOW: you learn nothing new! A lot of communication related problems are rooted in the analog domain and a problem may not repeat itself often. An oscilloscope with deep memory and good decoding tools really is very useful because it offers an all in one solution.
A couple of years ago I was involved in a project where someone had to interface with a circuit my customer provided. This was a half duplex UART over RS485 interface. After 3 weeks (or so) the engineer at the third party still was unable to get it to work. He followed your advice: look at the signals in the digital domain only. That way he was completely oblivious to the fact he got the RS485 rx/tx switching timing all wrong. I had to come over and connect his scope and on that the problem was immediately visible.
I'm not entirely sure what use-cases you mean, but it sounds like an infinite-persistence eye diagram is appropriate.
You get deep memory and good search functions with the low cost digital bus decoders, but like nctnico points out you won't get the full analog picture of what's going on at the physical protocol layer.
As I wrote before: that way you know something is wrong but not exactly what is wrong. IOW: you learn nothing new! A lot of communication related problems are rooted in the analog domain and a problem may not repeat itself often. An oscilloscope with deep memory and good decoding tools really is very useful because it offers an all in one solution.
A couple of years ago I was involved in a project where someone had to interface with a circuit my customer provided. This was a half duplex UART over RS485 interface. After 3 weeks (or so) the engineer at the third party still was unable to get it to work. He followed your advice: look at the signals in the digital domain only. That way he was completely oblivious to the fact he got the RS485 rx/tx switching timing all wrong. I had to come over and connect his scope and on that the problem was immediately visible.I think we may be in violent agreement. I'm an embedded designer - usually my I2C / SPI doesn't work first time, so I look at it with analogue scope, often with decoding too. Then I see that the voltage levels are wrong, or that my code is failing to send a restart - I fix this and data is now flowing as expected. I then switch to the LA to capture the actual data exchange.
I'm not entirely sure what use-cases you mean, but it sounds like an infinite-persistence eye diagram is appropriate.It can work well if you have stable timing, but if your protocol have random delays between bytes or messages it's not really working well with the eye diagram or mask function.
You get deep memory and good search functions with the low cost digital bus decoders, but like nctnico points out you won't get the full analog picture of what's going on at the physical protocol layer. I just wanted to point out that not all scopes suck totally at serial decoding. If you've got a deep segmented memory with memory based decoding and flexible content based trigger and search functions, it sucks less than screen based decoding without search functions. There are degrees of totality.
I'm not entirely sure what use-cases you mean, but it sounds like an infinite-persistence eye diagram is appropriate.It can work well if you have stable timing, but if your protocol have random delays between bytes or messages it's not really working well with the eye diagram or mask function.
You get deep memory and good search functions with the low cost digital bus decoders, but like nctnico points out you won't get the full analog picture of what's going on at the physical protocol layer. I just wanted to point out that not all scopes suck totally at serial decoding. If you've got a deep segmented memory with memory based decoding and flexible content based trigger and search functions, it sucks less than screen based decoding without search functions. There are degrees of totality.
The "full analog picture of what's going on at the physical protocol layer" is signal integrity. No doubt you have noticed that I have explicitly stated (reply #36) that my first step is to use a scope to ensure signal integrity. There's little point at examining bits until SI is solid! But after that, flipping tothe digital domain is often advantageous.
I'm not entirely sure what use-cases you mean, but it sounds like an infinite-persistence eye diagram is appropriate.It can work well if you have stable timing, but if your protocol have random delays between bytes or messages it's not really working well with the eye diagram or mask function.
You get deep memory and good search functions with the low cost digital bus decoders, but like nctnico points out you won't get the full analog picture of what's going on at the physical protocol layer. I just wanted to point out that not all scopes suck totally at serial decoding. If you've got a deep segmented memory with memory based decoding and flexible content based trigger and search functions, it sucks less than screen based decoding without search functions. There are degrees of totality.
The "full analog picture of what's going on at the physical protocol layer" is signal integrity. No doubt you have noticed that I have explicitly stated (reply #36) that my first step is to use a scope to ensure signal integrity. There's little point at examining bits until SI is solid! But after that, flipping tothe digital domain is often advantageous.The problem in this reasoning is that it assumes there is no outside influence and the software is 100% bug free.
Neither is the case so you can't discard the analog domain.
Over the years I have come across several situations where looking at digital domain only confirmed there is a problem but doesn't tell what the problem is. A modern DSO with deep memory and decoding speeds up debugging these kinds of cases significantly.
Naturally a full-featured and correspondingly expensive "professional" DSO is more likely to avoid limitations, but this forum is biassed towards hobbyists with limited money.
Naturally a full-featured and correspondingly expensive "professional" DSO is more likely to avoid limitations, but this forum is biassed towards hobbyists with limited money.Now you are just moving goalposts. Not everyone has to make-do. There are lots of people with money (or their boss' money) to buy scopes in the sub $10k range. Starting at around $2k you can buy a decent new scope which has good decoding and analysis features. Also the higher end scopes are available on the used market.
Naturally a full-featured and correspondingly expensive "professional" DSO is more likely to avoid limitations, but this forum is biassed towards hobbyists with limited money.Now you are just moving goalposts. Not everyone has to make-do. There are lots of people with money (or their boss' money) to buy scopes in the sub $10k range. Starting at around $2k you can buy a decent new scope which has good decoding and analysis features. Also the higher end scopes are available on the used market.You have chosen to comment on a tangential financial point, and to not comment on the substantive technical points. We presume that means you don't disagree with the technical points.
But there are many DSOs and many problems where the tools' limitation make them less than helpful. Examples:
- where you have a, say, 8-bit bus to capture, or when specifying the trigger, or filtering out uninteresting data
- where the trigger is a sequence of states
- where the decoding is so slow that the input is ignored for a substantial proportion of the time
- where the decoding only covers a small proportion of the captured signal, e.g. merely what's on the screen at that time
Naturally a full-featured and correspondingly expensive "professional" DSO is more likely to avoid limitations, but this forum is biassed towards hobbyists with limited money.
But there are many DSOs and many problems where the tools' limitation make them less than helpful. Examples:
- where you have a, say, 8-bit bus to capture, or when specifying the trigger, or filtering out uninteresting data
- where the trigger is a sequence of states
- where the decoding is so slow that the input is ignored for a substantial proportion of the time
- where the decoding only covers a small proportion of the captured signal, e.g. merely what's on the screen at that time
I fully agree. To maximize usability you need deep segmented memory, quick content triggers with wild cards and a search function with the same capabilities.QuoteNaturally a full-featured and correspondingly expensive "professional" DSO is more likely to avoid limitations, but this forum is biassed towards hobbyists with limited money.Yes, but the nice thing for us hobbyists is that these features are now becomming available in low cost scopes. The MDO-2204EX costs $1922 at Saelig.com.
If I wanted the same features in the Keysight scopes we use at work it would be more than 4 times that price - and I would still only have 1/10th of sample memory depth. These used to be expensive features, but some of the less known brands are putting some pretty useful bargins on the market compared to the better known brands.