How do you capture this long waveform?

In summary, you are trying to capture a serial data stream with good resolution by building a circuit that will output a delayed trigger pulse. You may have to do some hand-alignment of the boundaries, depending on what the data looks like, and how accurate your delayed triggers are. If it's really "weird", then it may be some kind of manchester encoding where you've got a sync bit at the beginning of a transfer. Alternatively, you can capture the whole serial stream but then you can't zoom in enough to read the serial data.
  • #1
david90
312
2
I have a 1sec serial data stream and my cheap PC based oscilloscope cannot capture it with good enough resolution where I can read the data.

What can I do to capture this serial data stream with good resolution? My scope has only edge trigger function.

I'm thinking of building a circuit that will output a delayed trigger pulse. I hope that this will allow me to capture the stream part by part. Is this a good idea or is there a better way?
 
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  • #2
Can you decrease your sampling rate? Alternately, if it's serial data, why not just capture it using a terminal program (for instance, TeraTerm if you're using Windows)
 
  • #3
when you say decrease sampling rate, you mean increase the time/div? I can capture the whole serial stream but then I can't zoom in enough to read the serial data.

I can't use a terminal program because it is not your typical rs232 serial data. It's some weird format that I haven't figured out yet. It's about 30-40 bit long per frame.
 
  • #4
david90 said:
when you say decrease sampling rate, you mean increase the time/div? I can capture the whole serial stream but then I can't zoom in enough to read the serial data.

I can't use a terminal program because it is not your typical rs232 serial data. It's some weird format that I haven't figured out yet. It's about 30-40 bit long per frame.

Sounds like you're trying to reverse-engineer something, without much equipment... :devil:

Your idea of multiple delay-triggers sounds like the best alternative. You may have to do some hand-alignment of the boundaries, depending on what the data looks like, and how accurate your delayed triggers are.
 
  • #5
yeah, you might want to add a delay timer, then play around with resolution until you see something significant. if it's really "weird", then it may be some kind of manchester encoding where you've got a sync bit at the beginning of a transfer. and this is confusing at first because, iirc, the sync looks like two bits but is over a three bit time period. once you figure out the encoding, you might want to look into buying a special purpose bus analyzer, which probably won't be cheap.
 

FAQ: How do you capture this long waveform?

1. How do you capture a long waveform?

Capturing a long waveform requires specialized equipment such as an oscilloscope or data logger. These devices are able to record and display the electrical signals over a period of time, allowing for the capture of a long waveform.

2. What is the maximum length of a waveform that can be captured?

The maximum length of a waveform that can be captured depends on the capabilities of the equipment being used. Some oscilloscopes can capture waveforms up to several hours in length, while others may have a shorter maximum recording time.

3. How do you ensure the accuracy of the captured waveform?

To ensure accuracy, it is important to calibrate the equipment and use appropriate probes or sensors. It is also important to minimize external interference and noise that can affect the waveform.

4. Can you capture multiple waveforms simultaneously?

Yes, some equipment has the capability to capture multiple waveforms simultaneously, which can be useful for comparing and analyzing different signals.

5. How do you save and analyze the captured waveform data?

The captured waveform data can be saved in various formats such as CSV or binary files. It can then be imported into software for further analysis, including measurements, filtering, and plotting.

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