Tektronix Oscilloscope: waveform capture

Programs

Here are some programs to help with getting waveform data from [some] Tek oscilloscopes by http, and reading it into Matlab/Octave arrays.

Generally, getting even some millions of samples over ethernet takes only a second or so by "internal" data format, instead of many many seconds if requesting the data in comma-separated-variable/CSV/"spreadsheet" format.

• get_tek_waveform_data.m: this matlab function combines the two tasks below: get the data from the oscilloscope, and interpret it into a numeric array of signal and time. It works purely in Matlab, without calling external help such as wget. Currently it uses a modified Matlab urlread to get the data, but this should be able to be made to work in Octave with e.g. double( typecast( urlget(URL), 'uint8' ) ); there was a problem with Matlab's urlread interpreting the data as utf8 characters. See the file contents or help, for options and to change the instrument address to suit your own.


• read_tekisf.m: this is mainly a part from within the above file get_tek_waveform_data.m, but it reads a local "internal"-format file saved from the oscilloscope, instead of reading directly from the oscilloscope. It should work with Matlab or Octave, and is tested on just TDS3052 and DPO4102B. The full invocation is [x,y,h] = read_tekisf('filename.isf'). It contains parts of a [substantially modified] file from `matlab central', as described in the commenting.


• get_tek_waveform_file.sh: (unix) shell script to download waveform data from a Tek scope. You need to modify the internet address for the scope in this file. Arguments are optional: the first is a title for the output, the second is the channel to capture; defaults are date_time and ch1. All that this actually does is to get the url 'http://INSTRUMENT.INTERNET.ADDRESS/getwfm.isf?command=select:ch1 on&command=save:waveform:fileformat internal&wfmsend=Get'. One can also use a webbrowser to the instrument's address, to download the file manually. (The get_tek_waveform_data.m file could be cut to give just the functionality of this shell-script, but in Matlab instead.)

Old notes on the save formats and finding converters

See the earlier page on just the TDS3052 for more about the origin of the above programs. Those older ones are now superseded by the above. E.g. the older ones interpreted the end of header in a way only valid for the exact 10k samples of 2 bytes each, true for the TDS3052.

If only companies making instruments (and general hardware) would provide details and open source-code / high-level scripts, it would make things a lot easier for a lot of people! But it must be admitted, this web interface is fairly transparent compared to some other products.

[an error occurred while processing this directive] Page started: 2015-07-24
Last change: 2015-07-25