Specifications

waveform w

. Each recorded waveform is called a frame. The B&K 2542B scope lets you set Δ t to

values between 1 ms and 1000 s and record from 1 to 1000 frames.

You can save the recorded frames to internal or external storage (such as a thumb drive). This lets you

review the recorded frames at a later time.

You can turn the scope's general-purpose knob and "page" through the frames looking for unusual

behavior. Or, you can watch a "movie" of the recorded traces by letting the scope automatically

sequence through the frames (the B&K 254xB scopes can play this movie at up to about 20 frames per

second). This can compress lots of information into a small time, allowing you to spot rare or

anomalous behavior. If you find one or more frames of interest, you can save them to a bitmap or CSV

file or have WaveXpress® download them for further processing (see WaveXpress® below).

Recording mode can let the oscilloscope emulate a chart recorder. Suppose you were interested in

seeing if an intermittent signal occurs overnight from a system you are studying. Using the B&K 254xB

scope, you'd set channel 1 to the proper gain to record the signal and set it to auto trigger. Suppose we

want to monitor the circuit from 5 pm today to 9 am tomorrow morning. This is 16 hours or 57,600

seconds. Since we can record 1000 frames, we'd need to record 57.6 seconds per frame to monitor

this period. There are 12 horizontal divisions on the scope's screen, choosing 5 s/div gives us 60 s of

recording per sweep. We'd set the recording system up to record 1000 frames, each separated by 60 s

and be able to examine the data in the morning.

A detail is that the scope will have a short period between the frames to allow it to save the data to

memory, arm the trigger, etc. (this is analogous to the scope's dead time in normal operation). Thus,

there can be small windows where a signal might be missed, so the emulation of a chart recorder

isn't perfect.

Digital filter

A digital oscilloscope may include the ability to filter the vertical channel with a digital filter. This can be

useful to get rid of unwanted portions of the signal.

Here's an example of the operation of the digital filter in the B&K 2542B oscilloscope. WaveXpress®

was used to create a sine wave with another sine wave of 10 times the frequency added to it. This was

then sent to an arbitrary waveform generator and displayed at 1 kHz, as shown at A in the following

figure:

Figure 33

Copying/reprinting/republishing without express written consent prohibited.