Oscilloscope:
Oscilloscope window
This figure displays the main program window when operating in the oscilloscope mode. In the center of the
window there is a work screen where the oscilloscope displays are shown. The red oscilloscope display
corresponds to channel А and blue one corresponds to channel В. To the left of the work screen frame there is a
voltage scale for channel A (red font), and to the right of the frame there is a voltage scale for channel B (blue
font). Values of both voltage scales are always expressed in volts. Beneath the work screen there is a time base
(trace).
To the left and right of the work screen there are two cursors 1 and 2 that allow shifting the zero of channel A
and channel B accordingly. It is expedient to shift the zero if the waveforms of both channels overlap one
another so much as to complicate their analysis. To install one of the nine standard zero positions you need to
right-click on the corresponding cursor and then select one of the possible zero position values from the pop-up
menu.
There are two markers 3 and 4 above the work screen frame that are used to perform the correct measurement
of time intervals and voltage amplitude values of each channel. The markers can be moved with the mouse by
left-clicking on the triangle and then moving the mouse to the left or right while keeping the left mouse button
pressed. When moving the marker within the work screen the signal parameters below the marker will be
displayed on the panel A .
To set a triggering level the two horizontal markers 5 and 6 are used. Marker 5 sets the voltage level
(amplitude) of channel A, which is used when triggering (absolute) is selected via channel A. Marker B similarly
sets the level used when triggering is selected via channel B. The triggering markers are moved in similar
manner to the markers 3 and 4 , and when moved the level to be set is correctly displayed on the status bar.
The Oscilloscope chart can be moved within the work screen using the standard scroll bar 7 . Upon changing
the time base or zoom the previous oscilloscope display may not fit inside the work screen in full, and so the slider will reduce in size within the scroll bar in proportion to the oscilloscope display length within the work
screen to the total oscilloscope display length ratio. There is a small button below the scroll bar that allows the
oscilloscope settings panel to be hidden so as to ensure greater area for the work screen.
The voltage scale range of channel A/B can be set on the panel 8 / 9 "Channel A/B (Volt/Screen)". Scale range
is set by the knob. Please note that PoScope Basic supports two input ranges: 0-2V and 2-20V by hardware. It
follows that to show the most reliable oscilloscope display when the amplitude is within ±2V it is prudent to
select the ±2Volt/Screen scale range or lower. As the turning error within the ±2Volt/Screen scale range and
lower will total 4V/1024 = 0.0039V (capacity 10 bits) whereas within the ±5Volt/Screen scale range and higher
the turning error will be 10 times larger 40V/1024 = 0.039 V. On/off buttons for the channels are positioned on
the same panels. If when analyzing the device it is not required to analyze two analog signals oncurrently then it
is recommended that one of the channels is turned off so as to allow the maximum sampling frequency of 100
kHz to 200 kHz.
The "Period" panel A allows the sampling period (time base) within which the analog input digitization starts to
be set. For normal previewing of the oscilloscope display it is recommended that the sampling frequency is set 5-
6 times higher than the maximum input frequency. In addition to selecting the time base on the "Period" panel
you can set the oscilloscope display zoom, i.e. stretch the oscilloscope display up to 4 times the time base for
more detailed analysis of any signal time parameters without any change in sampling period. In the upper right
corner of the "Period" panel there is a description of the reading mode (if enabled): buf - reading with
microcontroller internal buffer, or pipe - pipe reading in computer (sample buffer size increases several times but
requirements to the computer are getting tighter). Minimum/maximum period that allows determining the
reading mode is set in the Settings window. Double left-clicking on this reading mode description opens the
Settings window in a similar manner to the Service/Setup.
All the triggering control elements except for the markers are positioned on the "Triggering" panel B . The
On/Off button allows triggering to be turned on and off. The A and B buttons select the channel and
corresponding marker for the signal that will be used as the triggering source. The Ext button indicates that the
external source connected to the logic analyzer’s B.5 channel will be the triggering source that functions as the
input (external triggering is available only when buffer reading). The edge select buttons determine which signal
edge (rising or falling) will show the absolute triggering, which signal step (rising or falling) will show the
differential triggering and which external sync pulse edge (rising or falling) will show the external triggering.
The two buttons positioned beneath the panel determine the triggering type: absolute or differential. A field
positioned near the differential triggering settings button determines the difference between the adjacent
waveform samples that if exceeded will cause the triggering condition to be met. It is necessary to note that
when setting triggering parameters that cannot be met, e.g. if given level is 5V and maximum signal amplitude
does not exceed 2V, that the device will be continually waiting for the triggering condition to be met, i.e. one of
the start measurement buttons will be red. In this case it is not necessary to stop measuring when pressing the
Stop button as while measuring any triggering conditions they will be automatically transmitted to the device.
On the "Signal parameters below markers" panel C the position of each marker within the time base and signal
amplitude of both channels below each marker are displayed. The time difference and signal amplitude of the
markers is also calculated and the difference result color is determined by the color of the marker corresponding
to the larger value.
On the "Common signal parameters" panel D the calculated values of DC and AC voltage components are
displayed and also, if possible, the frequency value for each channel.
The "Filtering" panel E ensures connection and calculation of digital filters for each channel. To turn on
filtering for the channel it is first necessary to calculate the filter when opening the filter settings window while
pressing the "…" button and then tick off On for the selected channel.
To perform measurements it is necessary to press the Single or Cyclic button on the "Control" panel F . The
Single button presets only one measurement (sample digitization and accumulation by microcontroller and then
their transmission to shell when operating via buffer) after that the newly read oscilloscope displays are shownon the work screen. The Cyclic button carries out similar actions except that upon completing the measurement a
new measurement starts automatically. Upon pressing one of the start buttons it changes its name to Stop and its
color to red. Pressing this button will lead to immediate device reset and cause it to wait for termination of
measurement. The Stop button may be the only means to stop measuring, e.g. when the triggering level is set so
as to never occur.