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9

USERS TUTORIAL 

 

The sophisticated facilities of the DSA524 have resulted in a fairly complex instrument. This "hands-on" tutorial takes the user through 
most of the functions of the unit step by step, and provides an easy method of gaining familiarity with its operation. 

New users should follow the tutorial exactly and resist the temptation to experiment with functions before they have been covered. 

Existing users may find the tutorial useful for covering functions with which they are not yet familiar. Each section is complete in itself 
and commences with the DSA being "reset" using SHIFT followed by RESET, and with the signal generator being set to SINE, 20kHz, 
5V pk-pk. 

 

INDEX TO THE TUTORIAL 

 

Page 

Equipment Required  

10 

Setting up the Equipment 

10 

First Steps  

10 

What to Expect  

10 

The Display Oscilloscope  

10 

Front Panel Controls  

10 

Getting out of Trouble 

10 

 

Part One 

The Basic Functions. 

Controlling Digitising 

10 

Controlling the Input Channels  

11 

Controlling the Traces 

11 

Setting the Timebase  

12 

Normal Mode 

11 

Roll Mode 

12 

Repeat Mode 

12 

Triggering 

12 

 

Part Two

 More Advanced Functions. 

More about Triggering  

12 

More about Roll Mode  

13 

Memory Search 

13 

Display Update Rate  

13 

Indexed Waveform Memories 

14 

Cursor Measurement  

14 

Averaging 

14 

Dot Joining and Interpolation  

14 

Trace Multiply  

15 

Program Mode 

15 

Hardcopy Output 

15 

Remote Interfacing  

15 

A Final Word  

15 

Содержание DSA524

Страница 1: ...Thurlby DSA524 digital storage adaptor OPERATING MANUAL AND TUTORIAL V2 0 ...

Страница 2: ...anual applies to units with a firmware level of 2 71 and above IT IS VERY STRONGLY RECOMMENDED THAT NEW USERS START BY FOLLOWING THE TUTORIAL INDEX Title Section Page REFERENCE SECTION Connecting an Oscilloscope R1 2 Setting up the Display R2 2 Front Panel Controls R3 2 Escape and Reset R4 2 Controlling Digitising R5 2 Timebase Setting R6 2 CH1 and CH2 R7 3 Digitising Memories R8 3 Trigger R9 3 Tr...

Страница 3: ... NN the key will enter the number printed alongside it Note that when SHIFT or a function ending in NN is pressed the lamp marked ENTER will flash to indicate that one or more further key presses is required Any function that causes the ENTER lamp to flash can be cancelled by pressing that function key again Note that some of the functions including SET SCOPE automatically set the RUN HOLD functio...

Страница 4: ... TRIGGER RATE ABOVE 1MHz and the DSA will beep to indicate that the timebase speed may need to be set faster R7 CH1 AND CH2 The two input channels are identical The input sensitivity is variable between 10V and 2mV per division The maximum bandwidth is 35MHz down to 20mV div 20MHz at 10mV div 10MHz at 5mV div and 5MHz at 2mV div The volts per division keys autorepeat if held The input coupling can...

Страница 5: ... is automatically increased or decreased to maintain a constant time delay when the timebase speed is changed within a limit of 9 999 divisions maximum PRE there is no equivalent to pre trigger on a real time oscilloscope Pre trigger allows the part of the waveform which occurred before the trigger to be stored and observed The maximum pre trigger delay is 40 divisions Pressing either key shows th...

Страница 6: ...unaffected R12 INDEXED WAVEFORM MEMORIES The DSA524 has sixteen 1K word memories for temporary or permanent storage of waveforms Each memory is identified by a two digit number from 01 through to 16 The memory is sup ported by trickle charged Ni Cad batteries which will remain charged for several months should the unit be left unpowered To store a waveform in an indexed memory obtain the required ...

Страница 7: ...not captured the first section of the waveform captured starts 350 nanoseconds after the trigger event b Display Update Rate Repeat mode involves complex manipulation of data which can take several seconds per digitisation The display update rate varies between about one per second for a single channel at 2usecs div to one every 10 seconds for both channels at 50nsecs div The Rate key is disabled ...

Страница 8: ...hen overflows could occur on the multiplied waveform The displayed waveform is limited to 4 25 divisions and conse quently 3 divs multiplied by 2 5 divs will be displayed as 4 25 divs instead of 7 5 divs The AxB function cannot operate while digitising is taking place Pressing the AxB key will set RUN HOLD to HOLD The function multiplies the traces exactly as they appear at the moment that the AxB...

Страница 9: ... show baud rate 9600 for example Use the reference cursor keys keys 2 and 3 to increase or decrease the rate then press ESCAPE If the DSA is not connected to an oscilloscope the baud rate may be set directly using the FUNCTION NN key see Section R27 Note that as well as the options of 300 through to 38 400 there is a further option of IEEE This option is exclusively for use when the optional IEEE ...

Страница 10: ...g SHIFT followed by RESET and with the signal generator being set to SINE 20kHz 5V pk pk INDEX TO THE TUTORIAL Page Equipment Required 10 Setting up the Equipment 10 First Steps 10 What to Expect 10 The Display Oscilloscope 10 Front Panel Controls 10 Getting out of Trouble 10 Part One The Basic Functions Controlling Digitising 10 Controlling the Input Channels 11 Controlling the Traces 11 Setting ...

Страница 11: ...the display is made up of discrete steps waveforms do not look quite the same as they do with an analog oscilloscope The minimum level change between samples is one thirtieth of a division and even where the input signal level is constant the digitised level may vary slightly This variation is caused by noise on the signal noise in the input amplifiers or digitising noise in the ADC typically bit ...

Страница 12: ...es on the screen and provide 4 25 divisions of adjustment Press the key marked HOME VAR to enable variable posi tion it is enabled when the lamp is off Try varying the position of the traces note that whereas OFFSET only affects the waveform when digitising is taking place PO SITION affects it at all times whether RUN HOLD is at RUN or HOLD Press the key again to home the trace position 2 The GAIN...

Страница 13: ...els are on the ALT lamp illuminates for speeds of 10us div and faster and that the CHOP lamp illuminates for speeds of 20us div and slower CHOP indicates that both input channels are digitised together on opposite cycles of the sampling clock while ALT indicates that the input channels are digitised alternately CH2 followed by CH1 Thus if digitising is un triggered or if the input signals do not h...

Страница 14: ... digitising memory captures 4096 words 40 96 divisions per channel The SEARCH key enables the whole of the digitising memory to be accessed It also provides digital magnification by ten using linear interpolation 1 Press SEARCH once the COMP compress lamp will illu minate and a filled bar will appear at the top of the screen for 3 seconds the filled bar represents the 4K of the memory Note that th...

Страница 15: ... DSA reset and the generator set to SINE 20kHz 5V pk pk The DSA524 can average any number of readings from 2 up to 255 enabling large improvements to be made to the signal to noise ratio of noisy signals The average number is initially set to 16 1 Turn off Trace B and note the waveform amplitude on Trace A Then remove the trigger signal by setting the source to EXT The waveform should now be unsyn...

Страница 16: ...volatile memory and replay them on demand Up to 50 settings can be stored Each front panel setting includes the state of every key and rotary control and the source of each trace waveform Thus if a setting is learned which includes a trace recalled from a wave form store that same store will be recalled again when the setting is re played Thus reference waveforms can be recalled automatically with...

Страница 17: ...avoid aliasing Aliasing causes the apparent waveform frequency to be much lower than the real frequency Thus if the timebase is set too low an invalid display will result see Fig a To avoid aliasing the timebase must be set as follows Minimum time div 50 divided by the maximum cyclic signal frequency The difficulties occur when the signal frequency is unknown In this case it is safest to set a fas...

Страница 18: ...isplay are plot ted using a level of 100mV div for both Y and X at a rate selec table as 1 2 5 or 10 seconds per division The pen lift signal is normally low to lift but can be inverted To set the plot rate press SHIFT key 8 followed by SET PLOT key 5 The oscilloscope display will show the present plot rate Press one of the REF CURS keys key 2 or 3 to select a new value then press ESCAPE If the DS...

Страница 19: ...to have a buffer large enough to accept the data in one stream hand shaking will almost certainly be needed There are two basic types of handshaking hardware handshak ing and X ON X OFF handshaking Both types are provided on the DSA Hardware handshaking uses the RTS and CTS lines of the DSA When the RTS line is set to a 0 a positive voltage level the DSA is ready to receive data when it is set to ...

Страница 20: ...trace starting at word N MAG N where N is a decimal number between 0 and 900 This sets the SEARCH function into Magnify mode with the trace starting at word N SROFF This turns any of the SEARCH modes off NORM SLOW or FAST This sets the display update rate ION or IOFF This sets sine interpolation on or off AON or AOFF This sets averaging on or off Example TMB 10uS AON SLOW CR For TRA or TRB the sec...

Страница 21: ...ee previous section for an explanation of this command To load the data send the primary command MEM followed by a comma followed by one of the secondary commands listed below followed by a carriage return The secondary commands are as follows ACQ1 or AQU2 This loads the digitising memory of CH1 or CH2 4096 words must be sent TRA or TRB This loads the trace memory of Trace A or Trace B 1024 words ...

Страница 22: ...n OSCILLOSCOPE DISPLAY SYSTEM Trace A Displays 1024 words from either CH1 or any indexed waveform storage memory Trace B Displays 1024 words from either CH2 or any indexed waveform storage memory Line Type Selectable as individual levels dots or joined to form a smooth line Update Rate Selectable between 50 per second and Run Mode one every 3 seconds continuous in roll mode OSCILLOSCOPE DISPLAY VE...

Страница 23: ... dismantle it S4 FUSE REPLACEMENT The AC power fuse is mounted on the back panel within the AC line input socket housing To replace the fuse pull the clip in tray outwards The active fuse is at the back of the tray the front space is for a spare fuse The fuse must be replaced with a 500mA anti surge 20mm cartridge fuse A ceramic bodied HRC type should be used whenever possible S5 MAINTENANCE AND R...

Страница 24: ...Thurlby Electronics Ltd New Road Burrel Road St Ives Huntingdon Cambs England Telephone 0480 63570 Fax 0480 64832 Telex 32475 ...

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