CompuScope SDK Manua.. - Egmont Instruments

More documents

Recommendations

Info

Arbitrary Waveform GenerationOne common application of D/A conversion is Arbitrary Waveform Generation. An Arbitrary WaveformGenerator (ARB) is an instrument, which allows the user to generate complex periodic waveforms byspecifying a mathematical equation or a digital pattern. The CompuGen 1100 is an Arbitrary WaveformGenerator.Digital Pattern GenerationConceptually, a Digital Pattern Generator is an Arbitrary Waveform Generator with the D/A chip removed.The user us given access to the digital bits that normally drive the D/A chips.A Pattern Generator can output an n-bit-wide digital pattern which the user can program using simplecommands. The CompuGen 3250 is a Digital Pattern Generator.Conversion Rate vs. Output FrequencyAn analog signal is generated by an ARB by specifying a series of digital words, which are converted toanalog at the conversion rate. If the analog signal must be cyclical, (for example, a sine wave), the digitalpattern must be repeated over and over again to create the cyclical analog output. In general, there must be8 to 10 points per cycle in a pattern to create a good-quality analog signal. Waveforms with differentnumbers of points per cycle are illustrated below.4 PT8 PT16 PTMemory DepthThe maximum number of digital points that an ARB can use to generate analog signals is called theMemory Depth. Memory depth is measured in Kilosamples or Megasamples. For instance, the CompuGen1100 is available with 16 MS on on-board pattern memory.Memory LoopingOne way of increasing or optimizing the memory depth in an ARB is to allow it to loop on a specificpattern for a given number of times. While most commercial ARBs do not have this capability, allCompuGen cards do. Memory looping is completely seamless and the pattern goes from the last to the firstpoint in exactly one clock cycle. With memory looping, it is possible to generate 1000 cycles of a 1 MHzsine wave at a conversion rate of 80 MS/s, using only 80 sample points. Without memory looping, thesame output would have required 80,000 sample points!Page 76 Appendix D CompuScope SDK Manual
FilteringThe output of an ideal D/A converter is a step function, which contains very high frequency components,usually not desirable for testing analog circuits. The output of an ARB may therefore need to be filtered inorder to smooth the signal. The CompuGen 1100 comes equipped with several software selectable lowpass output filters.Output BandwidthThe output bandwidth of an ARB is related to the D/A conversion rate as well as the analog bandwidth ofthe output amplifier. For example, the bandwidth of the CompuGen 1100 is specified as 20 MHz, eventhough the conversion rate is 80 MS/s. Generally, the bandwidth is four to ten times less than theconversion rate.Glitch EnergyOne of the key characteristics of any ARB is the Glitch Energy of the D/A.Glitch Energy is defined as the area under the curve around zero-crossing, when the signal is changing itspolarity. In simpler terms, Glitch Energy measures the error signal generated by switching the MSB from,say, low to high, while all other bits are switching from high to low (and vice-versa). This error is causedby a small skew in the internal switching of the signals. CompuGen cards are carefully designed to providethe lowest possible glitch energy.CompuScope SDK Manual Appendix D Page 77
Page 1 and 2:
Volume I:CompuScope C/C++Software D
Page 3 and 4:
Gage Applied Technologies, Inc. Sof
Page 5:
Global Table of ContentsVolume I Co
Page 8 and 9:
Chapter 5: Sample ProgramsWindows S
Page 11 and 12:
PrefaceImportant Notes:• The Comp
Page 13:
Chapter 2: BasicCompuScopeOperation
Page 16 and 17:
CompuScope A/D cards generally oper
Page 18 and 19:
Multiple CompuScope SystemsThe Comp
Page 20 and 21:
Plug-n-Play is an inherent part of
Page 22 and 23:
On-Board MemoryOrganization of theC
Page 24 and 25:
memory counter overflow rolls over
Page 26 and 27:
If during the data acquisition the
Page 28 and 29:
On-board Memory: A Programmer’s V
Page 30 and 31:
CompuScope RepetitiveCapture Perfor
Page 32 and 33:
depth portion of the single channel
Page 34 and 35: Page 26CompuScope SDK Manual
Page 36 and 37: Sample Programs Folder Structure us
Page 38 and 39: • Gage_drv.hGage_drv.h contains g
Page 41 and 42: Writing a C Application forCompuSco
Page 43 and 44: The last routine, gage_trigger_cont
Page 45: Chapter 5:Sample Programs
Page 48 and 49: Program NameA2D_PAGED_TRANSFER.EXED
Page 50 and 51: Flow Chart describing the sample pr
Page 52 and 53: gage_trigger_control_2:gage_set_ext
Page 54 and 55: GAG2A2D_MUL_BM.EXEThe sample progra
Page 56 and 57: Gage API routines used:gage_get_dri
Page 58 and 59: DIGITAL_INPUT.EXEThe sample program
Page 61: Chapter 6:Appendices
Page 64 and 65: uInt32 sample_rate;void far *memptr
Page 66 and 67: trigger_level level at which trigge
Page 68 and 69: trigger_sensitivitytrigger_bandwidt
Page 70 and 71: Settings for boarddef structure fie
Page 72 and 73: 10 KHz SRTI_10_KHZ5 KHz SRTI_5_KHZ2
Page 74 and 75: • couple_eThe parameter couple_e
Page 76 and 77: Example:Below is illustrated a typi
Page 79 and 80: Appendix C: CompilingCompuScope SDK
Page 81: Creating a new LabWindows CVI proje
Page 86 and 87: Technical SupportGage Applied Techn
show all

CompuScope SDK Manua.. - Egmont Instruments

Create successful ePaper yourself

Delete template?

Save as template?