Items in Receiver Info cluster - PXI 5660

[modo]

Hello

Is there any help file that explains each item in Receiver Info cluster? Especially I'm interested in detail definition of following paramters:

- RxDigitizerCal;

- RxDCCal;

Many thanks for help,

Peter

[David S.]

Hi Peter -

I assume you're working in LabVIEW with the NI-5660 driver?  Inside this driver's VIs are some Modulation Toolkit VIs.  The receiver info cluster used by those VIs has only two elements:  An enumeration with only one value ("Receiver Info") and a variant whose attributes are set and read.  You don't have to directly access the variant's properties; instead just use the MT Get Attributes VI.

I couldn't find these two attributes among those returned by this function.  They both seem to describe functions performed by the PXI-5620/1 digitizer.  The first probabaly deals with calibration, and the second with the Digital Downconverter.  Can you tell me where you saw them? I'd also like to know which hardware you're working with and which version of the driver.

[modo]

Hi David,

Thanks for your reply.

Currently I used following hardware and software:

- RF Downconverter PXI - 5660;

- Digitizer PXI - 5620;

- NI RFSA version 2.0.1;

- NI Scope version 3.2.0f5;

- LabVIEW version 7.1;

- Digital Modulation version 3.0;

- Spectral Measurements version 2.0.3.36;

Example of variant properties that were generated in one of my application:

24 Attribute(s):
   'NI_MOD_Carrier' -> 12.500E+6
   'NI_MOD_CarrierIF' -> 12.500E+6
   'NI_MOD_CarrierPhi' -> -109.327E+3
   'NI_MOD_CarrierRF' -> 12.500E+6
   'NI_MOD_Queue' -> [0]
()
   'NI_MOD_RFSAConfigRef' -> 0x2AF00005
   'NI_MOD_RFSASetRecRef' -> 0x2AD00003
   'NI_MOD_Rx' -> {2, 0x062304B8}
   'NI_MOD_RxAutoSuppressSWIQ' -> on
   'NI_MOD_RxBandwidth' -> 3.760E+6
   'NI_MOD_RxDCAtten' -> 316.228E-3
   'NI_MOD_RxDCCal' -> 760.700E-3
   'NI_MOD_RxDataFormat' -> real
   'NI_MOD_RxDigitizerCal' -> 1.013E+0
   'NI_MOD_RxIQDemodulator' -> <typedef 'mod_IQ demodulator.ctl'
>
   'NI_MOD_RxIQSampleRate' -> 4.923E+6
   'NI_MOD_RxNumSamples' -> 3200003
   'NI_MOD_RxOversamplingRatio' -> 1.000E+0
   'NI_MOD_RxRFSAMixerLevel' -> -20
   'NI_MOD_RxRFSARefLevel' -> 0
   'NI_MOD_RxSamplestoTruncate' -> 3145
   'NI_MOD_RxType' -> RFSA
   'NI_MOD_Version' -> "1.1.0.0"
   'NI_MOD_tnrSetAttenRef' -> 0x2AE00006

Peter

[Andy_Hinde]

Hello,
The contents of the Receiver Info cluster are designed for Modulation Toolkit's internal use so there is limited documentation (if any) as to the individual items.

Let me explain the two items you have listed:

RxDigitizerCal
This is  a scalar voltage correction factor to account for the frequency reaponse of the PXI-5620. The frequency response of the 5620 is measured in calibration and polynomial coefficients are stored in firmware. During configuration the Modulation Toolkit retrieves these coefficients and calculates the voltage correction factor based on the IF center frequency of the PXI-5600 output / PXI-5620 input, all to improve amplitude accuracy.

RxDCCal
This is another scalar voltage correction factor, but based on the PXI-5600 RF Downconverter frequency response measured in calibration. It is also based on the IF center frequency of the PXI-5600 output.

These cal factors are all combined to correct the acquired IQ data as much as possible to improve amplitude accuracy.

Regards,
Andy Hinde
National Instruments