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How Do I Configure the NI PXI-5152 for Real-Time Sample Rates Over 1 GS/S?

Primary Software: Driver Software>>NI-SCOPE
Primary Software Version: 3.2
Primary Software Fixed Version: N/A
Secondary Software: N/A
Hardware: Modular Instruments>>High-Speed Digitizers (Scopes)>>PXI-5152, Modular Instruments>>High-Speed Digitizers (Scopes)>>PCI-5152

Problem:
I am trying to configure my NI-SCOPE code to acquire sample rates faster than 1 GS/s using the NI 5152. I have read that I can sample at 2 GS/s with this module, how can I achieve this?

Solution:
You can sample at a rate of 2 GS/s using Time Interleaved Sampling (TIS). TIS uses both ADCs to sample the same input waveform, but at different relative phases. The hardware then interleaves these samples to create a single waveform as if only a single channel is used at twice the sample rate.

Overview of Time Interleaved Sampling:
The NI PXI-5152 and PCI-5152 incorporate two analog-to-digital converters (ADC) in parallel, with one assigned to each channel. Each ADC is capable of sampling at rates up to 1 GS/s. You can see how these ADCs are incorporated in the overall device in the block diagram shown below.

When TIS is enabled, the process is automatically handled by the driver which performs the following steps:

1. Offset the sample clocks of the ADCs by 180 degrees.
2. Sample both channels half the desired sampling rate.
3. Interleave the resulting data to achieve double the rate of a single ADC

Note: Since both ADC's are used in parallel in TIS mode, only one channel of data can be acquired at 2 GS/s.

 

Sampling rates are achieved on a single channel through integer division of the clock. Therefore on a single channel you can sample at f/N where f is the maximum sample rate and N is a positive integer. By enabling TIS, you can increase your sample rate to 2f/N. Please see the specifications via the related links below for complete details on valid sampling rates.

Programming - How to Enable TIS:

• LabVIEW
1. Set the ‘Enable Time Interleaved Sampling’ property to TRUE.
2. Specify the single channel you wish to acquire on by using the “Active Channel’ NI-SCOPE property.
• C API
1. se the ‘NISCOPE_ATTR_ENABLE_TIME_INTERLEAVED_SAMPLING’ attribute.
2. Specify the single channel you wish to acquire on by using the ‘NISCOPE_ATTR_CHANNEL_ENABLED’ attribute.

Examples:

1. Open NI Example Finder » Hardware Input and Output » Modular Instruments» NI-SCOPE» Demos
2. In LabVIEW, open niScope EX Configure Acquisition.vi or in CVI open ConfiguredAcquisition.prj
3. Check the "Enable TIS" check box on the Front Panel.

It is important to note that if you do not set either of the above properties or attributes correctly an error will be thrown. The errors corresponding to each attribute are listed below:

• TIS not enabled: -1074118530






Channel not specified -1074135024

Related Links:
Product Page: NI PXI-5152 Digitizer
Product Page: NI PCI-5152 Digitizer
NI 5152 Specifications (Oct 2007)

Attachments:


- Error -107413502.JPG
- Error -1074118530.JPG


Report Date: 10/25/2006
Last Updated: 05/08/2008
Document ID: 42O43RPQ

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