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Modular instruments provide flexible RF measurements

Posted: 08 Aug 2008 ?? ?Print Version ?Bookmark and Share

Keywords:RF instrument? signal analyzer? PXI Express?

Flexibility in RF measurements up to 10 times faster than traditional RF instrumentation is what National Instruments offers with its new RF vector signal analyzer, RF vector signal generator and PXIe 18-slot chassis. The new modular instruments such as the NI PXIe-5663 6.6GHz RF vector signal analyzer and the NI PXIe-5673 6.6GHz RF vector signal generator function better when complemented by the NI PXIe-1075 18-slot high-bandwidth chassis. The NI PXIe-5663 can provide signal analysis from 10MHz to 6.6GHz reaching 50MHz of instantaneous bandwidth.

The NI PXIe-5673 has signal generation from 85MHz to 6.6GHz extending to 100MHz of instantaneous bandwidth. The NI PXIe-1075 is believed the first PXIe chassis with PCIe lanes connected to every slot offering up to 1GByte/s in each slot bandwidth and up to 4GBps total system bandwidth.

The new modular instruments, which maximize high-performance multicore processors, are suitable for high-speed RF and wireless automated test environments. Using LabVIEW 8.6 to have parallel measurement algorithms on multicore CPUs, engineers can employ the RF vector signal analyzer and RF vector signal generator to undergo many RF measurements significantly faster than traditional instruments. The RF modular instruments can make many individual W-CDMA measurements more than 20 times faster than traditional instruments. With the ability to implement measurements such as adjacent-channel leakage ratio (ACLR) in only 8ms, engineers can have full W-CDMA device characterizations up to five times faster.

At the same time, these instruments can be used in general-purpose measurements. For example, a typical 50MHz spectrum sweep with a 30KHz resolution bandwidth takes just under 4ms with an NI PXIe-8106 controller, while leading traditional instruments can take 100 ms or more for the same measurement. As new multicore processors are released, PXI-based RF measurement times will continue to decrease without requiring changes to the RF instrumentation or NI LabVIEW programming, thus providing maximum measurement performance, increased system longevity and decreased capital investment.

Aside from better capacity
Aside from performance, the new RF modular instruments also provide flexibility through a completely software-defined architecture. Wireless protocols can be developed and tested by reconfiguration of the software with the use of standard-specific LabVIEW toolkits or identifying their custom modulation algorithms. NI and National Instruments Alliance Partners have toolkits based on LabVIEW for many current and emerging communications technologies like WiMAX, GPS, W-CDMA, GSM, Edge, broadcast video, 802.11, Bluetooth, OFDM and MIMO. Engineers can also integrate PXI RF instrumentation with more than 1,500 PXI modules such as high-speed digitizers, signal generators and precision DC instruments to deliver their complete test needs.

The 6.6GHz modular instruments can reach new levels of performance with the use of the recent commercial technologies such as 16bit DACs and ADCs in generating and digitiziing signals for superior dynamic performance. The NI PXIe-5673 RF vector signal generator has direct RF conversion to achieve 100MHz of RF bandwidth. With the added 'impairments mode,' engineers can have an onboard FPGA in manually adjusting the gain imbalance, IQ offsets and quadrature skew quickly. With baseband impairments suited for a specific frequency, better than -85dBc of carrier and image suppression can be achieved. The NI PXIe-5663 RF vector signal analyzer gives passband flatness and low-phase noise so it can accurately detect modulated signals. The usual EVM performance for W-CDMA is 0.8 percent at 2GHz for more than 2,600 symbols. Meanwhile, the typical EVM performance for WiMAX is -52dB at 3.8GHz.

What engineers can expect
"At present, engineers can have performance benefits of true software-defined RF instrumentation based on LabVIEW and the PXI platform," said Joseph Kovacs, senior RF and communications manager, NI. "With the bandwidth of PXI Express and parallel processing capabilities of multicore processors, NI software-defined RF instrumentation is expected to get faster along with the evolution of technology. The users will be reaping the fruits of 10 times faster enhancements compared to the common instruments widely used and more developments are at stake as more cores will be available to the market," he added.

The NI PXIe-1075 18-slot chassis gives eight hybrid slots that can be used for either PXI Express or PXI hybrid-slot-compatible modules to enable reuse of existing PXI modules. Designed for high-performance systems, the NI PXIe-1075 chassis has an operating temperature range of 0C to 50C and offers integrated system monitoring features such as power management, fan health and temperature monitoring for the entire chassis.

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