modern devices like smart phones having multiple radios operating in multiple bands and therefore, tremendous new potential for adverse interactions between dissimilar signals, the need for just such a capability has become all the more critical. Significant benefit can be derived from being able to analyse the different signals at the same time to better understand their interactions and improve productivity. Moreover, signal analysis software that runs on a PC platform, like the 89600 VSA, can take advantage of parallelism (e.g., multiple cores), large memory and flexible displays to provide engineers with the views they need to simplify and improve their work (Figure 1).
Figure 1. Shown here is an example of the 89600 VSA’s multi-measurement capability. Its output shows the overlaid Spectrum and IQ Meas Time Trace Data for three simultaneous GSM (lower-left trace), W-CDMA (lower-middle trace) and LTE (lower-right trace) measurements.
The VSA software provides advanced, customisable general-purpose and standards-based signal analysis for evaluating signal spectra, modulation and time characteristics, supporting more than 70 signal standards and modulation types for cellular communications, wireless connectivity, aerospace and defence, and satellite communications applications. Rather than being embedded or limited to one piece of acquisition hardware, it is compatible with more than 30 Agilent measurement platforms, including: spectrum analysers, signal analysers, oscilloscopes, logic analysers, optical modulation analysers, and modular instrument systems. Its flexibility, in terms of multi-measurement analysis and front-ends, allows engineers to evaluate signals anywhere within a radio block diagram (analog and digital baseband; IF, RF, and microwave; and narrowband to ultra-wideband), as shown in Figure 2.
Figure 2. With its new multi-measurement capability, the 89600 VSA acquires complex, time-data inputs from four independent hardware front-ends and performs four different simultaneous signal analysis measurements: a digital baseband measurement using a logic analyser, a baseband measurement using a MSO oscilloscope, an IF measurement using an MXA analyser, and a RF measurement using a PXA signal analyser.
Multi-format measurement challenges
The increasing need for today’s wireless R&D and manufacturing engineers to design and test multi-carrier/multi-format waveforms for devices like Multi-Standard Radios (MSRs), is driving the demand for a test solution capable of providing simultaneous, multiple-signal measurements and correlated multi-signal test results. Traditional single-measurement analysers only analyse one signal at a time and are therefore, no longer practical or efficient. They fail to provide intelligence about the subtle interactions between dissimilar signals within a multi-signal device. The Agilent 89600 VSA software multi-measurement capability offers a viable test solution to meet these challenges, providing the simultaneous multiple-signal measurement functionality, simultaneous multi-signal side-by-side data results and increased test speed needed to resolve these issues. Fundamentally speaking, multi-measurement refers to the ability to process multiple measurements, for multiple diverse signal types—all at the same time. The VSA software’s new multi-measurement capability is an architectural enhancement that departs from the traditional ‘one-at-a-time’ measurement approach to a ‘multiple-at-a-time’ measurement approach. Traditional analysers are limited to single-carrier measurements, therefore, a multi-signal measurement process requires repeating a set of sequential independent measurements, one for each signal (measurement process: configure the analyser setup, acquire & process the data, display data, switch measurement mode, repeat). This produces a time intensive measurement process that can only provide results for one measurement at-a-time (not time aligned or simultaneous results).
In stark contrast to this ‘one-at-a-time’ measurement process, the 89600 VSA’s ‘multiple-at-a-time’ measurement architecture does allow multiple carrier measurements to be run concurrently ‘at the same time’. A multi-signal measurement starts by creating a user-defined Multi-Configuration Collection which includes the measurement configurations for each signal in the multi-signal measurement. When a multi-measurement is started, all measurements included in the multi-configuration collection are executed concurrently, all input data is acquired and processed, and all multi-measurement trace results are shown together side-by-side. Each measurement inherits the same trace data features and flexibility of an independent measurement, plus additional multi-measurement capabilities. For example, the engineer can overlay different measurement traces for visual comparison or apply math functions to calculate custom user-defined data results. Each multiple-signal measurement resides in memory as independent measurements; any or all of them can be called for immediate and coordinated execution. The 89600 VSA software takes advantage of PC multi-core technology by internally assigning each measurement to its own separate processing thread. This enables the host PC to manage, execute and switch between the various measurement tasks providing greatly improved efficiency and speed. This multi-measurement capability is designed for use in a variety of hardware and test scenarios. Implemented to be as flexible as possible, its multi-measurement capability supports three different input multi-measurement data acquisition styles: shared acquisition, independent concurrent acquisition and independent non-concurrent acquisition. The ‘shared’ acquisition style provides fully time-aligned simultaneous multi-signal measurement results. All measurements are run simultaneously, analysing the same ‘shared’ input data (data acquisition) from one analyser. Therefore, the combined multi-signal measurement span must fit within the analyser frequency range and bandwidth. (Figure 3).
Figure 3. With shared acquisition multi-measurement, analyser and input data is shared, producing fully time-aligned, simultaneous multi-measurement data results.
The ‘independent concurrent’ acquisition style is used to run concurrent multiple measurements from independent data acquisitions from multiple independent analysers. This acquisition style is used when the combined multi-signal bandwidth does not fit within the analyser maximum bandwidth (as shown in Figure 4), the physical test points locations prohibit the use of one analyser, or the multiple signal modulation types require different measurement hardware types (e.g., a simultaneous RF radio chain multi-measurement, see Figure 2). Even though the analysers are independent, the measurements are run concurrently ‘at-the-same-time’. Concurrent acquisition style measurements provide simultaneous wide-bandwidth multi-measurement results.
Figure 4. An independent, concurrent acquisition multi-measurement provides wide-bandwidth simultaneous measurements from independent analyser input data.
An ‘independent, non-concurrent’ acquisition style is used to run ‘fast-switching’ sequential measurements. Because individual measurement configurations reside in memory, they are ready for immediate execution resulting in fast switching and execution times between multiple measurements. Independent, non-concurrent acquisition is different from the previous two styles in that the measurements do not run concurrently. Instead, they are run sequentially. The measurement sequence can be placed in any arbitrary order (Figure 5).
Figure 5. An independent, non-concurrent acquisition multi-measurement provides independent, fast-switching sequential measurements.
For more than a decade, the 89600 VSA software has proven to be a test solution that effectively keeps pace with the industry’s ever-evolving communications and wireless technologies. The new multi-measurement capability is yet another example of this commitment, meeting the measurement and test challenges of MSRs and ensuring the success of today’s wireless R&D and manufacturing engineers.
Dale Wagner is a marketing engineer for Agilent Technologies, providing customer education materials and online help documentation for the Agilent 89600 software.