Introduction to WiMAX Transmitter Measurements

Overview

As the deployment of WiMAX devices continues to rise, test engineers face an increasing challenge to reduce test costs. Thus, automated test systems used in either design validation testing or production testing must be designed to perform fast, accurate, and repeatable WiMAX measurements. Read this white paper to understand the types of measurements typically required for characterization of Fixed WiMAX (IEEE 802.16-2004) and Mobile WiMAX (IEEE 802.16e-2005) devices.

Overview of the WiMAX Frame Structure

Each of the two WiMAX classifications, Fixed and Mobile, are based on a subset of the IEEE 802.16 standards and are defined by the WiMAX forum. More specifically, Fixed WiMAX is based on the orthogonal frequency division multiplexing(OFDM) physical layer of the 802.16-2004 specifications, which are sometimes called IEEE 802.16d. Mobile WiMAX is based on the orthogonal frequency division multiplexing access (OFDMA) physical layer of the 802.16e-2005 standard, which is a revision of the original Fixed WiMAX standard. Mobile WiMAX provides added functionality such as base station handoffs, multiple input multiple output (MIMO) transmit/receive diversity, and scalable fast Fourier transform (FFT) sizes [1]. Table 1 shows a high-level side-by-side comparison of the Fixed and Mobile WiMAX standards.

	Fixed WiMAX	Mobile WiMAX
Standard	IEEE 802.16-2004 (also called « d »)	IEEE 802.16e-2005
Multiplexing	OFDM	OFDMA
FFT size	256	Scalable (512, 1024, and so on)
Duplexing mode	TDD, FDD	TDD
Modulation scheme	BPSK, QPSK, 16-QAM, and 64-QAM	QPSK, 16-QAM, and 64-QAM
Subcarrier spacing	15.625, 31.25, 45 kHz	10.94 kHz
Signal bandwidths	3.5, 7, and 10 MHz	5, 7, 8.75, and 10 MHz
Spectrum	3.5 and 5.8 GHz	2.3, 2.5, and 3.5 GHz

Table 1. Fixed Versus Mobile WiMAX [1]-[3]

Fixed WiMAX Frame Structure

Fixed WiMAX supports both time division duplex (TDD) and frequency division duplex (FDD) modes. In addition, you can configure Fixed WiMAX frames to support multiple bursts that use various modulation schemes. In the following sections, learn about the structure of TDD and FDD frames, subframes, and duplex modes.

In FDD mode, transmit-and-receive signals from both the base and subscriber stations are on different channels. As shown in Figure 1, the base station transmits on the downlink channel frequency and the subscriber stations transmit on the uplink channel frequency. The WiMAX standard is also explicitly designed to concurrently support half-duplex and full-duplex subscriber stations, as shown in Figure 1.

Figure 1. Uplink and Downlink of FDD Mode [2]

From Figure 1, note that the base station uses a time-division multiple access (TDMA) transmit scheme. Under this configuration, the FDD downlink frame is used by multiple subscriber stations. Also observe that subscriber station 0 is supported with subframe 0 in both the uplink and downlink channels. This subscriber station (SS) in full-duplex mode is able to support simultaneous transmit and receive. By contrast, half-duplex subscriber stations are not able to transmit and receive simultaneously. Thus, the uplink and downlink subframes from subscriber stations 1 and 2 do not occur at the same time.

Time Division Duplex Mode

In TDD mode, the same channel is used for both uplink and downlink traffic. As a result, a TDD frame consists of an uplink and downlink subframe, each of which is separated by a timing transition gap (TTG). In addition, each subframe contains a preamble and one or more bursts. Note that each burst within a subframe must be arranged in decreasing order of robustness [3]. In Figure 2, observe that the QPSK (most robust) burst precedes the 16-QAM burst that precedes the 64-QAM burst (least robust).

Figure 2. TDD Downlink Subframe Structure

Mobile WiMAX Frame Structure

While the Mobile WiMAX profile allows for TDD and FDD operation, most deployed systems use TDD mode. Unlike Fixed WiMAX, which uses OFDM frames, Mobile WiMAX uses OFDMA frames. With OFDMA, multiple users can receive data from the base station at the same time. In this type of system, downlink bursts from the base station are divided by both time and frequency (subchannel) offset. Thus, each burst has unique time slot and subchannel allocations. An example of a TDD OFDMA burst used in Mobile WiMAX is shown in Figure 3.

Figure 3. OFDMA Downlink Subframe

In Figure 4, note that each burst in a Mobile WiMAX TDD subframe has a unique symbol and subcarrier offset. This burst allocation method allows for multiple subscriber stations to receive information from the base station simultaneously. One common visualization technique used to create Mobile WiMAX bursts is with the Zone map. Figure 4 illustrates an example map from the NI Mobile WiMAX Generation Soft Front Panel.

Figure 4. Soft Front Panel Zone Map

In Figure 4, each burst can have a unique modulation and coding scheme. In addition, Mobile WiMAX does not have the same “order of robustness” restrictions that apply to Fixed WiMAX signals.

WiMAX Transmitter Measurements

This white paper focuses exclusively on transmitter measurements and methods to reduce measurement time. In the following sections, explore measurements such as transmit power, error vector magnitude (EVM), subcarrier flatness, and spectral mask margin.

Transmit Power

The transmit power measurement is one of the simplest measurements for validating the RF front end. While you can measure transmit power with an RF power meter as well, using a vector signal analyzer to measure power provides benefits such as faster measurement times and more granular power measurements on the preamble and individual bursts. One common vector signal analyzer trace is “power versus time,” which is shown in Figure 5.

Figure 5. Power versus Time for a Mobile WiMAX Burst

Note that in both Fixed and Mobile WiMAX, the preamble is boosted by either +3 dB (Fixed WiMAX) or +9 dB (Mobile WiMAX) higher power than the data symbols.

Also observe that the OFDM and OFDMA signal structures used in Fixed and Mobile WiMAX fundamentally produce an inherently large peak-to-average-power ratio (PAPR). In fact, a Mobile WiMAX uplink signal can have a PAPR of up to 12 dB. When measuring RF power, it is important that the peak power of the burst does not exceed the peak overload power of the vector signal analyzer. Note that this is not the same as analyzer reference level. For example, the NI PXIe-5663 vector signal analyzer allows for a 10 dB peak-to-average headroom. When the analyzer is configured with a 0 dBm reference level, the instrument can accept signals up to +10 dBm before overloading  the instrument. Thus when measuring a burst that has an average power of +10 dBm, the vector signal analyzer reference level must be set to +12 dBm or higher.

Error Vector Magnitude (EVM) and Relative Constellation Error (RCE)

EVM and RCE are some of the most important metrics of a Fixed WiMAX transmitter’s performance because these measurements capture error due to a variety of impairments including quadrature skew, I/Q gain imbalance, phase noise, clock recovery, and nonlinear distortion. Note that the EVM and RCE are nearly interchangeable terms.In general, RCE describes an EVM measurement that is calculated over an entire Fixed WiMAX frame.

For a modulated signal, the EVM measurement compares the measured phase and amplitude of a signal with the expected phase and amplitude. The NI Fixed and Mobile WiMAX analysis toolkits calculate it by dividing the error vector|E| by the magnitude vector |V|, shown in Figure 6.

Figure 6. Graphical Representation of an EVM Measurement

The IEEE 802.16-2004 standard (Section 8.3.10.3) prescribes that a Fixed WiMAX transmitter must have a minimum RCE per each modulation scheme, as shown in Table 2.

Burst Type	SS RCE (dB)	BS (RCE)
BPSK-1/2	-13	-13
QPSK-1/2	-16	-16
QPSK-3/4	-18.5	-18.5
16-QAM-1/2	-21.5	-21.5
16-QAM-3/4	-25.0	-25.0
64-QAM-2/3	-29.0	-29.0
64-QAM-3/4	-30.0	-31.0

Table 2. 802.16d Minimum RCE for Various Modulation Types [3][4]

The IEEE 802.16e-2005 standard (8.4.12.3) prescribes that a Mobile WiMAX transmitter must have a minimum RCE per each modulation scheme, as shown in Table 3.

Burst Type	SS RCE (dB)	BS (RCE)
QPSK-1/2	-15.0	-15.0
QPSK-3/4	-18.0	-18.0
16-QAM-1/2	-20.5	-20.5
16-QAM-3/4	-24.0	-24.0
64-QAM-1/2	-26.0	-26.0
64-QAM-2/3	-28.0	-28.0
64-QAM-3/4	-30.0	-30.0

Table 3. 802.16e-2005 Minimum RCE for Various Modulation Types [4]

When characterizing a transmitter’s performance, your choice of modulation scheme at a given power level often has little effect on EVM performance. Thus, in a validation or production test environment, it is most common to simply measure the EVM or RCE for only a 64-QAM burst.

Visually, you can inspect EVM in several dimensions. A constellation plot provides the measured phase and amplitude of each recovered symbol. You can use this plot to identify signal impairments. In many cases, you can use this plot to identify which factor (AWGN, nonlinearity) contributes the most error to an EVM measurement. An example constellation plot showing QPSK, 16-QAM, and 64-QAM signals is shown in Figure 7.

Figure 7. Visualization Using the Constellation Plot

Also, the EVM versus subcarrier trace helps you identify if spurs or other in-band distortion is affecting the modulation quality of a given subcarrier.

Figure 8. EVM versus Subcarrier for a Mobile WiMAX Signal with a 1024 FFT Size

A final EVM visualization trace is the EVM versus symbol. With this trace, you can detect whether the modulation quality is consistent throughout the burst.

Figure 9. EVM versus Symbol for a Mobile WiMAX Burst

Subcarrier Flatness

Both the IEEE 802.16-2004 and the IEEE 802.16e-2005 specifications place requirements on the maximum channel-to-channel power offset between OFDM subcarriers. As shown in Table 1, the number of subcarriers varies between Fixed and Mobile WiMAX. While Fixed WiMAX signals have 256 subcarriers, Mobile WiMAX bursts can have 128, 512, 1024, or 2048 subcarriers. In both flavors of WiMAX, the maximum allowable subcarrier-to-subcarrier power difference is ±0.1 dB. In addition, the 802.16-2004 specifications for Fixed WiMAX mandate maximum and minimum power levels relative to the average power level as well. This is shown in Table 4.

Spectral Lines	Flatness Specification
–50 to -1 and +1 to +50	±2 dB of average power level
–100 to -1 and +1 to +100	+2 dB/-4 dB of average power level

Table 4. Tolerance for Fixed WiMAX Subcarrier Flatness

You can observe the spectral flatness of the NI PXIe-5673 vector signal generator and NI PXIe-5663 vector signal analyzer in Figure 10.

Figure 10. Vector Signal Analyzer and Vector Signal Generator with Maximum Flatness Less Than ±0.4 dB over the Entire Spectrum for a Mobile WiMAX Signal

Spectral Mask Margin

Spectrum mask, the final key transmitter measurement, provides a method to characterize transmitter nonlinearity and check for spurious signals. In general, you use the spectrum mask trace as a diagnostic tool. However, the spectrum mask margin measurement is a pass/fail test that is defined by the IEEE 802.16-2004 specifications in Section 8.5.2. According to these specifications, a transmitted signal in licensed bands must meet the mask specified in Table 5.

Bandwidth	A	B	C	D
20 MHz	9.5 MHz	10.9 MHz	19.5 MHz	29.5 MHz
10 MHz	4.75 MHz	5.45 MHz	9.75 MHz	14.75 MHz

Table 5. 802.16-2004 Spectral Mask Limits

Observe from Table 5 that the 802.16-2004 specifications provide unique spectral mask limits for the 10 and 20 MHz signal bandwidths. Note that for unlicensed band, the mask limits are determined by the local regulatory authority and are not prescribed by the IEEE 802.16-2004 specifications. Also, while the IEEE 802.16e-2005 specifications do not offer additional guidance on spectral mask measurements, the NI Signal Analysis Toolkit for Mobile WiMAX provides an adjacent channel power measurement.

With the NI WiMAX analysis toolkits, you can perform spectral mask either “instantaneously” on a nongated acquisition or on a burst using the gated spectrum measurement. Note that a gated spectrum measurement requires the transmit signal to be bursted and cannot be performed on a continuously modulated signal. Figure 11 illustrates a spectrum mask measurement on a Fixed WiMAX signal at 2.5 GHz.

Figure 11. Spectrum Mask of a Mobile WiMAX Signal

Conclusion

Testing today’s WiMAX devices requires accurate RF instrumentation and a variety of measurement techniques. For transmitter testing, measurements such as power, EVM, subcarrier flatness, and spectral mask margin are some of the common metrics used to characterize device or component performance. To learn more about the products used to perform the measurements in this white paper, view Preconfigured NI WiMAX Test System.

References

[1] Andrews, Ghosh, and Muhamed, Fundamentals of WiMAX: Understanding Broadband Wireless Networking. Prentice Hall, 2007.

[2] Mobile WiMAX – Part 1: A Technical Overview and Performance Evaluation, by WiMAX Forum, August, 2006.

[3] IEEE Standard for Local and Metropolitan Area Networks: IEEE Std. 802.16-2004.

[4] IEEE Standard for Local and Metropolitan Area Networks: IEEE Std. 802.16e-2005.

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ZigBee RF Testing (2)

By David A. Hall, National Instruments

Page 1 of 2

RF Designline (12/04/2007 3:40 AM EST)

ZigBee is a wireless standard for personal area network (PAN) sensor monitoring and control. National Instruments’ Alliance Partner SeaSolve has developed a test suite including transmit (Tx), receive (Rx) and compliancetesting for ZigBee. In this two-part article, we will describe test methodologies and techniques for each type of testing.Part 1 introduced ZigBee testing requirements and focused on transmitters. This part looks at receivers, frame types, and compliance testing. ZigBee Receiver Testing The requirements for testing a ZigBee receiver can generally be broken into two requirements: media access control (MAC) layer emulation and impairments testing at the physical layer (PHY). The first type, MAC layer emulation, can be used to ensure that the ZigBee receiver is able to respond appropriately to the generated commands. With the second type, impairments testing, a receiver is tested by intentionally reducing the modulation quality of the test stimulus. The examples below use SeaSolve’s WiPAN LVSG signal generation solution combined with a PXI vector signal generator, as illustrated in the Figure 8. 8. WiPAN mapping on ZigBee protocol stack.In Figure 8, we have illustrated that the IEEE 802.15.4 standard defines the MAC and PHY layers of a ZigBee transmissions. Typical test procedures involve both MAC layer emulation through packet generation and PHY layer testing by adding impairments. ZigBee Frame Types The MAC (Media Access Control) layer of a ZigBee transmission defines the basic packet and frame structures. The IEEE 802.15.4 specification defines four basic frame structures that can be used for receiver test. These frame types include: A beacon frame is used by a coordinator to transmit beacons. The beacon packet enables a node to identify the presence of other nearby A data frame, is used for all transfers of data payloads An acknowledgment frame is used for confirmation of a successful frame reception MAC command frame is used to handle MAC peer-entity control transfers The MAC command frame is the most flexible. Thus, receiver testing also involves selection of specific sub-frames, listed by type, below: Association request is a request for association with a PANcoordinator. Association response is a reply from coordinator with association status (possibilities include: Association Successful, PAN at capacity, Access denied) Disassociation notification is used by device or coordinator to inform other nodes about disassociation. Data requestis used to request data from a coordinator. PAN ID conflict notification is transmitted when a PAN identifier conflict is detected Orphan notification is used by an associated device that has lost synchronization with its coordinator Beacon request is used for synchronization and to transmit superframe information Coordinator realignment is used by the coordinator to reply to an orphan notification command. It is also used when PAN attributes change with the logical channel information. It can be transmitted to the whole PAN or to a single orphan device. GTS request is used by an associated device to request the allocation of a new guaranteed time slot (GTS) or to request the deallocation of an existing GTS from the PAN coordinator. It also defines the GTS fields such as length, direction, and type. MAC Frame fields configuration In addition, MAC frame fields can be configured as well. Common fields include: frame type, encryption, acknowledgement, frame pending, inter/intra PAN, addressing fields, destination and source addressing modes, sequence number, destination PAN identifier, destination MAC address, source PAN identifier, and source MAC address.Generator Impairments Because tradeoffs must frequently be made between performance, power, and cost, it is common for ZigBee transceivers to operate with a relatively low modulation quality. Thus, testing a ZigBee receiver offers unique challenges to the test engineer. When performing tests, the worst-case environment must be simulated in the lab to ensure that transceiver meets performance specifications and complies with the IEEE 802.15.4 standard. The WiPAN LVSG software enables users to test for interoperability by applying various impairments to model imperfect transmissions and challenges of the physical channel. The specific impairments that can be added include: memoryless nonlinearity, additive white Gaussian noise (AWGN), frequency offset, DC offset, in-phase/quadrature (I/Q) gain imbalance, quadrature skew, and phase noise. Memoryless Nonlinearity Components such as a power amplifier are inherently nonlinear and introduce distortion into a transmission signal. Generally, non-linearity is particularly problematic to modulated signals because of their constant fluctuations in amplitude. Fortunately, ZigBee devices use an OQPSK modulation scheme that is less susceptible to distortion than most modulation schemes. However, because of power requirements, ZigBee transceivers are often designed such that the power amplifier is driven almost into saturation. To illustrate this concept, we show a basic simulated model of a power amplifier in the Figure 9. 9. Saturation of a non-ideal power amplifierAs a power amplifier approaches the point of saturation, significant distortion is often introduced to the Tx signal. Thus, receiver validation requires us to simulate this characteristic of a ZigBee transceiver. AWGN AWGN is the most common mechanism for simulating the signal-to-noise ratio (SNR) of a Tx signal. The affect reducing SNR is that instantaneous phase and amplitude uncertainty is applied. This is most commonly observed on a constellation plot, where we can observe that AWGN causes symbol spreading. This is illustrated in the Figure 10. 10. ZigBee transmission with 25 dB Eb/N0.Because SNR deteriorates with transmit distance, ZigBee transmissions over a longer distance will result in reduced EVM at the receiver. As illustrated in Figure 3, a higher EVM will increase the probability of bit errors and reduce system performance as a whole. Frequency Offset Frequency offset occurs when the Tx and Rx local oscillators of two different devices operate at slightly different frequencies. The effect of frequency offset on an RF signal is that it produces a slight carrier offset in the baseband waveform. Typically, small carrier offsets in the baseband waveform can be removed through signal processing algorithms. Thus, this characteristic is often tested during the design validation phase by applying a slight carrier offset to the test stimulus. If not removed appropriately, frequency offset will prevent the receiver from achieving carrier lock with the transmit signal

ZigBee RF Testing (1)

RF Designline (11/27/2007 1:19 PM EST)

ZigBee is a wireless standard for personal area network (PAN) sensor monitoring and control. National Instruments’ Alliance Partner SeaSolve has developed a test suite including transmit (Tx), receive (Rx) and compliance testing for ZigBee. In this two-part article, we will describe test methodologies and techniques for each type of testing.Intro to ZigBee ZigBee, also known as IEEE 802.15.4 is a communications standard designed for low-power short-range communications between wireless devices. It is classified as a Wireless Personal Area Network (WiPAN), a term which includes the Bluetooth (IEEE 802.15.3) standard as well. The ZigBee standard has seen increasing interest from both commercial and military markets for applications such as wireless sensor networks, home automation, and industrial control. One interesting facet of the ZigBee standard is that it is designed such that devices can form a self-forming and self-healing ad hoc or mesh networks. In this scenario, a central ‘PAN coordinator’ device oversees the health of the network configuration. In recent years, sensor networks have been the subject of much research in military / battlefield applications as well. Thus, there is significant interest in using the ZigBee standard to define the communications links in ad-hoc battlefield intelligence scenarios. One design decision of the ZigBee specification that makes it ideal for remote wireless sensors is the implementation of a low-power physical layer (PHY). As an overview, the PHY specifications allow ZigBee devices to operate at one of three bands: 868 MHz (Europe), 915 MHz (North America), and 2.4 GHz (worldwide). The 2.4-GHz band, in which ZigBee transceivers are most commonly deployed, uses the offset quadrature phase-shift-keyed (OQPSK) modulation stream. This scheme is a derivation of traditional QPSK and is used because it requires less power than similar schemes, while achieving the same or better throughput. OQPSK uses a maximum phase transition of 90 degrees from one symbol to the next. This prevents symbol overshoot and requires slightly less transmission power than the traditional QPSK modulations scheme. This design decision, combined with the use of a 5-MHz channel bandwidth enables devices to achieve a data rate of up to 250 kb/sec in a reasonably power-efficient manner. Because ZigBee transceivers are designed for low-power applications, the PHY is relatively tolerant to significant error. In fact, devices are able to tolerate an error vector magnitude (EVM) of up to 35% while maintaining reasonable bit-error-rate (BER) performance. Thus, design validation and product request requires a variety of test methodologies. In the following sections, we will explain why specific tests much be conducted and provide tips to enable the most accurate testing methodologies. As an overview, we will divide our discussion into three parts. These include: Transmitter Testing with a vector signal analyzer (VSG) Receiver Testing with a vector signal generator (VSA) Automated Compliance Testing (ACT) with both VSA and VSG ZigBee Transmitter Testing When testing a ZigBee transceiver’s Tx signal quality, a VSA must be used in order to characterize both spectrum information and modulated signal quality. With the SeaSolve’s WiPAN LVSA Signal Analysis toolset along with a PXI-5660 VSA, we were able to perform both spectrum and modulation measurements on IEEE 802.15.4-compliant signals. It is important to remember that both measurement types are a requirement for both design validation and production test. As an overview, the spectral emissions of a ZigBee transmitter will dictate its interoperability with other devices in the industrial, scientific, and medical (ISM) band. In addition, the modulation quality of the Tx signal, combined with the antenna performance, dictates the range of distance over which the device can reliably perform. A typical test configuration is shown in Figure 1. 1. Typical transmitter is tested through either direct connection or air interfaceThe most common spectral measurements performed include: power spectral density, occupied bandwidth, power in upper/lower bands, and total power in band. In addition, typical modulation analysis tools include the: constellation plot, eye diagram, complementary cumulative distribution function curve (CCDF), and returned bitstream. Typical modulation measurements are: EVM, frequency offset, and BER. Note that various stages of product development will require different measurements and/or analysis. For example, the design validation and verification stage of development requires more intensive analysis tools such as a constellation plot to debug various issues in product design. On the other hand, production test requires more definitive measurements such as EVM and frequency offset such that performance can be compared to test limits. ZigBee Tx Spectrum Analysis Below, we describe each of the basic frequency domain measurements and explain their importance. Note that each of the following measurements can be made with either a spectrum analyzer or VSA. In general, a VSA is the recommended instrument because it can be used for modulation measurements (next section) as well. Power Spectral Density Power spectral density (PSD) is a measurement that describes how the power of a given packet of data is spread over a broad frequency range. This measurement is used to ensure that the transmitter operates within the spectral mask requirements of the IEEE 802.15.4 standard. As Figure 2illustrates, a frequency mask is compared with the output power. The frequency mask, shown as the white line, represents the limit of power that transmitter is allowed to emit into adjacent bands. When troubleshooting a device, factors such as poor filter design or images resulting from amplifier compression can contribute to unwanted power in adjacent frequency bands. 2. Plot of Power Spectral DensityPower in Band The power in band measurement calculates the integrated power (dBm) in the specified channel or band. This measurement is used to ensure that the transmitter does not exceed power specifications of the IEEE 802.15.2 standard. Occupied Bandwidth Occupied bandwidth returns the bandwidth of the specified frequency band that contains 99% percent of the total power of the span. Adjacent Channel Power Adjacent channel power measurement comprises of power in the upper and lower bands. According to IEEE 802.15.4, upper band is 5MHz towards the right of the operating frequency and the lower band is 5MHz towards the left of the operating frequency. Baseband Measurements Baseband parametric measurements are used to ensure that the ZigBee transmit packets will be able to be successfully decoded by the receiver. Because ZigBee transceivers are designed to operate at low-power and do not require high data throughput, modulation quality is often sacrificed to reduce power consumption. Overall, the purpose of measuring quality is to evaluate the likelihood of bit errors. As an example, we estimate BER as a function of EVM (%), shown in Figure 3. 3. BER vs. EVM for a QPSK Modulated TransmissionAs the graph shows, BER increased dramatically when the EVM of a QPSK transceiver increases from 15% to 30%. By contrast, most ZigBee devices are required to operate at an EVM that is below 35%. Thus, it is important to measure modulation accuracy to validate that a transceiver will operate effectively in its deployment environment. This can be done with several plots and measurements, shown below

Top 20 des spécialités de l’ingénierie des SI

Cette étude est réalisée auprès 1878 intégrateurs de systèmes d’information. Pourquoi publier cet article ? Figurez vous que nous possédons à l’ avance l’orientation future des sociétés intégrateur de SI !

Engineering specialties, top 20

1. 62% programmable logic controllers (including installation and programming)

2. 53% human-machine interfaces

3. 52% automation and control engineering (including designs and implementation)

4. 50% process control and automation

5. 48% instrumentation and data acquisition

6. 45% motors, drives, and motion control (including AC, DC, and variable frequency drives)

6. 45% control panels (including fabrication, installation, and UL listing)

6. 45% systems engineering (including design and integration)

7. 40% factory automation

7. 40% installation and start-up

7. 40% networking and communications (including fieldbus, Ethernet, and telemetry)

8. 39% computer engineering – software and programming

9. 38% turnkey systems

10. 37% batch control (including recipe management)

11. 36% CAD/CAM, drafting, and documentation

11. 36% distributed control systems (DCS)

12. 35% supervisory control

13. 34% SCADA (supervisory control and data acquisition)

13. 34% electrical/electronics engineering (including electrical contracting)

13. 34% project management

14. 33% automated assembly

14. 33% designs and specifications (including P&ID development)

15. 31% data processing and database management (including SQL programming)

15. 31% project planning and consulting

15. 31% machine design and controls

16. 30% robotics

16. 30% discrete and sequential control

17. 29% vision systems (including image processing and OCR)

18. 28% water, wastewater, and groundwater systems

19. 26% data collection and reporting (including historians)

19. 26% field service

20. 25% personal computers (PCs)

20. 25% product tracking and identification (including bar codes and radio frequency tags)

20. 25% training and education

Source: 2009 Control Engineering Automation Integrator Guide

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1. Quel gestionnaire de projet utilisez-vous ?
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6. Avez-vous planifié un agenda fixant les dates importantes tout au long du projet ?
7. Avez-vous rédigé un dossier de spécification ?
8. Vos programmeurs ont-ils des conditions saines de travail ?
9. Offrez vous de meilleurs moyen et outils à votre équipe de développement ?
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11. Faites-vous coder les candidats pendant les entretiens d’embauche ?
12. Utiliser vous votre entourage pour tester vos applications ?

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