Electronic Military & Defense Annual Resource

5th Edition

Electronic Military & Defense magazine was developed for engineers, program managers, project managers, and those involved in the design and development of electronic and electro-optic systems for military, defense, and aerospace applications.

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Feature Electronic Military & Defense Annual Resource, 5th Edition 21 for storm dynamics and convective initiation, as well as better detection of small-scale phenomena, including tornados and microbursts. All of this translates into increased lead time for warnings and improved weather prediction. Thus, it is clear that the instrumentation of a phased array radar system with a multichannel transmitter and receiver suite gives researchers the ability to use advanced techniques for maximizing the utility of information gleaned from radar observations. However, engineers working on such systems should consider carefully the following five elements of phased array operation. For purposes of this discussion, we will focus on a two-channel receiver system, characterized as digitizer A and digitizer B. Also, baseband in-phase (I) signals will be used to explain the underlying concepts. 1. Trigger Synchronization: Engineers should ensure that all receiver (Rx) channels start togeth- er. If the acquisition engine on multiple channels is not initiated simultaneously, the trigger skew leads directly to equivalent skew in the relative timing between the acquired waveforms. In a use case like beamforming with continuous wave (CW) signals, this creates an artificial phase offset between the channels. For modulated signals, if the relative magnitude and phase relationship between the channels is important, then trigger skew also creates issues. Most of the signal processing on the receiver side intuitively assumes that data from all the channels is aligned in time. If this is not the case, post- processing is needed to realign the channels. This may be possible only if there is some type of pilot signal or some other mechanism to re-establish a timing reference common to each channel, which often is not the case in radar applications. This makes trigger synchronization fundamental to all multichannel applications, even if they are not phase-coherent appli- cations. 2. ADC/DAC Alignment: Analog- to-digital converter (ADC) align- ment is vital because, even if all channels receive a trigger at the same time, they cannot simultane- ously react to the trigger if their baseband clocks are not aligned. In such cases, the clock skew persists even after triggering. The result is the residual (or internal) clock skew plus one sample period, depending on when the trigger is received rela- tive to the clock edges. For this reason, it is important to align all the baseband clocks to remove the residual skew and then to provide a simultaneous trigger to all channels so they all trigger on the same baseband clock edge. For Industry, for Defense. Frequency 10 - 50 MHz Attributes Tight Stability Dual Compensation Best Stability ±0.03 ppm Output CMOS Squarewave Size 12.70 x 20.32 x10.92 mm 0.50 x 0.80 x 0.43 in., SMD Frequency 10 - 50 MHz Attributes g-Sensitivity to 7 x 10 -11 /g Best Stability ±0.5 ppm Output CMOS, Clipped Sine Size 9.0 x 7.0 x 3.7 mm 0.35 x 0.28 x 0.15 in., SMD Frequency 50 - 100 MHz Attributes Low Phase Noise Best Stability ±1.0 ppm Phase Noise -135 dBc/Hz @ 1kHz Output CMOS Size 17.27 x 17.27 x 5.0 mm 0.68 x 0.68 x 0.20 in., SMD Tough...But Oh, So Sensitive. Greenray TCXOs are tough as nails – but they've got a sensitive side, too. As in 7 x 10 - 11 /g g-Sensitivity, for example. Our TCXOs are achieving new performance standards for phase noise, g-Sensitivity, and temperature stability, providing Aerospace, De- fense and Commercial customers precision signal sources that work – on the ground, in the air, and most defnitely, in motion. Designing for demanding Defense or Industrial applications? Let's put Greenray innovation to work for you. Here are a few examples from our latest catalog:

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