In this episode Shahriar demonstrates the functionality and applications of an Agilent 11896A Polarization Controller. Various fiber optic communication methods are presented. This includes the use of complex modulation schemes (such as PAM and QAM for coherent receivers), polarization division multiplexing (PDM), wavelength division multiplexing (WDM), and spatial division multiplexing (SDM). The concept of light polarization is demonstrated by using a pair lenses from a consumer theater 3D glasses and two blue LEDs with uncorrelated lighting patterns.
In order to test the polarization controller, a solid-state laser source, SMF fiber with APC/PC connectors as well as a polarization beam splitter is presented. By using a pair of optical power sensors, the functionality of the polarization controller is verified. Finally, the teardown of the unit is presented and the method to achieve polarization control is observed.
The fiber optic communication overview document can be downloaded here. I’d also like to acknowledge my colleague and friend Dr. Timo Pfau for his expertise and consult on fiber optic communication methods.
In this episode, Shahriar presents the theory, design and characterization of Nyquist Digital to Analog Converters (DACs). After a brief overview of DAC operation and theory, the schematic of an 8-Bit R-2R DAC is presented. The R-2R DAC, which is driven by a dsPIC30F6014A Microchip microcontroller is capable of producing ramps and arbitrary waveforms uploaded through an RS232 interface. The static integral non-linearity (INL) and differential non-linearity (DNL) is measured by using a Rigol DM3068 Multimeter through a Matlab interface program. The dynamic performance of the DAC is characterized using an Analog Devices AD6645 105MSps 14-Bit ADC evaluation board coupled with a USB FIFO interface board. By using the ‘Visual Analog’ software, the spectrum of the DAC output as well as the signal to quantization and distortion ratio (SQNDR) is calculated. Finally, the impact of component mismatches, operational amplifier non-linearity and timing uncertainty on the INL/DNL and SQNDR (ENOB) of the DAC is examined.
In this episode Shahriar investigates the cause of failure of a Keithley 220 Programmable Current Source. Despite being manufactured in the mid-1980′s, the Keithley 220 is still a very popular programmable current source. Alongside the repair efforts, the schematic of various analog, digital and power supply boards are also presented. By interpreting the failure mechanism, the fault is traced and corrected. The Keithley 220 is then calibrated and the calibration procedure of the sub-100nA range is explained. Finally, the performance of the calibrated unit is verified using a Rigol DM3068 Multimeter.
In this episode Shahriar extensively reviews the Rigol DSA1030A-TG3 Spectrum Analyzer. A wide variety of experiments are performed using the Rigol spectrum analyzer to serve both as a tutorial to use the instrument and to demonstrate its capabilities. Some measurement results are also performed using other calibrated instruments to verify the accuracy of the spectrum analyzer. The Rigol DSA1030A-TG3 can be purchased directly from Rigol Inc.
The following experiments are performed:
1) Signal amplitude, frequency and phase-noise measurements. 2) Low amplitude signal measurements (< -130dBm). 3) Low frequency measurement capabilities (< 9kHz). 4) PRBS length calculations and characterization. 5) Wireless 2.5GHz FM signal transmission and demodulation. 6) Attenuator and band-pass filter response measurements. 7) Amplifier bandwidth and output compression measurements. 8) Calibration and measurements of VSWR using the tracking generator. 9) Characterization of the tracking generator signal quality.
In this episode, Shahriar reviews the Rigol DM3068 6.5 Digit Digital Multimeter. The Model DM3068 DMM gives reliable, cost effective, full DMM capabilities measuring DCV, ACV, DCI, ACI, Resistance (2 & 4 Wire), Capacitance, Diode Test, Frequency, and Temperature. These DMMs are designed for simple and efficient bench top use, but include software options for datalogging and remote programming from almost any interface.
Shahriar demonstrates various functionality including a computer guided destructive LED IV tracer to investigate LED failure patterns. The DM3068 can be purchased for $799 US dollars from Rigol Inc. The DM3058 offers similar functionality at 5.5 Digits for $695 US dollars.
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