Archive for Experiments

Rohde & Schwarz 4.0GHz Portable Spectrum Rider FPH Review, Teardown & Experiments

In this episode Shahriar reviews the Rohde & Schwarz 4.0GHz Spectrum Rider FPH. The new design of the FPH series is aimed for ease of use in outdoor situations as well as offering several software features for data collection, analysis and debugging of standard wireless communication protocols. The review is organized as follows:

1:10 – Model comparison of R&S portable spectrum analyzers.
5:44 – Instrument hardware overview and GUI characteristics.
22:24 – Using the FPH Spectrum Rider to analyze unknown wireless signals including a multi-tone, QPSK modulated signal, AM/FM demodulation analysis and frequency hopping.
46:46 – FPH teardown and analysis.
55:33 – Overview of the Instrument View remote connection software.
57:42 – Concluding remarks.

Teardown, Repair & Calibration of a Keithley 2400 Source Measure Unit (SMU)

In this short episode Shahriar investigates the failure cause of a Keithley 2400 SMU. The unit powers on and responds to controls however produces no output signal. Further examination reveals that the VFD display shows no activity when the output is enabled; normally the measured output voltage and current are displayed. This failure points to a digital problem, potentially a failure in the analog board FPGA.

Upon close inspection the FPGA clocking circuitry appears to have a failed solder-joint. A quick re-flow of the affected part corrects the problem and the unit reports the appropriate readings. The unit is then upgraded to the latest firmware and calibrated using a Keithley 7510 DMM.

Keysight MXA Revision-B Signal Analyzer / Spectrum Analyzer Review, Analysis & Experiments

In this episode Shahriar reviews the long awaited Keysight MXA Signal Analyzer (N9020B). The new X-Series Spectrum Analyzers from Keysight offer an entirely re-designed GUI interface which supports multiple tabs as well as multi-touch interaction. The review is organized as follows:

1:07 –   Model comparison and overview of x-series spectrum analyzers.
7:08 –   Instrument physical overview.
11:49 – New GUI overview and demonstrations.
22:44 – Instrument block diagrams and analysis.
28:46 – Brief look inside the MXA spectrum analyzer.
32:53 – Back-scattering communication experiment block diagram and description.
37:16 – Phase noise characterization of doubler and amplifier.
51:54 – Complete back-scattering experiment measurements and analysis.
1:04:45 – Analysis of broadband modulated signals by using the S-Series scope and MXA Signal analyzer at the same time.
1:13:56 – Concluding remarks.

DeoxIT Challenge & Restoration of a Precision Decade Resistor Box

In this short episode Shahriar attempts to revive a high-accuracy decade resistance box using the famous DeoxIT cleaning and restoration products from CAIG Laboratories. The DeoxIT D-Series products are particularly aimed at metal-metal contacts which have suffered oxidization and can provide a low-resistance repeatable contact after application.

The existing decade resistance box shows inconsistent measurements and intermittent contacts prior to the DeoxIT application. After spraying all contacts the instrument is significantly improved with repeatable and accurate resistance measurements. DeoxIT can be purchased from a variety of suppliers and vendors including Amazon.

Teardown & Analysis of an Anritsu MN9610B Variable Optical Attenuator

In this short episode Shahriar takes a detailed look at an Anritsu variable optical attenuator operating in the L- and C-Bands. The mechanical attenuator is defective and provides an opportunity for complete disassembly and examination of the free-space optics, mechanical components and electronics.

The electronics drive a pair of DC motors with potentiometer decoders in feedback along with operational amplifiers and a DAC. This allows the microprocessor to set the exact position of the motors based on calibrated values stored on EPROM. The free-space optics consists of two back-to-back disks with radial metal coatings. Depending on the position of each wheel, the coating limits the transmission of the light through the wheel causing attenuation. The entire housing is hermetically sealed to prevent degradation of the disks.

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