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The Signal Path 116K

TSP #236 - A 77GHz Automotive Radar Module Measurement, Reverse Engineering & RFIC/Antenna Analysis

views November 30, 2023 10:00 PM

In this episode Shahriar takes a detailed look at two different automotive 77GHz radar modules. Each module design is presented along with the overall architecture and functional blocks.

The working module measurements are presented with discussions on how to capture an FMCW waveform at mm-wave frequencies. The teardown of the faulty module reveals the overall synthetic aperture design, antenna placement and design considerations and the digital backend processing. A close look at the Infineon 77GHz RFICs are also presented.

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TSP #235 - Stanford Research SR650 Dual Programmable Filter HP/LP Repair, Teardown & Experiments

views November 25, 2023 11:49 AM

In this episode Shahriar repairs an SRS SR650 dual programmable filter. The unit powers on with nearly all the front-panel LEDs illuminated but does not respond to any buttons. Schematic and internal measurements show a lack of activity on any of the main processor pins which is traced to a faulty inverter IC responsible for clock generation. The main SRAM IC is also missing and needs to be replaced.
Additional analysis of the circuits and modifications are also presented. However, the unit develops a new problem due to very high thermal dissipation of the 5V regular and full bridge rectifier. A new rectifier is installed and the faulty 5V regular is also replaced. The QuantAsylum QA403 Audio Analyzer is used to characterized the filter and ensure both the high-pass and low-pass filter sections are functional.

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TNP #43 - Rohde & Schwarz URE2 DC - 25MHz 300V RMS Voltmeter Teardown, Repair & Experiments

views November 23, 2023 6:46 PM

In this episode Shahriar takes a look at a fault Rohde & Schwarz URE2 which is a highly sought after RMS voltmeter. The ability of the RE2 to provide accurate RMS measurement up to 25MHz as well as provide DC measurement makes it an excellent instrument for characterizing DC/DC converter output noise characteristics.
The faulty instrument can measure AC, however no DC measurement can be made. The unit also occasionally generates an error code 0080 which points to a fault in the main analog board. Teardown of the instrument reveals a pair of front-end relays responsible for mode switching which are the likely cause of the DC measurement problem. The relays are replaced and the instrument returns to full operation. The performance and functionality of the unit is verified through several experiments.

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TNP #42 - Combustion Gas & Emissions Analyzer E1500 (O2, CO, CO2) Repair, Teardown & Experiments

views November 18, 2023 2:24 PM

In this episode Shahriar explores the technology behind combustion gas analyzers. These instruments are capable of measuring the concentration of various gasses such as O2, CO, CO2, NO2, SO2, etc. The particular unit shown in this video (E-Instruments E1500) is capable of holding two sensors.

The end-of-life Oxygen sensor is replaced to bring the unit back to life. The teardown of the instrument as well as the faulty Oxygen sensor are presented along with Raman chemical analysis of the sensor electrolyte. The biproduct of a burning candle as well as a HotHands hand warmer are analyzed using the instrument.

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TNP #41 - Stanford Research SR620 Universal Time Interval Counter Teardown, Repair & Experiments

views November 17, 2023 1:09 PM

In this episode Shahriar repairs an SRS SR620 frequency interval counter where the magic smoke has escaped! The instrument does not power on and the teardown reveals a burnt resistor. The circuit examination shows a voltage regular for the 5V output which has a short circuit the the chassis. A simple repair and resistor replacement brings the unit back to life.

The performance of the internal OCXO is measured against a Rubidium oscillator and the unit is frequency calibrated. The XY output mode of the unit as well as its ability to measure propagation delays are also shown.

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TNP #40 - Stanford Research FS735 Dual Distribution Amplifier Teardown, Repair & Experiments

views November 12, 2023 9:52 PM

In this episode Shahriar repairs a fault SRS FS735 dual distribution amplifier. These instruments provide two independent 7-channel 10MHz distribution modules with exceptional signal purity and isolation. The instrument does not properly powers on which points to a potential problem with the internal power supply.
The unit has two identical power supplies; one for each module. Both power supplies have a failed startup capacitor which can be easily replaced. After the repair, the power supplies are verified for functionality and power delivery. The schematic of the entire unit is described as well as a view of the module PCB. The performance of the unit across frequency, harmonic distortion as well as isolation behavior is also measured and verified.

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TSP #234 - QuantAsylum QA403 24-bit, 0.0001% THD Audio Analyzer Review, Teardown & Experiments

views October 29, 2023 8:16 AM

In this episode Shahriar takes a detailed look at the QuantAsylum QA403 24-bit, extraordinary linear & low-noise audio analyzer. This low-cost instrument provides the means to test a wide range devices in the audio frequency range:

The review of the instrument is organized as follows:

00:00 - Introduction, instrument interfaces and overview
01:03 - Detailed teardown, architecture overview, ADC, DAC, amplifiers, attenuators and interface challenges; isolated properties, THD and SNR considerations
10:14 - Instrument extreme performance verification through loop-back; detailed GUI overview, ADC & DAC operations, attenuators, THD measurements, built-in generators and measurement functions
22:47 - Stanford Research Systems (SRS) DS360 Ultra Low Distortion Generator performance verification using the QA403
25:28 - Characterization of the SRS SR560 Low-Noise Preamplifier, linearity, THD+N, low-pass and high-pass filters responses, low-noise versus dynamic reserve measurements, automated sweeps
35:40 - Characterization of a two-stage audio amplifier and headphone driver module; gain and THD variation measurements as a function of frequency
38:55 - QuantAsylum family of products, example measurements and additional resources
39:27 - Concluding remarks

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TSP #233 - How good is an $85, 10GHz Power Sensor? Detailed Teardown, Analysis & Experiments

views October 14, 2023 7:22 PM

In this episode Shahriar takes a look at an inexpensive power sensor module with built-in battery and a tiny LCD screen. The instrument claims a large dynamic range of -60dBm to +30dBm!
A leaky internal battery prevents the unit form powering on initially. After analysis of the chemical leakage (using an Agilent Resolve Raman) as well as repair of the battery, the unit return to normal operation. A detailed teardown of the sensor is presented along with the theory of operation for the front-end RF circuits and sub-components. The unit is then measured against a R&S 3-Diode Path NRP power sensor. Although it does not perform nearly as well, it can be used within +/-2dBm accuracy. The unit is then measured against its highest claimed frequency of operation and input power.

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TNP #39 - Faxitron MX-20 Digital Micro-Focus X-Ray Machine Teardown, Repair & Experiments

views September 17, 2023 3:16 PM

In this episode Shahriar repairs his Faxitron MX-20 digital x-ray system. Although the machine has been producing beautiful images for years, recently it has been outputting out-of-focus images intermittently.
The principle of x-ray focusing and beam-spot generation is presented along with potential electronic methods of achieving focus. The teardown of the unit reveals the main x-ray tube controller PCB which houses the focus control high-voltage modules. Since the problem is intermittent, a reed switch is also suspected. The high-voltage module is measured and appears fully functional. Replacing the reed switch corrects the out-of-focus images. Several x-ray images showcases the sharpness of the unit after the repair.

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TSP #232 - Near-THz Sub-Harmonic Mixers (Tektronix 75 - 140GHz) Tutorial, Teardown & Experiments

views August 12, 2023 7:05 PM

In this episode Shahriar takes a deep dive into near-THz sub-harmonic mixers. To demonstrate the concepts, measurements and teardowns a set of Tektronix Sub-Harmonic mixers have been acquired (WM 490-F & WM 490-W) which operate from 90-140GHz & 75-110GHz respectively. This video is organized as follows:

00:00 - Introductions
00:50 - Acquired near-THz sub-harmonic mixers & diplexers
01:26 - Theoretical background, non-linear devices, harmonic generation
06:05 - Spectrum analyzers utilizing sub-harmonic mixers, signal ID
08:27 - Tektronix sub-harmonic mixer design, schematic & principle of operation
15:11 - Mixer diode characterization using Keithley SMUs & I/V tracer application
19:59 - Mixer teardown, analysis and microscope view of THz diode
28:07 - Diplexer architecture & characterization using a 4-port Siglent network analyzer
33:24 - Complete near-THz down-conversion setup using a x6 mm-wave multiplier source and Tektronix MSO68-B oscilloscope, conversion loss, harmonic number verification, signal ID process
45:35 - Using a ~100GHz carrier to determine the RPM of an optical chopper
48:15 - Concluding remarks

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TSP #231 - Sanko BN100+ 300kHz - 6.5GHz USB Vector Network Analyzer Review, Teardown & Experiments

views August 7, 2023 6:28 PM

In this episode Shahriar reviews the Sanko BN100+ USB vector network analyzer which has been designed in partnership with Bird RF:

The review is organized as follows:

00:00 - Introductions
00:27 - Instrument front & back panels
02:15 - Teardown, internal architecture, front-end coupler design
06:03 - Firmware distribution
06:36 - VNA output signal performance, sweep types, sweep speed, harmonics (THD), power sweep
14:00 - Calibration, built-in models, calibration procedure & standards
15:35 - Port to port isolation, noise floor, minimum detectable response
16:18 - Extreme filter dynamic range measurements
18:07 - VGA measurements, dynamic s-parameters, trigger in/out
24:11 - Time domain analysis, impulse response measurements
26:27 - Frequency accuracy measurements
27:01 - Concluding remarks​​​

TSP #230 - A Real-Life Tricorder! Agilent Raman Resolve Through-Barrier Chemical Analyzer

views July 20, 2023 6:49 PM

In this episode Shahriar takes a close look at the Resolve Handheld Raman Analyzer for Chemical Identification from Agilent. This instrument resembles a real-life Tricorder with its ability to identify chemicals through various opaque containers.

This video explores every aspect of this instrument's design from principle of operation to the modern electronics required to realize its function. The video is organized as follows:

00:00 - Introductions & first through-barrier scan example
02:46 - Raman history, invention & Nobel prize
04:41 - Infrared absorption, Raman spectroscopy theory, challenges and importance of fluoresce
10:49 - Fluorescence example & measurement using Uranium glass & HeCd laser
15:21 - Other applications of fluorescence such as microscopy
16:48 - Nonlinear optical effect and frequency doubling crystals, measurement of green laser
20:13 - Other applications of nonlinear optics, autocorrelation instrument to measure femtosecond pulses
23:18 - Electron excitation of atoms to produce photon emissions using Helium & Neon gasses
24:23 - Components required to build a Raman spectrometer
25:15 - Monochromator & spectrometer architectures, limitations & design
29:07 - Agilent Raman Spectrometer overall architecture, Raman chemical fingerprints
31:10 - Spatially Offset Raman Spectroscopy (SORS) theory & application
32:43 - Agilent Raman Resolve use-cases, accessories and application scenarios
36:03 - Measurements & identification of spilled unknown powders & liquids
40:53 - Through-barrier plastics & glass measurement of mixed liquids & acids
42:52 - Agilent Resolve extensive library & material categories, Reach-back support
44:03 - Chemical identification examples using the Vial accessory
47:26 - Trace chemical concentration & sensitivity measurement
48:34 - Concluding remarks

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