Youtube category

Teardown, Repair & Analysis of an Agilent E4443A 3Hz – 6.7GHz PSA Series Spectrum Analyzer

In this episode Shahriar repairs an Agilent PSA Series Spectrum Analyzer. The instrument generates many errors during self-alignment and produces no measurements below 3.2GHz. The block diagram of the unit is thoroughly presented and various possible failure points are considered. Based on the observation of the noise floor, the most likely cause is the second LO module. The measurement of the LO power indicates that the second LO power is fall below nominal.

Teardown, Repair & Analysis of an Agilent E4443A 3Hz – 6.7GHz PSA Series Spectrum Analyzer – [Link]

Teardown & Repair of an Agilent N1912A P-Series Power Meter

In this episode Shahriar investigates a peculiar problem with an Agilent P-Series Power Meter. While the instruments works during startup, after about 10 minutes the LCD screen begins to flicker and become scrambled. Initial investigation reveals that the issue is not likely with the main motherboard since USB connection to the instrument and data-readout is possible even when the LCD screen is malfunctioning.

Teardown & Repair of an Agilent N1912A P-Series Power Meter – [Link]

YouTube Subscriber Counter with Wemos D1 mini

educ8s.tv @ youtube.com uploaded a new tutorial. Nick writes:

Today we are going to build a DIY YouTube subscriber counter with a big LCD display and a 3D printed enclosure

YouTube Subscriber Counter with Wemos D1 mini – [Link]

What Is Household Ground?

Image source: RimstarOrg Youtube channel
Image source: RimstarOrg Youtube channel

RimstarOrg published an interesting video on his Youtube channel to demonstrate why In north America you can find 3 holes in the electricity socket; which are hot, neutral and ground.

Image source: RimstarOrg Youtube channel
Image source: RimstarOrg Youtube channel

The hot wire goes to a breaker-panel and then to electricity grid and finally to a transformer somewhere. While the neutral line is connected with a bar in the breaker-panel and goes directly to the electricity grid and then to the transformer. Mostly, these wires’ colors are respectively black, white.

Breaker-panel — Image source: RimstarOrg Youtube channel
Breaker-panel — Image source: RimstarOrg Youtube channel

To understand why having a ground in household appliances is important, the video explained a use-case; a microwave-oven with 3 wires electricity plug where the electricity flows between the hot and the neutral, while the ground is connected to the external case. However, if the hot wire isolation gets damaged and attached to the case, the grounded case will make a low resistance path for the electricity. This will protect you from an electric shock because the electricity in this low resistance path will be very high forcing the breaker switches off.

Image source: RimstarOrg Youtube channel
Image source: RimstarOrg Youtube channel

Having a ground in the electrical system can play a role in the places where lightning can occur by forming a discharging path for charged cases in your house.
To understand more about household ground and other different meanings and applications of earth and ground watch the complete video below:

 

Source: Adafruit Blog

Know your Tool – Optimize C Code for microcontrollers

One of the talks in the “Embedded Linux Conference 2016” was about best practices to optimize C for microcontrollers. This talk deserves to be mentioned to Electronics-lab readers.

The presenter Khem Raj worked on Comcast’s (broadcasting and cable television company) reference design kit for STB, Gateway and IoT platforms.

We will cover some important points that have been suggested by the presenter:

Optimization Levels

Optimization in compilers in general (GCC is the one in Khem’s case) has different levels (5 Levels: Os, O1, O2, O3 and Og). Os is for size optimization while O1, O2 and O3 are for performance.

Optimization Levels - From Khem’s slides
Optimization Levels – From Khem’s slides

Linker

Linker which is an important tool in microcontrollers’ software toolchain, is mentioned in Khem’s talk.

Linker script is written in the linker command language and controls the memory layout of the output file (what goes where). Moreover, Linker can output a map file which is very useful when you want to track down references to symbols in the MCU memory.

Linker Script File - From Khem’s slides
Linker Script File – From Khem’s slides

Objdump

GNU GCC has a collection of binary tools; they are called (binutils); and objdump is one of them. It interleaves your assembly code with source code so you can do disassembling using it.

Variables

Talking about best practices with variables. If the concept of local, global, volatile, const and static are blurred for you, then watching this presentation will clarify them besides other important terms.

Khem also mentioned special integer types in C99; they are “fast” and “least” types. So you can allocate your variable like that:

  • Fixed width unsigned 8 bit integer uint8_t
  • Minimum width unsigned 8 bit integer uint_least8_t
  • Fastest minimum width unsigned 8 bit integer uint_fast8_t

To ensure portability of your code, Khem advised to use portable datatypes using uint{8,16,32,64}_t type declaration. This avoids effects of changing size of int type across different processors (compilers).

Using global and local variables is another concern. Khem advised to use local variable as much as possible. Global variable needs to be loaded from memory and stored back every time it is used. So if you use a global variable in a loop you will have multiple loading and storing operations.

Khem’s presentation has other tips about: array subscript Vs. pointer access, loop increments Vs. loop decrements and other stuff. Make sure to watch the presentation, all of it!
Slides

Siglent SSA3032X Spectrum Analyzer Review & Experiments

Afroman reviews Siglent’s SSA3000X series spectrum analyzer and all the options. There is some RF information for beginners and usage experiments are also performed.

Siglent SSA3032X Spectrum Analyzer Review & Experiments [Link]