I receive requests to explain how the liquid crystal display (LCD) works. Which is this post’s subject.
Resistance, Capacitance, Inductance, Impedance and Reactance
This is another post about basic concepts of electricity. This time I will talk about resistors, capacitors, inductors in CC and AC.
My master degree work
In this post I will give an explanation about my research project which became my master dissertation. It is a complicated subject which uses technical terms.
My dissertation’s title is “Optimized System Design of Radiofrequency Receivers Based on Consumption Power Models”, that is, a circuit design block method of a radiofrequency receiver to the receiver consume the minimum energy possible without harm the performance. For a long time the block design was based on the designer’s experience and this design not always is the most economical in power consumption. This work is about only the receiver’s analog part.
Receiver
First I have to choose a receiver architecture to define the circuit blocks to be designed, the chosen architecture is the Zero-IF, because it has the less number of blocks, therefore consume less power. Here is the RF transceiver in Zero-IF, the receiver above and the transmitter below.
Chosen the architecture, were selected the circuit blocks to be designed, the blocks are: RF filter, LNA (Low Noise Amplifier), Mixer, Base Band Filter, VGA (Voltage Gain Control) and ADC (Analog Digital Converter).
The adopted standard is the LTE, a forth generation standard, in the parameters distribution I had to respect the gain, noise figure and IIP3 limits.
Method
To prove the method effectiveness I choose two models very different for each other, I make arbitrary distributions to see the power consumption and later I applied the optimization. The optimization method is an algorithm whose fluxogram is below, it make random distributions of gain, signal-noise rate and signal-noise + distortion rate, calculate the power consumption and repeat the cycle a number of times. After apply the optimization, calculate the power consumption and repeat a number of times. To more information see in the document I put in the end of post to download.
Simulation
There is a table with the models, the distributions and how much the algorithm reduces the power consumption.
| Model 1 | Model 2 | |
| Uniform (Case 1) | 15,37mW | 447,6mW |
| 1-x to SNR_{deg} and SNDR_{deg} (Case 2) | 6,72mW | 341,29mW |
| 1-x to SNR_{deg} and x to SNDR_{deg} (Case 3) | 11,64mW | 325,86mW |
| Average | 11,24mW | 371,58mW |
| With optimization | 1,90mW | 190,35mW |
| Reduction comparing to average | 83% | 48,8% |
The power consumption graphics of each circuit block to comparison, the model 1 is (a) and the model 2 is (b).
To know more with more details about my thesis, here is the complete thesis in pdf, only available in Portuguese.
NTC and PTC
Just like you can build light resistive sensors, it is possible to build temperature resistive sensors. There are many types of temperature transducers, in this post I will talk just about NTC and PTC, also called thermistors. Others sensors will stay to others posts.
LiPo batteries
There is a essential component that without it autonomous robots don’t work: battery. The LiPo battery are the most used to drone and aeromodels, in this post, I will explain how they work and protection measures to avoid accidents.
What is VoIP?
I will give an introduction to VoIP, which means Voice over IP. As the name tells it serves to transmit voice via internet by IP.
News: Sunglasses can generate energy
A sunglasses uses organic solar panels in lens to produce electrical energy.
What is WiMAX?
In this post I will explain what is WiMAX. WiMAX means Wordwide Interoperability for Microwave Acess, is a technology which follows the IEEE 802.16 standard to wireless communications to provide fixed and mobile broad band internet.
Features
Some WiMAX features:
- 6 to 9 Km range, vary with obstacles;
- Can be used when is not viable to install cable or optics fibers;
- Since it follows the IEEE 802.16 standard, operate in 2 to 10 GHz;
- Provide internet and telephone access, data and voice transfer;
- 70 Mbps speed;
- User and base station don’t need to stay in visible range.
Architecture
This is the IP based WiMAX architecture:
MS are mobile stations which are consumer’s smartphones, tablets, PC. ASN is Access Service Network composed by base stations which function is provide interface to mobile stations, ASN Gateway (GW) is an aggregation traffic layer and form the radio access network. CSN provides connection with the internet, ASP, private and public networks.
AAA means Authentication, Authorization and Accounting server; used to services which demand subscription, PSTN is public telephone network, OSS/BSS are operation system support and business operation system, 3GPP/3GPP2 are third generation standard, MIP-HA is Mobile IP Home Agent which is a router to keep information about the device’s location.
Infrastructure
This figure shows the architecture with device’s representations.
Since WiMAX has a bigger range than WiFi, it needs more powerful transceivers. Here is a directional antenna WiMAX model PA-3500.
WiMAX towers use the same principle of cellphones, a WiMAX tower below.
WiMAX receivers to users.
