I’ve for some time now wanted to do more RF design. Although I have taken some RF design courses, I haven’t actually made a single RF design before. But you can’t learn without doing and inspired by the MIT coffee can radar designed by Gregory Charvat, I figured that building a radar should be a doable project that would offer some challenge while also having some real world use.
The simplest radar is a continuous wave Doppler radar, which continuously transmit a constant frequency signal. This signal reflects from a moving target and Doppler shift causes reflected signal to change frequency. This reflected signal is then received and mixed with the transmitted signal. Mixer product is the difference of the frequencies which is proportional to the speed of the target. This kind of radar is very simple to make, in fact there are even some children’s toys. Unfortunately it can’t detect the range of the target and isn’t that exiting.
6 GHz frequency modulated radar - [Link]
by Colin Jeffrey @ gizmag.com:
In the world of electronic components, there are many devices out there that do their job well and reliably, but are almost never heard of – even though they may be vital to equipment that plays a role in our technology-driven lives. The radio frequency (RF) circulator is just such a device: it has simply done its job as a nondescript box of gubbins buried in radio communications systems, quietly directing radio frequency signals to the places they should go. Now researchers at the University of Texas have given the RF circulator a makeover. Not only is the new prototype smaller, lighter, and cheaper, it’s also claimed to be easily adapted to different frequencies on the fly, which is something the old style circulator cannot do.
New RF circulator to run rings around old technology - [Link]
RaysHobby build a project called RFToy:
it’s an Arduino-compatible microcontroller board for interfacing with radio frequency (RF) modules, such as the popular 433/315MHz transmitter/receiver, and the nRF24L01 transceiver. The RFToy has a built-in ATmega328, USB-serial converter (CH340G), 128×64 OLED display, three buttons, and a coin battery holder. Programming is done in Arduino through the on-board mini-USB port. It has three sets of pin headers to directly fit RF modules, and an audio jack to output RF receiver signals to a computer’s sound card. Using RFToy you can build a variety of projects involving RF modules, such as remote control and wireless sensors.
Introducing RFToy, an Arduino-compatible gadget for radio frequency modules - [Link]
by Bill Schweber @ digikey.com:
With very few exceptions, every electronic circuit needs an oscillator, also referred to as a clock, clock generator, or timing circuit. Its role is to provide the “heartbeat” for the processor, memory functions, communications ports, A/D and D/A converters (if any) and many other functions. In non-critical, low-budget situations such as $10 mass-market electronic thermometers, this clock may be made from a simple resistor/capacitor (RC) oscillator. However, for the vast majority of situations which are more critical, the oscillator is based on a quartz crystal (Figure 1). This is a mature (80+ years) and highly effective technology which can support of wide range of frequencies from kHz to hundreds of MHz, with performance spanning fairly good to excellent, depending on the crystal cut, fabrication, packaging, and other considerations.
MEMS Oscillators Challenge Quartz Crystals in RF Applications - [Link]
You are planning to use Arduino in your project but you need some kind of remote control functionality. A standalone Arduino won’t provide what you need but this DIY shield may be a good solution for you. It includes a 433.92Mhz RF receiver which lets you send commands to Arduino wirelessly and four SPDT relays which can be used for switching purposes.
Each relay is capable of switching up to 10A @ 250VAC so they can be used to control mains powered devices. There are four LEDS indicating the status of the relays. The terminal blocks on the shield lets you easily connect the devices you will control.
The RF receiver is a module that can be found in the market easily. It is directly soldered to the shield and runs at 4800bps. The board has an antenna input which lets you solder your custom antenna to increase the wireless range.
DIY 433MHz RF Receiver and 4 x SPDT Relay Shield - [Link]
The Wireless Inventors Kit for the Raspberry Pi (RasWIK) is an exciting and affordable addition to the Raspberry Pi. RasWIK demonstrates that with our leading edge technology anyone (and we mean anyone) can build wireless sensors and actuators , you do not need huge experience, a degree or even any tools. We show you even how to connect the devices you build to “the Internet of Things” (IoT) service providers such as Xively.
Getting started is just 5 simple steps:
1. Insert the preconfigured SD card to your Pi
2. Plug in the Slice of Radio to the GPIO connector
3. Turn on the Pi
4. Power the XinoRF development board
5. Lauch the Python based example application on your Pi
Thats it!……..you are now past step one of your journey to wireless nirvana
RasWIK – Raspberry Pi Wireless Inventors Kit - [Link]
A press release from the University of Southern California describes a novel transmission technique which can achieve very high data rates. The research led by Alan Willner of the USC Viterbi School of Engineering does not use a single carrier to send information but instead combines independent radio beams using a ‘spiral phase plate’ that twists each radio beam into a unique and orthogonal DNA-like helical shape. The receiver untwists the beams and recovers the different data streams. “Not only is this a way to transmit multiple spatially collocated radio data streams through a single aperture, it is also one of the fastest data transmission via radio waves that has been demonstrated,” Willner said.
Twisted RF beams achieve 32 GB/s - [Link]
Ondřej Karas of DoItWireless writes:
If You are interested in LED driving through RF, this article would be interesting for you. I tested own PCA9634 breakout board for this chip and wrote simple low level driver for IQRF TR-52D module. Next week, I am going to publish PC application for comfortable operation with that.
Wireless LED driver with PCA9634 - [Link]
HOPERF modules enable to gain a wireless data transfer or remote control of devices simply and without excessive costs.
A company, which specializes over a quarter of century on a given segment usually has experience and production capacities to develop and produce quality components. This is also a case of company HOPERF Micro-electronics and moreover – thanks to high production capacities the prices of their products are very attractive. HOPERF produces RF chips themselves, as well as read-made RF modules usable for virtually any application requiring a wireless control or data transfer, for example: remote keyless entry (RKE), control, security systems, telemetry, voice and data communication, control of processes and many others.
HOPERF modules offer besides a great price also a very high flexibility of usage. In contrast to many “fix-set” modules, RF modules HOPERF usually offer very wide possibilities to dynamically adjust many parameters, like for example: FSK/ OOK/ ASK modulation, possibility to work in a wide frequency range including free ISM bands 315, 433, 868 and 915MHz, while all main RF communication parameters are programmable.
In our stock can be found for example:
- RFM65CW-433S2 and RFM65CW-868S2 – 433/868 MHz FSK receivers. RFM65CW offers a unique possibility to use narrow-band and also wide-band communication modes. RFM65CW is optimized for a low power consumption while maintaining high sensitivity.
- RFM68CW-433S2 and RFM68CW-868S2 – 433/868 MHz FSK transmitters. It can be used without configuration from an MCU. However, in connection with MCU, it´s possible to change many parameters including output power, modulation format and a working channel.
- RFM73-S – 2,4 GHz transceiver, including a high power +20dBm version RFM73P-S2.
- RFM83C-433S1 – sophisticated 433 MHz ASK/OOK receiver including a version for low voltages RFM83CL-433S operating already from 2.1V
- RFM85W-433D – 433 MHz ASK transmitter. Excellent features and simple usage. Specially designed for remote control, car-alarms etc. working on 433.92 MHz.
- RFM12B-868S2P – multichannel 868 MHz FSK transceiver. RFM12B contains integrated functions of a digital data processing like: data filtering, clock recovery, data pattern recognition, integrated FIFO and TX data register. RFM12B enables to provide a clock for microcontroller.
HOPERF – universal RF modules for surprising prices - [Link]
We have already seen a number of ideas for tracking tags seeking funds on Kickstarter, most systems are limited by the range of Bluetooth communication with a smart device. This system from Iotera tackles the problem using cloud-based thinking: The basic wireless system consists of one or more tags or ‘iotas’ and a home base unit. Each 22 x 11 x 3 mm iota contains a chip, accelerometer, temperature sensor, speaker, RF transceiver, Bluetooth (unused so far) and a battery to give up to three months operation. Each iota communicates with the home base unit using wireless channels in the 902 to 928 MHz band giving a range of up to four-miles. Back home, the base unit receives the low-speed transmissions from the iota tag and forwards the information to a server via a Wi-Fi connection.
Novel Cloud-based Tag System - [Link]