An introduction to why and when terminations are needed for transmission lines in both high speed digital applications and RF applications. 50 ohm termination examples are given, but the principles apply for other line impedances as well. The basic operating principles of signal propagation down a transmission line and the effects of reflections coming from improperly terminated are covered. Examples for digital-like signals as well as RF signals are given. A description and examples of what is meant by Standing Waves is also given. As a bonus, the properties of quarter wavelength transmission lines in RF applications is also presented.
Transmission Line Terminations for Digital and RF signals - [Link]
High-performance RF signal source family offers AM/FM/Phase modulation with I/Q modulation option
Fairport NY: Saelig Company Inc. (www.saelig.com) has introduced a high-performance RF signal source family, the DSG3000 3GHz/6GHz series, offering standard AM/FM/Phase modulation, as well as options for I/Q modulation and I/Q baseband output. The DSG3000 Series generates waveforms with high signal purity, typical phase noise of less than 110dBc/Hz@20kHz, and a wide output range of -130dBm to +13dBm. The DSG3000 RF signal generator has standard pulse modulation with an on/off ratio of up to 80dB, with an optional pulse train generator also available. The DSG3000 series has a typical amplitude accuracy of better than 0.5dB, and the standard 0.5ppm internal clock can be upgraded to an optional 5ppb high stability oven-controlled clock.
The DSG3000 series RF signal generators support internal and external modulation capabilities and operate with USB, LAN, LXI-C, and GPIB remote control interfaces. They also feature a wear-free electronic attenuator design and an automatic flatness calibration function via external automated power meter control over USB. This can be used as an automatic flatness calibration test system functionality for cables, attenuators, amplifiers, etc. The DSG3000ʼs standard 2U height is designed to save space when used with the optional rack mount kit.
Offering remarkable value for the money, the DSG3000 Series RF source is ideal for applications in wireless communication, radar test, audio/video broadcasting, as well as for general purpose, educational, and consumer electronics needs.
DSG3000 Signal Generators are made by RIGOL Technologies, a rapidly growing test and measurement company and the worldʼs second largest oscilloscope manufacturer by volume. RIGOL delivers high quality, high performance and value-priced test equipment for engineers, technicians and students worldwide. Offered with a remarkable 3-year warranty, the DSG3000 series is available now from Saelig Company, Inc. 1-888-772-3544 email@example.com
Saelig Announces Economical 3GHz/6GHz RF Signal Generator Series - [Link]
mcuoneclipse.com explains how to use the HC-06 Bluetooth Module. They write:
After my first post using a Bluetooth module, things have evolved a bit. The challenge with these Bluetooth modules is: they look the same, but having different firmware. I did not fully realize that until I have ordered another bluetooth module from dx.com: That module comes already on a carrier, so I assumed I can use the same driver as for my other module. I was wrong :-(.
HC-05 or HC-06
My earlier module which I received from another source (without an adapter, see this post) has a different firmware on it, known as HC-05, while my DX.com module has a HC-06 firmware. To be clear: the modules are the same, but the software/firmware on it is different, and the firmware uses the pins differently too
Using the HC-06 Bluetooth Module - [Link]
Admittance control, movement of goods, tickets for various cultural events and sport matches, travel tickets, parking,… thanks to a permanently lower price and bigger possibilities of RFID cards (tags) the Mifare system (13,56 Mhz) in various variations runs forward even to segment where an older 125 kHz system didn´t suite. Complete RFID solution for a very affordable price, it is a short summary of RFID modules features from company Stronglink, which we already introduced to you in several articles.
Group of modules SL03x – SL030, SL031 and SL032 represents complete OEM RFID modules with antenna integrated on a PCB, intended to be built into an end device. All these three modules support Mifare Mini, Mifare 1k, Mifare 4k, Mifare Plus and Mifare Ultralight. SL032 further supports also the DESFire protocol. SL030 has an I2C communication interface, while the SL031 and SL032 have a UART. Modules are controlled by a set of simple commands, thus an integration into a device should cause no troubles even to less-experienced developers.
Thanks to a close cooperation with a producer, we aim to keep a sufficient amount of STRONGLINK RFID modules in stock.
SL030, 031, 032 … Mifare RFID available for you - [Link]
Ever wondered how they transmit your TV signal?
David Kilpatrick from TXAustralia takes us on a detailed tour of the old decommissioned 10kW analog TV transmission system at the Artarmon facility in Sydney. It is still used to transmit digital TV. How it all works from the broadcaster video input to final transmission output up the 180m broadcast antenna. Plus some teardowns of the old equipment that’s been used to transmit the Channel 7 TV signal in Sydney since 1981.
Copper rigid coaxial lines, waveguides, filters, splitters, combiners, converters, transmission valve, power supplies and all the equipment necessary to transmit a 10kW analog or digital TV signal in a major city like Sydney.
EEVblog #569 – Tour of an Analog TV Transmission Facility - [Link]
This project is car hands free that retransmits the audio signal from a cell phone to the FM broadcast band. By placing the cell phone’s speaker near the microphone, the user can use the phone as a hands-free device while driving.
MAX2606 – Hands-Free Car Kit for Cell Phones - [Link]
A small, simple AM receiver project. This AM receiver can pick up medium wave stations in your area
This circuit can use general purpose transistors, and in this example there are 3 BC109C transistors. In this schematic and BOM there is a 200uH inductor and a trimmer 150-500pF capacitor, though these parts can be salvaged from an old AM radio, to preserve the directional nature of a tuning coil, and an adjustment knob (plate capacitor) that work well for radio reception.
The 120k resistor is for regenerative feedback between the Q2 NPN transistor and the input to the tank circuit. The value of this resistor is important to the performance of the entire circuit. In fact, it may be better to replace the fixed value with a variable resistor paired with a fixed resistor to adjust the oscillation and sensitivity of the circuit. All the connections in this circuit should be short to minimize interference.
Performance of the circuit will vary depending on stray capacitance in your layout, the inductor winding/core/length, etc. Changing values of some of the capacitors, or adding them, as well as a potentiometer in the feedback loop can help with the performance of the receiver. With such a small circuit that is affected so much by its construction and its environment, a lot of hand tuning and experimentation will be fun, instructive, and possibly necessary to make it work best.
Simple AM Receiver Project - [Link]
This is a VCO FM Transmitter with range 500m – 4km depending on antenna used
- Power supply: 12-14 V stab., 100 mA
- RF power: 400 mW
- Impedance: 50-75 ohm
- Frequency range: 87,5-108 MHz
- Modulation: wideband FM
FM VCO Transmitter - [Link]
By Bill Schweber:
In a wireless design, two components are the critical interfaces between the antenna and the electronic circuits, the low-noise amplifier (LNA) and the power amplifier (PA). However, that is where their commonality ends. Although both have very simple functional block diagrams and roles in principle, they have very different challenges, priorities, and performance parameters.
How so? The LNA functions in a world of unknowns. As the “front end” of the receiver channel, it must capture and amplify a very-low-power, low-voltage signal plus associated random noise which the antenna presents to it, within the bandwidth of interest. In signal theory, this is called the unknown signal/unknown noise challenge, the most difficult of all signal-processing challenges.
Understanding the Basics of Low-Noise and Power Amplifiers in Wireless Designs - [Link]
This is a small circuit with two maxim’s ic, MAX4467 as microphone amplifier and MAX406 as VCO FM transmitter. It’s suitable for short range FM transmittion aka wireless FM microphone.
Here is a very simple, inexpensive and interesting project which provides lot of fun to a home experimenter or hobbyist. This simple transmitter can transmit speech over a short range. It can be used as a simple cordless microphone. The circuit uses two integrated circuits from Maxim. IC1 a MAX4467, is an amplifier raising the microphone signal to a level suitable for frequency modulation (FM). IC2 is a voltage-controlled oscillator (VCO) with integrated varactor (a.k.a. varicap diode).
FM Transmitter MAX4467 & MAX2606 - [Link]