Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.

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RF Wireless Help

I'm trying incorporate wireless control into my design rather than have hard wired components due to cosmetics and the installation I have no knowledge whatsoever of wireless apparatus and components ...
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1answer
22 views

Can a PLL work with a sine signal as its XIN?

I need to generate a 150.012MHz signal. I am going to this with a PLL for RF purposes, so I am thinking to buy a 10Mhz osc with a sine output, will this work with all PLLs? as they are digital I'm not ...
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1answer
45 views

RF: Do I need a resistor at line driver output for impedance matching?

I have a digital RF signal (~50Mbps max) passing through SN74BCT25240, a 25-ohm octal buffer/driver. This is on a 4-layer PCB with a ground/power planes and proper bypassing, etc. I was wondering do I ...
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1answer
71 views

Old Radio RF Transformmers [on hold]

I want to make a TV transmitter (http://electronics-diy.com/electronic_schematic.php?id=851). There is an RF transformer on it (T1:4.5MHz 1F-can-style RF transformer) that I want to find it from old ...
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2answers
51 views

How to design a metal plate for PCB

I am designing a Esp8266 based WiFi module, and I' not sure if I need one of those metal plates. They are suppose to protect a sensitive area from EMI/RFI, right? Also, how can I design one with ...
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1answer
59 views

how to determine if system is matched in system

I'm concerned about matching. If you look at the pictures, there is a certain tracewidth optimized for 50 ohm that is then changed to fit the pad of the rf component. How would I measure the amount of ...
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1answer
75 views

Why does EM radiation travel much further than the magnetic field of an equivalent power electromagnet?

If both fall of as 1/r^2 from the source then why can radio waves travel around the world and still be picked up easily at the right frequency but the field from a powerful electromagnet can not?
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4answers
983 views

Why do characteristic impedances matter only when traces are longer than half a wavelength?

Why are characteristic impedances of traces not considered when the traces are shorter than half a wavelength? I've had the same issue with light diffraction, which happens when pinholes are smaller ...
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95 views

Operational Amplifier frequency problem

I am using an operational amplifier in an inverting configuration with a gain of 10. (-R2/R1= 10), with a high cut-off frequency of almost 30 Mhz. However, while testing whenever I apply an input ...
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1answer
45 views

Two rf 433 transmiter and one receiver connection won't work?

This is my problem. I want to transmit from two transmitters and capture data with a single receiver. I bought two pairs of rf433 and was able to transmit data between each of these rx-tx pairs ...
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1answer
88 views

How to amplify a very small signal

I am trying to wrap my mind around very small signals; what they mean, and how to amplify them. For example, here is a screenshot from my cell phone. Notice the signal level received is -97dBm. ...
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1answer
38 views

Wireless amplifier antenna

There is something like an antenna that works like an amplifier, repeating every signal in the device frequency operation range but wireless. I mean that this "dumb" active antenna receive every ...
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25 views

How do I sniff packets with a Zulu chip based on Si1000?

Tried to ask the question in another SE but was directed here. I'm trying to sniff the communication between Z-Wave devices. I've set up a "smart home" consisting of a few devices using Z-Wave ...
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1answer
59 views

XBee Synchronization

I am using 64 XBee modules (XB24-Z7UIT-004) as sensors and I am trying to synchronize all the modules to execute a command all at the same time. What happens is that it takes about 500ms to send the ...
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1answer
63 views

Will coiling a mains power electrical cord cause interference?

I am a maker working on a lamp design in which a decorative power cord is wound through the structure, creating a coil down the lamp's main structure. The coils are about 3cm apart and the same in ...
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0answers
63 views

Who has manufactured this IC?

This is a RF receiver IC from a cheap Chinese radio controlled toy. I am not able to figure out whose logo this is.
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1answer
39 views

impedance matching and impedance briging

Why in RF receiver we need impedance matching for maximum power transfer but not maximum voltage? And why there is no Impedance matching or Power matching in audio engineering? Is it depends on the ...
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0answers
60 views

60 dB gain at 20 MHz

I am designing an IF amplifier circuit that needs roughly 60 dB of gain at 20 MHz. I was considering a cascade of 3 x 20 dB MMIC gain blocks but I am wondering if there is a better way? The ...
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1answer
66 views

RF coil impedance matching inconsistant result

I'm trying to do impedance matching from a signal generator (60MHz with 50ohms impedance) to a copper wire coil (6 rounds). The coil is connected by a wire (~6 meters long) with resistance 0.9 ohms. ...
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1answer
66 views

How do you implement wifi with a front-end chip?

I was looking around for a solution to hook up an application with an MCU to a wifi network. I'm basically looking for a chip that can talk to my MCU via an interface like I2C or SPI and is able to ...
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1answer
38 views

Should there be more clearance on RF vias with microstrip?

I'm routing an RF board ( above 1 Ghz) with microstrip lines. Our plan is to feed it from the backside, take it through the via onto the top layer and continue routing. as part of our rules we pull ...
8
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1answer
124 views

what are tuning dots and how to effectively use them

I've come across some template designs that have tuning dots included for RF matching. Unfortunately they are using a different dielectric than I am. What are the basic principles of tuning dots ...
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0answers
16 views

Max RF Chip SPI speed LT8900

I'm using an LT8900 chip for RF communication. I can not use the chip on a high speed and only on Maximum of 2Mhz. The datasheets say "CLK frequency range (SPI) FSPI 12 MHz" so why don't I see ...
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2answers
799 views

RF Energy Harvesting

Why can energy invested in RF radiation not be harvested fully? What are the main factors that affect this? Is there any significant research nowadays that fully describes this process? I stand on the ...
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2answers
127 views

Amplifying a high frequency signal of 30 Mhz or above using OpAmps

I am testing a 34 Mhz amplifier in an inverting configuration with a gain of 20. The cutt-off freqeuncy of amplification stops almost at 15 Mhz , which is very low. I want it to continue up to 27 ...
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1answer
54 views

Can you implement WLAN on a ZigBee chip?

I've spent my afternoon browsing around the web looking for a microcontroller that has integrated WLAN (802.11), but I haven't managed to find any on the market. There are lots of cheap ...
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49 views

Demodulated I/Q signals are “flipping” in test setup

Background: I'm testing an RF demodulation board to make sure I understand its operation correctly. Prior to introducing signals from the actual application, I am generating known I/Q signals from a ...
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3answers
113 views

What are the basics I need to know to power LEDs with RF at a range of 30 feet?

I would like to light up a path in the woods with hundreds of LEDs using RF. The idea is that I would carry a RF transmitter powerful enough to light LEDs. As I approach the LEDs would get brighter, ...
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1answer
34 views

How to identify when a pulsed rf supply is active

I have a signal that consists of a 13MHz RF signal inside a pulse envelope (around 100ms on, 300ms off). I want to convert this to a 0-5V pulse that will just tell me when the primary RF signal is ...
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1answer
50 views

Two way communication between two arduinos using rf modules [closed]

I have two arduinos. I am trying to communicate between them in both direction (A to B and B to A) using 433 mhz rf modules. I am switching the operations so as arduino acts only as transmitter or ...
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1answer
25 views

Match impedance and net dimensions of RF power amplifier

this could sound a repeated answer but to me it seems to be not so trivial. Or at least, it is so due to my ignorance. I need to use an RF6886 power amplifier to interface it with a 50 ohm antenna. ...
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2answers
41 views

How to implement TDMA with basic 433MHz transmitter receiver pairs ?

Is it possible to use TDMA or some kind of time synchronization / psuedo random coding for a number of transmitters so that they can be interfaced with a single master receiver without jamming?
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2answers
51 views

RF Communication [closed]

My friend and i have a project. We should make a rf communication system in mines. This system should run from 1km distance. It will send and take cryptic information. Mine's shapes are variable. We ...
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44 views

Disciplining a TCXO from a broadcast reference source

In the UK (and much of europe), a broadcast time and frequency reference is available in the form of the MST radio time signal. This is broadcast using on-off keying on a frequency of 60 kilohertz, to ...
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3answers
135 views

Possibility of an extremely directional antenna

I'm fairly new to RF technology, but a direction-finding application has come up where a highly directional antenna can offer a convenient solution, so I started searching for such antennas. Most, ...
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5answers
2k views

Forgot to put a via near bypass capacitor, and now the boards have been fab'd - what can I do?

I goofed and didn't notice this until the board was already fab'd and assembled. The board is an RF amplifier; the portion I have pictured is a part of the DC control pat (so no RF is nearby but we're ...
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1answer
121 views

Should the unused areas on the top layer of my RF PCB have ground pours?

I realize there are some questions that are related to this topic but I didn't see any that are really RF specific. I am working on a 2-layer Bluetooth module and I have some unused spaces on the top ...
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25 views

TI RF solution - MSP43x+CC1100 vs. CC1110, toolchain

I'm looking for low-power RF solution working in sub 1GHz band (868MHz, battery powered, mostly sleeping). Originally I considered AVR with Digi Xbee 868LP module but doing deeper research I found TI ...
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1answer
42 views

900 MHz I/Q Direct Conversion SDR

I am in the process of designing an SDR and have completed a block diagram of its architecture. Before proceeding with more thorough component identification, I was hoping to receive confirmation that ...
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1answer
31 views

MX-FS-03V one transmitter to many recivers

I want to use MX-FS-03V RF module as single transmitter to many receivers. As this module sold as pairs I don't know if this works or not or any trick to do this. i think the screw on the module ...
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1answer
52 views

Detection of the 3G network

Is it possible to detect a 3G mobile network without having the orthogonal code or the spreading code used in 3G? By detect I mean pick up the radiated radio frequency from the mobile phone then see ...
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1answer
121 views

Best communication option for multiple arduinos?

my father and I want to develop a cow pedometer to measure cows activity. The idea is that if you can measure a cow´s activity you can detect when she enters heat. Detecting heat with sensors will ...
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1answer
94 views

Getting GPS coordinates with GPRS/GSM module

I'm trying to understand if I can get GPS coordinates using only a gprs/gsm module. Probably I can do it by triangulation using BTS on the terrain and based on the RF signal but is that possible? ...
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1answer
46 views

Issues with RF transmitter project

I've constructed a RF transmitter circuit and have been getting numerous problems. after modelling the circuit on a breadboard and testing it we got unexpected readings. these include 411.5hz ...
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23 views

Transmit distance (Frequency)? [duplicate]

How frequency affects the signal transmit distance? Is there any equations that describes this? I know that input power is important factor, but what about frequency?
6
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1answer
556 views

Why are the capacitors set up this way in this old tube radio?

I'm trying to figure out what's going on with these capacitors, so I can replace them in an old tube radio, but why are they connected in this way? simulate this circuit – Schematic ...
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2answers
164 views

RF Receiver for 433mhz and 315mhz?

I have a XD-RF-5V receiver wired to my Raspberry Pi listening with RFSniffer (433Utils). I also have a XD-FST 433.92mhz transmitter wired to my Raspberry Pi running codesend (433Utils). I can ...
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5answers
87 views

Does increasing the amplitude of a signal also increase the data rate?

I face an ambiguity when considering the carrier frequency, signal frequency, bandwidth and data rate. When I consider the Shannon formula, I wonder if increasing the transmission power also means ...
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2answers
31 views

Dipole antenna VS. coil for RF transmission or recieving

Correct me if I am wrong, but all RF light waves are created via a changing electric and magnetic field. But when looking at all kinds of radios and RF circuits, this light wave is always made with a ...
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1answer
56 views

Reliable way to transport data over 1-2 km distance

I am looking for some way to transport data (around 3000Kbps) omnidirectional. Transmitter should not weight more than 300 grams but receiver can be much heavier. The range I am trying to achieve is ...