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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Better data encoding for 433 Mhz OOK communication

I'm looking for a Manchester Encoding alternative for 433 Mhz OOK communication. Is 5B/6B data encoding appropriate for this application? It also provides 0 DC voltage average. And it doesn't require ...
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1answer
23 views

How to fix a frequency shifted audio part of an RF signal?

I tried to connect an old Japanese (NTSC, System M) video gaming system (an original Famicom, HVC-001) to a rather modern multisystem LCD TV-set (Sharp LC-43CFE5222E). The TV tuner is capable of ...
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1answer
33 views

RF one-shot circuit capable of producing 5-ns pulse [on hold]

I am looking for a one-shot circuit capable of producing a 5-ns output pulse with short switching time. I saw this one (http://www.nxp.com/documents/data_sheet/74LV123.pdf) in a previous question, ...
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16 views

How can I check a transmitter module for antenna continuity of its connections?

I am soldering a IPX U.fl PCB Mount Socket connector to a FlySky 2.4 GHz module and I want to check that I have proper continuity connection with my soldering. See here where I have more info: ...
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1answer
75 views

how to reproduce a matching network of a vendor

I'm trying to create a board using the BGT24MTR chip from infinion. I noticed that they said that there is a Tx/Txx impedance. To compensate for this impedance they created a matching network. ...
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1answer
43 views

ECL output termination

This is a rookie question, but I'm quite confused about the ECL termination used on the ADCMP565 evaluation board First, in the IC datasheet, they show how to terminate the ECL outputs to drive 50Ω ...
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21 views

RF Power meter how its work [on hold]

What do this mean RF Power meter = -2.645dBm. How does this affect my transmission. and RF Power is 37.6dBm
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2answers
36 views

Adjusting OCXO frequency via VFC pin

I have a used OCXO Morion MV85. According to datasheet linked above, it has GND, VCC or Uin, RF out and VFC pins. As far as I was able to find out by googling, the purpose of VFC pin is to adjust ...
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46 views

What is the coupling coeffecient of a 10.7Mhz if transformer?

Does anyone have a rough range? I just need to be in the ball park. As an experiment, I'm simulating some if amp circuits in LTspice and it looks like they are very overcoupled when using a coupling ...
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2answers
79 views

Is it possible to transmitting video signal on 433MHz? [closed]

A video of 2MP or lesser at a distance of 2-3Km. Is it possible to transmit it on 433MHz ISM band?
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108 views

Ringing at the output of a microcontroller

I'm generating a pwm signal of 125khz, I've no problems with the frequency but the signal has an overshoot: This is a big issue because I'm using this signal to control a dc/dc converter and the ...
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2answers
67 views

RF power meter circuit

I want to setup a radio transmitter and reciever a few centimeters apart and measure the signal strength i get. There will be a filter in between which absorbs particles and the idea is that i want ...
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38 views

Raspberry Pi 2 to arduino RF Serial link with USB to Serial TTL Converter

This is my first question here. I want to have a communication channel which will use a 433 MHz RF TX-RX pair. I want to use a Raspberry Pi 2 as a transmitter and an Arduino Mega as a receiver. Is it ...
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1answer
69 views

How to identify a component on a board?

I am trying to identify a component on a board of my roller shutter remote control. Here is the board: The main component is very likely the one top-right, identified by ...
5
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1answer
140 views

Making aluminium conductive for an RF shield enclosure

I'm not sure if it's appropriate to ask here, but I would assume many people in electronics would have experience with this. I'm enclosing an RF sensitive PCB into an sealed aluminium enclosure. ...
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1answer
120 views

Options for matching 75 to 50Ohms on PCB

I'm collecting information for a project I've got in mind. Clarification: I'm not looking for someone to help me do the calculations. I'm not to that point yet. I'm basically looking for "the ...
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91 views

How to Filter Very High Voltage Power Supply Noise

Any suggestions of how to filter out this noise? Basic filter math is not working out. I am adapting a cheap commercial HV supply (variable DC voltage up to 40kV at 10mA) for physics experiments. ...
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2answers
55 views

Dispersal of radio energy as it moves further away from the source

I apologise for the wording of my question, it will no doubt come across as confusing. If there is anything you are unsure about please feel free to ask me. Question As a radio wave moves further ...
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1answer
68 views

Why does the 802.11b DSSS signal have 22 MHz of channel width? How does the information get spread over that width? [duplicate]

This topic has got me so much confused. In terms of Wi-Fi, when we say the 802.11b has 22 MHz of Channel Bandwidth, what does it mean? When we refer to a particular Channel No. say Channel 1, it has ...
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1answer
39 views

How to make an impedance matched circuit for fabbed antenna?

Okay I have developed an antenna for a system and need to create an impedance matching circuit. The theory of conjugate matching is simple, but actually implementing it is something I can't find ...
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1answer
59 views

“Chamfered” Routing in Eagle

I need to create the following trace in Eagle but I can't work out how to make it go from one width to another across a set distance like below.
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1answer
69 views

Maximum range of 27 MHz ISM band NLOS radio broadcast

What is the maximum range of a 27 MHz ISM band when transmitting at full power? I am interested in general situation for US and EU but that will go back to the power limits allowed. My country (CZ in ...
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1answer
87 views

RF Emissions (Unintentional) [closed]

Hello can a device emit unintentional RF emissions when there is no power supplied to the RF embedded device such as a wireless router ? [UPDATE 1] YES when there is absolute NO power whatsoever ...
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7answers
4k views

Why are RF components and cables still so large?

With the advent of ICs in the past decades, circuits have decreased in size exponentially over time. However, it appears RF components and connections, with coax SMA cable, connectors, and components, ...
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42 views

RF Inductor orientation

In RF PCB design ~1GHz, when should I worry about orientation of inductors in relation to the magnetic fields, I have seen application notes from manufactures where they pointed out, that it was very ...
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2answers
127 views

Boost the signal of an FM transmitter using an “emitter follower” transistor [closed]

EDIT: I've seen an alert under my question: “Please clarify your specific problem or add additional details to highlight exactly what you need. “ Maybe this is due to the fact that I'm not very good ...
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2answers
50 views

How might this RF double pole switch be constructed and perform?

So I'm aware that there are some high speed RF SPDT switches e.g. Single-Pole Double-Throw (SPDT) switch offering 20nS switching time. I'm interested in a switch like the following picture. This is ...
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27 views

the needs of CRC on communication using 3DRadio

I've been designing a system to communicate between an UAV to GCS by using 3DRadio module, and on its page it seems that it already features CRC The ECC parameter makes a big difference to the ...
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2answers
113 views

RF layout good practices

I was during a 868MHz transmitter layout, and as always, I have placed the filter and matching inductors and capacitors in a "straigt line" from the TX output pin to the antenna. See picture below. ...
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1answer
98 views

Optional feature in PCB layout of MMCX board edge connector. What's it for?

I'm designing a circuit requiring MMCX board edge connectors, specifically using the Molex 73415-0961 jack. When looking through the datasheet for suggested PCB layout, I see mention of an additional ...
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1answer
45 views

FCC-approval and “modular” integration

I see that a PCB requires certification even if it incorporates a certified RF module, so EMC tests for spurious emissions will still be needed. Is FCC-approval needed if a Raspberry Pi is ...
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2answers
40 views

I'm confused about how to calculate noise for an SNR? [closed]

My Rx radio is getting -60 dBm but I don't know how to find the noise. My thermal noise is on the order of E-12 so it barely affects my SNR. Where does noise come from and how can I calculate it?
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31 views

Low Frequency signal detector with MOSFETs

Does anyone have any ideas on creating a very basic signal detector (low frequency is fine) with MOSFETs? trying to design a small profile detector. My idea was to use a basic field strength meter, ...
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33 views

Definition of a discriminator output

I want to use a GMSK-Modem (CMX589A). I have trouble understanding the necessary input for this modem. It says, that I should connect the RX-Input of the modem to the output of a frequency ...
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31 views

TX output power and RF range

I am using Atmel ranging tool box for indoor ranging right now. I am wondering why it is suggested to operate at a lower Tx output power. In the user guide, we are suggested to Operate lowest ...
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0answers
14 views

CP antenna module with UART

I am searching for a replacement of XBEE pro S1 XbeeModule with some module with CP antenna (2.4 GHZ IEEE 802.15.4) ? This module should have a UART interface so that can directly connected to my ...
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1answer
34 views

Antenna and balun for MRF49XA

I am trying to do a project that involves proximity detection. I need a few devices omnidirectionally detecting each other at short distance (under 20 feet). It seemed to me that sub-1Ghz RF is the ...
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1answer
25 views

Bluetooth device spurious emissions test

I'm reading an outline of spurious emission test for Bluetooth devices which states that The Equipment Under Test (EUT), a Bluetooth module is switched to a test nullmode in which it ...
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1answer
42 views

Energy Harvesting Primary VDD and Battery Backup VDD power for MCU

Currently I am in the design process of circuitry for my energy harvesting circuit. I am using the CC1110F32 MCU from TI. I am using the Development kit boards that they created for this project. The ...
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117 views

Will FCC EMC tests need to be redone?

In light of the new FCC rules that Chinese (and all non-MRA) labs will no longer recognised in July and all EMC tests need to be done at FCC-authorized Telecommunications Certification Bodies, for FCC ...
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25 views

Pcb trace monopole antenna effeciency calculation

I have designed a pcb trace quater-wave monopole antenna for the 868MHz band. But because the transmitter IC also supports 433MHz, we would like the antenna to be used at this frequency. The feed to ...
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1answer
68 views

RF energy harvesting using UHF and HF from tv, radio and cell towers [duplicate]

I am busy with a project where I want to harvest energy from UHF and VHF such as tv broadcasts, radio and cell phone towers to charge a 100uf capacitor to be able to power a low power appliance such ...
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2answers
252 views

Any idea on what this component is?

It's an 0402 sized component. Measures about 50 milliohms out of circuit. I also measured it with a cheap LCR meter and it shows -47nH. Capacitance measures 350mF. So I'm pretty sure it's a jumper. ...
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1answer
35 views

'Filtering' a modulated signal

The pictured circuit comes from Build Your Own Transistor Radios: A Hobbyist's Guide to High-Performance and Low-Powered Radio Circuits (2012) by Ronald Quan, p. 73. I am puzzled by Quan’s ...
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2answers
59 views

Calculating RF attenuation through plastic container

I need to provide a customer with an analysis for the maximum range of transmission for a wifi system. I have a raspberry pi with an XBee transceiver module on one end and a laptop with an XBee ...
2
votes
1answer
30 views

Power output by an RF switch

I am using the PE42423MLBA-Z RF switch. I am trying to get an idea of the output current given by this chip. Now E = Sqrt(P)*R. E =5V, R = 50Ohms. So, P = 10mW. But, this is a switch, that merely ...
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1answer
24 views

possible to you add an external RF PA LNA to a chip that internal ones?

I'm working with a new generation of a wireless chip that now has a built-in PA and LNA. The trouble is that its sensitivity is -92dBm and my old version that did not have internal RF amplifier ...
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3answers
320 views

How can I reproduce ambient EM fields inside a Faraday enclosure?

I am part of a research team looking at the possible effects of EM fields on psychological function. The experiment calls for participants to perform a series of tests while inside a Faraday tent that ...
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26 views

Compact alternative to discone for wideband VHF/UHF reception?

I have a discone antenna and it works great for wideband reception in a stationary configuration. The discone, however, is somewhat unwieldy and would not work well on a car. I am trying to find a ...
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1answer
61 views

How this device “Electronic Anti-lost-Anti-theft-Flashlight” measure distance?

Sorry i don't speak english but ill try. We want to design a system of a receiver and transmitter in RF, that it "beeps" when it is a certain distance one of each other. I found this: ...