Questions tagged [radio]
Radio is the technology of signaling and communicating using radio waves. Consider using the rf (radio frequency) tag.
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How can radio LCR circuits help read FM signals?
I just read about the application of LCR circuits in radio tuning in my textbook. The book does not go into much detail so I had to search for most of the information online.
Here's what I understood -...
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Do radios need a minimum range to function properly?
I'm going to use some well-known radios (nRF24L01+) to wirelessly read some voltage/current sensor data over little distances on a quad-copter since the drone is quite populated and we don't want to ...
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Is there a limit to how much power could be transmitted wirelessly?
This question kind of goes back to Nikolas Tesla's ambitious project of transmitting power wirelessly. I know that project failed for multiple reasons, but my question is more straight forward. I know ...
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Heising Modulation Reactor Inductance [closed]
I am trying to build a simple 5W tube Radio AM transmitter using Heising modulation. There is one thing I don't understand though. Does the inductance of the Heising reactor matter as long as it's ...
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Placement of ferrite choke in detector circuit
While reading through the RCA Receiving Tube manual, I came upon this circuit:
This is a tube-based grid-leak detector for a radio. Why is the RF choke placed in the signal path rather than '...
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Can radio waves be focused to a point using a phased array?
I've seen many examples of ultrasonic phased arrays being used with non-linear phase relationship between elements to concentrate all the power at a specific point, for example here:
...
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Communicating 1/4 miles without Wi-Fi. (I want to design a driveway alarm.) [closed]
We live in a very rural area of Ohio. Our driveway is 0.25 miles (400 m) long. I would like to design an alarm that will alert us when someone turns into our driveway.
The easy part is the optical ...
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How exactly does RF to IF conversion work in an AM radio?
I am currently researching AM radio detection circuits. From my understanding, RF is received, amplified and converted to an IF(455khz for AM) before being converted into an audible frequency for ...
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P2P communication: maximum range for low power & low bandwidth
I've started a little side project with the goal of tracking my cat's location in real time.
To transmit the GPS-data, it seems like I have two options: I can either use cellular communication or (...
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Accessing the FM 19kHz Pilot?
How can one attach an oscilloscope probe to the mono mode output of an FM station to pick up the 19kHz pilot (normally used for stereo)?
Is it expected that FM tuners such as the RDA5807 will, in mono ...
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Audio engineering: amplifying two different sources
I've started a small project to renovate/rebuild an old record player for my wife. I have a degree in Electrical Engineering, but it's been almost 15 years since I last had to project/build a circuit, ...
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How can an audio signal with varying frequency be modulated using FM? [closed]
An audio signal can have varying frequency and amplitude and both are the part of the information. As I understand it, frequency modulation is a technique where the frequency of the carrier wave is ...
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how do tube filament resistors work on this Type 10?
picture source: "Building a 1929 style TNT Transmitter", The VE7SL Radio Notebook, 2009 https://qsl.net/ve7sl/tnt.html, originally referenced from the 1929 ARRL Handbook
I don't know how ...
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Sending control signal via FM
Is it possible to send different signals to a receiver using FM which then the receiver would be able to distinguish between and do a set act based on the signal? How to?
For example, the transmitter ...
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Crystal radio antenna question
I am trying to make crystal radio.
I have almost everything I need (magnet wire, high impedance headphones, germanium diode.) The only thing I am missing is the antenna.
I know that if I want to ...
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Why do we need a diode in an AM demodulation circuit?
The incoming signal is a modulated carrier wave, right? If we only apply a low-pass filter to it, we will get an AC signal that can be passed to a speaker directly, right?
Using a diode, we end up ...
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Wideband Dipole Antenna Ideas
I am home brewing an FM radio and have this so far. It works great for stations within +-5 MHz of my antennas resonance, but I want to hear more stations farther away on the spectrum. For this reason ...
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Why can I hear a radio station when probing with oscilloscope? [duplicate]
I assembled this on a breadboard:
and am hearing a faint buzzing sound...
My first question is, what could be causing this sound? It does not go away if I connect VIN to ground. With or without VIN ...
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Difference between radio transmitter roll-off and bandwidth-time (BT) product
For any radio transmitter, the output signal will likely have a shape filter to manage bandwidth. However I am struggling to understand the relationship between a roll-off (e.g. 0.35) and a bandwidth-...
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Can two interfering light beams create radio waves?
Two sound frequencies differing in only a few hertz can create ‘beats’ and this has been popularized in music designed to produce ‘binaural beats’. Can two lasers be tuned in a similar fashion so that ...
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How to terminate a monopole antenna
There seems to be some debate on emphasizing the importance of impedance matching for maximum power transfer vs maximizing signal to noise ratio with receiving antennas. Some vote for one, some state ...
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How many independent test transceiver modules are truly required for MIMO testing?
In most if not all of the app notes I have ever seen from the major test equipment vendors, such as R&S and Keysight, it is strongly implied if not explicitly stated that in order to do an NxN ...
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Do sidebands exist physically?
This is a concept that has puzzled me for a long time:
from the Wikipedia: "In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency"
My ...
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Must LC resonant frequency be identical to oscillating frequency in RF circuit?
I am developing an RF circuit for 503.3 MHz. It will be an AM RF transmitter. The LC circuit I built into this circuit consists of L = 0.1 μH and C = 1 pF.
The carrier frequency which carries the ...
user321220
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Why does this AM radio circuit not work?
I have been trying to make an AM radio over the last couple days and am very confused as to why this circuit is not working. I found the circuit on this website
and I saw this video
on this design. I ...
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Rewinding a Tecsun AN-100 MW antenna for LW application
The antenna has a diameter of 23cm. It is 0.8mm diameter wire, with a total of 30 turns.
The primary winding is 360 µH with a variable capacitor for tuning with a capacitance between 5.3 pF and 280 pF....
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Is it possible to receive an FM signal without a tank circuit?
I was broadcasting FM signals at MHz frequencies in my room. I know that an AM radio will not work to receive FM transmissions.
The special issue is that an AM radio can get any AM signal without a ...
user321220
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Piezo electric buzzer as a crystal earpiece? [closed]
Making a foxhole radio, saw on https://rimstar.org/equip/crystal_earphone_earpiece_for_crystal_radio.htm
can you actually use a buzzer as a crystal earpiece?
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How can VHF signal be amplified with respective gain by simple BJT circuit design?
I am studying RF amplifiers. Most of the time, when I simulate several BJT amplifiers at a very high frequency, I do not get a good voltage or current gain. I have heard of Miller effect. What does it ...
user321220
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Why use a loopstick rather than a choke for MW radio frequency reception?
For reception in the medium wave range (500-1600kHz) a ferrite rod (loopstick) has a measured inductance of Lc=2mH and a resistance Rf=5 ohms, whereas an RF choke with Lf=2mH has a resistance Rc=8 ...
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Problems with regenerative receiver circuit
Im trying to build a regenerative receiver, that is supposed to receive a ASK/OOK modulated signal. but there are a few problems. Keep in mind this circuit might be horrendous, but it's just a proof ...
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Where is the transmit power of antenna in RF circuit schematic calculated?
I want to measure the transmit power of my AM modulated RF circuit. Below is the RF circuit from LTSpice. Should the power be calculated at nodes R5 or C3? Which node can serve as an antenna? The ...
user321220
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Why won't the TL084 amplify the RF output of a tank circuit?
Specifically, if a circuit can amplify a 10mV (10kHz) injected sinusoidal signal to about 6V, why does it not amplify the 10kHz RF output of a L-C tank circuit?
The tank circuit below has a resonant ...
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RF signal chain gain
In conventional electrical signal chain design, we now exactly what is the amplitude of signal in any node, from source to load. In radio frequency circuits which contains antenna. We don't know the ...
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Wi-Fi radio without an antenna [closed]
I'm mostly unfamiliar with radio, but I've read that you will eventually fry a transmitter if you operate it without some kind of antenna or at least a dummy load attached to it.
The question is ...
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I am trying to building an AM radio using SMD components [closed]
I have a lot of SMD components, and I would like to build an AM radio using these components. I tried to search for radio circuit SMD, but doesn't exist. Is it possible to do so?
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Ferrite Loopstick Antenna Grounding
I've built a simple tuned frequency radio based a description in Ronald Quan's book. I have two questions about the tuning part of the circuit. The radio has a ferrite core antenna with two separate ...
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Does adding DC offset to RF output signal affect the range of RF transmission?
Does adding DC offset to AC output signal affect the range of RF transmission?
Adding DC offset does not magnify the AC signal, it is just an offset with more power for the output.
I had once asked a ...
user321220
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What is this type of radio aerial called?
I need a replacement aerial for my FM radio, but I can't seem to find the right type. I suspect that this type of aerial has a name. It's telescopic, and has a joint so that you can angle and rotate ...
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Soldering the AUX IN cable to the JVC KD-161 radio
I soldered the AUX IN cable as in the diagram, added capacitors. In the diagram, pin 4 is GND. I insert a CD with a silent recording and unfortunately nothing comes from the smartphone. I will add ...
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How can a Faraday cage absorb and reflect waves, yet antennas mostly absorb and can be used on signals?
I understand they are very different in structure but comparing a simple monopole to a Faraday cage, they both are constructed from metal. Why is it the sides of the Faraday cage absorb the waves and ...
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Why are signals reflected from an antennas dish as opposed to being absorbed?
I am trying to learn in the area of electromagnetic noise ect.
I see online that a Faraday cage can work without been contected to ground (like the ones found on radio PCBs.) It sort of makes sense to ...
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SRIX4K Emulator - ASK transceiver
I'm trying to build a simple SRIX4K emulator using an ATMEGA328p, I found this circuit on the internet, and it should work as a simple ASK transceiver, using the MCU to transfer data using the SRIX4K ...
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Does the law of reciprocity hold true for the phase response of an antenna?
I know that an antennas spectral transfer function should be the same in both transmit and receive due to the law of reciprocity, however does this law hold true for the phase response (AKA phase ...
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Demodulation of FM signal frequency
After playing with homemade AM radios, I noticed that it is boring to broadcast AM signals all alone. I have also noticed that the AM stations around us, are so limited that I had no other chance than ...
user321220
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Review of PCB RF Design
I designed a 4 layer RF board with the NRF24L01+. When I got the boards in to test I was not able to establish a radio link with some other NRF24L01+ modules. I have attached my schematic and board ...
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If my radio is tuned to a slightly different frequency, should the audio be largely inaccurate?
So we may have a radio station on AM 1400, or AM 1450, or it can be FM 96.5 or FM 98.1.
My question is, it seems the "1400" means, we pick up a signal (either 0 or 1, or an amplitude) every ...
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NF (Noise Figure) calculation - task
In a 622 Mbps radio-link interface, it was assumed that the BER would
be 10^-10 when the signal-to-noise ratio at the receiver point is 7.8
dB, while its sensitivity for a fixed modulation-code scheme ...
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Debugging an automotive FM transmitter
Transmitter is a 12V automotive audio-to-FM transmitter unit. Belkin Tunecast F8M066.
Receives both power and audio fine over the cables into the unit as measured on the board. 7.6 MHz crystal is ...
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Is this circuit for attaching an amplifier to crystal radio going to work? [closed]
This is a circuit I created and I was wondering if its going to work, by the way I am new to electronics so if you see any obvious mistakes please let me know.
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