Questions tagged [radio]
Consider also the rf tag.
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45 views
Explain The Radio Receiver Diagram [on hold]
Hello I am curious about radio. But I don't know how a capacitor, diode, amplifier and receiver works in radio. I want to know how they work technically.
For example, describe the components using ...
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1answer
47 views
How does adding more coils to an AM tuner coil allow it to tune Shortwave?
I have seen several tutorials about how to turn an AM radio into a Shortwave radio. They add more coils to the inductor (is that the correct name for the tuning coil?).
Here is one example,
https://...
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2answers
91 views
Why FM has larger range than cellular network [closed]
I can receive FM signal about 50km away from the transmitting station but I lose signal from cell towers in about few km (1-3km)
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0answers
49 views
Transitor Aerial pre-amp for an old valve radio (see edit blow main text) [closed]
Please suggest an available RF transistor type that could operate in MW bands to boost the aerial signal to an old battery valve radio. LT of 3V is available as is an HT of 90V
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36 views
Active phased antenna array for Wi-Fi efficiency compared to a directional antenna?
I'm interested in mesh networking of poorly controllable autonomous aerial vehicles (like blimps), so i wonder whether it is viable to use a phased antenna array versus a few traditional directional ...
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1answer
28 views
Radio Telescope Rx/Tx resolution
Very simple question. If (say) a 65m radiotelescope obeserving at 5cm (6GHz) has a resolution of about 1mRad, if it becomes a transmitter at that frequency does it radiate a beam of the same ...
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0answers
50 views
Locate objects within a bus using RF signals
I am designing a tracking system for transportation services (mainly buses for now). There will be a host device(s) on the bus and small tags on the objects needed to be tracked. I need to know in ...
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3answers
79 views
Is a modern radio wave broadcasting station a very fast spark gap transmitter?
In a spark gap transmitter, is that a "real" radio wave that is produced? I know you can hear it on an AM radio, if you are close to the gap, but is it a radio wave the same as from a radio station? ...
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33 views
What does (frequency band: 80 MHz to 2 000 MHz; • carrier modulated with 80 % AM at 1 kHz sine wave.) mean in terms of FM signal?
I am trying to simulate a signal (Frequency modulated) with certain specs which i am finding it hard to understand basic terminologies of FM (like which one is baseband/modulating signal, which one is ...
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1answer
119 views
UHF transmitter Range for 50 W
Very curious to know the range of 50 W transmitter of UHF range in nautical miles? The antenna used is 1/4 wave antenna of Jaybeam company. Can someone tell the exact formulation to find out the ...
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0answers
36 views
Derive required carrier to noise or signal to noise from receiver sensitivity on FM receiver
Can I extrapolate the required C/N based on reported receiver sensitivity?
I'm plotting coverage for a repeated radio system for handheld radios. The system is analog, FM narrow band. I've ...
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1answer
52 views
Understanding the Practical Application of a Simple Antenna made from Coax
I am here today to gain a deeper understanding of the fundamentals of using antennas in RC applications. I am trying to understand what exactly is going on with a particular 2.4GHz receiver a picture ...
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1answer
57 views
EHF RF Transmitter and Receiver
We are working on a blood glucose meter that will measure BG readings through radio waves with a frequency between 60-70 GHz.
That range is necessary to allow penetration through the tissue and we ...
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1answer
31 views
True near field distance for a short monopole antenna
Antenna properties:
Height x Diameter = 3.3 inches x 1.4 inches
Test Frequency: 900 MHz
(Wavelength = 33 cm or 13 inches)
I see some conflicting formulas to calculate the near field distance for ...
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0answers
10 views
HM-TRP radio module works at 56K data speed but only in delayed chunks
I created the following setup:
I created one circuit in which the PC connects to an HM-TRP radio module via a max232 DIP IC. This circuit for the test is the master to all devices and sends a 16 byte ...
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2answers
186 views
Is a regulator necessary?
Sorry for the provocative subject line. I was looking at using one of those integrated ESP32 + SX1276 + SSD1306 boards (there are a few that have popped up) in a battery powered application. I would ...
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1answer
46 views
RF Combiner Losses
I'm having a hard time understanding what is actually achievable with an RF combiner.
Let's consider this scenario, here port 1 of the RF combiner has a sinusoid at f1=100Hz and port 2 has a sinusoid ...
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1answer
45 views
How to test an RF crystal oscillator performance integrated into a Cellular radio?
I have a couple of reference designs with 2 different crystal oscillators integrated into it. These are cellular radio and can generate standard LTE QAM signals out of it. But I do not have access to ...
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3answers
117 views
Can I apply gorrila glue on to a AAA battery to attach a wire to it? [closed]
I am repairing a old CB radio I got at a yard sale and I'm powering it with 2 AAAs and a 9 volt. I have to attach a wire to all of the ports, and tape isn't very effective. I'm wondering if it it safe ...
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3answers
142 views
Radio Transmitter Circuit [closed]
I have seen previous similar answers about radio transmission, but looking at the following scheme I am not sure about the role C3 plays in the circuit. I guess it is needed to remove the DC signal ...
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1answer
17 views
Regulated power for radio module HM-TRP. Is config correct?
I'm trying to figure out how to make a nice power supply to the radio module HM-TRP.
I heard that running certain voltage regulators with capacitors having high ESR values is a bad idea and will ...
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0answers
54 views
Crystal Radio Help
Me and my uncle have been working on making a crystal radio for the last few days and have had no success. We have used multiple designs but none of them seem to work. This is the one we've been ...
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2answers
62 views
Question on Use of Y2 Saftey Capacitor in AA5 Style Tube Radio
In a radio I am restoring, there is a 0.1 uF capacitor between B- and chassis, designated as C12. My thought process is that if this capacitor were to fail, I would not want B- shorted to chassis as ...
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3answers
61 views
Use existing WiFi hardware as an RF receiver? [closed]
I have seen mine & many others' (Android) devices nowadays have WiFi hardware capable of connecting with 2.4Ghz & 5Ghz APs. Wanted to know if I could tweak the WiFi driver in the kernel source ...
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0answers
41 views
Will 2 nearby crystal radios affect each other's strength?
I'm working on a project which involves 2 nearby crystal radios. Their cases almost touch each other. They are tuned at different frequencies. I was wondering if they would affect each other's ...
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1answer
51 views
Low power local area radio controller chipset [closed]
I have a project where I need to remotely control up to 128 individual relay boards within a maximum 30 meter radius. I need each of these wireless relay controllers to be uniquely addressable to ...
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2answers
181 views
Are IOT wireless network protocol right for high throughput point to point communication?
I am trying to build a "professional" 2 way point to point radio system (like this) to control a RC 1/10 scale car (like this ) using UART, the challenge I am currently facing is finding the right ...
3
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2answers
454 views
Expected peak-to-peak output voltage of satellite LNB
Anyone know what the output voltage of a typical DirecTV LNB might be?
I've converted an old dish to be a backyard radio telescope and I'm hoping to record output levels with a USB oscilloscope, as I ...
2
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1answer
122 views
Old Radio Colpitts Oscillator? Or not?
I am a beginner hobbyist form Brasil, posting here for the first time.
I am trying to understand the schematic of an old Transglobe radio that my late grandfather gave me. It motivates me to learn ...
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2answers
49 views
Antenna Design for Omnidirectional transmission
I have been working on a custom drone for quite some time now. One thing I have found an issue with is the remote control antenna orientation in relation to the drone. In some directions I will get ...
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2answers
158 views
calculating maximum transmission distance of radio module based on dbm and open air
I own several HM-TRP TTL FSK radio modules, and every time I turn one on, it reports it as being version 2.
Anyways I did read the manual and it has a setting for transmitter power as follows:
<...
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1answer
77 views
What single feature will enable ultra low latencies for 5G communications? [closed]
there has been a recent buzz around 5G and its ultra low latency use cases. Additionally, some people claim that data rates around 10 Gbps are a feasible scenario if mmWaves are to be used.
I was ...
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3answers
74 views
Consistent Radio wave detection timing
Bigger picture:
What do I need to do? I need to send a radio signal and have another device receive that and output a voltage pulse, with the time between starting to send the signal and starting to ...
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1answer
142 views
Dip switch or rolling code garage door opener?
I'm a total noob in electronics field and want to begin. (I'm an IT engineer).
I'm trying to use my remote garage door opener (868 MHz HF) to create a system with my Raspberry Pi so I can replicate ...
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0answers
76 views
Why do I hear static when the radio is turned off?
I've been keeping around and old radio which I use every now and then (last time was about two months ago). One day it just started making white noise. I checked if I might have left it turned on, but ...
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2answers
87 views
Why do rubber duck antennas have this metal part, while other antennas do not?
If you open up a rubber duck antenna, it usually has a wire inside, plus a crimped on piece of metal, like this:
Other antennas, like those on an RC receiver do not have this second metal part:
Both ...
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0answers
32 views
Discrepancies in calculating the edge impedance (resonant input impedance) of a basic Microstrip Patch Antenna
Before I jump to my problem, here is a bit of context.
I have been working on a MATLAB code that can help me calculate all the required parameters for a patch antenna. These parameters are for ...
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1answer
74 views
Ground Plane for Antenna on Carbon
I'm working on a radio module that is made to transmit from a rocket to a ground station for a homemade project. The airframe is made of carbon, therefore I cannot place the antenna(s) inside the ...
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1answer
56 views
In heterodyn receiver circuits, why is the LO not chosen to match the target frequency?
I'm trying to design a device that detects motion using sonar. I'm basing it on a common superheterodyne receiver like this:
Now from what I've read, in radio audio receivers the local oscillator is ...
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0answers
48 views
Why is it difficult to localize shortwave transmissions?
I have read that it is difficult to localize shortwave transmissions, but I don't understand why that is. I know that localizing the bounced transmission is obviously difficult, but when the antenna ...
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1answer
89 views
Radio frequency detection without digital clock [closed]
Is it possible to have a circuit that does something (fires a pulse, turns on a voltage, whatever) when it detects a radio signal at a specific frequency? One crucial point is that it should do this ...
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3answers
98 views
How do I check whether my GSM Modem works in some other country?
I am a new to choosing RF modules and I am trying to choose a module that works in Qatar.
I see on FrequencyCheck, Qatar is having GSM band of 900 and 1800.
So, if I choose GSM800 C, having quad ...
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1answer
48 views
Unbalanced RF output to FEM module with balanced input
I have a working ZigBee system based on ATMEGA256RFR2.
(Datasheet)
On page 33 you can check the RF system of this IC.
Now I want to use a FEM module to increase the performance and I found the ...
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0answers
48 views
need partial resistance to go to ground
Easy question I hope. I am wiring a push to talk system. Pushing the button produces a resistance of 56 ohms at the pin. The problem is, the UHF ham radio I'm installing requires a total ground to ...
0
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1answer
60 views
AM radio Attenuation.
I have built the following AM radio circuit :
I was able to pick several radio stations. I fixed the variable capacitor so that I can only hear the 1230 kHz station which I identified from the FCC ...
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1answer
82 views
How to Bais a tuned rf amplifier and compute I/O Impedances
Can anyone point me in the right direction on how to implemented the depicted tuned r.f amplifier? Since the load resistance at the collector is replaced by the LC tank how does one go about in ...
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302 views
Old Transistor radio troubleshooting
I am repairing an old four band Transistor MW+ SW radio for which a circuit diagram is unavailable. The radio has four RF transistors, four AF transistors and a Germanium detector diode. Suddenly it ...
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1answer
83 views
Upgrade ZN416 Radio on a Chip to two Tuned RF Stages [closed]
looking to upgrade this Radio/Circuit to two Tuned Circuits with another ZN416 not shunting RF to ground butsending it to the nextZN416.
Will be usingAntique /Vuntage Components Variometer; ...
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0answers
104 views
Reading Radio Frequency signal in audacity
I am wanting to read radio signal I captured with my RTL-SLR, I record it in .wav file using SDR#, The Frequency was at 315MHz. I am what I believe is the preamble of the signal, and I would like ...
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1answer
112 views
How to improve design of naive MW AM transmitter for lab demo
I'm trying to prepare small demo for school lecture on radio history.
sorry for confusion, MW here means medium wave, not megawatt :)
And I want to create small and very simple transmitter which ...
