Questions tagged [frequency]
Use this tag for questions about which frequencies to use or not use in certain locations/situations.
69
questions
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GMRS not transmitting within a half mile
I recently got my GMRS license from the FCC, and I wanted to try out a couple radios for hiking and emergency communication. I have two tenway UV-5R pro radios (these do have an FCC ID) that are set ...
4
votes
2answers
71 views
What causes the light and dark bands (of background noise) in an HF waterfall display?
While monitoring the 40-meter band (among others) throughout a typical day/night as propagation changes I have noticed there are often bands of very low noise (black area) and others with much higher ...
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1answer
55 views
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2answers
107 views
Full Duplex Radio Communication On a Single Frequency
I am an ELECTRONICS final year student and I am working on a project, "Full Duplex Radio On a Single Frequency". So is it possible to design such a project. If so then give me the idea about it, how ...
0
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1answer
90 views
Locate a ball 1000 times a second
I want to locate a small ball in the air 1000 times a second. The ball is thrown from the ground and then flies in the air for 0.5 seconds until it lands. Distance from the location instrument is 1 ...
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0answers
97 views
communication with underground mines?
I have a meter that will analyze limited RF spectrum in my area. One frequency that keeps coming up is 2.498 kHz. An FCC site listed that as the frequency used to communicate with underground mines. ...
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0answers
52 views
Can my neighbors ham radio station be preventing my TV antenna from proper reception? [duplicate]
I have a winegard 8200 series antenna and it worked flawlessly in getting me reception of more than 70 stations. The wind blew it down and I couldn't replace it for about 6 months due to the fact that ...
3
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0answers
93 views
GnuRadio RF transmission, legal and safety issues
I'm trying to run some transmit/receive RF examples that I found online using GNU Radio with USRP B200. I read and heard about some cautions in terms of transmitted frequencies here in the USA which ...
5
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4answers
2k views
How does a receiver know the exact frequency in the channel to “listen to”?
I am reading about how radio communication works and I have an unanswered question.
We have wideband channels with 25kHz of radio spectrum. The transmitter modulates a signal and sends it.
The ...
3
votes
3answers
130 views
Applications for 100 GHz band?
I was reading this paper and I found it very interesting and the following question came up,
What are the main applications (what is used for) 100 GHz band?
I couldn't find any reference on what is ...
5
votes
2answers
69 views
Why do receiver sensitivities vary so much with frequency?
I was looking for a 2.4 GHz WiFi antenna to catch a weak free WiFi signal, and amplify it so I can use it. I found Ruckus Metroflex NG, which can receive signals down to -108 dBm. Which is amazingly ...
4
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3answers
190 views
What are these antennas used for?
I noticed this antenna park in Heidmoosstrasse, Switzerland. What is it used for?
4
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1answer
252 views
What are Radio-location Services in the 1.9-2.0 MHz range?
I'm currently studying for the General Exam and in looking at charts of the new frequency privileges have run across a restriction I would like to have further defined. In the 160 meter band the books ...
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1answer
55 views
Can radio waves be made to travel as or along a particle beam? [closed]
Can a laser be used as an antenna?
Can a beam of any type extend transmission distance of an electromagnetic field?
https://medium.com/starts-with-a-bang/this-is-why-the-2018-nobel-prize-in-...
5
votes
2answers
761 views
What is the frequency range 2300-21950 kHz used for?
I was checking out the gizmo mentioned in this question, and I see that it can receive "shortwave" in the frequency range 2300-21950 kHz. Most times I see "shortwave" mentioned, it's by sales or ...
5
votes
2answers
519 views
What is inside a 50 ohm termination?
I see RF applications requiring 50 ohm termination to avoid any open port reflections. Curious what is actually inside a 50 ohm termination connector. Is it simply a 50 ohm resistor? But then it is ...
5
votes
1answer
167 views
Can my laptop pick up CB radio frequencies?
I was on my laptop watching a show and I paused to look something up and since there was no sound I could hear a voice talking. It sounded distorted like it was coming over a radio and I couldn't make ...
8
votes
2answers
281 views
Why do the ham radio bands get broader with increasing frequency?
The ham radio frequency allocations tend to comprise a larger frequency range for increasing frequency (also see this plot). For example, the 40 meters band is from 7,0 to 7,2 MHz, thus 200 kHz, while ...
2
votes
3answers
187 views
Radio Range vs. Frequency [closed]
Let's say you have two mobile simplex transceivers running on (for example) SSB. Mobile means that the antenna height and TX power have limitations. Say if we limit the Antenna height to 2m and the TX ...
8
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4answers
1k views
How to tune an FM transmitter to a specific frequency?
I am planning to organise a simple fox hunt, a family event. This includes building a transmitter. I am currently considering the following schematics:
https://maker.pro/education/diy-fm-transmitter
...
5
votes
1answer
155 views
What are these continuous sine wave tones I keep hearing?
I'm messing around on WebSDR and by just scanning through I sometimes come across these continuous tones in USB. One in particular was 28.800 MHz USB.
I've picked them up on nearly every WebSDR unit ...
0
votes
1answer
70 views
Are there receivers and transmitters that can be tuned to multiple frequencies at once? [closed]
What kind of hardware/circuitry would be needed for a device to be able to transmit and receive over a range of frequencies at once?
2
votes
2answers
83 views
Antenna Q vs pattern shape
Is there any reason to think that changing the Q of an antenna would affect the directional pattern, assuming that is the only variable that changes?
Restricting to values of Q say less than 1000.
...
3
votes
2answers
330 views
What are the technical reasons that there are no frequency modulated transmissions on the long- and medium wave?
Why are there no frequency modulated broadcasts on the long/medium/short wave, but only on VHF? I'm sure there are many historical and political reasons (long/medium/short wave were already in use for ...
3
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3answers
579 views
Can 2 uhf beam yagi antennas be used on a transmitter to get a diversity effect?
I'm having a problem getting a good signal up to a repeater site on UHF. I'm running 20W in a neighborhood with lots of trees, and the signal is fading in and out due to trees and the wind.
I can't ...
2
votes
3answers
344 views
What are the 3 or 5 peaks in an FM broadcast during silence?
Looking at the waterfall spectrum of any ordinary FM public broadcast station (88-108 MHz), during the silence, there are 3 or 5 visible peaks.
What are they?
It's possible this has a trivial ...
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1answer
247 views
How is the PRC-152 able to achieve such a wide frequency range?
I am referring to the Harris Falcon III designed for military. It has a frequency range from 30MHz - 870MHz.
However, when I look at commercial radios, their frequency ranges are usually limited to ...
4
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2answers
2k views
Where can I find a listening guide for different frequencies and their usages to listen to on SDR?
I just got an RTL-SDR dongle by Nooelec and am using CubicSDR on Mac (which supports AM, FM, and SSB), and I'm in Canada. I'm able to easily find FM radio stations, but outside of that I'm not sure ...
2
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3answers
2k views
Private Channel?
Is there a method to limit the people with access to a simplex channel? I would like to utilize a channel that is set up for just myself and my wife. If I gave directions to meet somewhere I would ...
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1answer
84 views
overly large bandwith for a FSK signal?
I am trying to recover my 2FSK signal using an SDR. I have centered the SDR modem on the median frequency (the virtual carrier) and captured my signal via some 90 kHz bw modem. THis is the recording ...
2
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2answers
2k views
Does antenna frequency matter when trying to pick up radio waves?
I'm buying the following: https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2/ref=sr_1_3?ie=UTF8&qid=1480215974&sr=8-3&keywords=RTL-SDR to analyze radio waves as ...
4
votes
1answer
2k views
How many frequency channels are there in a frequency band?
I've often heard people saying that 4G uses the 1800 MHz band but precisely what all frequencies does it work upon? Does it mean that is just uses one frequency i.e. 1800 MHz, well in that case wouldn'...
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0answers
51 views
How to connect a motorola RVA50UL with MR350?
Currently I use a Motorola MR30R radio in the frequency 20 (462,6750 Mhz) with Interference Eliminator Code 59. I also have a Motorola RVA50UL, according to the manual, the frequency will be available ...
2
votes
1answer
594 views
FM transmitter sending to multiple frequencies
I bought Veronica 1W FM Transmitter online, hooking it up and tuning the radio beside me, I can hear the audio on multiple 'stations' or frequencies.
I've tried screwing the vc1 which the seller said ...
4
votes
1answer
162 views
How can we determine what repeaters to use?
My wife and I are studying for our Technician class licenses. We are thinking about how we could communicate with each other while both of us are at work, she being in Oakland, CA and myself in ...
6
votes
2answers
6k views
What is a “calling frequency”?
Doing some study for the ham test, I read a question asking about a certain “national calling frequency”.
What is a “calling frequency”?
What is meant by “calling” in this instance?
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votes
5answers
506 views
Why do Hams refer to bands by wavelength and not frequency?
I've noticed while reading literature and websites geared towards and written by amateurs and ham radio enthiuasts that frequency bands are commonly referred to by wavelength.
In professional ...
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2answers
278 views
Scanner radio purchase advice for someone that's nosy but not technological?
If it sounds like a stupid question, it probably is.
My mom loves being nosy... When she hears the police siren, an ambulance, firefighters, or something like that, she's the first one to run to the ...
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1answer
2k views
Transmit on multiple frequencies with USRP using GRC
I am using an Ettus Research B200 with GNU Radio Companion (GRC) and I would like to transmit two signals at two different frequencies simultaneously.
As a simple example, I would like to transmit a ...
2
votes
3answers
587 views
Would a 2.4ghz yagi antenna work for Ham Radio?
I am building a miniature yagi antenna that is made for 2.4ghz. Would a 2.4ghz yagi antenna work for Ham Radio?
0
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1answer
109 views
List of capturable data services (diy)
Looking for a list of capture-able data services.
By browsing some sites I accidentally discovered
that it is possible to receive NOAA satellite weather images with DIY receiver (link) or (here), ...
0
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1answer
1k views
Frequencies as 5 digits and 6 or 7 digits
Why are some frequencies 5 digits like 51344 and some six or seven digits long like 158.7600?
9
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4answers
32k views
What is the difference between channel & frequency & band in RF?
I am reading about wireless networks basics. I found three terms I cannot find exact definition for: channel, frequency band, frequency.
Can anyone give exact definitions for them?
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1answer
83 views
Australian Police Radio Frequency [closed]
Does any one know or have a frequency chart with Australian Emergency services?
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2answers
210 views
EMT radio communications
I just joined the community, and I got a communication question. Based on searches most relevant questions were posted in this community, so I hope I can get a proper answer!
EMT, first responders, ...
2
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2answers
2k views
Mix of Sine waves with different frequencies
What is the mix of a received frequency 27 MHz and a oscillator frequency of 27.001 MHz?
I expect the mix of them would be 1 KHz.
2
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2answers
2k views
Which Frequency Band(VHF/UHF) is most useful for satellite in MEO?
I want to get to know about the satellite communication at 8000-10000 km,
During that, I come across the VHF and UHF.
In that I am facing problem for deciding the frequency band for communicating with ...
8
votes
1answer
190 views
Antenna size for wideband
I just bought a SDR dongle that comes with an antenna. The dongle is for DVB-T.
The antenna is very small but the specs say that the dongle can go 30Mhz to 850Mhz.
From my knowledge of antenna ...
2
votes
3answers
237 views
Is 2.4Ghz good for an UAV?
I'm designing a drone(UAV) as a hobbyist, and radio communications is not my strong point. I will be transmitting waypoints from a portable control station and receiving video(a low frame rate is ok). ...
3
votes
1answer
570 views
What determines the optimum frequency range for the transmission of signals?
What determines the optimum frequency range for the transmission of signals in a system that's transmitting electromagnetic signals between an antenna on the surface of the earth and an orbiting ...
