Questions tagged [frequency]
Use this tag for questions about which frequencies to use or not use in certain locations/situations.
4
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2answers
47 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 ...
3
votes
2answers
103 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
239 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 ...
0
votes
1answer
52 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
693 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
138 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 ...
4
votes
1answer
142 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 ...
7
votes
2answers
156 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
167 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 ...
7
votes
4answers
729 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
...
6
votes
1answer
129 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
58 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
79 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
301 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 ...
4
votes
3answers
440 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 ...
3
votes
3answers
281 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 ...
1
vote
1answer
155 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 ...
3
votes
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 ...
3
votes
3answers
1k 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 ...
1
vote
1answer
75 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
votes
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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vote
0answers
47 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
517 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
153 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
5k 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?
6
votes
5answers
450 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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vote
2answers
271 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 ...
1
vote
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
2answers
493 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
votes
1answer
101 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
votes
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
votes
4answers
28k 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?
1
vote
1answer
79 views
Australian Police Radio Frequency [closed]
Does any one know or have a frequency chart with Australian Emergency services?
1
vote
2answers
188 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
votes
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 ...
7
votes
1answer
185 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
229 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
539 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 ...
3
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2answers
4k views
Can a Baofeng UV-5R+ be used on FRS, GMRS, and MURS?
Is this secure if I was talking to another Baofeng UV-5R+?
4
votes
1answer
767 views
Why does the ionosphere reflect some frequencies and not others?
Why is it that some frequencies transmitted at some known direction are reflected back to earth, yet others transmitted at the same direction, power and polarity pass through into space with no ...
7
votes
3answers
18k views
How can you calculate the frequencies for each band?
I've just started studying for my HAM license a couple of weeks ago, so please excuse me if this is a remedial question...
I have the Canadian Amateur Radio Basic Qualification Study Guide (which I'm ...
3
votes
1answer
336 views
How can I tell the frequency without an oscilloscope, or frequency counter?
Just going through the RF oscillator listed on SM0VPO's web-site. I replaced C1 by a reverse biased 6A8, and used an E-core transformer pulled out of a Compact Fluorescent Lamp instead of an inductor ...
4
votes
3answers
1k views
SSB demodulation
I was building the superhet receiver for ham radio. But I seem to have got stuck at the demodulation stage.
As an example:
Suppose the person is transmitting SSB signal (20m band) at 14.250 MHz ...
5
votes
1answer
570 views
Doppler Shift Compensation in Inter Satellite Communication
I am currently doing a project in the area of optical inter-satellite communication (GEO-LEO).
I am using a optical carrier of 281 THz, and the Doppler shift corresponding to it is ±7 GHz. I ...
4
votes
2answers
745 views
Wouxun KG-UV6D PMR frequency “spillover”
So I recently bought a pair of Wouxun KG-UV6D. We don't have the license required to operate outside of PMR frequencies, but that's fine, as we will be using these for airsoft. The programming of 8 ...
6
votes
1answer
650 views
Why are there no amateur allocations in the LF and VLF spectrum?
Amateur radio enthusiasts have slices of spectrum at every magnitude of spectrum MF and above, but in the US none are below MF.
Why are there no spectrum allocations below 160M?
7
votes
2answers
220 views
What will I need to receive the ICE/ISEE-3 transmitter?
The ICE/ISEE-3 spacecraft, launched in 1979, is due to pass by the earth in August, 2014. It was commanded to power down completely years ago, but it appears to have failed to do so, and while it ...
7
votes
1answer
2k views
Is the bandwidth of an LCR resonant circuit independent of the capacitance?
Is the bandwidth of an LCR resonant circuit independent of the capacitance, if the inductance and its series resistance are kept the same, and the Q is high?
This question and the calculation ...
