Questions tagged [frequency]

Use this tag for questions about which frequencies to use or not use in certain locations/situations.

Filter by
Sorted by
Tagged with
0
votes
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 ...
1
vote
0answers
94 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. ...
1
vote
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
votes
0answers
92 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
votes
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
129 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
votes
3answers
188 views

What are these antennas used for?

I noticed this antenna park in Heidmoosstrasse, Switzerland. What is it used for?
4
votes
1answer
250 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
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
753 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
469 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
164 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
277 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
votes
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
152 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
69 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
329 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
votes
3answers
575 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
339 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
235 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
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 ...
2
votes
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 ...
1
vote
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
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'...
1
vote
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
588 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?
7
votes
5answers
503 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 ...
1
vote
2answers
277 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
3answers
577 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
106 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
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?
1
vote
1answer
83 views

Australian Police Radio Frequency [closed]

Does any one know or have a frequency chart with Australian Emergency services?
1
vote
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
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
votes
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
189 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 ...
3
votes
2answers
7k 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+?
5
votes
1answer
832 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 ...
9
votes
3answers
20k 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
351 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 ...