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Questions tagged [frequency]

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

3
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1answer
90 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 ...
6
votes
2answers
89 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
155 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
312 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
111 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
57 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
75 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
262 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
343 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
207 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
115 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 ...
2
votes
2answers
1k 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
907 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
60 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
1k 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
1k 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
42 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
423 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
128 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
4k 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?
5
votes
5answers
394 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
266 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
410 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
95 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
945 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?
7
votes
4answers
24k 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
77 views

Australian Police Radio Frequency [closed]

Does any one know or have a frequency chart with Australian Emergency services?
1
vote
2answers
171 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
1k 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
168 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
219 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). ...
2
votes
1answer
478 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
2k 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
701 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
15k 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
318 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
969 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
539 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
710 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
634 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
216 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 ...
2
votes
1answer
512 views

Two transmitters on same frequency

What are the repercussions of using 2 transmitters on same frequency? Tx are ~50 feet apart and the freq is 447.800 mhz.
6
votes
3answers
371 views

What is the permissible frequency error for US amateur radio transmissions?

What are my requirements as a licensed Amateur Radio operator in the US to keep to a single frequency? How much drift can I have during transmission and still be within my license? Does it depend on ...
6
votes
2answers
598 views

Why do some DX listen on a different frequency than they transmit on?

I've heard some DX indicate "CQ up 5" for instance, indicating that they are listening on a different frequency than they are transmitting on. What are the reasons one might want to do that?
10
votes
2answers
533 views

What does a SSB frequency actually indicate?

An SSB signal is an AM signal with the carrier and other sideband filtered out, if I understand correctly. As such, when specifying an SSB frequency do you specify the carrier frequency, then state ...
4
votes
2answers
2k views

What are the default repeater offsets on 70cm in different countries? [closed]

I am looking for a reference list of the default repeater offsets by frequency and country on the 70cm band, to supply it into a radio control software. Most radios come with a list built-in, but the ...
-1
votes
3answers
139 views

Are some frequencies regulated ? if not which ones are free to use? [closed]

I could be wrong on this one, but I understand that in some countries, radio frequencies are regulated, with licences being require to OPERATE on the the networks. As mentioned most channels are ...