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Questions tagged [frequency]

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

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51 votes
5 answers
9k views

How do I report an emergency using ham radio?

If I'm in the wilderness with ham equipment but no phone signal, how would I report an emergency? Is there a particular frequency I would use, a particular protocol or suchlike?
berry120's user avatar
  • 1,744
11 votes
2 answers
2k 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?
Adam Davis's user avatar
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3 votes
2 answers
48k 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+?
Webhobo's user avatar
  • 41
12 votes
5 answers
52k 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?
ashok's user avatar
  • 221
9 votes
5 answers
2k 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 ...
YetAnotherRandomUser's user avatar
8 votes
1 answer
867 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?
Adam Davis's user avatar
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8 votes
1 answer
2k 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 ...
user avatar
6 votes
2 answers
944 views

Why does a sine wave show two peaks in the frequency domain on GNUradio?

I constructed the flow graph in GNUradio 3.7 as below: I know a sine wave has only one frequency, so what causes the frequency sink to show two peaks?
kittygirl's user avatar
  • 650
5 votes
3 answers
358 views

What are these antennas used for?

I noticed this antenna park in Heidmoosstrasse, Switzerland. What is it used for?
Loreno Heer's user avatar
5 votes
3 answers
8k views

What frequencies am I not allowed to use north of line A in the USA?

What frequencies can I not use if I live north of line A in the USA?
Timtech's user avatar
  • 2,336
4 votes
1 answer
510 views

Gnuradio bandwidth of sink cause signal frequency changed?

System is debian 10 with gnuradio 3.7. untitled.grc create simple flow graph as below: The only difference between 2 flows is bandwidth of gui sink,cause 2 ...
kittygirl's user avatar
  • 650
3 votes
1 answer
529 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 ...
VU2NHW's user avatar
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1 vote
2 answers
1k views

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 ...
user16052's user avatar
0 votes
3 answers
84 views

change LC parameter digitally

LC circuit is the main element of every frequency generator, I intend to make an FM transmitter, but many opensource circuit use analog variable L or C part to set and adjust the target frequency My ...
Mehrdad Hrsk's user avatar
0 votes
1 answer
695 views

Is Gnuradio `file sink` data time domain data or frequency domain data?

When I enable file sink,I could save and read data of Gnuradio as below: Questions as below: 1.Is the file sink data time ...
kittygirl's user avatar
  • 650
-3 votes
1 answer
218 views

GNU Radio does not work expectedly when the frequency is 2x the sample rate

Simple flow in GNU Radio 3.8.2.0 (Python 3.9.2). If samp rate is 32k, when Frequency moves to 64k the recovered ...
kittygirl's user avatar
  • 650