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6 votes
Accepted

What is this weird interference/strange radio station?

Oceanographic radar, aka CODAR. It's used to measure ocean currents, wave heights and frequencies by the way the waves reflect RF.
hobbs - KC2G's user avatar
  • 12.5k
5 votes
Accepted

How important is the impedance and resonance of a receive antenna?

The answers given so far provide good food for thought. I would like to add a slightly different perspective. Today's home is loaded with sources of RFI (radio frequency interference). Routers, ...
Glenn W9IQ's user avatar
  • 18.6k
5 votes

I would like to listen to a red roadster in space

Good find of all the frequencies and powers, it sounds like you have all the right basic equipment. But sadly for the roadster, you're too late, it's out of range. The video link is designed for a ...
tomnexus's user avatar
  • 11.3k
5 votes

Signal on various frequencies, about 2.5k bandwidth, sounds like a broken motor turning: What is it?

These are data transmissions using OFDM. They are government or military point to point data links. I would expect that the data would be encrypted.
Frank Johnson's user avatar
4 votes
Accepted

Are there many analog (AM) shortwave broadcast stations left?

There are still many AM shortwave stations. A great way to find out the state of the spectrum for yourself is to use WebSDR sites, which let you use many different receivers around the world from ...
Kevin Reid AG6YO's user avatar
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4 votes
Accepted

How can AM radio work differently when approaching the true frequency from different directions?

I can tell you of how your radio is built: It's got an integrated radio IC that does everything, from preselection to mixing (if any) to digitization to digital filtering, audio demodulation, audio ...
Marcus Müller's user avatar
3 votes

How can AM radio work differently when approaching the true frequency from different directions?

Your radio, as do many of the inexpensive portables over the last five years or so, uses the Silicon Labs Si473x DSP chip or one of the recent Asian clones. Tuning is controlled entirely by software. ...
timetraveller's user avatar
3 votes
Accepted

Receiving shortwave frequencies from different countries (e.g. North Korea)

The frequencies in your pasted image of a table are in kilohertz (kHz). These days frequencies are more often expressed in megahertz or gigahertz (MHz or GHz). Anyway, frequencies ranging from 3560 ...
rclocher3's user avatar
  • 9,242
3 votes

What are these serial number pileups on 20m and 40m?

What you're talking about sounds like activity that is common for a contest or a QSO party. If you're not familiar with QSO parties they are organized like contests, but the organizers try to ...
rclocher3's user avatar
  • 9,242
3 votes

How important is the impedance and resonance of a receive antenna?

The simple case would be a 75 foot wire whose far end is an open-end tied to a high support, and whose near end feeds directly to your SDR-dongle. It is assumed the dongle is a single-ended input ...
glen_geek's user avatar
  • 941
2 votes
Accepted

DRM standard receiving on shortwave

No, not every shortwave radio can receive DRM. A basic shortwave receiver will only support AM, conventional analog shortwave broadcasting. DRM (as well as SSB, another additional mode) are additional ...
Kevin Reid AG6YO's user avatar
  • 24.6k
2 votes

I would like to listen to a red roadster in space

The batteries are now dead and there is no onboard power source, so we cannot listen to it. See the comments at https://space.stackexchange.com/questions/25010/current-position-of-starman
Mike Waters's user avatar
  • 8,042
2 votes

What are these serial number pileups on 20m and 40m?

Guessing it was a contest, and the numbers were the exchanges, per the contest rules. The exchanges vary by contest, so it depends on which contest you heard. Try searching the contest-calendar, here: ...
t252's user avatar
  • 697
1 vote

What are these serial number pileups on 20m and 40m?

You may have stumbled onto a net that is specifically designed to allow amateurs to work on getting awards quickly by contacting others via net, such as the ARRL Worked All States (WAS) award. There'...
KS4TD's user avatar
  • 69
1 vote

How important is the impedance and resonance of a receive antenna?

I have an MFJ 9200 CW rig that only transmits in CW on ham freqs, but I can listen on SW broadcast freqs. I always carry it on bikepacking and backpacking trips. I spend over 6 months a year in the ...
user10992's user avatar
1 vote

How important is the impedance and resonance of a receive antenna?

I decided to add another answer. This because I was curious about some of the calculators which would calculate the ideal length of wire. These calculators can be found by simple searches. Some of ...
Edwin van Mierlo's user avatar
1 vote

How important is the impedance and resonance of a receive antenna?

Yes, do experiment, and "toss a length of wire in a tree" is definitely how most SWL's are starting. However if you have a choice, the you should avoid 1/2 wave lengths, or multiples thereof. A good ...
Edwin van Mierlo's user avatar
1 vote

What are some shortwave radio stations I ought to reliably receive in New Hampshire?

We definitely need more information to answer appropriately, but I'm willing to answer as best I can with the information given. The receiver you have chosen is referred to as an Ultralight and is ...
Earl Higgins's user avatar

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