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1500 questions
6
votes
3 answers
Does a person still need a ham radio license?
Way back when, if my recollection is correct, the requirement for using ham radio was to have a license and the required skill was some level of Morse code proficiency.
I have heard that Morse code is no longer required — if that's true, does a…
gerryLowry
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6
votes
2 answers
80/160m Shortened Dipole Trap Questions
I seem to have forgotten some things I learned years ago for my amateur radio exams. If I am building a 2 band shortened dipole and want a trap between 80 and 160 do I make the trap resonant on 80 or 160 or elsewhere? I guess I may be mistakenly…
Marcus
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6
votes
2 answers
Is it possible for an amateur to transmit ATSC?
Amateur television has long used the NTSC (analog) television standards to transmit video and audio. Several years ago, the digital broadcast television transition made higher-quality television signals possible. Can amateurs acquire and use digital…
JC Hulce
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6
votes
2 answers
doppler LEO satellite
I am trying to model Doppler shift of LEO satellite,
From my research so far I have come across the following formula:
\begin{equation}
\frac{f_r}{f_s}=\frac{1-\frac{u}{c}cos\theta}{\sqrt{1-\frac{u^2}{c^2}}}
\end{equation}
that in my understanding…
Rizias
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6
votes
2 answers
Filtering for PSK31 demodulation
What's the ideal filter for PSK31 demodulation? That is, something that minimizes ISI, while having a narrow bandwidth to reject adjacent channels, while being reasonably matched?
Most PSK modes use a root raised cosine pulse shape, thus the…
Phil Frost - W8II
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6
votes
1 answer
What is spin fading in satellite signals?
Why do signals from satellites experience "spin fading" as the satellite rotates? What are the effects that spin fading has on a radio signal?
From test question: T8B09
JC Hulce
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6
votes
2 answers
Mobile phone models that contain 2 way radio functionality
Are there any mobile phone models there that contain 2 way radio functionality?
S-K'
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6
votes
4 answers
UV-5R 4W BFB297 vs UV-5R 8W BFP3-23 (difference 4W vs 8W)
How big difference will it be between UV-5R 4W & newer UV-5R 8W (difference between 4W & 8W), in real life use 1 on 1 HT.
In SAME conditions, how much different distance / range will we get? (simple example)
So I want to buy two HTs and change stock…
SxOne
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6
votes
2 answers
Is there any downside to getting a vanity callsign?
I just got my HAM license, and I have been thinking about getting a 1×3 vanity that I can remember more easily.
This question is partially in reference to this passage on the FCC site:
A club station trustee of a club that has been assigned a…
Stephen Smith
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6
votes
1 answer
How to determine antenna height for given HF frequency and coverage radius?
I'm planning on setting up a low-HF antenna for near to mid-range contacts.
In my particular case, ideally I would like to be able to cover a radius of approximately 1000-1200 km with good reliability, operating on 3.5 MHz and possibly supplanted by…
user
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6
votes
3 answers
Cause of harmonic spurs?
Harmonic spurs (harmonics of the transmitter frequency, as seen by a wide-band receiver or SDR) in the RF spectrum might be caused by an imperfectly sinusoidal or badly filtered transmitter carrier frequency oscillator, non-linearities in the…
hotpaw2
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6
votes
1 answer
What kind of antenna is this?
This was found among some old ham stuff and is believed to have been used on 2 meters.
The vertical elements are 17 1/2" long and the connector on the bottom is a standard SO-239.
Antenna (left) and Connector (right)
(See test results below…
Lance
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6
votes
2 answers
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 where to look for interesting frequencies to listen…
user9315
6
votes
3 answers
How to determine the PPM value of a NESDR SMArt?
a) Given that I don't have a frequency standard or other known transmitter available, what is the easiest way to calibrate the NooElec NESDR SMArt which is using a TCXO rated at 0.5 PPM.? I.e. to determine the PPM calibration value?
b) Also, is…
not2qubit
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6
votes
1 answer
1280 MHz propagation out of a mountain valley
I live in a small valley, surrounded on three sides by 200-300 foot ridges. I'm trying to figure out where to place an antenna mast to receive 1280 MHz video from a long range aerial vehicle (20-30 mile radius).
At this frequency, how important will…
Chris
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