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1500 questions
4
votes
2 answers
Sound quality in portable FM radio devices vs dedicated stations
When speaking to a portable radio transmitter the sounds usually gets distorted. However in radio stations that are dedicated to play music the sound is significantly better.
First of all, why? And second how can I make it better?
The system I use…
Adam Katav
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4
votes
6 answers
Cordless phone consistently experiencing RFI
I've tried several cordless phones (most recently KX-TG570), and all seem to frequently pick up terrible RF interference. I have a neighbor that is a ham enthusiast, with large antenna masts on the first rooftop, and it does seem to coincide with…
g g
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4
votes
1 answer
How to measure signal power in GNU Radio.(I wondered how much dBm is specific.)
I used the "QT GUI frequency sink" and "WX GUI FFT sink" to measure the signal.
But I got different value. I would like to know what dB stands for in them. Whether it is dBm or just a ratio.
H.Dog
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4
votes
3 answers
What is the process of sending an NTS message in to a disaster area?
I have a friend of mine that is from Puerto Rico, and hasn't heard from her family in some time.
I am aware of the NTS, and have considered sending a message into the area to see if any word of her family could be determined.
I'm not sure what the…
PearsonArtPhoto
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4
votes
3 answers
2m Biquad - Why not?
I'm thinking about putting together an Echolink link node on my local repeater frequency so I can participate in the weekly net when out of town. This seems straightforward as it's simply:
Being in an HOA, I have to try and keep my house from…
William
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4
votes
3 answers
Substitute for Dacron rope in antennas
I am building an antenna that specifies the use of Dacron rope to help support the spreaders, but that is not readily available in Trinidad and Tobago.
What will be a good replacement with regards to UV resistance?
bigaone22
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4
votes
3 answers
What are the technical reasons that there are no FM transmissions on the long, medium, or shortwave?
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 AM when FM radio was developed, VHF still had…
JanKanis
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4
votes
1 answer
Is ladder line necessary when using a non-resonant dipole through a tuner?
I've heard if I have a dipole of some arbitrary length, or a random wire, the SWR can be very bad. An antenna tuner can present a decent match to the transmitter, but the SWR on the feedline will be very high, and thus ladder line is required.
Is…
Phil Frost - W8II
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4
votes
3 answers
What kind of antenna connector is this?
I'm looking for antennas to attach to my CB radio. This one is a "rubber ducky" antenna.
I'm not sure what the connector is, can anyone identify it for me?
[edit] Here are some other pictures
ToastHouse
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4
votes
2 answers
Choosing a wideband antenna design
On a previous question I asked about proper antenna design for wideband SDR receiver and ways to improve signal/noise ratio. Ideally the reciever has a range of 100kHz-2GHz. Keeping in mind is impossible to cover the whole spectrum with one antenna,…
Luca
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4
votes
3 answers
Antenna tuner design
In a related question about a broadband antenna for SDR it was suggested me to build or buy an antenna tuner.
Since maybe it was not clear to everybody, I'm designing an antenna tuner for reception, not transmission.
Searching around I concluded…
Luca
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4
votes
3 answers
Broadband antenna for SDR radio
I recently bought a very wideband SDR receiver (DX-Patrol MK4, declared covered frequencies are 100kHz-2GHz). I'm experimenting with antenna designs because unfortunately I live in an apartment building in the middle of the city and is not exactly…
Luca
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4
votes
1 answer
Is the error rate for QPSK31 in a white noise channel worse than BPSK31?
I've read in a couple sources that in a channel consisting of only additive white Gaussian noise (AWGN), at low SNR, QPSK31 is actually worse than BPSK31.
http://www.arrl.org/psk31-spec, probably copied verbatim from…
Phil Frost - W8II
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4
votes
1 answer
Could UHF Earth-Satellite-Earth bouncing of signals off of this large metallized foil satellite be feasible?
The July 14, 2017 NASA Spaceflight article Soyuz 2-1A launches with Kanopus-V-IK and over 70 satellites says:
Mayak is a three-unit CubeSat which was built by Tvoii Sektor Kosmosa – or “Your Sector of Space” – an independent, crowd-funded team of…
uhoh
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4
votes
1 answer
What would letter T mean in this radio beacon message?
I'm currently picking up signal from a beacon using RTL-SDR and decoding the Morse code on a computer using gMFSK program.
The beacon is sending message which decodes as "T DE YU1VHF LOC KN04OO".
I still haven't started learning how to decode the…
AndrejaKo
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