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1500 questions
6
votes
1 answer
Pseudorange in VHF band navigation and precision phase tracking
I am thinking on what is the practical limit of precision for VHF positioning system (like currently obsolete and gone "Transit" system).
It is well known how GPS receivers calculates pseudorange to each satellite to calculate the position of the…
BarsMonster - R2AYN
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6
votes
7 answers
Are there any commonly used digital modes that work with an FM transceiver?
Like many new hams, I have just one radio: an inexpensive 2m/70cm FM transceiver. It doesn't do SSB and it doesn't have a digital input. If I wire up a connection between the radio and my computer's sound card, are there any digital modes that I…
mrog
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6
votes
4 answers
What is propagation like when there are no sunspots?
Am considering getting my license again after raising kids, and wondering if there is any point in HF operation besides local chats — that is, what is propagation like when there are no sunspots?
nzc
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6
votes
5 answers
Shortwave Antenna Listening with Portable Receiver Like TECSUN PL-660?
I have a Tecsun PL-660 (link is to the manual) has the usual AM/FM radio telescoping internal antenna, and a 1/8th-inch jack for an external shortwave antenna. There appears to be no facility for attaching to station ground, unless one of the…
Warren VA7WPX
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6
votes
2 answers
Antenna length in relation to lambda length
I'm pretty new with antenna stuff. I'm not sure how to understand antenna length in relation to lambda with dipole antennas.
If a simple dipole antenna is lambda/4, has it a total length of lambda/2 (every pole lambda/4 long) or a total length of…
leAthlon
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6
votes
1 answer
What kind of modulation is this?
I was able to demodulate a signal I've received in gnuradio. Here you can see my flowgraph:
But now I would like to be able to send data as well. But how should I modulate my data? As you can see I've demodulated with Quadrature Demod -> Hilbert ->…
Thanathan
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6
votes
1 answer
What happens to the "Yo-Yo Tenna" when you coil up its ends for use on higher frequencies?
I have gathered what is basically a Yo-Yo Tenna using some Camco laundry reels and a spool of cheap speaker wire split in half (pretty much exact duplicate of this build as it turns out). I've got a bit of equipment to measure the amount of noise…
natevw - AF7TB
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6
votes
2 answers
Weather Imaging with NOAA satellites - legal?
I would like to build an antenna for receiving NOAA weather satellites. They're receivable at around 137.5 Mhz. I'm a total new to amateur radio stuff. I know that it's not legal to communicate as private person on several frequency areas- so I…
leAthlon
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6
votes
4 answers
What is the minimum signal strength I need to receive?
Let's say a transmitting station is using a 8W radio with a J pole antenna. The cable connecting the radio to the antenna is RG-58A/U and is 25ft long.
At 144.075MHz, the attenuation of the cable is 1.5dB. At 8W, the power from the radio is 9.03dB.…
KM4NTK
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6
votes
3 answers
Correct number of elements in 4nec2 antenna simulation
I am designing a 1.25-wavelength dipole antenna with the 4nec2 software. What I noticed is that the input impedance of antenna is changing greatly when I change the number of segments.
How many segments should I choose?
Shiva Mudide
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6
votes
3 answers
How to improve reception with a headphone-cord antenna?
I have a headphone and a cellphone that has built-in FM radio, and the headphone acts as the radio antenna.
but my problem is the radio stations I listen to are very far from my place,
good thing there are some position where the sound is very…
m0Onfang
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6
votes
1 answer
What is Part 97 a part of?
The regulations that govern Amateur Radio in the United States are often described as Part 97.
What statute are they a part of? Where can I find other parts of the same law?
Nick ODell - KD0OCR
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6
votes
3 answers
What is this large, flat microwave coaxial connector?
I picked up a random piece of RF hardware at a flea market. I'd like to know what these unusual connectors on it are.
The jack is flat on its face except for the gold ring. Inside the gold ring appear to be fingers gripping the central pin (which…
Kevin Reid AG6YO
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6
votes
1 answer
Can a Yaesu FT-7900R be physically connected to both KPC-9612+ ports?
The Yaesu FT-7900R has a single data port (mini DIN 6-pin) for 1200 and 9600 bps TNCs. Page 10 of the manual states:
In accordance with industry standards, the signal levels, impedances, and bandwidths are significantly different on 9600 bps as…
Jacob
- 442
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6
votes
3 answers
How to stop interference on shortwave radio when connecting to a computer
I have a Tecsun PL-600 and when I can receive clear signals, and they come through just fine on headphones, and through the speaker. If I'm trying to receive RTTY or fax, when I connect the radio to my computer the signal becomes inaudible because a…
smithy212000
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