Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [direction-finding]

Questions related to fox hunting (chasing in some areas) and radio direction finding.

19 questions
14
votes
8 answers

Why are Wullenweber CDAAs obsolete?

Wullenweber circularly-disposed antenna arrays (CDAAs) are large HF direction-finding antennas, sometimes colloquially referred to as "elephant cages", that were popular in the Cold War. They allowed the bearing of an incoming signal to be located…
rclocher3
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14
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1 answer

How would a time-difference-of-arrival receiver with two antennas know which side the signal is from?

An easy TDOA design by Byonics was published with the following schematic: It appears that the antennas are switched at a rate of 640Hz, which allows a 640Hz tone to be heard in the radio when the antennas are not in phase. When the antennas are…
Adam Davis
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13
votes
2 answers

Direction finding: How to find a stuck FM transmitter on 70cm?

There's a blank carrier on a 433 MHz FM voice frequency here. How should we go on about finding the transmitter's location? Practical procedure? Could be somewhere downtown.
oh7lzb
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11
votes
1 answer

What is body blocking, and does it work with a stock HT on a foxhunt?

I've heard that you might not need a special directional antenna to participate in a foxhunt, that some people are able to use their body to help determine the direction of a signal. How does this work? More specifically, what is the process to do…
Adam Davis
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8
votes
1 answer

Is FM appropriate for foxhunting?

I'm thinking about an inexpensive way to create a foxhunt kit for youth groups, and am wondering if the cheap dual band HTs could be used. However, it occurs to me that FM doesn't provide any good audio queues for signal strength, and the SWR meters…
Adam Davis
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7
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1 answer

Is bending the tips of the antenna wires going to affect the effective length?

I'm looking at designs for low cost DIY yagi antennas for a fox hunt, and pondering coat hanger wire and PVC piping. I'd like them to be built by the youth who will be doing the fox hunt, but that requires some safety considerations. If I plan to…
Adam Davis
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7
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2 answers

Apps and or equipment needed to document local interference?

A neighbor ham user recently started doing something that causes very noticeable feedback/buzzing in AM radio as well as any device that uses a wired microphone (such as a gopro with wired mic). Before I approach this individual, I'd like to make…
a coder
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6
votes
3 answers

How can I construct a practical loop antenna for 2m band?

How can I construct a practical loop antenna for 2m band to use in a fox hunt? Is it even possible to construct a hand-held antenna for the 2m and 70 cm bands? I tried to calculate the dimensions using a few online tools and formula, and the…
KF5RRR
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4
votes
3 answers

Receive directionality of a sub-optimal Yagi

How do I build the best antenna for a given VHF frequency given that an optimal design is too large? I am trying to understand the properties of a directional antenna of sub-optimal design. All the discussions of directional antennas assume…
dwitten
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4
votes
2 answers

Audio tones and patterns used for fox-hunt transmitters?

Question: What are the most effective audio tone frequency(s) and pattern(s) used in direction finding in the world of amateur radio? Also: Is there a specification for the tones that amateur radio fox hunt transmitters use, and if so, is it…
Steve
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4
votes
7 answers

QRN: How to chase down a solid S9 noise floor on 40m only

I am new to this, having just set up my station. I have "very bad" QRN on 40m: S9. Here is the setup: High density suburb with flats and houses Yaesu FT450D with fan dipole at 6m-9m above ground (sloping), this is lower than a building with flats…
Oliver Schönrock
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3
votes
2 answers

How to make a "you're getting warm/cold"/"fox hunting" game based on RF signals

I would like to build a system in which the emitter emits omnidirectional RF signals, and the receiver gets a stronger signal (it does not have to be accurate) with a) closer distance from the emitter b) better pointing with the emitter (directional…
user42875
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2
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Direction Finder using directional antenna, digital signals amid clutter

There are several methods for implementing direction finder. 1. One of the method is by using directional antenna pointing to target device, and reading the received signal strength from the target device. This method also need the device to keep…
ransh
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2
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2 answers

antenna circuit to hear or show radio direction

Is it possible to create a circuit to hear (through earphones) or show (with an LED) the direction of a radio source? What does a really simple circuit look like and how does it work? How does the frequency of the radio source affect this circuit…
awde
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1
vote
1 answer

2m loop with sense antenna for DF

I would like to construct a 2m Loop with a sense antenna. I have built just a loop antenna with great success that is resonant at 2m finding null's works quite well on local repeater outputs. I would like to further my project and create one with a…
KD2KUB
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