Questions tagged [transmitter]

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3answers
470 views

Weird Harmonic Issue on Raspberry PI FM Transmitter

So I talked to my neighbor about my Raspberry PI, harmonics and his emergency radio. He told me to fire it up, as we saw the FCC sticker on it, meaning it is in compliance with Part 15. I started my ...
0
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1answer
95 views

Are there receivers and transmitters that can be tuned to multiple frequencies at once? [closed]

What kind of hardware/circuitry would be needed for a device to be able to transmit and receive over a range of frequencies at once?
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2answers
1k views

Ettus B210 USRP Is it possible to transmit on both Tx Ports either with same or different application?

Just getting up to speed on the ettus B210 - basically the same as the B200 but with two Rf boards. I am testing using gnuradio-companion. I have setup a very simple transmitter consisting of: ...
2
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2answers
993 views

Is my low-power VHF transmitter dangerous?

I use a Raspberry Pi for transmitting FM on 107.9 Mhz. It uses square waves and has a power of approx 0.085 Watts, but just to be safe: If I have a 1 watt transmitter approximately 1 metre away from ...
5
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2answers
1k views

How to transmit images and video through a hurricane?

Background You're in the path of a hurricane, and the eye just passed over your head. There is no electricity (apart from your own generator or battery), there is no mobile network and there is ...
4
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2answers
239 views

Is using a DDS chip directly a viable way to transmit 2FSK and PSK on HF?

I'm thinking of building an HF transmitter for data (AX.25 or PSK31). Rather than using an IF stage, I'm thinking of generating the RF frequencies (or phases) directly with a Direct Digital Synthesis ...
1
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2answers
94 views

Is there an advantage with having a DC bias for a FM radio transmission?

I'm studying FM radio transmissions at the moment. I'm using an NTX2B transmitter to experiment naturally assumed I'd use 0V for False/No signal and 3V for True. However, a lot of articles that I ...
1
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3answers
147 views

Is there a risk of interference between a 403 MHz and a 433 MHz Radio?

I hope the question is not too stupid, as I am very new to Radio. According to my logic, the obvious answer is no. However I believe to have read somewhere that interference may be a problem when the ...
3
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3answers
1k views

What is the output impedance of a typical solid state ham transmitter?

I've often heard that the output impedance is 50Ω, and the load impedance should be matched to that and also 50Ω. While the reasons for the load impedance to be 50Ω are clear, is the output impedance ...
2
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2answers
2k views

How far does a watt equal in range in the FM band?

How many watts would be needed to cover a 10 mile radius with good sound for music on the 88-108 MHz FM broadcast band? I am an amateur and for fun only.
1
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1answer
363 views

Would I be able to legally operate this FM transmitter without a license in Canada?

I've been looking into FM transmitters, and I've found one that I think I may use. The transmitter is based off of the KT0803L integrated circuit (http://radio-z.ucoz.lv/kt_0803/KT0803L_V1.3.pdf). The ...
0
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1answer
180 views

Signal booster with transistor

How can I make a simple signal booster without introducing too much noise? My first thought was to just feed the signal into transistor base (capable of 4GHz) through a 1K resistor. I could get a 1.2W ...
2
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1answer
407 views

Detecting the listeners

I wonder, if a broadcasting radiostation can detect, how many receivers are tuned on it, and if it possible - how exactly this detection is happening? Thanks.
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1answer
78 views

How does inductive coupling between transmitter amplifier stages reduce harmonics

In some notes on transmitters I have found the statement that "inductive coupling between transmitter amplifier stages reduces the generation of harmonics", with no further explanation. Can anyone ...
0
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1answer
145 views

is fm transmitters legal in japan

I was wondering what the laws are in Japan concerning FM Transmitters. I recently purchased one of eBay (http://www.ebay.com/itm/401047827071) I don't have a license or anything so I would like to ...
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4answers
12k views

How To Join Packet Radio BBS

I'm a complete newbie here, and on the Southeast Coast of the USA. I don't even own a ham radio yet. Some preppers and I got to talking about a dystopian time of Internet collapse where shortwave ...
2
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1answer
204 views

Is it possible to generate rf by directly programming a pc parallel port?

From what info I've found, it seems a pc parport has a max speed of ~2meg /sec ? So transmission on medium wave, to ~160 meters should be possible ? With antenna than possibly a small wire, I ...
2
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2answers
137 views

Reproduce ambient EM fields inside a Faraday cage?

I am part of a research team looking at the possible effects of EM fields on psychological function. The experiment calls for participants to perform a series of tests while inside a Faraday tent that ...
4
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4answers
395 views

Low power long distance wireless data communication

I am looking for a communication solution with the following requirements: wireless unidirectional, point to point low power (li-ion battery powered, should operate at least one hour on the single ...
1
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1answer
929 views

2-Pin Kenwood to Sound Card (Beofeng UV-82HP & ASUS Xonar Essence STX)

I have a Baofeng UV-82HP that I want to use to TX and RX to a TeamSpeak Server. For this I'm going to use a dedicated computer, for both the client and server that has a sound card (ASUS Xonar Essence ...
2
votes
1answer
2k views

How to set trasmit freq. on Baofeng UV5R to 0MHz manually

On this quesiton: How can I avoid accidentally transmitting with a Baofeng UV-5R? I learned how one can avoid accidentally transmitting on a Baofeng UV5R. This can be done using software by setting ...
4
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2answers
128 views

What does radiation power mean?

I would like to ask you what it means when it is written that a transmitter has 10 dBm power. Does that mean that 10 dBm is provided to the antenna, or that 10 dBm is measured at particular frequency ...
1
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2answers
258 views

How difficult is it to build a basic transmitter and receiver

Preferably something that could transmit LED lights, like patterns. After that I'd like to advance to audio and video. But for the basic radio transmitting and receiving how difficult of a job would ...
1
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1answer
153 views

International Broadcast - database programs? [closed]

In my search to identify the stations I can (barely) hear on my small shortwave setup, I discovered the HFCC. They have a tool that takes your location and UTC time, and provides a list of stations ...
3
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1answer
289 views

SSB modulation image rejection

I'm trying to figure out how SSB transmitters manage to get rid of the images created when mixing up audio frequencies. For example, when mixing a 1KHz signal with a 7MHz one you will end up with two ...
3
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1answer
2k views

Jamming with USB SDR

Could an attacker use a simple USB SDR dongle, as long as it is capable of transmitting within a certain range, to jam frequencies? I saw Lady Ada build the WaveBubble which is basically a dual-band, ...
3
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1answer
659 views

Audio Morse Code to CW converter?

What kind of circuit can be constructed and/or could be used to convert audio containing Morse Code sounds (say from an old practice tape, or from computer generated audio) into key, switch or relay ...
2
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2answers
1k views

What is a “dip relay” and how does one use it to build a transmitter?

Reading a discussion on low parts count transmitters, I came across this description, which lacked schematics and build instructions: Re: PROJECT 14: THE WORLD'S SMALLEST TRANSMITTER Are y'all ...
6
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2answers
3k views

Preventing CW key clicks

What are "key clicks"? How much does the rise time or bandwidth of a CW signal need to be limited to prevent other QSOs on adjacent frequencies from being annoyed by "key clicks"? Is there a legal ...
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1answer
174 views

How do I radio? [closed]

What's the simplest way to make a radio station from my home? I just want to bump this city with some slick tunes. What do I need to buy and about how much am I to spend?

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