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Questions tagged [transmitter]

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0
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1answer
42 views

Is there any way in which elevation *does* affect medium frequency (AM radio) transmissions?

This is a followup to this question of mine. From reading the wiki article, I get that: Radio waves at MF wavelengths propagate via ground waves and reflection from the ionosphere ( called skywaves)...
1
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0answers
132 views

LimeSDR Mini + Raspberry Pi 3 B+ Transmission problem

I am new at this. I would like to transmit an audio signal cleanly using WBFM but I see two signal peaks occur around my fundamental frequency when I start transmitting. In this case I am using a ...
1
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1answer
80 views

Why would a nearby antenna cause intermittent transmission?

I'm having an issue with some handheld transmitters, and not sure if they're bad, or the newly-installed antenna is bad, or if this even makes sense. I've been using a handheld Icom aviation radio (...
9
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3answers
393 views

What does the spark-gap do in a spark-gap transmitter?

I read the Wikipedia article about spark-gap transmitters and I have to admit that I’m even more confused as to what the spark-gap actually did. The article references this simplified circuit ...
7
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4answers
303 views

How to tune an FM transmitter to a specific frequency?

I am planning to organise a simple fox hunt, a family event. This includes building a transmitter. I am currently considering the following schematics: https://maker.pro/education/diy-fm-transmitter ...
1
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1answer
71 views

Parts for a 915 MHz low power transmitter

I'm interested in doing some experimentation with custom modulation in the 915 ISM band. Off-the-shelf radio modules use specific known modulations (FSK, QAM, etc.) so those won't work for my ...
1
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3answers
146 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
57 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?
0
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1answer
383 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
304 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 ...
4
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2answers
443 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
112 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
78 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
95 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 ...
4
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3answers
516 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
952 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
201 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
98 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 ...
4
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1answer
308 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.
0
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1answer
62 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
121 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 ...
10
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4answers
5k 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
154 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 ...
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2answers
111 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 ...
3
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4answers
328 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 ...
0
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1answer
578 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
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1answer
1k 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 ...
2
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2answers
105 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
219 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
121 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
votes
1answer
212 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
votes
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
507 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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1answer
713 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
2k 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 ...
-2
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1answer
138 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?