How does a ht transmit?

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reconrider8

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i know this can go very deep but how does a ham radio transmit? from the time you push the ptt to the time the other person hears your voice what happens in the radio? im not asking about repeater operation but inside the radio.
 

k9rzz

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In 20 words or less? LOL I suppose, these days you can probably get everything on one IC chip, but here's a simple diagram. Basically, you need a circuit to generate the proper RF signal, and you modulate it with your audio. Then there's filtering too.

txdiagram.gif
 

reconrider8

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In 20 words or less? LOL I suppose, these days you can probably get everything on one IC chip, but here's a simple diagram. Basically, you need a circuit to generate the proper RF signal, and you modulate it with your audio. Then there's filtering too.

txdiagram.gif

thanks i think... :p i guess my question now is what does each of these do as far as transmitting. just passed my ham test saturday and im trying to get a feel for how these work. i tried youtube to try and find an animated video but no such luck lol thanks in advanced
 

cmjonesinc

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It's always blown my mind how someone just sat down one day and thought "well if I combine all these pieces I can get it to do this". I understand building smaller circuits but even then I scratch my head sometimes. It just amazes me what goes into building a radio or even a computer from the ground up. People knock the cheap Chinese radios but even their engineers know more than I could ever dream of about making something work haha. I suppose if you go back to the early days it may be easier to understand but even then there's a lot to wrap your mind around.
 

reconrider8

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It's always blown my mind how someone just sat down one day and thought "well if I combine all these pieces I can get it to do this". I understand building smaller circuits but even then I scratch my head sometimes. It just amazes me what goes into building a radio or even a computer from the ground up. People knock the cheap Chinese radios but even their engineers know more than I could ever dream of about making something work haha. I suppose if you go back to the early days it may be easier to understand but even then there's a lot to wrap your mind around.

thats kinda what im wondering now is just how do these work. its gotta be more then just pushing the button and talking. gotta have power from the battery and that power has to go through something then somewhere along the line it has to pick up your voice and then add it into a carrier i would guess and then push it out to the repeater. LOL
 

n0nhp

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I'll bet your local community college has an electronics technology course that would probably answer your question within two years or so.
I don't think we are going to be able to answer your question in a forum post or two. Be prepared to learn some physics and math along the way.
The best answer I usually give to the layman who asks the question is "See it says FM transmitter, you know what FM stands for? F***ing Magic". For as a favorite author once said "any technology sufficiently advanced is indistinguishable from magic"

:)

Bruce
 

riveter

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In super oversimple half-assed terms for FM modulation:

1) The vibrations in the microphone turn into a modulated electrical signal going into the Frequency Generation Unit.

FGU is two parts: frequency synthesizer and signal oscillator/mixer.

2) Reference oscillator in frequency synthesizer oscillates its own generated signal at a constant rate (say, for instance, 869.8875 MHz). A variation is applied to this reference frequency to generate the RF frequency on which the radio itself transmits (say, for instance, 870.2125 MHz). This signal is passed to the signal oscillator.

3) The signal oscillator superimposes a filtered version of the audio modulation signal on to the signal coming from the frequency synthesizer. This produces a modulation in the RF frequency, and the composite signal is then passed to the PA.

4) The power amplifier ramps up the signal strength of the composite (modulated) RF signal and passes this signal to the antenna.

5) The antenna resonates with this oscillating signal, causing energy to dissipate out from the antenna with relatively high efficency.

6) Receiving radios essentially do the same process in reverse - receiving, demodulating, and filtering to output audio.
 

reconrider8

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In super oversimple half-assed terms for FM modulation:

1) The vibrations in the microphone turn into a modulated electrical signal going into the Frequency Generation Unit.

FGU is two parts: frequency synthesizer and signal oscillator/mixer.

2) Reference oscillator in frequency synthesizer oscillates its own generated signal at a constant rate (say, for instance, 869.8875 MHz). A variation is applied to this reference frequency to generate the RF frequency on which the radio itself transmits (say, for instance, 870.2125 MHz). This signal is passed to the signal oscillator.

3) The signal oscillator superimposes a filtered version of the audio modulation signal on to the signal coming from the frequency synthesizer. This produces a modulation in the RF frequency, and the composite signal is then passed to the PA.

4) The power amplifier ramps up the signal strength of the composite (modulated) RF signal and passes this signal to the antenna.

5) The antenna resonates with this oscillating signal, causing energy to dissipate out from the antenna with relatively high efficency.

6) Receiving radios essentially do the same process in reverse - receiving, demodulating, and filtering to output audio.

Perfect :)
 

Ed_Seedhouse

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It's always blown my mind how someone just sat down one day and thought "well if I combine all these pieces I can get it to do this".

That didn't happen. What happened was, starting with spark gaps and making incremental improvements, inventing tubes and figuring out what they could do, and so on. And on. Each generation built on the achievements of the previous one and so here we are today.
 

Ed_Seedhouse

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To simplify even more, what causes a radio signal is moving electrons back and forth on a wire at a given frequency. Electrons moving back and forth generate electromagnetic fields, and that's radio. Of course there are other minor details like modulation and such, but without electrons moving back and forth on a wire ya got nuthin.
 

K3DCX

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It's always blown my mind how someone just sat down one day and thought "well if I combine all these pieces I can get it to do this". ....

You have to remember that at one time, the pieces did not exist.

It starts with Maxwell and his theory on electromagnetism. His math theorize that radio waves could propogate through space. Later, Hertz proved this with his experiments on Hertzilian Waves.

That set the ball rolling as innovators saw uses in wireless energy. One notable was Tesla who dream of wireless light and power distribution. A lot of folks went to work on communication applications. Marconi worked on a commercial wireless telegraph system for marine and military. He was credited for saving lives on the titanic. So then others worked on voice, which requires microphones, and better bandwidth management(spectral power management). Westinghouse invented the detector vacuum tube. That and a broadcast using a rotary spark transmitter , achieved the first AM transmission.

So the game was on. Some leaps were inventors trying to solve a problem, or scientist that stumbled across an unexpected result. Many advances come from other industries.

It's been an awesome ride!

Homework: lookup and study Superheterodyne




Sent from Foxtrot-Mike 19
 

N8IAA

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How does someone come up with the idea that radio waves can bounce off.. I guess I'm just to stupid to figure out stuff

It's the physics of the radio wave. Different wave lengths either get absorbed by certain materials, others, bounce off.
Larry
 

mmckenna

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You guys are making this way too complicated. Albert Einstein was asked how radio works, he had a very simple (and accurate) description:

"“The wireless telegraph is not difficult to understand. The ordinary telegraph is like a very long cat. You pull the tail in New York, and it meows in Los Angeles. The wireless is exactly the same, only without the cat.”

That, my friends, is the simplified description on how radio works.
 

K3DCX

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How does someone come up with the idea that radio waves can bounce off.. I guess I'm just to stupid to figure out stuff


As Hertz experimented proving Maxwell's equations, he observed that radio waves exhibited the same propagation phenomenon as light waves, such as reflection, refraction, scattering, absorbsion, etc...

I think you beat yourself up on some of this. Dont bog yourself down on some of this.

ARRL has a pretty decent antenna book.




Sent from Foxtrot-Mike 19
 
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