Boosting cell phone reception in underground parking garages

[Jarhyn]

Put a sine wave into an audio amp and increase the amplitude. At some point the output clips and is no longer a sine. Linear dynamic range is exceeded and the anp has gone nonlinear.

Reminds me of being in a car stereo place a few years ago. A couple teenagers came in with a couple huge subwoofers in their arms. While waiting for the clerk who was helping other customers we got to talking. The one guy said they bought those SWs a few weeks ago and they sounded great at first. Now they sound terrible and they smell burnt. He said "I have a thousand watt amp and these are rated to take a thousand watts." I immediately figured out what was going on but all I said was "You know enough to be dangerous". The clerk told them they have to place them back into the system and come back with the whole car.

Obviously he figured 1000 watt amp, 1000 watt speakers. Turn the gain all the way up. Obviously he didn't know power rating of amplifiers is where they stop putting out clean power. After that you get clipping and you might as well just hook the speakers up straight to the car battery. Not to mention the high frequency harmonics that come with the clipping.

If he's been inside a car with a kilowatt of amplified music, it's almost impressive that he is still able to hear anything at all.

I live on a somewhat busy street. These assholes go by with such systems they rattle my windows from a block away.

In the news a car company is designing an EV muscle car. Thy are ading pipes that will sound like a gas engine, 100db.

127 db, I've read. It also includes fake shift points so it feels like a multi-geared transmission.

To be fair it's nice having a good long range warning so you know to roll out the spike strips...

 

[ZiprHead]

Put a sine wave into an audio amp and increase the amplitude. At some point the output clips and is no longer a sine. Linear dynamic range is exceeded and the anp has gone nonlinear.

Reminds me of being in a car stereo place a few years ago. A couple teenagers came in with a couple huge subwoofers in their arms. While waiting for the clerk who was helping other customers we got to talking. The one guy said they bought those SWs a few weeks ago and they sounded great at first. Now they sound terrible and they smell burnt. He said "I have a thousand watt amp and these are rated to take a thousand watts." I immediately figured out what was going on but all I said was "You know enough to be dangerous". The clerk told them they have to place them back into the system and come back with the whole car.

Obviously he figured 1000 watt amp, 1000 watt speakers. Turn the gain all the way up. Obviously he didn't know power rating of amplifiers is where they stop putting out clean power. After that you get clipping and you might as well just hook the speakers up straight to the car battery. Not to mention the high frequency harmonics that come with the clipping.

If he's been inside a car with a kilowatt of amplified music, it's almost impressive that he is still able to hear anything at all.

I live on a somewhat busy street. These assholes go by with such systems they rattle my windows from a block away.

In the news a car company is designing an EV muscle car. Thy are ading pipes that will sound like a gas engine, 100db.

127 db, I've read. It also includes fake shift points so it feels like a multi-geared transmission.

To be fair it's nice having a good long range warning so you know to roll out the spike strips...

I was behind a Tesla Model Y yesterday. Very fast and driven very stupidly.

 

[Jarhyn]

Put a sine wave into an audio amp and increase the amplitude. At some point the output clips and is no longer a sine. Linear dynamic range is exceeded and the anp has gone nonlinear.

Reminds me of being in a car stereo place a few years ago. A couple teenagers came in with a couple huge subwoofers in their arms. While waiting for the clerk who was helping other customers we got to talking. The one guy said they bought those SWs a few weeks ago and they sounded great at first. Now they sound terrible and they smell burnt. He said "I have a thousand watt amp and these are rated to take a thousand watts." I immediately figured out what was going on but all I said was "You know enough to be dangerous". The clerk told them they have to place them back into the system and come back with the whole car.

Obviously he figured 1000 watt amp, 1000 watt speakers. Turn the gain all the way up. Obviously he didn't know power rating of amplifiers is where they stop putting out clean power. After that you get clipping and you might as well just hook the speakers up straight to the car battery. Not to mention the high frequency harmonics that come with the clipping.

If he's been inside a car with a kilowatt of amplified music, it's almost impressive that he is still able to hear anything at all.

I live on a somewhat busy street. These assholes go by with such systems they rattle my windows from a block away.

In the news a car company is designing an EV muscle car. Thy are ading pipes that will sound like a gas engine, 100db.

127 db, I've read. It also includes fake shift points so it feels like a multi-geared transmission.

To be fair it's nice having a good long range warning so you know to roll out the spike strips...

I was behind a Tesla Model Y yesterday. Very fast and driven very stupidly.

If I could make every person who drives fast and stupid experience all of the terror and pain of seeing their reckless driving, through clear fault own, lead to a collision with terrain that flips several times and they get crushed under its own weight, and then wake up otherwise unscathed in their own bed but with their car destroyed exactly like that, I would smash that button so hard.

 

[steve_bank]

Sounds like one of those stupid answers on your other thread. An antenna and the front end are two different things. It is like saying front end of a car means the engine as well.

Not for the majority of consideration for most people. "My cellphone doesn't have a 5-g antenna" in common use is a reference to the full front end receiver.

For the record, I've seen some actual antennas get so hot that they stop working properly, or even start to arc out and even melt. Those were transmitter antennas though.

More appropriately, it would be like calling "everything under the hood" or even "the power train", "the engine".

It's not entirely accurate to the pedant but it isn't important to the discussion either.

What is important for most of us is "too much energy in wave make thing hear only noise."

Hmmm. You were standing near the antenna?

How would you say an antenna works and what the purpose of an antenna is?

 

[steve_bank]

And there I was thinking EVs wold bring down traffic noise.

 

[Jarhyn]

Sounds like one of those stupid answers on your other thread. An antenna and the front end are two different things. It is like saying front end of a car means the engine as well.

Not for the majority of consideration for most people. "My cellphone doesn't have a 5-g antenna" in common use is a reference to the full front end receiver.

For the record, I've seen some actual antennas get so hot that they stop working properly, or even start to arc out and even melt. Those were transmitter antennas though.

More appropriately, it would be like calling "everything under the hood" or even "the power train", "the engine".

It's not entirely accurate to the pedant but it isn't important to the discussion either.

What is important for most of us is "too much energy in wave make thing hear only noise."

Hmmm. You were standing near the antenna?

How would you say an antenna works and what the purpose of an antenna is?

The actual physical antenna is a piece of metal whose length corresponds roughly to the wavelength it is supposed to recieve a carrier wave on.

The electromagnetic wave, as it passes the length of metal, pushes the electrons in the antenna as it passes, causing a charge potential on the front end receiver to shift. These shifts are captured, in shift of the frequency domain of (not sure if it's normally the center tone or a side tone, though I'm guessing it could be either depending on the technology) frequency modulated signals, and in the size of the center tone for amplitude modulated signals.

The more force in the wave, the more it shoves around electrons on the front end receiver, as the wave transits the antenna.

 

[bilby]

And there I was thinking EVs wold bring down traffic noise.

Most modern vehicles generate far more noise due to the tyre/roadway interface than from their engines.

Larger and less streamlined vehicles also generate a lot of noise from airflow over their structure.

Neither effect is significantly different for electric vs internal combustion as a power source.

Our old CNG powered buses have noisy engines (by comparison to those of cars), but even so, when you start up an 18m (59ft) long link bus, you need to watch the tachometer to tell whether the engine is running or not, because it's at the opposite end of the vehicle from the driver, so you can't hear it at all, and it's separated by the turntable and concertina from the section the driver occupies, so there's no detectable vibration transmitted by the structure of the vehicle.

As soon as you start moving, the noise from the tyres and the slipstream is plenty of loud enough though.

 

[steve_bank]

The generall purpose ofan antenna is a transducer that matches the typical 50 ohm source impermeable of the transmitter to the 377 ohm impedance of free space.

It is analogus to an audio speaker. A speaker matches the low output electrical impedance to the mechanical impedance of free air. There are design trade offs that result in the typical 8 ohm speaker impedance.

The Maximum Power Transfer Theorem applies to both speakers and antennas. Max power transfer occurs when source and load impedance are the same. That is why the antenna input impedance and the transmitter output impedance are matched.

AM, FM or unmodulated does not matter.

Side band is the correct term.

Electrons in motion give rise to photons. Photons interacting with a conductor give rise to electrons.

An EM wave has orthogonal thematic and electric fields. E/H is the impedance. Voltage/Current.

Your inertial post was essentially nonsense.

In your last post you synthesized a response from general bits and pieces you have read or heard. You nyerpreted bits and pieces. That indicates imagination. Couple imagination with theory and you have scientists and engineers.

Imagination without theory and math is philosophy and metaphysics.

 

[Jarhyn]

Imagination without theory and math is philosophy and metaphysics

No, actual metaphysics is just math: that which is "around" physics.

Which, again, is to say "higher logics and math".

As to where I "piece it together from" it's actually from first hand application: my job is literally tuning a sensor for comparing the amplitude on different tones in the electromagnetic variance of a sensor.

FM and AM only matter to the front end, and depending on which you use is exactly how you are translating the variation and strength of the output of the Fourier transform. As long as you can hide one wave in the other, it's all good.

As stated, signals can interpreted from an antenna in a variety of ways, though the principle is always in catching the variance of voltage spewing off the antenna over time.

Anyway, you're clearly trying to get into a dick measuring contest. If you feel inadequate there, I'd say you could just have mine but I don't think it would survive shipping it.

If you don't like contemplating metaphysics, you got into the wrong profession because software engineers are intrinsically metaphysicists: we play in the space wherein we discuss things about whole mathematical systems without specific concern to what those systems are.

The metaphysicist can build a physics. The physicist can only discover the physics they are handed to figure out.

 

[steve_bank]

You are still dancing around your lack of tecnical knowledge.

Anteater radio folks teach themselves electronics and radio theory without any training in math and electronics. They build their own radios and antennas at home. They are people with a natural curiosity in how things work.

A good intro to radio communication, EM propagation, and antennas is the ARRL Antenna Handbook. 1st addition was the 40s or 50s. It does not require calculus only arithmetic and algebra, but it does require effort. The ARRL also has a book on radio theory.

When I was confronted with something I did not understand I my curiosity drove me to get a book.

Amazon product ASIN 1625950446

Learning theory takes more effort than reading philosophy or metaphysics. Metaphysics is abstract concepts. One can create metaphyscal abstractions at will. Math and science are tied to unambiguous objective reference points.

A rationalization I heard on the forum. Science is philosophy, I am a philosopher, therefore I am a scientist. Saying something is metaphysics does not mean one has actual knowledge. Your knowledge of electroncs is non existent. You speak metaphysically-philosphicaly not mathematical and scintifically as practioners of electronics would.

Theory may be categorically metaphysics in philosophy, but 'metaphysics' is inadequate in communicating theory. That is why Natural Philosophy evolved into modern model based science.

If you want to talk intelligently about radios use the appropriate models and equations.

Use a microcontroller yo A a signal prtoprtional to a voltge. I would use a DDS direct digital synthesis chip to do the modulation.

Demodulate and use a FT to recover the voltage. Pretty straight forward. Depnding on the carrier freqeuncy you can direcly digitize the recieved signal or dwon convert by under-sampling and aliasing.


Philosophy bakes no bread and theory builds cell phones.