Hey lazy question, so if you buy this and program it is it already FCC / CE certified for say 802.11a? And could you sell it like how companies sell RPis pre-packaged up with some software?
This is a guess, but it is a good one: no. It may not even be possible to get it certified (wrong interpretation of the law to me, but the government has more lawyers than anybody else). Many SDR boards don't have the power required to do actual transmission as it is hard to design a front end that pleases everyone, but equally as important, any real transmit power could mean the device is construed as non test equip…
It would matter to anyone who might want to build it in to a product.
How is it that an SDR is being praised for a $1K price-point, but I can buy an FM/AM radio for single-digit $ - yet I pay $1,000 for a cell phone today and it doesnt have a native FM/AM radio on it? People keep saying "just use data" - which is what I think to be a fn bullshit response. give me a device that has actual FM/AM capabilities natively. Seriously - the most high-tech wireless device in my pocket MUST inclu…
While receiving analog radio is trivial for the processing required, it is fairly low frequency transmission which requires antenna sizes which are not entirely practical for phone-like device. I would even assume that many phones contain the required hardware (which usually involve using headset cable as antenna) but don't have any kind of software support for it because of combination of minimal demand for such a f…
I think the main reason that phones don't have broadcast AM and FM enabled (even though the hardware is present in the chips), is because the digital chips in the phone (micro-processor etc) would generate so much interference (at these relatively low frequencies) that it would be unworkable. To sufficiently shield the main PCB would require a huge effort, which means weight, size and cost.
To get an idea, you only need to hold your AM/FM radio near your PC or Laptop.
Speaking of radios, I’ve been trying to understand light recently and it’s difficult. I find that for most things, I have a visual intuitive model to reason about things. But I have a hard time visualizing RF light. There aren’t any good videos out there of just a straight forward visualization of RF light. It’s all abstractions with a sine wave, but no visceral visualizations, rendered or otherwise. The closest thin…
> Why can’t they make visible light with an antenna? Why can't an oscillator and antenna emit matter? Is some matter transparent to other matter in the same way that some matter is transparent to light? This idea that matter and energy are equivalent and that the same wave physics underlies it all doesn't seem to be true in reality. Instead it seems that phenomena are divided into regimes and in each regime behavior…
You can (for the most part) produce bosons (e.g. photons, aka light), individually or in big piles, out of thin air. You cannot produce fermions (e.g. electrons, protons, neutrons) out of thin air like this. To make an electron, you need to also produce a positron or do something else that satisfies the various conservation laws. You can make an electron-positron pair in a collider, but doing this in large amounts takes absurd amounts of energy.
Speaking of radios, I’ve been trying to understand light recently and it’s difficult. I find that for most things, I have a visual intuitive model to reason about things. But I have a hard time visualizing RF light. There aren’t any good videos out there of just a straight forward visualization of RF light. It’s all abstractions with a sine wave, but no visceral visualizations, rendered or otherwise. The closest thin…
> And also, why can visible light pass through other visible light without causing interference? Radio passing through radio doesn't interfere with thr signal. Its just more likely that the interfering signal will also be picked up by a receiver. Think about a bright white lighbulb next to a small red LED; you won't be able to see the small LED. The other part is that out eyes are essentially 2d grids that are fairly…
Thanks for that explanation. This radio stuff is heavy duty!
Speaking of radios, I’ve been trying to understand light recently and it’s difficult. I find that for most things, I have a visual intuitive model to reason about things. But I have a hard time visualizing RF light. There aren’t any good videos out there of just a straight forward visualization of RF light. It’s all abstractions with a sine wave, but no visceral visualizations, rendered or otherwise. The closest thin…
> And also, why can visible light pass through other visible light without causing interference? Radio passing through radio doesn't interfere with thr signal. Its just more likely that the interfering signal will also be picked up by a receiver. Think about a bright white lighbulb next to a small red LED; you won't be able to see the small LED. The other part is that out eyes are essentially 2d grids that are fairly…
>> Why can’t they make visible light with an antenna?
> In terms of normal radio antenna designs, you could, I think, but antennas need to be sized proportional to the wave length of the light.
There is also one more difference to mention. For antenna design in radio frequencies the metals are taken as perfect conductors—meaning that the fields inside the metal are zero. This assumption relies on the fact that electrons in the metal respond the electric field basically instantaneously. However, the optical frequencies are significantly higher, so the movement of the electron cloud in the metal is no longer instantaneous relative to the outside fields. As a result metals at frequencies of visible light are way less "metal-like" when looking from the perspective of RF antenna design, so you can't directly use the exact same approaches for designing antennas.
While receiving analog radio is trivial for the processing required, it is fairly low frequency transmission which requires antenna sizes which are not entirely practical for phone-like device. I would even assume that many phones contain the required hardware (which usually involve using headset cable as antenna) but don't have any kind of software support for it because of combination of minimal demand for such a f…
I think the main reason that phones don't have broadcast AM and FM enabled (even though the hardware is present in the chips), is because the digital chips in the phone (micro-processor etc) would generate so much interference (at these relatively low frequencies) that it would be unworkable. To sufficiently shield the main PCB would require a huge effort, which means weight, size and cost. To get an idea, you only n…
FM radio works pretty well on a lot of smartphones.
This is a guess, but it is a good one: no. It may not even be possible to get it certified (wrong interpretation of the law to me, but the government has more lawyers than anybody else). Many SDR boards don't have the power required to do actual transmission as it is hard to design a front end that pleases everyone, but equally as important, any real transmit power could mean the device is construed as non test equip…
It would matter to anyone who might want to build it in to a product.
This would be a horrible way to make a product which isn't a piece of test equipment. The power consumption and manufacturing cost is orders of magnitude higher than a specific purpose device.