51–60 of 101 posts
I might have missed it, how does OP broadcast across 80mhz with a 20mhz SDR? I think my mental model about SDR capability is wrong, does sample rate not necessarily gate the range at which an SDR can TX/RX? Really funny idea!
Code: https://github.com/anfractuosity/musicplayer
Based on the work of https://github.com/fulldecent/system-bus-radio
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The main problem with this line of reasoning is that it neglects important parts defined elsewhere making it seem like this is legal when its not. IANAL, but I do hang out with a lot of hammies. You can't help but absorb a lot of technical stuff with them around. Like for example, https://www.fcc.gov/enforcement/areas/jammers It need not saturate the bands, you technically are in violation the moment a non-licensed e…
For what it's worth (which isn't much), all of that hinges upon the FCC's motivation and capacity to enforce its rules. If amateur and citizens band radio shenanigans over the last few decades have proved anything, it's that you have to be an absolutely massive pain in the radio-wave-receiving public's ass to really get their attention. If you had this device on 14.300, 7.200, or channel 6? Meh. No one's gonna care.
With some filtering on the output to knock down harmonics and aliasing noise, and as long as the power output is low enough, this could actually be legal in the US. IANAL, etc, but this is my understanding: It's actually ridiculously tricky to measure transmitter power output in the terms that the FCC regs are written in, but the rule of thumb is that, given the receiver sensitivity of a typical radio, if you lose th…
If by "ridiculously tricky" you mean "requires specialized equipment and domain knowledge". Like say, skiing. With a cheapish Rigol spectrum analyzer and homebrew receive antennas and DIY wooden/pvc tripods you could probably do 3m open-air measurements to within 3dB of what you would measure in an anechoic chamber at a test laboratory if you were very careful. I can 100% assure you that is possible with a commercial…
They're written as field strength in free space (microvolts per meter), which as I understand it, either requires a calibrated field probe, or a calibrated antenna. I'm sure there's a way to perform such calibrations from first principles, but that's where I'm invoking "tricky". If you've got a trick to it, please share.
In practice, Part 15.23 is pretty generous about home-built equipment, and I think since the "200 foot" thing came from the FCC's own mouth, if you can show that you walked the perimeter with a portable radio and confirmed that you're good, that probably shows good faith on the power issue.
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Absolutely yes a spectrum analyzer is helpful to make sure your harmonic filtering is working. I would put that forth as "good engineering practice" under 15.5, and it's far more than any hobbyist could be reasonably expected to do even just a few years ago; this equipment has gotten mindbogglingly affordable and accessible.
With some filtering on the output to knock down harmonics and aliasing noise, and as long as the power output is low enough, this could actually be legal in the US. IANAL, etc, but this is my understanding: It's actually ridiculously tricky to measure transmitter power output in the terms that the FCC regs are written in, but the rule of thumb is that, given the receiver sensitivity of a typical radio, if you lose th…
The main problem with this line of reasoning is that it neglects important parts defined elsewhere making it seem like this is legal when its not. IANAL, but I do hang out with a lot of hammies. You can't help but absorb a lot of technical stuff with them around. Like for example, https://www.fcc.gov/enforcement/areas/jammers It need not saturate the bands, you technically are in violation the moment a non-licensed e…
https://transition.fcc.gov/oet/info/documents/bulletins/oet6...
Earlier quoted context omitted.
Ah, yeah. If this signal reaches your neighbor across the street, then maybe it's a "public performance" and you've got to get ASCAP and BMI licenses. (And start taking requests.)
I'm going to need a device that allows requests to be made by calling any phone number.
I believe the odd-numbered frequencies were chosen because if only even were allowed then there would be legal knock-down-drag-out fights over the round numbers.
> The Taylorator is a piece of software which allows me to flood the FM broadcast band with Taylor Swift's music. I suppose, you could call it a Taylor Series . (I'm sorry)
I suppose if I make this comment in sotto voce it IS a taylor sum..
> Stations will only appear on odd-numbered frequencies, like 88.1 MHz, 94.5 MHz, 107.3 MHz, etc. There's a technical reason for this - every FM broadcast takes up about 150 KHz of bandwidth, and spacing the broadcasts like this allows for an extra 50 KHz of wiggle room. I believe the odd-numbered frequencies were chosen because if only even were allowed then there would be legal knock-down-drag-out fights over the r…
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Yeah, until you have a 5 year old (probably me in this case in the 80s) that plays with random knobs on the dash when they get in the car. Is it volume? Is it the tuner? We’ll know once the car turns on!
It's broadcasting on every valid ("odd") frequency. I guess it still depends on if you have an analog or digital dial.