This is plainly false though. You're saying beats can't be localized to less than one second of precision (regardless of track length, which already smells suspect). Humans can localize a beat to within 50ms.
Yes, I got lost in the numbers and made a blunder by misinterpreting what we mean by frequency resolution expressed in "BPM" instead of Hz.
It is correct to say "0.0046237213 Hz which is 0.27742328 BPM". My mistake was to interpret 0.27742328 BPM as the limit of frequency resolution in units of BPM. Rather, any BPM measured must be an exact multiple of 0.27742328 BPM.
Thanks for pointing out my mistake!
> (regardless of track length, which already smells suspect)
Frequency resolution being dependent on the number of samples is a very well known property of basic sampling theory and signal analysis.
In fact, one can interpolate the frequency spectrum by zero-padding the time samples. This increases the resolution in an artificial way because it is after all an interpolation. However, a longer song has more natural frequency resolution than a shorter song.
Note, this frequency resolution is not related to fidelity which is some messy human related thing that is over a sliding window of shorter duration that I don't pretend to understand.
BTW, the opposite is also possible. You can zero-pad the spectrum as a means of resampling (interpolating) the time domain. This is slower but more spectrally correct than say time-domain linear or cubic interpolation.
These techniques require an FFT and so are somewhat expensive to apply to long signals like an entire song, as I did for the plot. Daft Punk's HBFS takes about 8 seconds on one CPU core with Numpy's FFT.
There's a concrete ship wrecked just offshore of Cape May Point in NJ. It has been deteriorating for many years and soon nothing will remain above the waterline.
At the southern tip of Virginia’s Eastern Shore there are 9 concrete ships, left over from WWII, that were deliberately sunk in a large arc to form a break-water.
It’s at a state park called Kiptopeke. You can rent kayaks and paddle out to see them up close.
I did raise eyebrows once of the person in the row behind me. I said I was listening to ATC and that seemed to placate him. I do believe most airlines have a blanket ban on radio equipment, even receive only. Some even ban using GPS!
Here are some more things you can do with your RTL-SDR after the first 50:
Meteor weather satellite reception (Russian counterpart of the NOAA satellites, but digital, so higher res and in color)
Digital Radio Mondiale -- digital radio but for shortwave
Analog TV -- if you're in an area that still broadcasts this (unlikely), you can receive a black & white picture and closed captioning. If no OTA broadcasts remain, you can use the analog output of a VCR or DVD player
GPS -- rtlsdr is capable of decoding GPS, Galileo, and BeiDou! (Likely not GLONASS since each satellite uses a separate frequency, spreading the signal beyond the sdr's bandwidth)
Hidden secondary audio broadcasts inside FM radio (like the stereo audio hack, but using higher frequencies in the demodulated stream)
Brazilian outlaws and UHF pirates using open repeaters on US military satellites launched in the 70s
TEMPEST / "Van Eck phreaking" where you can remotely read a nearby screen due to leakage from the monitor or video cabling
Instrument landing system -- if you're near an airport you can tune to a runway's ILS frequency and see the signal change as you move from the left side of the runway to the right
Infrared remotes -- stick an IR photodiode in the antenna port and you can demodulate codes from remote controls
Passive radar -- Tune into a very narrowband signal like a VOR or ATSC pilot signal, set your decimation extremely high (i.e., trading bandwidth for dynamic range) and you can see nearby planes in the area from their doppler-shifted reflections of the main signal
It's not like you can apply a software security patch to a 1970's hardware communication device in orbit. They're likely going to continue acting as open repeaters until their orbit decays and they fall.
The receiving IR remotes with an SDR by connecting an IR photodiode across the antenna input sounded like nonsense to me. I googled and could it be you meant people using the IR receiver feature of the RTLSDR's? It may still require connecting a photodiode, but to a different set of inputs.
As to connecting a photodiode to the antenna input, I don't see how that would work, but that may well be due to my limited understanding and imagination.
Do you mean using the photodiode in a photovoltaic mode? Also, presumably you'd have to bypass the tuner and hook to the direct sampling pins on an RTLSDR? Even with direct sampling, wouldn't the 38kHz of IR remote modulation get filtered out by the DC blocking?
A photodiode (BPV23NF iirc) connected straight to the dongle's SMA connector. Yes, I believe it would be operating in photovoltaic mode, where the incident IR light from the remote control will induce a small voltage. Yes, I had direct sampling mode turned on (but the rtl-sdr.com V3 can do this through the normal antenna port). I pointed the remote at the sensor (admittedly quite close) and saw a signal centered on 38 kHz in the waterfall, and was able to export the binary pulses.
I imagine, provided the IR's frequency can be sampled by the SDR, it would look like fairly wide band bursts that could be decoded? Especially if you just treat the SDR as a ADC Oscilloscope
> Do you like feeling safe about leaving your expensive stuff in your hotel room? Have you ever had anything stolen out of your room, or discovered someone has gained access to your room while you weren't there? .. what about .. other rooms? Maybe not EXACTLY a hotel room? I've presented on securing hotel rooms in the past, but adding home assistant, zwave devices, co2 sensors and millimeter wave radar it's become a whole new game
> We use the GNURadio software along with RTL-SDR and ADALM-PLUTO hardware to explore the world of digital communication. We build up to a simple QPSK modem and rudimentary GPS reception.
> official [PlutoSDR] firmware updates are no longer focus on new features for SDR enthusiastic people.. tezuka.. aims to be Universal Zynq/AD9363 firmware builder for.. PlutoSDR, Pluto+, AntSDR (e200), LibreSDR
Specifically mine deals with what you'd hit looking across the ocean from a coast. I had long wanted to make mine an interactive app but could never fully motivate myself to do it, so congrats for shipping.
I think you're confusing a NEMA 5-20 (120V, 20A) and NEMA 6-20 (240V, 20A). Each has one blade sideways but they're mirror images of each other. T-slot varieties of both outlets are common, which can accept both 15A and 20A versions of their respective voltages. You won't find outlets that can accept both a 120V and 240V plug.
This house had sockets that would accept NMEA 5-15, 5-20, 6-15 or 6-20. (I forgot the numbers until you mentioned them). It wouldn't be allowed now, but my guess is the house was built in the 1950s.
Those outlets existed because pre-NEMA there were competing parallel and tandem bladed plugs/sockets [1]. The plugs you saw were probably like examples 2 & 3 in that link. The parallel configuration became NEMA 5-15P and the tandem became NEMA 2-15P.
The NEMA 6 series is wider than the 5 series and the 6-15P probably won't fit in those old outlets, but the NEMA 2-15P would. . . if you could find one.
Ah yes, I have seen those before (quite rare). IIRC they don't have holes for the grounding prong, which should prevent plugging in any modern 240V appliance.
I just had some fraudulent withdrawals on my bank account pretending to be paypal. They did the two sub-$1 authorization transactions, then took out $400 then "reversed" it by putting it back into my account... maybe to attract less suspicion and execute a larger fraud later?? Anyway, my bank reversed the withdrawals and I just got to keep the $400 the scammers deposited in.
> They are not identical. The aspects you are willing to ignore are more important than the aspects you are willing to accept. Robbery is not just another way of making a living, rape is not just another way of satisfying basic human needs, torture is not just another way of interrogation. And XML is not just another way of writing S-exps. There are some things in life that you do not do if you want to be a moral being and feel proud of what you have accomplished.
If there is an argument beneath the hyperbole and i-am-very-smart posturing, it seem very weak. He end up advocating a binary format (like TCP/IP) instead of a text-based like XML because it will be faster to parse. And because a binary format is harder to change, people will be sure to get it right the first time.
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