Measure the round trip and divide by two for the approximate one way time. It'd be really neat to measure the time it takes for a packet to travel in one direction, but it's somewhere between hard and impossible[1]; a very short path has less room to be asymetric though.
[1] If the clocks are synchronized, you can measure send time on one end, and receive time on the other. But synchronizing clocks involves estimating the time it takes for signals to pass im each direction, typically assuming each direction takes half the round trip.
You can use something like White Rabbit (https://en.wikipedia.org/wiki/White_Rabbit_Project) to keep clocks in sync. That still involves estimates, but a dedicated time sync network can do things like make sure all the cables are the same length.
To work towards eliminating PFAS in everyday products, I envisioned a service where people could send in things they own to have them tested, and the results would be published on a website/app and searchable via barcode. Win/win: users get free PFAS testing, and the service gets free products to test to create a database.
I researched how to perform rigorous PFAS testing but it looks like the best method is PIGE which requires a particle accelerator, which aren’t exactly easy to come by.
Anyway just posting this in case anyone has thoughts or would be interested in working on something like this.
I love the idea. Kind of like harm reduction through drug testing. Except the drugs are legal and don’t give you a high.
I would probably rather advocate for Which (UK), Consumer Reports (US) and various similar organisations to work on this than start a new org.
Unless you just use this as a marketing strategy for a commercial lab (in which case you will simply forget the noble initial goal and end up simply operating a testing laboratory business.)
I always assumed it was because FM station bandwidths (200kHz) are much wider than AM (10kHz). AM's 10 kHz chops off a lot of human-hearable frequencies.
When you amplitude-modulate a carrier wave with an audio signal, you spread it out into a bunch of sum and difference frequencies, as you can see if you use the trigonometric angle-sum formula to factor cos(85000·2πt) · (2 + cos(440·2πt)), a 440-hertz flute being transmitted on 85-kilohertz AM. These so-called "sidebands" mean that the bandwidth of AM does matter, and consequently, using a too-narrow bandpass filter on your AM radio station will result in low-pass filtering your demodulated audio signal.
AM does use the frequency, it just doesn't need as much and uses it differently than FM. If it was all at a single frequency, there just be a single tone getting louder and softer.
Once you change the amplitude of a sine wave (modulate it) it's no longer a side wave. It spreads in the frequency domain. Take the fourier transform of that and you can see the frequency components.
- I think the most important skill for making hardware is just having a good fundamental understanding of electricity. Just developing an intuition around Ohm's law gets you remarkably far in terms of developing and debugging circuits. Towards that end, Khan's "Introduction to electrical engineering" and MIT's 6.01SC Unit 3 both look great.
- For this specific project, I needed to program an FPGA so I drew on my college experience (18-240) where we learned about FPGAs and Verilog. Coursera's "Introduction to FPGA Design for Embedded Systems" looks like a good option.
- Don't be discouraged by hardware tools. Coming from a software background, using hardware tools is like traveling to a foreign land where good UX is punishable by death. At its core, designing PCBs is really just drawing 2D shapes, and it's striking how painful drawing is using hardware tools (eg Eagle, Kicad) versus how delightful drawing is using artistic tools (eg Sketch, Figma).
Is the battery soldered? Is it a fairly standard kind of thing like an 18650 (obviously not the same size, but I'm not familiar with what "standard" pouch style batteries exist)?
It’s not soldered, but it does have a Molex Pico-EZmate connector (chosen for its low profile), and I’m not sure you can find batteries premade with that kind of connector. You could reuse the existing connector with a new battery, but that would ideally involve soldering.
Send me an email (support@toaster.llc) and I can make a custom Stripe invoice / shipping label. Still need to figure out how to automate international shipping!
> How does your manufacturing process look like if someone decides to click the "buy" button and do you have any open orders currently?
I assembled ~120 of these devices beforehand so I just need to package them up and ship them out when I get an order.
> Also do you actively use it currently on your bike or do you know some use cases of someone that bought/has it?
I intended to put the device in the garage to catch the thief, rather than attach it to the bike. But with a good mounting solution (which I should invest some time into!) you could certainly use it on a bike for time-lapses. It should work great for a cross-country road trip.
A friend of mine is using it to do a timelapse of a house construction project, and I mailed out the first orders today so they're in the wild now!
In case it helps explain the wording: I went with "exclusively for Mac" because I intended it to be an in-group signal to Mac folks that the product is high quality and conforms to the norms of the Mac platform. In my experience, cross-platform GUI software usually doesn't conform to Mac software conventions (and IMO just kinda sucks by Mac software standards). So my wording is trying to convey that the software isn't your typical cross-platform Electron/QT/GTK app.
Anyway, would love to add Linux support, just trying to figure out if that's what I want to do with my life right now.
Aren’t these numbers .2 ms, ie 200 microseconds?