colanderman

8 ms·

1.
by colanderman 4mo ago
Anything physical which dampens higher frequency oscillations would act as an antialiasing filter.
2.
by colanderman 5mo ago
Spectral power density is the primary concern. The legal power limit in these bands is 1 W. If you spread that out over 500 kHz, that signal is weaker than background noise at any given frequency for anyone more than about a city block awa
3.
by colanderman 5mo ago
Correct. The LoRa configurations mentioned which offer 100× the speed of Meshtastic/Core operate at 800 kHz and 1.6 MHz bandwidth, which are permitted by the FCC in 15.247. As far as I know there's not actually anything particular
4.
by colanderman 5mo ago
The 915 MHz, 2.4 GHz and 5.8 GHz bands are regulated in the US largely in the same manner, see https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A...
5.
by colanderman 5mo ago
I did not state that humans cannot see corona. Nor is the paper is about humans seeing corona. It is about detecting UV photons using specialized equipment.
6.
by colanderman 5mo ago
Which photograph? The one in the article is not from the paper. The paper contains no photographs of corona.
7.
by colanderman 5mo ago
Can you point me to the images of corona in the paper which I missed?
8.
by colanderman 5mo ago
The images in the article are not from the paper. The paper contains no images of corona.
9.
by colanderman 5mo ago
There is in fact no photograph of treetops glowing. There is a digital UV-wavelength video of the corona, and a visible-wavelength video of the trees. The paper [1] contains a sole picture with tiny circles indicating where the UV-video det
10.
by colanderman 7mo ago
Nice! I've been looking for such a thing lately. KISSLoraTNC [1] is another implementation: The radio control interfaces differ though. [1] https://github.com/kc1awv/KISSLoRaTNC
11.
by colanderman 7mo ago
I am just getting into the packet scene in the Boston area. APRS aside, as far as I've found, there are about a half dozen Winlink nodes in the area and one BBS. And one lovely node in Cambridge (KZ2X-1 [1]) which provides connectivit
12.
by colanderman 7mo ago
Hah! I was literally about to open up my nascent userland AX.25 stack. Is yours open-source, or would you mind sharing? (My e-mail is in my profile.) I want to get something running on an ESP32-S3. My goal is to turn a Cardputer into a
13.
by colanderman 7mo ago
You may find a good fit at a UU church.
14.
by colanderman 8mo ago
I have nostalgia for Wario Land, because I played it for 5 minutes in a Toys'R'Us, and it's a good game which I never got to play in full until decades later. But I never owned one, so everything else you said rings true to m
15.
by colanderman 9mo ago
I know only basics about mesh networks per se . I'm speaking here from a background in signal theory / amateur radio / research on the LoRa protocol. If you have specific questions on those aspects feel free to contact me,
16.
by colanderman 9mo ago
Correction (too late to edit), MeshCore is 62.5 kHz bandwidth, not 125 kHz.
17.
by colanderman 9mo ago
I am pretty sure (though have not vetted) that triangulation of LoRa is possible even at very low SNR. The trick is understanding LoRa's trick, which is simply to "skew" the signal across time (via chirps), modulo a window of
18.
by colanderman 9mo ago
A gentle FYI for casuals interested in Meshtastic / MeshCore in the the USA: the default radio settings promoted by both these services are actually outside the parameters permitted by the FCC for unlicensed spread-spectrum operation,
19.
Google and Apple roll out emergency security updates after zero-day attacks(techcrunch.com)
5 points by colanderman 9mo ago|0 comments
20.
by colanderman 10mo ago
No, but all MeshCore radios operating in Companion Radio mode do, which is what my post is about.
21.
by colanderman 10mo ago
Agreed – and MeshCore follows a similar "security on the radio" design. With the "cell phone + companion radio" setup which is currently very popular, it would seem the correct solution is to perform encryption on the ph
22.
by colanderman 1y ago
Ah TDoA might not have the resolution you need for that, unless you are working with very wideband signals. Probably ~100 m resolution is the best you can get from it.
23.
by colanderman 1y ago
Oh wow that's a fantastic resource thank you!
24.
by colanderman 1y ago
https://khanfar-spectrum-analyzer.web.app/ also has some phase-based direction-finding software and upcoming hardware. For triangulation though, if you have a reference signal at a known location, TDoA (time difference of a
25.
by colanderman 1y ago
Oh I really like this idea! If you do make this please post it here. This would be a great learning tool for those of us who are trying to learn it also.
26.
by colanderman 1y ago
Not a bug, it was an explicit change they made about a year ago. I used to enjoy the recommendations based on my likes and they took that away.
27.
by colanderman 1y ago
The common guidance I've seen is en dash with spaces, em dash without.
28.
by colanderman 1y ago
Terminology nit: "file descriptor" is the reference itself. "Open file description" is the thing referenced. dup(2) and fork(2) create new file descriptors which reference the same underlying open file descriptions.
29.
by colanderman 1y ago
Not all reals are expressible: to be expressible is to have a finite representation in some language. Definable numbers [1] are that (countably infinite) subset of the reals which can be expressed individually. Almost all reals are not def
30.
by colanderman 1y ago
Why, in your own words , is the jump supposed to be there? (Keep in mind this code is in between two functions.) And why, in your own words , is it OK for the jump to be a conditional backwards jump?

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