Recent submissions

Comment · 19 days ago
RTL-SDR can do GPS L1CA signal processing easily, but you need to use the RTL-SDR Blog dongles not the blue no-name DVB-T dongles as:

- You need stable clock for the processing algorithms to be happy, RTL-SDR blog dongle have 0.5ppm TCXO while who knows what crystal they use on the no-name ones

- RTL-SDR blog dongles have bias-T, and a lot of GPS patch antennas are active antenna that need power from the coax to power the LNA

Comment · 1 month ago
I'm guessing that you're exploiting some sort of exploit (buffer overflow???) on the DVB-T demodulator
Comment · 2 months ago
The tech is already there, but the reason those antenna are not widely used is that they used to fall under ITAR, so no US companies want to touch those for civilian uses. Of course Turkey and China is not US so they don't give a damn about ITAR compliance, and so you can buy those anti jam antennas out of alibaba.

Brad Parkinson, the father of GPS and PNTAB, they've been trying to lobby the US government to remove ITAR from that technology so the civilian can benefit from anti jamming, and finally they managed to do it sometime last year. Now it falls under EAR

Comment · 2 months ago
Not just a requirement, 1gig ethernet transmit and receive at all of those 4 pairs simultaneously to get the throughput
Comment · 2 months ago
I'm guessing you're using one of RISC-V ESP32 variant (ESP32-C3?)
Comment · 2 months ago
My thoughts as several things can be true at once:

- This study is the source of LinkedIn ads from climate change where they try to convince people to move from gas to electric because of bad health effects

- But it doesn't invalidate the study, because of course burning something indoors creates some sort of emission, which may causes asthma in kids

- But its not relevant for me because I'm a single adult not a child and I don't cook that much anyway

- And even when I used to have a gas stove, I used my induction burner more often as its more powerful and makes less waste heat compared to my gas stove

- and the reason I bought an induction wok burner from aliexpress, it can go much hotter than my gas stove

- But one thing that gas stoves excel is even the cheapest gas stoves have a smooth analog control, making it possible to gently heat things, which is important for cooking omelette. For the induction burners I have, it uses on off control, which will scorch the food if your setup (food + cookware) have low thermal mass to smooth it out. You think with the advancement of power electronics because of EV, ebikes, drones and AI data center power supplies someone is able to make a cheap induction burner with analog power control

Comment · 3 months ago
Comment · 3 months ago
That brings up some weird memories.. I saw 2 different researchers do bit manipulation in Matlab by printing the binary data as hexadecimal string, doing string manipulation on it and convert it back to binary
Comment · 3 months ago
There's a strong indication that SpaceX does use software receiver in Falcon 9 and Starlink: when they didn't encrypt the downlink telemetry someone captured the signal and found some plain text: https://www.rtl-sdr.com/receiving-space-x-falcon-9-telemetry...

That plain text looks like what a software GNSS receiver outputs as its very verbose, and this paper: https://radionavlab.ae.utexas.edu/wp-content/uploads/2022/10... , a paper about a software receiver mentioned this:

> PpRx has been licensed through the Radionavigation Lab to multiple commercial companies, but notably a major aerospace company that uses the technology across their suite of advanced spacecraft and satellites. The SDR is deployed across the company’s mega-constellation of satellites used for broadband Internet

Comment · 3 months ago
Comment · 3 months ago
> remove bit twiddling — System programming languages like C, C++, Odin, and Zig need to manipulate bits, but a scientific DSL like Fortran does not need bit twiddling operators like &, |, ~, and so on. Bits are, after all, hardware-level concepts.

Yeah no, your language will be DOA if you don't have bit twiddling, because you can't write arbitrary binary file parser / writer without some sort of bit manipulation.

Even matlab have bit twiddling function

Comment · 4 months ago
Because ITAR only applies to US companies, non-US companies can do and sell whatever they want. My favorite example is CRPA antenna, where they can block the jamming signal, so it was on ITAR. Other countries like Turkey and China doesn't care so you can even buy one of them in alibaba. They got all the money while the US company can't compete because they're not allowed to, so after several lobbying efforts, that technology got downgraded from ITAR, very toxic export control, to EAR, your normal export control.

Another example is high frame rate thermal camera, US companies are banned from exporting cameras above 9 fps, while chinese companies freely sells 50 fps cameras

Comment · 4 months ago
Its an active research topic called signal of opportunity navigation, and papers has been written saying this is possible, some of the uses the idea you mentioned. I used to be involved in using starlink signals for positioning and there are problems:

1. Public ephemeris from space-track (celestrak) is notoriously inaccurate after a while. Less of a problem for starlink as they give free access to high accuracy ephemeris from their onboard GPS receiver: https://starlink.com/satellite-operators

2. For proprietary signals like starlink they can change signals whenever they want without telling you and break your positioning algorithm. For example, starlink used to transmit some sort of narrowband CW wave at their frequency band, which can be received by cheap ($20 ish) RTL-SDR dongle and satellite TV antenna: https://www.rtl-sdr.com/receiving-starlink-signals-with-an-r... . Everyone speculates that its a beacon signal, research papers were written trying to exploit doppler positioning from those signals. Then the signal disappears, as its possible that they don't intentionally transmit those signal. They you can't use cheap hardware to capture the signal, you need expensive hardware that can capture the full 250 MHz bandwidth. This is not a problem if you use standardized signals where they can even intentionally add positioning signals like 5G or digital TV

Comment · 4 months ago
My pedantic self says GNSS includes other non-US constellations such as GLONASS, Galileo and Beidou, and they flew those satellites because they don't fully trust US GPS
Comment · 5 months ago

Live from the official Hacker News API

A modern reader for Hacker News · SvelteKit + Skeleton