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The_Double commented on BPS is a GPS alternative that nobody's heard of   jeffgeerling.com/blog/202... · Posted by u/sksxihve
geerlingguy · 8 months ago
Note that this blog post (and the associated video) were a quick off-the-cuff thing while I was on the NAB show floor—I have been talking to a few of those involved in the testing at NIST, Sinclair, and Avateq (among others), and will hopefully have a lot more in a follow-up.

Right now it's in the experimental stage, with only 6 towers total deployed (only 5 were operational during NAB, and only one in Nevada... so timing, not navigation yet).

The ultimate plan—which is probably dependent on how well ATSC 3.0 rolls out (which has plenty of hurdles[1])—is to encourage broadcasters to add on the necessary timing equipment to their transmitter sites, to build a mesh network for timing.

That would allow the system to be 100% independent of GPS (time transfer could be done via dark fiber and/or ground-satellite-ground directly to some 'master' sites).

The advantages for BPS are coverage (somewhat) inside buildings, the ability to have line of sight nearly everywhere in populated areas, and resilience to jamming you can't get with GPS (a 100 kW transmitter signal 10 miles away is a lot harder to defeat than a weak GPS signal hundreds of miles away in the sky).

The demo on the show floor was also using eLoran to distribute time from a site in Nevada to the transmitter facility on Black Mountain outside Vegas, showing a way to be fully GPS-independent (though the current eLoran timing was sourced from GPS).

[1] ATSC 3.0, as it is being rolled out in the US, doesn't even add on 4K (just 1080p HDR), and tacks on 'features' like 'show replay' (where you tap a button and an app can stream a show you're watching on OTA TV through the Internet... amazing! /s), DRM (at stations' discretion, ugh), and 'personalized ad injection' (no doubt requiring you to connect your TV to the Internet so advertisers can get your precise location too...). Because ATSC 3.0 requires new hardware, consumers have to be motivated to buy new TVs or converter boxes—I don't see anything that motivates me to do so. I feel like it may be a lot like the (forever ongoing) HD Radio rollout.

The_Double · 8 months ago
How does it solve for time without location? With GPS location and time are one solution to an equation with 4 unknowns (x,y,z,t). Without location you won't know the time delay between you and the transmitter.
The_Double commented on Show HN: My $1k self-install, off-grid solar backup build for renters   sunboxlabs.com... · Posted by u/nikodunk
millebe · 2 years ago
This is dangerous and illegal everywhere in the United States. DO NOT DO THIS!

All 50 states have adopted NFPA 70, the National Electric Code, and the linked article shows a bunch of things that absolutely DO require a permit and would absolutely FAIL to be approved:

First and foremost, running bare high voltage DC wires through an open window is in violation of a pile of building codes and very dangerous. The linked solar panels have an open circuit voltage of 64.8V, so with four of them in parallel there can be 260V of direct current. This can and will kill you, especially if you touch it in such a way where muscular tetanus prevents you from releasing the cable.

Electrical extension cords are intended to be temporary, and the article's use of them violates a bunch of codes. Here are some of the relevant ones:

    400.10 Uses Permitted
    (A) Uses
    Flexible cords and flexible cables shall be used only for the following:
        (1) Pendants.
        (2) Wiring of luminaires.
        (3) Connection of portable luminaires, portable and mobile signs, or appliances.
        (4) Elevator cables.
        (5) Wiring of cranes and hoists.
        (6) Connection of utilization equipment to facilitate frequent interchange.
        (7) Prevention of the transmission of noise or vibration.
        (8) Appliances where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance and repair, and the appliance is intended or identified for flexible cord connection.
        (9) Connection of moving parts.
        (10) Where specifically permitted elsewhere in this Code.
        (11) Between an existing receptacle outlet and an inlet, where the inlet provides power to an additional single receptacle outlet. The wiring interconnecting the inlet to the single receptacle outlet shall be a Chapter 3 wiring method. The inlet, receptacle outlet, and Chapter 3 wiring method, including the flexible cord and fittings, shall be a listed assembly specific for this application.
    
    400.12 Uses Not Permitted
    Unless specifically permitted in 400.10, flexible cables, flexible cord sets, and power supply cords shall not be used for the following:
        (1) As a substitute for the fixed wiring of a structure
        (2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors
        (3) Where run through doorways, windows, or similar openings
        (4) Where attached to building surfaces
        Exception to (4): Flexible cord and flexible cable shall be permitted to be attached to building surfaces in accordance with 368.56(B).
        (5) Where concealed by walls, floors, or ceilings or located above suspended or dropped ceilings
        Exception to (5): Flexible cord and flexible cable shall be permitted if contained within an enclosure for use in Other Spaces Used for Environmental Air as permitted by 300.22(C)(3).
        (7) Where subject to physical damage
    
    400.17 Protection From Damage
    Flexible cords and flexible cables shall be protected by bushings or fittings where passing through holes in covers, outlet boxes, or similar enclosures.
You absolutely cannot and should not run bare wires through a window. This manages to violate basically all of Chapter 3 of the NEC:

    300.3 Conductors
    (A) Single Conductors
    Single conductors specified in Table 310.104(A) shall only be installed where part of a recognized wiring method of Chapter 3.

    300.4 Protection Against Physical Damage
    Where subject to physical damage, conductors, raceways, and cables shall be protected.
    
    300.6 Protection Against Corrosion and Deterioration
    Raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes, cable sheathing, cabinets, elbows, couplings, fittings, supports, and support hardware shall be of materials suitable for the environment in which they are to be installed.
    
    300.11 Securing and Supporting
    (A) Secured in Place
    Raceways, cable assemblies, boxes, cabinets, and fittings shall be securely fastened in place.
    
    300.12 Mechanical Continuity — Raceways and Cables
    Raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fittings, or other enclosures or outlets.
    
    310.10 Uses Permitted
    (C) Wet Locations
    Insulated conductors and cables used in wet locations shall comply with one of the following:
    
        Be moisture-impervious metal-sheathed
        Be types MTW, RHW, RHW-2, TW, THW, THW-2, THHW, THWN, THWN-2, XHHW, XHHW-2, or ZW
        Be of a type listed for use in wet locations
    
    (D) Locations Exposed to Direct Sunlight
    Insulated conductors or cables used where exposed to direct rays of the sun shall comply with (D)(1) or (D)(2):
    
        Conductors and cables shall be listed, or listed and marked, as being sunlight resistant
        Conductors and cables shall be covered with insulating material, such as tape or sleeving, that is listed, or listed and marked, as being sunlight resistant
Both the solar panels and the inverter are listed products and are required to be installed in accordance with their listings. In particular, this means they must be permanently fastened to the structure in the manner of the manufacturer's instructions.

    110.3 Examination, Identification, Installation, Use, and Listing (Product Certification) of Equipment
    (B) Installation and Use
    Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
The solar panels must be fastened to the structure in a way that resists wind and weather loads. There are entire sections of the NEC and various IBC codes devoted to this.

Other various code sections that this would fail:

    110.8 Wiring Methods
    Only wiring methods recognized as suitable are included in this Code. The recognized methods of wiring shall be permitted to be installed in any type of building or occupancy, except as otherwise provided in this Code.
    
    110.12 Mechanical Execution of Work
    Electrical equipment shall be installed in a neat and workmanlike manner.
    
    110.13 Mounting and Cooling of Equipment
    (A) Mounting
    Electrical equipment shall be firmly secured to the surface on which it is mounted. Wooden plugs driven into holes in masonry, concrete, plaster, or similar materials shall not be used.
    
    110.26 Spaces About Electrical Equipment
    Access and working space shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment.
    (A) Working Space
    Working space for equipment operating at 1000 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the dimensions of 110.26(A)(1), (A)(2), (A)(3), and (A)(4) or as required or permitted elsewhere in this Code.
    
    (B) Clear Spaces
    Working space required by this section shall not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.
    
    (E) Dedicated Equipment Space
    All switchboards, switchgear, panelboards, and motor control centers shall be located in dedicated spaces and protected from damage. 
    (1) Indoor
    Indoor installations shall comply with 110.26(E)(1)(a) through (E)(1)(d).
    (a) Dedicated Electrical Space. The space equal to the width and depth of the equipment and extending from the floor to a height of 1.8 m (6 ft) above the equipment or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation. No piping, ducts, leak protection apparatus, or other equipment foreign to the electrical installation shall be located in this zone.
    (2) Outdoor
    Outdoor installations shall comply with 110.26(E)(2)(a) through (c).
    (a) Installation Requirements. Outdoor electrical equipment shall be the following:
        (1) Installed in identified enclosures
    
    110.27 Guarding of Live Parts
    (A) Live Parts Guarded Against Accidental Contact
    Except as elsewhere required or permitted by this Code, live parts of electrical equipment operating at 50 to 1000 volts, nominal shall be guarded against accidental contact by approved enclosures or by any of the following means: 
    (1) By location in a room, vault, or similar enclosure that is accessible only to qualified persons.
    (3) By location on a balcony, gallery, or platform elevated and arranged so as to exclude unqualified persons.
    (4) By elevation above the floor or other working surface as follows:
        A minimum of 2.5 m (8 ft) for 50 volts to 300 volts between ungrounded conductors
    
    (B) Prevent Physical Damage
    In locations where electrical equipment is likely to be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage.

The_Double · 2 years ago
I appreciate the effort you put in the comment, and úsed sources rather than just voicing unsubstantiated criticisms.

But still, the mentality in this thread made me double-check if i'm on hacker news or bureaucrat news.

The_Double commented on How to attach logic probes to tiny SMD components (2021)   reddit.com/r/AskElectroni... · Posted by u/dcminter
YiraldyGuber · 2 years ago
I have a bunch of these. They're great, except for being frustratingly "floppy" at times. Imagine huddling over a PCB carefully positioning all these probes, not daring to breathe... only for the slightest brush to send them all tumbling over like dominoes. More than a few curse words have been let loose over this gear, but I couldn't do without them.

It looks like they have new ones that address this: "The new SQ series of handsfree probes from Sensepeek have a lower point of gravity making them even more stable compared with the original SP series of handsfree probes."

The_Double · 2 years ago
I have bought the new SQ probes and went back to only buying the older version.

The new ones are heavier, but that makes it harder to put them at an angle, they fall over more quickly. And the probe heads are bigger so you can't put as many close together.

The_Double commented on New world record with an electric racing car: From 0 to 100 in 0.956 seconds   ethz.ch/en/news-and-event... · Posted by u/ldes
namdnay · 2 years ago
Modern motors get lighter in part because they can offer lower torque with a smaller rotor but compensate with higher rpm. That’s not possible for a hub motor
The_Double · 2 years ago
The hub motors on the car in the OP run at ~24k RPM (faster than any production electric car AFAIK) and have a multistage planetary gearbox for reduction.

Pretty much all top Formula Student cars now use hub motors. Mainly for packaging reasons. Putting the motor in the unused space in the wheel means you can make a smaller chassis and have more space for wings and underbody aero.

The_Double commented on New world record with an electric racing car: From 0 to 100 in 0.956 seconds   ethz.ch/en/news-and-event... · Posted by u/ldes
TaylorAlexander · 2 years ago
They could boost with super capacitors.
The_Double · 2 years ago
Super capacitors are highly overrated by the general public. They really aren't that much better than lithium ion except for in a very narrow power/time bandwidth.
The_Double commented on Superconductor news: What’s claimed, and how strong the evidence seems to be   science.org/content/blog-... · Posted by u/etiam
The_Double · 2 years ago
The strangest thing to me is that apparently this material has been developed years ago, the video of a piece floating was uploaded 3 months ago, and apparently it's easy to produce more samples, but the papers still reads like they have been thrown together in less than a week. (English might not be their first language, but the presentation of the figures is also poor) And it also seems like they haven't spent that time by doing high quality experiments. Surely if you have found a magic material that can change the world you would spend more effort than this on doing experiments and publishing a good paper as soon as possible.

The low quality video and poorly presented graphs are reminiscent of Victor Ninov's fraud.

The_Double commented on Sweden Sans   identity.sweden.se/en/des... · Posted by u/2143
etiennemarcel · 2 years ago
France also has its own design system and font (Marianne): https://www.systeme-de-design.gouv.fr/elements-d-interface/f...
The_Double · 2 years ago
To add to the list: The Netherlands has "rijksoverheid" (government) in sans and serif. https://www.rijkshuisstijl.nl/publiek/modules/product/Digita...
The_Double commented on Threads, an Instagram app   apps.apple.com/us/app/thr... · Posted by u/Xeophon
brucethemoose2 · 2 years ago
Oh, wait, this feels like the start of a cyberpunk story.

If TikTok gets banned, where to the users go? Instagram.

Threads could replace Twitter.

Reddit is going downhill... Maybe Meta could even buy it in a firesale?

Outside of chat apps like Discord, Slack, Teams and Telegram (which compete with WhatsApp), Meta will have consolidated most of the world's social media under them. And that's assuming they dont buy out Discord.

The_Double · 2 years ago
Reddit going downhill is mostly because they are trying to become more like Meta. A competitor should be less meta, not more meta.
The_Double commented on Tell HN: "I don't care about cookies” extension bought by Avast, users jump ship   addons.mozilla.org/en-US/... · Posted by u/popcalc
bandrami · 3 years ago
Between GDPR warnings and ubiquitous site notification pop-ups (side question: has anyone ever intentionally clicked "yes" to a site notifications request? can the browsers just admit this was a horrible idea and move on?) out-of-the-box browsers are basically unusable on just about every website. Leading to extensions and situations like this.
The_Double · 3 years ago
I think the original goal, and one I still support, is for websites to realize that they are better off with not showing the banners and just defaulting to "no". It's been surprising to me that an industry that has been somewhat obsessed with click latencies and getting users to content quickly are willing to annoy all their users for the extra income from personalized ads. The difference in value must be a lot.
The_Double commented on The tiny corp raised $5.1M   geohot.github.io//blog/je... · Posted by u/super256
zaroth · 3 years ago
They removed the human from the car. There’s still humans to recover from the edge cases. I don’t know if they actually remote control the cars or if they have to send a driver though.
The_Double · 3 years ago
When I tried waymo a month or two ago a remote "driver" took over. When we called the support center about it later they told us that it's not them literally taking over the controls, but only giving some additional guidance to the system.

u/The_Double

KarmaCake day315September 8, 2013View Original