7 ms·
A 60 GHz phased array for $10
- inetknght 7y agoI wonder what sort of API could be used to control that kind of phased array. I guess that's the point of the blog post though: asking for help with reverse engineering its interface.
- nsxwolf 7y agoIs this appropriate for creating a wireless HDMI interface for VR headsets?
- thinkmassive 7y ago"That chip was the SB9210 from SiBeam. This part was originally intended to be used for WirelessHD, a protocol for wireless video streaming that never took off. ...at one time they were included in some smart TVs and in some high end laptops." It sounds like it would be very suitable for a VR headset.
- opwieurposiu 7y agoDatasheet says it add 5ms latency, latency in VR causes nausea.
- csours 7y agoI'm not up to date on VR tech - is the video memory on board the VR headset? If the memory is onboard, you could do some simple rotations and translations on the current frame while the render pipeline caught up.
- Rebelgecko 7y agoThere's an overview of some of the various techniques that Oculus uses here: https://uploadvr.com/reprojection-explained/ https://uploadvr.com/reprojection-explained/
- deleted 7y ago[deleted]
- londons_explore 7y ago5ms isn't yet at nausea levels though...
- sp332 7y agoIn 2014, Michael Abrash gave a talk summarizing what's needed for a feeling of presence in VR. He said 20 ms motion-to-photon latency is required for the virtual world to feel like it's "nailed in place". So 5 ms is 25% of the latency budget.
- nathancahill 7y agoThe number I've heard, don't ask me from where, is 16 ms.
- SAI_Peregrinus 7y ago60FPS ~= 16.67ms/frame. So if you don't want to drop frames on a 60Hz monitor, your frame time budget is 16ms. If you want input to appear on the next frame, you've got at most 16ms. If you're targeting a 120Hz monitor then you've got 8ms. Etc.
- AYBABTME 7y agoThat's framerate (how often images need to be rendered) at 60hz. Latency is separate from that: you can have a 60hz framerate with 24h latency if you watch a video you recorded yesterday. In the parent's case, 20ms latency from movement to visible motion is part of the pipeline that: - reads input - evaluates solution - returns solution to your screen All kinds of things add to this latency: polling frequency of your input device, bus speed of the device, how fast you can update the world, how fast you can render the update, how quickly that updated image can be sent to the screen, how quickly the screen is able to turn this into visible light. etc.
- vlovich123 7y agoNot all motion-to-photon latency is created equal. EDIT: To clarify what I meant, HMDs typically use techniques like ATW/ASW/etc (link posted by Rebelgecko) to do just-in-time correction of the rendered image. The end-to-end motion-to-photon latency of the entire pipeline grows but the part that generates "sick" is very short.
- Polylactic_acid 7y agoI haven't used it but the reports I have seen say the vive wireless seems to work fine without noticeable latency.
- danbr 7y agoYep. It’s already being done by oculus or one of those VR startups. https://www.displaylink.com/vr https://www.displaylink.com/vr
- DarmokJalad1701 7y agoI am pretty sure HTC's Vive Wireless adapter uses a 60GHz link made by Intel ("WiGig").
- hinkley 7y agoDoes anyone recall in the Long Dark Ago when there was a startup that was planning to embed a phased antenna array into a cubicle wall? It still gets me the level of miniaturization that happens when you come back to an idea 20 years later, instead of watching the incremental changes along the way.
- stefan_ 7y agoI love how industry came up with ever crazier schemes to stream content from phones and laptops to TVs. There must have been three different attempts involving WiFi alone, but this phased array mmWave 60 GHz million bucks basic research abomination surely takes the cake. Meanwhile, some Google engineer realized you could solve 90% of phone-to-TV streaming applications and 100% of the hard technical problems by just telling the TV to download and display the YouTube video itself. Genius!
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- LASR 7y agoTurns out the dumbest solutions to effectively solve a particular problem are the best.
- TehCorwiz 7y agoYes, genius if the content is asynchronous. Any real-time or interactive display will need to be able to stream at sub-frame latencies. At 60fps that means less than 16ms, at VR friendly refresh rates ~90fps that means 11ms. While their approach works beautifully for their core competencies, static and non-interactive streaming content, it doesn't really work for any other application.
- foota 7y agoDoesn't stadia use it?
- ben-schaaf 7y agoStadia is riddled with latency issues. Taking numbers from Gamers Nexus review (https://www.youtube.com/watch?v=m0gILReDQsY https://www.youtube.com/watch?v=m0gILReDQsY) in a high framerate game it has 85ms input lag (22ms for local play) and low framerate games it has 110ms (61ms local). Of course these numbers depend a lot on your internet connection.
- droithomme 7y agoI wonder what sorts of things the chips were used for inside laptops and smart TVs. He mentions it being used for streaming, but it's a directional radar chip, seems it would be used for doing a 3d scan of an area?
- aidenn0 7y agoIt's a directional transceiver. Directional transceivers happen to be usable as radar, but these were not intended for that usecase: https://en.wikipedia.org/wiki/WirelessHD https://en.wikipedia.org/wiki/WirelessHD
- Animats 7y agoWhatever happened to that Google millimeter radar project to allow devices to see your hand positions? It ended up in the Pixel 4 as Motion Sense, but all it does is let you make swiping gestures in the vicinity of the phone. There should be more useful applications for that technology.
- Reelin 7y agoIt's not limited to Google. For example, this TI mmWave sensor (http://www.ti.com/product/IWR6843 http://www.ti.com/product/IWR6843) has an associated reference design for gesture control (http://www.ti.com/tool/TIDEP-01013 http://www.ti.com/tool/TIDEP-01013). (Disclaimer: I've never actually used that chip or reference design and have no idea how well it actually works in practice. I just think it's really neat that mmWave radar chips are readily available at very affordable price points.)
- syphilis2 7y agoThe last application I saw was using micro Doppler signal recognition to determine if someone has fallen down. Consider a nursing home or hospital bathroom where cameras would be considered intrusive.
- Traster 7y ago>Now the bad news: SiBeam was bought by Lattice Semiconductor, and right before I gave this talk, Lattice shut down the entire SiBeam organization and ended support and production of this part. I didn’t find out about this until months later, when I contacted the sales engineers I had been talking to about this part and they told me what happened. This is one thing that really pisses me off. Time and time again you've got small(ish) companies doing interesting stuff, succeeding and then they step on a landline. They do something that gets them in the cross hairs of a big company and suddenly BOOM big company buys small company for ridiculous money and then inexplicably shuts down 90% of what the small company was doing. The sale happens for a nice premium and yet the second the sale is closed 90% of the things that the company did that made it valuable are jettisoned. How can it be that these companies can afford to buy companies at a premium, throw away massive parts of the value of the company and yet: this obvious value destruction seems to be standard operating procedure for large companies.
- colechristensen 7y agoSome companies are purchased only so they won't become major competitors.
- TomMarius 7y agoCompanies are not primarily purchased, but sold. The previous owner could've continued, but they've chosen not to. We can't dictate them what to do, right?
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- colechristensen 7y agoThe people selling (or at least that have any say in making the sale) and the people doing are more or less always different sets of people. It is not a matter of a blacksmith hanging up their hammer but boardrooms playing wealth games. I wouldn't shed any tears for restrictions and obligations on the actions put on the latter.
- lachlan-sneff 7y agoPhased arrays are very cool tech. Personally, I can't wait for visible-wavelength optical phased arrays to hit the mainstream (they're just now being implemented), since they'd enable tech like legitimately holographic displays and video cameras with digitally programmable optical zoom.
- jobseeker990 7y agoHave any further reading I can do on this?
- hwillis 7y agohttps://www.spar3d.com/news/lidar/mits-10-lidar-chip-will-change-3d-scanning-know/ https://www.spar3d.com/news/lidar/mits-10-lidar-chip-will-ch... holographic displays would use eye trackers to show each eye a different image. Solid state zoom is maybe a bit of a stretch, but it would involve pixels becoming sensitive to angles more inward or outward from the sensor's center.
- lachlan-sneff 7y agoI'm not an expert, but I believe that's not how holographic displays would work with optical phased arrays. I believe a phased array can make it seem that light is being emitted from any point above the display (within the display angle of the opposite side of the display). There's no need to track observers, because it would be an honest reconstruction of the light emitted from a real 3d dimensional object.
- Fredej 7y agoI believe that's correct - see http://www.phased-array.com/1996-Book-Chapter.html http://www.phased-array.com/1996-Book-Chapter.html "Front projection Images" for details.
- ani-ani 7y agoThis chapter by Brian Wowk is a good start. It explains the basics and compares optical phase arrays against holography (that poor word, keeps getting abused!): https://www.phased-array.com/1996-Book-Chapter.html https://www.phased-array.com/1996-Book-Chapter.html
- tlrobinson 7y ago> What would be really cool is to build a USB board that plugs into one of the SB9210 boards and connects to gnuradio. You could do all kinds of neat radar experiments, presence detection, beam forming, you name it. Kind of like a 60 GHz RTL-SDR. Maybe a dumb question, but how is it even possible to do SDR with 60GHz signal on a ~4GHz CPU via a 5Gbps USB3 connection? EDIT: I guess via down-conversion? https://en.wikipedia.org/wiki/Digital_down_converter https://en.wikipedia.org/wiki/Digital_down_converter
- derefr 7y agoOr just buffer each broadcast segment into some 60GHz memory (is there such a thing?), and either rely on your signalling protocol being TDMI (and you therefore not needing to send/receive more than a fraction of the time) or on your broadcast signal being periodically repeating, such that the radio can just treat that memory as a ring buffer to play over and over. Or, do what old computer architectures did when their CPUs were slower than their DACs: add a Programmable Interval Timer (i.e. a very simple synthesizer) in between, such that you just send a few commands and it adds together some 60GHz triangle and square waves to achieve the signal shape you want. Maybe even add a sequencer, and then stream it some 60GHz MIDI files!
- blueintegral 7y agoThe data itself isn't 60 GHz, you're just modulating it onto a 60 GHz carrier. https://en.wikipedia.org/wiki/Modulation https://en.wikipedia.org/wiki/Modulation
- numpad0 7y agoModulated carriers are rarely directly synthesized by logic circuitries, even with phased arrays. You tap off a “white light source” of correct wavelength just like you do with LCD. TX/RX rates are thus independent to the carrier frequency. Only local oscillator must to be able to be configured to the correct carrier frequency.
- bschwindHN 7y agoFor a concrete example, infrared (such as what's used for TV remotes) typically transmits data on a carrier frequency of 38Khz, but the actual data rate is much less, just a few hundred bits per second. https://techdocs.altium.com/display/FPGA/NEC+Infrared+Transmission+Protocol https://techdocs.altium.com/display/FPGA/NEC+Infrared+Transm...
- robocat 7y agoSince the wavelength of 60GHz is approximately 5 millimeters, this technology is sometimes referred to as millimeter-wave (mm-wave). (Copied quote). That explains how close together the antennas are - close enough compared to wavelength to be able to beamform. Edit: also explains why it would be extremely difficult to build something yourself at 60GHz - where every wire needs length to be matched to submillimeter length, and a submillimeter tail acts as an antenna and as an electronic component.
- dclaw 7y agoBought some from ebay... Cost about $26 but the post has been out ~2 weeks. Can't wait to play with it and see what can be done.
- glax 7y agoHope you make a post about it.
- philprx 7y agoMaybe silly question, Are there some other commercially available chips with phased arrays? I believe RTL SDR did extend the RTL products end of life much further. COuld this occur with this (or similar) phased array chips?
- petee 7y agoThe closest thing i can find is this similar sounding 60ghz radar chip on digikey by Acconeer, but it doesn't look like you could control it or use it like the sibeam does... https://www.digikey.com/product-detail/en/acconeer-ab/A111-001-T-R/1891-A111-001-T-RCT-ND/8040771 https://www.digikey.com/product-detail/en/acconeer-ab/A111-0...
- petee 7y agoYes, I was indeed mistaken, this is just a Doppler module and not a phased array. Bummer