[HN Gopher] 43 km line of sight with USB WiFi stick (2005) ___________________________________________________________________ 43 km line of sight with USB WiFi stick (2005) Author : NotAWorkNick Score : 269 points Date : 2022-03-03 14:38 UTC (8 hours ago) (HTM) web link (www.qsl.net) (TXT) w3m dump (www.qsl.net) | aledalgrande wrote: | To someone that understands this, I'm curious: is line of sight, | especially this far, impacted by something like a bird flying in | the middle? | topspin wrote: | Not unless the bird is very close to the antennas at either | end. | | This is a neat exercise in antenna design. They've built high | gain directional antennas and minimized transmission line | losses. The 15 dBi antennas aren't even that remarkable; you | can buy 30+ dBi wifi antennas. | | My first 'better than dial-up' internet connection was a 2.4 | GHz wifi service across 7 miles. On my end was a roof mounted | aluminum parabolic grid antenna. It worked rather well and | sometimes I wish I still had it. | creeble wrote: | Mine too! Though mine was the other way 'round: I had a frac | T1 line (256kbps iirc) and shared it with two other locations | via a central omni antenna. Breezecom radios that I think | were frequency-hopping (pre-spread-spectrum). | marcodiego wrote: | By line of sight, I think it means that it must be held in a | tall enough mast not to be impacted by curvature of the earth. | IIRC curvature of the earth limits line of sight to around 35km | at 1.7m of height. | Reventlov wrote: | This might interest you: | https://en.wikipedia.org/wiki/Fresnel_zone | ajsnigrutin wrote: | Nope, not really. | | Very simplified, the signal is carried within a "fresnell | zone", which s basically a 3d ellipse, that is relatively wide | in the middle, and you'd have to cover a lot of that area, to | block the signal... definitely more than a bird can do. | https://en.wikipedia.org/wiki/Fresnel_zone#Clearance_calcula... | | ...unless the bird is standing infront of the | transmitter/receiver.. then yes. | stagger87 wrote: | The WIFI beacon he received is likely using the 1Mbps DSSS | 802.11b PHY, which has 11dB of processing gain which also helps | quite a bit here. | chrissnell wrote: | And why not? When I lived in Utah, I could easily hit a mountain- | top ham radio repeater 20+ miles away with my little 5W handheld | radio. A small weather balloon with a sub-1W transmitter can | easily be heard at 100K feet altitude by people hundreds of miles | away. So long as you have LoS, it's not problem. | dragontamer wrote: | Water molecules block 2.4Ghz spectrum that WiFi uses. | | This is on purpose: the idea is to make the common WiFi (and | Bluetooth) bands short range on purpose, so that many people | within a city block can have local WiFi or local Bluetooth | without interfering with each other. | | So 2.4GHz over a long distance kinda goes against the design of | WiFi / Bluetooth. | ac29 wrote: | > Water molecules block 2.4Ghz spectrum that WiFi uses. | | This isnt really true to any significant degree that matters, | unless you are literally under water. | | Rain fade is a thing, but is really only meaningful above | 10GHz. | | edit: I should note, its not that water droplets dont | attenuate radio signals, its just that losses on a typical | radio path are already huge in perfectly clear weather - you | might lose 99.99999999% (100dB) or more of your signal | strength between transmitter and receiver anyways. | bonzini wrote: | The idea really was that 2.4GHz spectrum was already polluted | by microwave ovens (because microwave ovens operate at the | resonance frequency of water molecules), so it was left for | public use. | jwilk wrote: | That's a common misconception: | | https://www.wtamu.edu/~cbaird/sq/2014/10/15/why-are-the- | micr... | | > _The microwaves in a microwave oven are not tuned to a | resonant frequency of water._ [...] | | > _They heat the food through simple dielectric heating._ | [...] _Many types of molecules in the food absorb energy | from the microwaves in this way, and not just water | molecules._ | sandworm101 wrote: | Almost. 2.4GHz had been set aside for consumer devices long | before wifi. Microwaves are essentially very powerful | unlicensed transmitters. Wifi devices are also all | unlicensed transmitters. So 2.4GHz devices don't use the | same space despite microwaves, they use it because that | space had already been given over to unlicensed devices. If | not for microwave ovens we might not have wifi as it is | today. | | Back when people were gobbling up the spectrum, the | military didn't care about 2.4GHz because of the water | absorption issues. It wasn't good for communication at long | distances and so it was allowed for consumer devices. | Johnythree wrote: | 2.4Ghz was a ISM junk band long before domestic microwave | ovens arrived. In fact 2.4Ghz was used for microwave ovens | specifically because it was an ISM band, and therefore was | available. | meatsauce wrote: | You can work the ISS voice repeater with a handheld and it is | around 400km away. Line of sight is everything and more so as | you increase the frequency. | codazoda wrote: | I'm from Northern Utah and used to try to get a response from | repeaters on my handheld radio. Being and introvert, that | didn't really want to talk to people, it was one of the few | things I really found interesting on HAM. I got pretty far but | I was unable to hit the repeater in Wendover, NV (it was my | next goal before I gave up). I used the local mountains to get | myself up to an elevation where the curvature of the earth | still allowed line of sight. I think Wendover is about 120 | miles, line of sight, from the drive-able mountain top I | selected. The expanse has two mountain ranges but there are | some low spots that I thought I might be able to get through. | The rest of it runs pretty flat over the salt flats. | ajsnigrutin wrote: | 1W at a very narrow bandwidth, is a very different thing form a | 20mhz wide signal at 2.4ghz with ~71mW transmitter (100mW eirp | with a dipole). Just calculate the peak power at those | bandwidths. | PaulHoule wrote: | Overall I've had very good luck with the RF performance of | external WiFi sticks. All too often the antennas inside laptops | and phones are really an afterthought so the WiFi and | (particularly) Bluetooth performance is awful. | NotAWorkNick wrote: | An easier to find link that shows how to make the home-brewed | antenna for those interested in trying it out for themselves | | https://flylib.com/books/en/2.434.1/hack_83_make_a_deep_dish... | genewitch wrote: | I seem to have a recollection that a cheap DIY system is to get | two RCA 18" dishes (or larger) and remove the LNB from the dish | (or whatever the horn part is called) and affix a "cantenna" or | other waveguide to the arm, then, using the shortest, largest | coax you can manage, connect the two cantenna/waveguides | together, and aim them 180 degrees apart. I also seem to | remember that putting this "halfway", even if halfway happened | to be the highest point, wasn't ideal, it was something like | 60/40 or 70/30. | | Now-a-days, mikrotik or ubnt make doodads you can replace the | LNB with that instead provides some wifi band, with PoE, so two | of those up on a tower means you have active repeating, and you | can probably push that solution out a lot further than 43km. | | For the record, i put a USB wifi stick inside of a pirouette | cookie can and it was a phenomenal "war driving" antenna. I use | folded-dipole-fed yagi antennas now for doing wifi surveys, but | in a pinch 802.11B 1000mW+ wifi cards are stacked up in a | filing cabinet... | ge96 wrote: | Those propagation maps are cool, was learning about them 12 | years ago for FPV | londons_explore wrote: | And mine keeps cutting out if someone fat walks between my laptop | and the router 6 feet away... | Nextgrid wrote: | A lot of people don't realize that Wi-Fi pretty much always | operates in an extremely degraded mode (on the verge of not | working at all - which is why a person walking past can be | enough to break it) and it only seems to work for certain | applications due to the magic of protocols such as TCP which | can recover and essentially conceal packet loss. Jumping onto a | call or some other real-time application (where retransmissions | don't help and actually make the problem worse) will break the | illusion and show you the reality of things. | | There's also this misconception that speed is the only thing | that matters, so "higher speed = better connection" and the | vast majority of consumer-grade tools only ever test for this. | This is where it will mislead you, as an unstable connection | with short bursts of high speed will appear "better" (despite | being fragile and completely unusable for anything real-time) | than a slower but more reliable connection. In-browser speed | tests are extremely bad for this because all the buffering & | various layers could even fool the test code itself, making it | believe it's getting a steady stream while in reality it's | getting merely short bursts of data (in between tons of | underlying TCP retransmissions). Iperf & ping are the tools of | choice if you actually want to look into it - they are closer | to the metal and will give you faster feedback (you will be | able to actually see the dropouts due to packet loss). | nearlyepic wrote: | Is there anything short of "get a better antenna" that helps | address these issues? Recently had to switch to Wi-Fi for my | desktop and have been frustrated with the inability to stop | the connection from constantly being on the edge of not- | working. | Nextgrid wrote: | More access points is the only real solution. Ideally with | Ethernet backhaul - mesh systems still consume spectrum | which is what you're after - there's a finite amount of it | (that you need to share with neighbors - especially on | 2.4Ghz - and potential interference) and you need to | maximize efficiency, so only use it for mobile devices that | can't be wired - static access points (and other devices, | TV, gaming console, etc) should be wired. | | Mesh systems are a step up and _can_ work but due to their | cost (and also the fact it 's usually hard to tell how well | it'll perform without actually buying it and trying it out | in the field) I would very much recommend just biting the | bullet and doing it once and well with wired access points. | A stop-gap solution would be to use powerline adapters to | provide the Ethernet backhaul to the access points; you'll | be limited in terms of bandwidth (mine top out at ~100Mbps | in my current property, but went to ~300 in my previous | one) but latency and packet loss-wise they're rock-solid | and won't hog the precious Wi-Fi spectrum. | | Forget consumer-grade crap as well, go for enterprise-grade | equipment or at the very least "prosumer" grade such as | Ubiquiti. | gunfighthacksaw wrote: | Are you sure your friend is fat, and not just wearing a bulky | faraday cage? | bjt2n3904 wrote: | But did they establish a link and transfer data? | | Broadcast packets with the SSID aren't too difficult to get. You | only need to get one. | | Fun regardless, but I'm curious for more info. | jandrese wrote: | I doubt it. The remote side was a generic AP with an omni | antenna I think. The return traffic is going to be way down in | the noise floor. | mcgeez wrote: | This is an old article, dating back to at least 2005 as per Web | Archive[0] please edit the title to reflect that. | | [0]https://web.archive.org/web/20050201000000*/https://www.qsl... | . | ajross wrote: | And the ideas are older still. The days of the Pringles Can | Antenna were pretty wild. I'm not aware of any similar hacks at | 5 GHz though. | rolph wrote: | a 5GHz waveguide AKA "cantenna" is between beer can and | bean/soup can | | https://en.wikipedia.org/wiki/Cantenna | | width or diameter is a criticalproperty: | | https://www.everythingrf.com/tech-resources/waveguides-sizes | | https://web.archive.org/web/20161029045619/http://www.pwmn.n. | .. | | have fun, and dont cut yourself, they do work well when used | at both ends of the line. | | https://web.archive.org/web/20071012133113/http://www.saunal. | .. | dang wrote: | Year added above. Thanks! | 0000011111 wrote: | You can hit the space stations repeater with a $40 boafeng radio. | Line of site baby! | beeskneecaps wrote: | Love my UV5R! I put a telescopic, 1 meter antenna on mine and | was able to hit a repeater on Mount Diablo from the Twin Peaks | in SF ~42 miles away! | | PSA: we need more HAMs out there! Check out | https://hamstudy.org and get your license | https://hamstudy.org/sessions/remote | throwaway48375 wrote: | What antenna? | genewitch wrote: | just get a legitimate nagoya and call it good, if you want | 100% portable and "not likely to break if you sneeze while | using it". | creeble wrote: | Let me add my favorite, https://hamexam.org | Zenst wrote: | Yes though the issue with many boafend radios is that they get | banned in countries due to the bleed over other frequencies | with the harmonics that break the rules. Covered better here: | https://www.youtube.com/watch?v=V0EdkdNqczk | genewitch wrote: | Baofeng caught heat because their radios are "unlocked" and | in the US you _cannot_ sell a radio that can set arbitrary | frequencies in the FRS or GMRS bands (i forget which and it | 's irrelevant) - that is, they can't have keypads for one | thing. Another issue is the power, if your radio can transmit | on those two bands it must use <=1000mW, and all of the | baofengs claim at least 5W transmit. Yet another reason is | FRS/GMRS radios (whichever) _must_ have *fixed* antennas. | | The hash is just a reason for people to complain about them. | As shipped from the factory, they're below the minimum hash | levels required. Now, if you connect them to a cheap RF | amplifier, you might run afoul of your license's rules about | hashing up the harmonics. | | Personally i prefer quansheng, as their speakers are louder, | but i've never had an issue with a baofeng, especially with | an external speaker/mic/antenna. | | for posterity, i am extremely tired, and i welcome all | elucidations and corrections, because i'm probably | misremembering something, here. | jollybean wrote: | Ukranians interested in this now. | NovemberWhiskey wrote: | As always with radio, it's mostly about unobstructed line of | sight and the gain in your antenna system. | | We're still in communication with Voyager 1, which is operating | on a grand total of about 20W of RF power; and is currently about | 14.5 billion miles away. | agumonkey wrote: | doesn't atmosphere (or the lack thereof) plays a role in power | losses too ? | jupp0r wrote: | Yes, radio waves are attenuated in the atmosphere. This is | highly frequency dependent - for practical applications the | lower the frequency, the less radio waves are attenuated. In | comparison with attenuation from obstacles in non-line-of- | sight situations, the atmospheric component is not | significant. | | For really long range propagation on earth, reflections on | atmospheric layers are the dominant factor (as there is no | line of sights due to the curvature of the planetary | surface). | | See https://www.sciencedirect.com/topics/engineering/atmosphe | ric... for some nice graphs. | Anunayj wrote: | it does, but it is not as significant in normal weather | conditions in the frequency ranges we're dealing with here | (Likely sub 2.4 Ghz) [1], (General rule of thumb, Atmosphere | absorbs everything except visible spectrum and 10 cm - 10 m | wavelength), compare this to effect from the inverse square | law. :) | | Now this _might_ be significant enough in directional waves | with a huge constant multiplier (like a 'ideal' laser with | no divergence). Someone can probably give insight on it here. | | 1. https://www.researchgate.net/publication/270512069_Propaga | ti... | genewitch wrote: | I'm curious why you ordered the wavelengths the way you | did, you totally potholed my entire comprehension. 10 | meters (28mhz) through 10cm (2800mhz) to me reads "left to | right". | wildzzz wrote: | Atmosphere does play a part but just freespace losses are | going to be massive, probably at least 250dB just for the | distance voyager is at. Atmosphere could add another | 60-100dB. Voyager's antenna has about 40dB of gain but the | DSN network can array multiple antennas to make up for the | losses. They have up to 2 70m dishes and several 34m dishes | that can point at Voyager, quite a massive antenna gain. | MadVikingGod wrote: | So by the articles calculations voyager 1 is a steal. | | At $865 million[1] and 14.5B miles that about 0.034 Euros/Km. | 1/20 of what he did in 2005. | | 1: https://voyager.jpl.nasa.gov/frequently-asked- | questions/fact... | Sporktacular wrote: | It's also handy when you only need a low data rate and can make | your channel bandwidth was wide as you like without worrying | about licensing restrictions. | KennyBlanken wrote: | That's...not how that works. The FCC requires power be | dropped to compensate for antenna gain. | | https://afar.net/tutorials/fcc-rules/ | gorgoiler wrote: | Thanks for sharing those figures. I've always known "it's | amazing" and "it's far away", but those numbers really put | things into perspective. | | Is there anything particularly special about the antennae on | the spaceship? They must be rigorously aligned to point at | Earth, and even a slight knock would spoil everything? Or is it | more resilient than that? | jjeaff wrote: | I would think the biggest part of being able to transmit that | far is the perfect vacuum of space. There is almost nothing, | not even air particles between us and the probe. | | If you threw a beach ball from the distance of voyager | straight to earth it would eventually make it here. | lultimouomo wrote: | Vacuum is good, but inverse-square law still applies. | | There is almost perfect vacuum between Earth and every star | in the galaxy, and yet they don't appear nearly as bright | as the Sun. | thfuran wrote: | But you can see the Andromeda galaxy, which is several | quintillion miles away. | josephg wrote: | Sure, but the andromeda galaxy doesn't have a power | budget of 20 watts. | thfuran wrote: | Well, orbital mechanics would mess up a straight toss but | at least it wouldn't be stopped by air resistance. | causi wrote: | _As always with radio, it 's mostly about unobstructed line of | sight and the gain in your antenna system._ | | Indeed. If you grow up with your most common radio interactions | being an FM car radio and a dumbphone, you get the impression | it's entirely about range. Then you buy a drone and find out | one pine needle shaves 50% off of your signal strength. | genewitch wrote: | the mavic 2 series of drones by DJI don't have this issue, | but the tradeoff is the controller weighs like 40 pounds, | because it's a quite powerful wireless access point. Every | other drone i've owned that supported video used an android | or ios device to connect to the drone via wifi (drone | presents as a WAP). | | iirc the claimed range is around 8km on the one i have, about | 5 miles. I have assuredly gone well over 2km with no issues | with control or video feed. This was over a straight highway. | I routinely fly around a kilometer away, and the only issues | i have is if i launch from an extremely dense patch of pine | trees, and only at about 800-900 meters, i will lose video | (artifacting for a second), but not control. It's never had | to RTH. | | In case you're curious about city usage, i have a friend that | has one he launches from a culdesac in Orange County and can | fly in nearly any direction for about 8 minutes* before he | hits a geofence, the drone still functions normally. If there | is any issues, he can just fly higher. | | The newest _newest_ DJI stuff claims even more ridiculous | range, 15km+ over open water, for instance. | | If i hadn't used it myself, i wouldn't have believed it, it | sounds like BS. | | * this is 5-7km depending on the tailwind | dbcurtis wrote: | The "path loss equation" goes something like: | | At the receiver, you have "minimum detectable signal", MDS, | measured in dBm. | | At the transmitter, you have power out, measured in dBm. Add | transmitting antenna gain, in dB, subtract propagation loss | through medium(s), add receiving antenna gain, and if that | number is greater than MDS, you win! The Really Great Science | in Voyager is the added factor of "coding gain" -- | sophisticated error correction codes can give you a many dB | adder, at the expense of data rate (nobody cheats Claude | Shannon). | dr_orpheus wrote: | And gets up to a whopping 1.4 kbps downlink and 16 bps uplink! | | https://voyager.jpl.nasa.gov/mission/spacecraft/ | timbit42 wrote: | The first modems were only 110 bps. | nonsapreiche wrote: | You mean bauds | anaganisk wrote: | Which somehow is a dream on a few networks. | mshockwave wrote: | that is amazing for something 14.5 billion miles away | iszomer wrote: | What's more amazing is how NASA's Deep Space Network | continues to make communication with Voyager possible. | | https://www.nasa.gov/feature/jpl/nasa-contacts- | voyager-2-usi... | benbristow wrote: | I wonder what the ping/latency is... | Frost1x wrote: | ~23.2B km / c (m/s) seconds, so about 43 hours or roughly | the time to get through to an arbitrary customer service | representative these days. | tomxor wrote: | (Current) One-Way Light Time = 21:35:13 [0] | | So 43 hours 10 minutes 26 seconds minimum, excluding | processing time. | | That's probably another record... Although I'm pretty | sure it can't process ICMPs, so "ping" in the more | general sense. | | [0] https://voyager.jpl.nasa.gov/mission/status/ | benbristow wrote: | That must be fun over SSH/Telnet. 43 hours between every | key press | | Joking, but thanks for the interesting info (and Frost1x | also). | _joel wrote: | Come on, SSH and Telnet? That's ludicrous. It's a job for | https://mosh.org/ | tanbogy wrote: | And I used to get angry with 250ms ping playing WoW. | tomxor wrote: | It's also amazing considering it's using a computer built | over 45 years ago from discrete components with only 70Kb | of memory, while operating on a gradually failing | thermonuclear power source. Voyager 1 also holds the world | record for the longest continual operation of a computer: | | https://www.guinnessworldrecords.com/world- | records/635980-lo... | ge96 wrote: | > ...the last of the project's original programmers, | retired, and it was difficult to find a replacement with | such in-depth knowledge of what now seem like ancient | hardware and design principles | | Man I would not want to be the one to brick that. | admiral33 wrote: | What an incredible project. Does anyone know of any good | interviews or written content from the engineers? | ProAm wrote: | There are tons of documentaries and interviews. [1] | | [2] https://www.pbs.org/the-farthest/ | dTal wrote: | Wow. World record for the longest continual operation of | a computer... achieved in a radiation bath. | tomxor wrote: | Pretty much, although I think the RTG is mounted on a | limb as far away from the other equipment as possible, | but still the computer needs to be able to tolerate a | decent amount of radiation. It also has an interesting | redundant design where it has double the component count | and can either exploit that for extra compute or | redundancy in case of component failure. | anthropodie wrote: | I think parent comment is talking about cosmic radiation | and not the one from RTG which most probably is properly | shielded. | tomxor wrote: | Possibly. I wonder which is the more significant source | given it's distance from the Sun. | monocasa wrote: | It used a memory called "plated wire memory" which, like | the very related core memory is very resistant to changes | caused by radiation. | | https://en.wikipedia.org/wiki/Plated_wire_memory | 1024core wrote: | Reminds me of the early days of dial-up Internet... ;-D | mrfusion wrote: | What about the curvature of the earth? | sushibowl wrote: | OP chose a hill 250 meters above sea level, and also has an | antenna about 5m high. According to a calculator I found[1] | that puts the distance of the horizon at roughly 57km. So | plenty of range to still be in LOS of the transmitter. | | [1] https://www.omnicalculator.com/physics/earth-curvature | ck2 wrote: | (after posting this I thought of "liquid/atmosphere only" | planets and how they are round so obviously my initial thought | process on this was wrong, I thought water followed the bottom | of its curved-earth container while trying to remain level on | top) | orangepurple wrote: | This is nonsense. Do you believe that water forms a cliff at | the edge of the beach so that its curvature tangent to the | center of the body of water is zero? Hilarious | [deleted] | aeastw wrote: | I'm fairly sure water follows the curvature of the earth... | smilespray wrote: | Teach us more science facts, professor! | blueprint wrote: | meniscus please | meatsauce wrote: | My guess is that they had an inversion layer, tropospheric duct, | or other enhancement condition. 43km is a long way on 0.02 watts. | ryanmarsh wrote: | From the diagram in the article the entire fresnel zone was | unoccluded. | bprater wrote: | As a reference, folks that fly quadcopters, drones and flying | wings often will transmit at 1 to 2 watts of power using line | of sight. (Yes, at the edge of legal.) .02 watts is an | insignificant amount of power for radio transmission. | bananasbandanas wrote: | Given a good control link such as ExpressLRS [0], people can | also fly quadcopters 10+ kilometers on as little as 10 mW. | See for example the range competition at [1]. | | Of course, the VTX is usually a different matter.. | | [0]https://www.expresslrs.org | [1]https://www.expresslrs.org/2.0/info/long-range/ | bri3d wrote: | I think it's much more fair to compare EIRP to EIRP, I don't | know the gain of this crazy foil dish but it's probably | pretty high. FPV is way harder since you can't use a highly | directional transmit antenna and you're weight and size | constrained, so you usually have dinky <3dB transmit gain and | have to make up for it with big radio amplifiers. | spookthesunset wrote: | It's not edge if legal if you are a licensed ham operator. | Then could fly with more than a thousand watts! | | Of course you'd have a little problem with the battery :-) | jll29 wrote: | I wonder how modern (2022) equipment might fare? | | Certainly the author picked a beautiful region to do that kind of | outdoor experiment in. | OJFord wrote: | > Certainly the author picked a beautiful region to do that | kind of outdoor experiment in. | | I don't mean to be argumentative, but I wonder what the ugliest | 43.33km line of sight environment one could find would be? I | imagine it's quite a good proxy for beauty, the maximum | distance you can see. | amelius wrote: | Regions that are covered in dense fog often. | thehappypm wrote: | Alberta tar sands, maybe. Bleak nature + industrial | hellscape. | | Or maybe somewhere like North Korea. | sandworm101 wrote: | https://en.wikipedia.org/wiki/Saskatchewan_Highway_3 | | https://en.wikipedia.org/wiki/File:Fillmore_03_Hwy_33.jpg | | Flat. Flatter. Flattest. With virtually zero change in | elevation there is very little to see but pavement and sky. | bri3d wrote: | The flatness makes this not a workable line of sight | environment without towers due to the Fresnel zone though, | the topography is the only reason this 43km link worked. | Need to find an ugly hilly region, a much harder task than | an ugly flat region :) | bombcar wrote: | Ugliest would be point-to-point in a some run-down city. | OJFord wrote: | 43.33km line of sight though? How run-down is this city? | bombcar wrote: | Los Angeles is wider than that, and I'm sure you could | get a high-rise to high-rise line of sight. | thehappypm wrote: | That would probably be pretty though. Mountain | backgrounds, full city skyline. | bombcar wrote: | Yeah even Wall-E's trash piles get decent from far away. | cardiffspaceman wrote: | In Los Angeles, California, there is a street called | Sepulveda Blvd[1]. With extensions outside the city | proper that have the same name, it once went 68.9 km end | to end. Unfortunately for my hypothetical, it is not a | straight line. But to me, it increases the odds that | there is a street somewhere in the world's large | metropolises that extends that far, and that it goes in a | straight line, and you could see one end from the other, | or at least the tops of buildings at either end could see | each other. And then run-down is in the eye of the | beholder. | | [1] Part of the street was renamed. | https://en.wikipedia.org/wiki/Sepulveda_Boulevard | genewitch wrote: | Sepulveda is a good one, but i remember for a small | section it's called "Imperial Highway"[1] And that is | 169km, and the longest "straight" section is 50km[2]. I | have driven that stretch many many times, and it takes | hours, even at midnight. | | [1] https://en.wikipedia.org/wiki/Imperial_Highway | | [2] https://i.imgur.com/c7Og4sr.png | drewzero1 wrote: | There's an old dish antenna on the roof of my office that's | pointed at a building we used to have in the 90s. I've | wondered if I could get it to do anything cool, since my | house is near the other building, but I don't think I could | get an antenna high enough to get line of sight. | bombcar wrote: | I would not be surprised at all if half or more of the | dishes you see on commercial buildings are just | vestigial, waiting for a signal that will never come | again. | falcolas wrote: | My vote would be for over badlands. They're fairly flat on | the median, but it looks like a pockmarked hellscape of dirt | and rock with little greenery. | titzer wrote: | I find natural vistas, even the pockmarked hellscapes, to | be oddly beautiful. It's in the eye of the beholder :) | mikepurvis wrote: | I'm interested in this too-- ten years or so ago I briefly got | into long range wifi and bought a bunch of Ubiquiti gear (eg | https://dl.ubnt.com/sr71a_datasheet.pdf). I was never | successful in getting much more than 1km, even with their | recommended antennas, but I was also working with watercraft, | and I know that's hard mode for 2.4GHz, particularly when your | antenna isn't able to be very far off the surface and only one | end can be directional. | | My impression though is that recent advancements in wifi have | all been focused on getting high bandwidth at very short range, | like same room line-of-sight, so I wouldn't assume there'd be | much to be gained over b/g/n range performance in trying an ac- | or 6-based system. | genewitch wrote: | I made a comment above about the mavic drones having | 8km-15km+ "line of sight" range with their handheld WAP | controllers, and my having flown 2km without any issues. I | doubt i'll ever go to the max range, but the power is there | to get in and around trees, towers, whatever. | | But with 440mhz i've transmitted data over 100 _miles_ with | full decode, from my driveway in a forest with a 6 element | yagi. And a couple of years ago the first trans-atlantic 440 | (UHF) transmission ever was accomplished. | | The main issue with consumer wifi is that it's attenuated by | water, and by nature, nature is full of water. That's why | UBNT switched to 12ghz or 24ghz for their long range | "airfiber" stuff, and hacker hams try and find 902MHZ band | capable equipment, as 900mhz can "punch through" more | vegetation than 2.4 or 5.8ghz. | nathancahill wrote: | Truly. I biked the coastal highway around the Istria peninsula | last year. Never had better views or better food. Rijeka itself | is a fun city too. | giantg2 wrote: | I wonder if you could boost output even farther using a colinear | antenna in the reflector dish. | alasr wrote: | Approximate locations of the setup & measurement on the | OpenStreetMap: | | https://www.openstreetmap.org/directions?engine=fossgis_osrm... | ng55QPSK wrote: | actually, LoS over open water, is following physical laws. GSM | (with a range limitation of 35km by timing) was very well | recievable from ships. | 1970-01-01 wrote: | This reminds me of another old story I have bookmarked, but it's | for a wireless keyboard: | | https://web.archive.org/web/20061205205844/http://www.aftenp... | bombcar wrote: | He got the Wifi network to show up, but did he get a connection? | | A bit higher quality point-to-point can be obtained with a bit of | specialized equipment, Mikrotik has a bunch: | https://mikrotik.com/product/MTAD-5G-30D3-PA for example, can go | 40+ km. | [deleted] | wanderer_ wrote: | I loved looking at that laptop - a translucent chassis, crazy! | foobarbecue wrote: | Very impressive! Please correct the error in the title -- it's | "line of sight," not "line of site." | NotAWorkNick wrote: | Done, thanks for the heads-up! (Also corrected it to read | 'achieved' ;-) | digitallyfree wrote: | I wonder if optical communications (with lasers or similar | technology) would be a better choice in this situation, given | that there is line of sight. With WiFi you are mostly limited by | the legal requirements regarding transmit power. | | See https://en.wikipedia.org/wiki/Free- | space_optical_communicati.... | Sporktacular wrote: | Nope, they suck. Rain, pollution, low clouds, fog, thermals etc | and it drops to nothing. | wmf wrote: | With eye-safe optical power, FSO is limited to very short range | under 5 km. | RF_Savage wrote: | Huh, did not know that Adam 9A4QV had also that site in addition | to the Microwave Croatia blog and the LNA4ALL product blog. Dude | has done all kinds of cool stuff. | Sporktacular wrote: | Without the bit rate there's not enough information to know if | it's impressive or not. Define a low enough bit rate as a usable | radio link and it can be 10 times that length with a 10th of the | power level (Shannon-Hartley). | | Perhaps given the limitations of 802.11 it means something but in | theory it's meh. | subinsebastien wrote: | I want this to be part of a Hollywood movie. The protagonist is | using his makeshift wifi setup to hack into a bank computer | systems 43Km away from his location, and the bank people has no | idea what is going on. | teaearlgraycold wrote: | I wonder what feats such a hacker could pull off once they hear | about the internet. | anaganisk wrote: | Why? Im not interested to answer why our router is not capable | of that, and there is no such router in the market. But on a | serious note, some enterprise networks are unsecured enough, | that you could probably login to root of their server from | anywhere in the world. | kayodelycaon wrote: | CW: TV Tropes... | | https://tvtropes.org/pmwiki/pmwiki.php/Main/RuleOfCool | sgt wrote: | Unless the bank has a 43km perimeter with trenches and guard | dogs, why doesn't he just move closer? | contingencies wrote: | Uhh, maybe a believable plotline like "Because the | protagonist lives on a crumbling bridge with a military- | trained dolphin encircled by cyborg psychopaths and Japanese | megacorp military types while a highly infectious disease | ravages remnant humanity and it's the end of the world?" | https://www.imdb.com/title/tt0113481/ | ant6n wrote: | Well, obviously. | ape4 wrote: | Now LoRa seems like a better choice ___________________________________________________________________ (page generated 2022-03-03 23:00 UTC)