[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
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(page generated 2022-03-03 23:00 UTC)