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59

Wired ethernet is not losing it's advantage. There are standards out there for 10Gig Ethernet (802.3ae), 40Gig (802.3ba), 25Gig (802.3bq). These are primarily backbone/backhaul standards. It's not apples to apples to compare 20 year old (1 Gb Ethernet) or 25 year old (100 Mb/s "Fast Ethernet") technology to the latest in wireless just because that's what's ...


49

You are confusing band with bandwidth. Band - The frequency of the carrier. Bandwidth - the width of the signal, usually around the carrier. So a typical 802.11b signal may operate at a 2.4GHz carrier - the band - it will only occupy 22MHz of the spectrum - the bandwidth. It's the bandwidth that determines the link throughput, not the band. The band is ...


41

2.4 GHz is one of the industrial, scientific and medical (ISM) radio bands. ISM bands are unlicensed, which makes it easier to certify the equipment with FCC (or its counterparts in other countries). However, what special about 2.4 GHz? There is about a dozen ISM bands. Some at higher frequency, others have lower frequency. Not all ISM bands are ...


38

Yes, WiFi and Bluetooth can disturb each other. But both are equipped to handle that. A standard that is not capable to handle disturbance and/or interference will simply be unusable under many circumstances. The 2.5 GHz ISM band is also used by Microwave ovens and other wireless standards like Zigbee. Wifi transceivers are able to detect when certain ...


33

As @Colin mentions the scheme that TI now use to communicate a network SSID and keyphrase from a setup application to a CC3000 enabled device is called Smart Config. Smart Config has to communicate information (the network SSID and keyphrase) from a secure wifi network to a CC3000 enabled device that is not yet able to decrypt the traffic on that network. ...


27

We see now the MKBHD guy going to some street with a phone and getting over 1Gbps. Surly a reserved and shielded Ethernet channel should give us 1Tbps right? nope, why should it? Data rate is a function of SNR and bandwidth. (Shannon Capacity: you can only transport a limited amount of bits per second over a medium with limited bandwidth and limited signal ...


26

The "special" thing about 2.4GHz is that when spectrum was allocated for various needs in the 60's and 70's, no one wanted it, because it was thought that atmospheric water absorption made it useless.


25

Well, it has the potential to work. You would have to line the inside with RF absorbing material, otherwise the incoming waves would just bounce all over the place. Using copper plates to detect the RF power probably isn't the best idea. I would recommend using actual wifi antennas for that purpose, each one connected to an LNA and 2.4 GHz bandpass ...


25

As with any radio receiver, if it can handle a higher data rate, then it is usually burdened with having a higher RF bandwidth and this inevitably means more received background noise i.e. a wider BW lets in more noise and hence, you need a higher received signal level to operate with a decent SNR (signal to noise ratio). Therefore WiFi is at a significant ...


22

In free space with a nice direct path, it would make little difference. Unfortunately, WiFi doesn't operate in free space: it operates in a complicated sea of reflections from walls, people, furniture, wiring etc. The reflections add together in more or less random phases, and from time to time the signal level can drop quite significantly. This is called ...


20

So why is wireless transmission catching up to Ethernet in therms of transmission speed? Wireless is not catching up to Ethernet in terms of transmission speed, but it is becoming fast enough that most people don't need to use faster wired systems. However, if you want to buy faster wireless devices, checking the prices ethernet modules on fs.com is ...


19

The bandwidth of the Wifi signal is nothing like 2.4GHz-it's 20 or 40MHZ. What you are suggesting (baseband 2.4GHz) would use up the entire EM spectrum to 2.4GHz for a single channel of communication. As you can see from this, it's already pretty well used for various other things: Essentially, the 2.4GHz carrier is wobbled a little bit to send data and ...


19

So you want to transport that 2.5 GHz (or even 5 GHz ?) Wifi signal over TV COAX cable ? Indeed to the non-RF people you'd just think that would work. And it does BUT there will be almost no signal coming through that cable. The Wifi signal will be attenuated so much in that COAX cable that it will defeat the whole purpose of having an antenna on the roof. ...


18

The statement: Host interface supports USB.2.0 Works with any board with mini PCIe. Means: The card in question physically interfaces via a PCIe "socket". One of the connections which can be established over this connector is USB2. The USB data lines are usually on pins 36 & 38 of the connector, BUT they are not present in some implementations and if ...


17

Wifi uses a listen before transmit system. If the channel is busy, it holds off transmitting. Eventually it gets through. Each channel is fixed. If it tries to use a channel that is busy, from bluetooth, then it will wait. This may reduce the data speed for wifi if it has to wait too much. Bluetooth for over a decade now uses adaptive frequency hopping (...


17

So why is wireless transmission catching up to Ethernet in therms of transmission speed? Money. Time is money, but convenience is REAL money. Because the speed-per-user cost is relatively low, and because the portability of wireless has a value almost beyond price. Yes, the infrastructure to get GHz data to hundreds (thousands?) of phones per cell tower ...


16

Ferrite rod antennas were historically used for broadcast AM receivers. These signals are around 1 MHz, which corresponds to a wavelength on the order of 300 meters. A half-wave dipole at this frequency would be on the order of 150 meters long. The very high permeability of ferrite allows this antenna to be made smaller, at the cost of some performance. It ...


15

Parallel capacitor plates of 25 mm by 25 mm seperated by 4mm of glass with a relative permittivity of 4 would give a coupling capacitance of about 5 pF. That capacitance is in series with an antenna signal and at 2.5 GHz, would act as a blocking impedance of about 13 ohms so, it's feasible it could be used without disrupting the VSWR too much. k is the ...


14

It is 'special' since it does not go very far. Strangely, this turns out to be an important advantage as many devices and people can use the same band in near by area without interference. Tele density is the term used in phone industry as how many cordless phone per square mile. Early generations (25 years ago) coreless phone use few MHz and tens of MHz ...


14

It seems to be a patch antenna array, analogous (among many images you could find googling around) to this one: Patch antenna arrays are a special kind of microstrip antennas. You can find many details about them in this article. A relevant excerpt: PLANAR MICROSTRIP ARRAYS Planar microstrip arrays are used to form a pencil beam and array elements ...


14

There's room for argument about some of the details. For example, I've omitted some of the rarely-used standards such as the original 802.11 and 802.11a, as well as some of the early 100 GBps Ethernet standards, in attempt at getting at least some approximation of speeds that were used fairly widely, not things that ended up as little more than technology ...


12

They put them where ever they can find an opening and try to do a good job tuning them. Form comes first at apple ;) Take a look at this, they've mounted one antenna just inside the opening for the optical drive on a recent macbook pro. Also they have a patent for a logo antenna I once did a tear down and comparison of a bunch of apple products ...


12

Your assumptions are close :D. It doesn't turn on the wifi unless you go through the menu to enable wifi and add the ap settings and all. Based on the FCC ID AZDK30306 (AZD is the Grantee Code, K30306 is the model), searching on The FCC ID page, it's 3.3v (not 5v tolerant), no internal regulator. Peak 0.6A. Based on USB. Full 802.11b/g support. Pins from ...


12

You should not expect any problems, other than the same problem any piece of metal poses. The magnetic field does not mask or influence any GHz transmissions. TV, Radio, 60Hz power lines should not pose a problem either. Think of the magnet as 0Hz; a DC electromagnetic field that is stuck in the magnetic form, with zero electrical component.


12

In order for the 2.4 GHz Wi-Fi signal to avoid trampling on the 900/1800 MHz mobile phone signals, 100 MHz FM signals, and a whole vast range of other signals, there is a hard limit on how much the signal is allowed to differ from a 2.4 GHz sinewave. That's a layman way of understanding "bandwidth". The point of having one transmitter at 2412 MHz and ...


11

Yes, you will get more signal strength from a 7 dBI antenna than a 2.2dBI (specifically 4.8 dB). It solves that by radiating energy more directionally than an idea antenna that radiates evenly in all directions (0 dBI). This increased signal strength of 4.8 dB is 10^(4.8/10) = 3 times more power. That will increase your range by about 70% in ideal ...


11

You can think of antennas similar to your vision. 0dB would be considered you just as you with nothing artificial. Now you decide that you would like to use a pair of binoculars to see further. The problem with binoculars is that your viewing range is not as large as you have with out them. However, binoculars are helpful, they let you see things that you ...


11

Ferrite kind of gives up the ghost as a useful concentrator of magnetic flux above 100MHz. As WiFi operates 2.5GHz, ferrite isn't very useful. If you look at the highest frequency ferrite Fair-rite have to offer you'll see this graph: - Notable is the permeability - only 16. Also notable is the frequency at which the resistive losses equal the permeability -...


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