Showing posts with label GHz. Show all posts
Showing posts with label GHz. Show all posts

Thursday, December 10, 2015

WiFi Spectrum Anayzers


WiFi - CR Park, Delhi

These days, there are few things as indispensible as WiFi networks.

No hotel or restaurant worth its salt will scrimp on bandwidth when it comes to offering WiFi as a free service to its customers. Forget the McDonald's even most ramshackle dhaba's along the national highways are offering it as a bait for those who are hungry for data.

In this scenario, it is interesting to scan WiFi networks while you are on the move. The above screenshot was taken at CR Park market in South Delhi. Well past 8:00 PM, the analyser showed up no less than 20 separate routers in a 20 sqft area.

It is one thing to see the colorful parabola's bobbing up and down the graph and another to actually understand what they actually mean.

Why, for instance, is the signal strength in dBm (decibels milliwatts)  going upwards from negative hundred (-100 dBm) towards zero?

How does the address system in WiFi devices various devices link up to the the IP addresses? Why are these in six sets of alphanumeric characters separated by a colon, as opposed to numeric IP addresses that come in sets of four numbers each?

Why is the bandwidth restricted to 11 to 14 channels?

How do the WiFi transmitting devices manage to keep their frequencies in such a sharp range? Rather mindboggling when you learn that these signals are being sent out in Giga Hertz -- 1000,000,000 vibrations per second!

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LINKS

* dBm in Wiki -- https://en.wikipedia.org/wiki/DBm

* how to fix your wifi network - http://www.pcworld.com/article/260524/how_to_fix_your_wi_fi_network_7_tips.html

Saturday, August 22, 2015

Giga Hertz

1,000,000,000 vibrations per second. This is one Giga Hertz (GHz).

GHz is just a tiny sliver of the electromagnetic spectrum (EM) that surrounds us. Yet, it has become so indispensible in our lives that most of us barely give it a second thought.


Just consider this:

* Bluetooth Devices used in personal area networks (wireless earphones, speakers, etc.,) use the frequency range 2.4 to 2.4835 GHz. The protocol divides the band into 79 channels (each 1 MHz wide) and changes channels up to 1600 times per second!

* Micowave Ovens cooks your food and heats your coffee using high power magnetrons to transmit EM radiation in the 2.4 GHz band.

* Telecom Towers - Use the range 1 GHz to 300 GHz. Interfering with the high power transmission of these towers can be fatal, as proven by this case of Darwin Awards, titled "Christmans Roast".

I am yet to figure out how we managed to get such precise control over anything that transmits signals at amazingly high frequencies...


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LINKS

* Connectivity failure while using Bluetooth and USB-3 devices simultaneously - http://www.bluetoothandusb3.com/

* EM interference at 2.4 GHz - https://en.wikipedia.org/wiki/Electromagnetic_interference_at_2.4_GHz

* Instructables - http://www.instructables.com/id/Car-motorcycle-or-bicycle-wifi-alarm-rang-500m-10-/