Saturday, April 3, 2010

Land Line Network basics

How are landlines connected?
What are those boxes that you find in every street that a lineman peeps into and gets himself in jumbling those wires?
Why the hell do the govt people often dig out the roads for wiring down the ground?
How is my land phone connected to the exchange?

Guys all the above questions were in my mind.... They are getting cleared every day... So i feel its very important to share this information to the rest of the world...

Starting with Exchanges. Exchanges are the places where a landline cable starts till your home. They are the nodes or the end places where your call is being connected to other subscriber's line.
Cables are the wires that connect your landline phone to the Exchange (Local) through various other junctions or subnodes.
Ok to get a clarity on what i am talking about just see the below image. You can visualize how a network is established. Ofcourse all the exchanges are CONNECTED. Just to avoid confusion i have not connected them in the below picture.

Exchange: It is the place where the following functions take place.
  • Subscriber has a meter to calculate his duration of calls
  • Subscriber info is in his exchange.
  • Connects to the subscriber through cabinets, pillors and DPs
  • Place where the switching takes place to connect various subscribers. Till exchange the wires are independent.
  • Depending upon the called user the call would be routed either to its own cabinet or to other exchange.
and many more... I think you can guess how a exchange would look like. If not pls look at the below pic.





Cabinet: Cross connection network between the primary cable and secondary cable as you can see in the first  figure. 
Cabinet consists of various CT boxes where the many primary cables terminate their conductors. Again there are set of CT boxes which take the connections and terminate out of the Cabinet to connect to a particular Pillor

Pillor is a Smaller version of Cabinet. It Cross connects the Secondary cable to the distribution cables. Pillor looks like below. Cabinet looks the same but with many CT boxes.



Then comes your Distribution Point. This is the point from where your landline cable comes into your house.
I guess you recognize with the pic below




Hey you know what they call the cable from the distribution point to your phone.
Its called DROP WIRE. It has generally two conductors and caries -48V. See the below image. The conductors are called A and B. 

From the exchange till the subscriber end, the cable consists of these pair of conductors to serve the calling purpose.



Now with this i end this connectivity. There are alot details about the cables. If interested pls drop a mail regarding your queries and i will be more than happy to reply you.


Tuesday, February 23, 2010

Problems with Vista64 - For USBasp programmer installation

I think now a days as serial and parallel ports are no more in use....with all programmers using laptops... USB AVR programmer is the most sorted for...
I have purchased the same from internet and faced following issues before i could properly get it installed...
Ok let me go one by one

Vista 64 bit: If this is your OS then boss you got to do many things before you start your actual programming.
As you know AVR Studio; WinAVR; Ponyprog are the tools that are used for programming an AVR MCU, we get compilation problems with WinAVR in Vista 64.
Pls click here to get you to the post regarding the same.

Then comes the part where you have to install drivers to recognize your USB programmer.
There are drivers provided in the kit that you buy, but most often its likely that they dont give the drivers for Vista 64.
So pls download the drivers from the below link for Vista 64
http://www.protostack.com/download/USBasp-driver-0.1.12.2.zip

Once you download connect your USB programmer and direct the hardware installation wizard to the path where you have downloaded the driver and install the same.
And when you install the same you may encounter erros saying that digital signature is required and so and so.
Pls go with the option of install it any way.
Then go to the device manager in Control panel. You can see that USBasp is installed but will have a yellow triangle indicating that its not properly installed.
Do nothing now.
Reboot the system and press F8 before its starts. You will find an option where you can "Disable driver signature enforcement". Once the computer starts check for the device manger and you will see that the yellow triangle disappeared.
This indicates that boss you have successfully installed USBasp driver in order to recognize your programmer.

Here is the link of the vendor where i bought the USB AVR programmer.
http://extremeelectronics.co.in/

Enjoy programming!!!! :) :)

Sunday, February 21, 2010

DRDO sets up a platform for Students to build Machines infact heavy robots

Hi All,
DRDO hosts a competition for the students in Engineering to build a heavy robot that could transit in all possible surfaces and hurdles..
The event also has attractive cash prizes...
Check out in the below URL
http://www.drdo.gov.in/scomp2010/index.html

WinAVR vs Vista 64bit

Hi Friends,
I faced some problem in compiling a c code that i wanted to dump into the Atmel Atmega8 MCU.
When i ran the basic simple code in my Vista 64 bit lappy.
It throws an error as below

"make.exe" all
0 [main] sh 3792 sync_with_child: child 1880(0x11C) died before initialization with status code 0x0
38726 [main] sh 3792 sync_with_child: *** child state waiting for longjmp
/usr/bin/sh: fork: Resource temporarily unavailable
0 [main] sh 6668 sync_with_child: child 5760(0x120) died before initialization with status code 0x0
34379 [main] sh 6668 sync_with_child: *** child state waiting for longjmp
/usr/bin/sh: fork: Resource temporarily unavailable

-------- begin --------
avr-gcc (WinAVR 20100110) 4.3.3
Copyright (C) 2008 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


Compiling C: main.c
avr-gcc -c -mmcu=atmega8 -I. -gstabs -DF_CPU=8000000UL -Os -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -Wall -Wstrict-prototypes -Wa,-adhlns=./main.lst -std=gnu99 -MMD -MP -MF .dep/main.o.d main.c -o main.o
main.c:13: fatal error: opening dependency file .dep/main.o.d: No such file or directory
compilation terminated.
make.exe: *** [main.o] Error 1

> Process Exit Code: 2
> Time Taken: 00:01

I posted this in forums and searched in google and found the solution.
There is a .dll file in \utils\bin folder of your WinAVR install folder with name "msys-1.0.dll"
which we have to replace with the file in the following path

There ends the problem. :) :) :)