digital recording equipments

use this because there is some process to do on the trace

using computers ,depends on storage capacity ,computer technology ,analog data was convert to digital by the digitizing technique usin an electonic circuit (adc)analog digital converter

analog and digital data
analog data is the signal (wave )henced by the geophones but digital data is to take the values of amplitudes (make spikes)




suppose the t axes is the time ,and the n axes is the amplitude,at t=200,n=2
t=400,n=-1
t=600,n=2
and so ..........

the values of amplitude is the desimal amplitude
the disimal amplitude for this wave is 2,-1,2,...etc
this desimal amplitude should converted to binary data ,how
example: if desimal=1247=1*10^3+2*10^2+4*10^1+7*10^0
for binary=11001,desimal=1*2^4+1*2^3+0*2^2+1*2^1+1*2^0
note that sampling interval=2 and we used power=4 while digits=5 ,use
power=digits-1
note also that binary is 0 and 1 number that can digitized on computers.

another example suppose u have one desimal amplitude=28 of a signal and sampling interval =2msec,what is the binary recording?easy
desimal=28=2^4+2^3+2^2 ,
this can make as 28=0*2^1+1*2^2+1*2^3+1*2^4+0*2^5
so,binary is 01110,the 0 is not magnetic on the magnetic tape ,but 1 is magnetised

بالضبط شبه الكلمات المتقاطعه ، المربع رقم 1 يظلل ، ورقم 0 لا يظلل



i hope u know the game now ,this game was done by computers
using linux system that deal with graphs and unix system ...if u work in seismic processing ,u will be amachine..all u work with computers not by u self....the human become amachine move it machine

dynamic range in digital recording
ratio between maximum amplitude and minimum amplitude ,can be stored on computers ,depends on number of bits,digital more usueful more than analog,
can store dynamic range more than analog,there is atechnique is float point system (if u have weak refletion with high noise , can enhance the signal )

example
A1/A2=1024/1
DYNAMIC RANGE =20 log 1024=60 db(desibel),but in digital,ratio=1024=2^10,so use 10 bits words
number of bits proportional to dynamic range



aliasing

nuquist frequency =sampling frequency /2
if the sampling interval is 2 milli second , the sampling frequency =500 hz ,nyquist =250 hz
frequecies under nyquist will preserved (0-250)hz ,but for frequencies > nyquist frequency (proplem of aliasing)distorion of output .

this graph is very good for aliasing
that mean that if u have one input frequency ,this will meet two output frequency,
the solution wth proplem is to use
1-reduce to nyquist
2-high cut filter antialias filter to remove frequences>nyquist
3-make attenuation of insignficiant amplitude

sources :introduction to geophysical prospecting .milton dobrin
for more about aliasing
http://en.wikipedia.org/wiki/Aliasing

بسم الله
اهلا بيك معانا يا takey
منتظرين مواضيعك
وانا بجد مبسوط ان فيه حد بيعقب علي كلامي



ok, your info is more right, but ,i donot want to tell the digitizing adc is the linux , the adc is complex electronic circuit, and i know that linux and unix is open sources system (the whole system we deal with), all the thing that i want to link our studies to the practical application

متشكر كمان مره ع الاضافه

i you have afigure for analog digital converter, put it please

al salam 3alykom ya basha mafesh da3i ll sokr
how da hadaf el montada

nekamel kalam 3ala mawo3 el analog-to-digital converter







Talking about the A/D open the door of speaking about where
the digitizing of the analog data done???


Is that happen in the geophone? in the cables? In the
office? Or somewhere else?


I will wait the members answers before talking about that ??


Another question we should ask it ….. what is the
configuration and the layout of the seismic acquisition field?? And how the
geophone connected to the recording truck? Is it connected only by cables???

the first question about digitizing,i think is it be the field , the analog ouput of seismic amplifiers has o pass through ADC , which is used to digitize all seismic channels by muliplexing,and then for each channel, sampling he instantanous output values and register it in digital using binary ,
all my info is theoritical and me not know alot about the real work in petrolum campanies, i have not trained yet,train the next summer

the other question , idonnot know about? tell us if it isnot the trace gathers

ok ya basha kalamk 3an en el digitizing we el multiplixing bey7sal fee el field sa7.....
bas 7'alina nefaker sheyaya ezay bey7sal fee el geophone??







Remember, the geophone
consist of coil, magnet and resistance???


So, where the multiplexing and digitizing is
done??? In the BOX , what is the box?


To know what is the
box we should know how we connect the
geophones to the recorder truck, i.e. the distribution of your equipment in the
field.





Distributed systems have cable connections
between the units that record the field data and the control system in the
recording truck. Usually, these connections are made via a line unit (Figure 1)
that gathers the information from several different geophone
groups. The recording equipment is set up in an arrangement similar to the one
in Figure 2. In most distributed systems, some number of groups of geophones
are connected to a box. These boxes convert the analog signal to digital form
(samples). The boxes are normally wired together along a “branch line” that
usually takes the form of a twisted pair. Branch lines feed into cross-line
units, which in turn are connected by a “trunk line” and fed directly into the
central recorder.







Fig.
1. Solar battery powered boxes




Fig.
2 Typical field setup for a distribution system (Input/ Output System Two). ALX
( advance line tap), MRX( miniature remote signal conditioner).


this is the layout of the equipment in (I/O 2) in sercel is differrent but the same concept

thanks alot for u info , my feel tell me that u work in apetrolum campany, if u , tell us please about any thing of geophysics u work with, if not , tell us also, thanks

aywa sa7 ya basha we en sha2 allah a3raf afeed be7aga kewayesa

we rabena yesahel we lama anzel el gam3a a3raf a2ablk ..(low kont bete7dar ya3ni).