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What is differential ouput?

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Squintz

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My DAS has the option of putting out a differential PCM output. I know in order for us to record data onto a SVHS we need to use the differential output and the clock output. But when we are transmitting RF all we need is the normal PCM output which im not sure of the technical term for a norm PCM output is.

If i were to build a Compact Flash Card Recorder would i need to use differential output or could i record straight PCM
 

ezwizzard

New Member
Hi, PCM Pulse-code Modulation is the trasmission of intelligence by varying the characteristics of a series of electromagnetic pulses. Pulse modulation is accomplished by varying the amplitude ,the duration, the frequency or the position of the pulses. Hope this helps??? :wink:
 

Squintz

New Member
Did not help much. Sorry! i still don't know what differential PCM means. Or differential ouput? I think the word differential is whats confusing me. And i still dont know why i would need it along with a seperate differential Clock output to be able to record to SVHS
 

kinjalgp

Active Member
Differential PCM is enhanced version of Pulse Code Modulation (PCM). In normal PCM, very high bandwidth is required for high data rates. To avoid this problem DPCM was developed which compresses data by transmitting only a single bit correspnding to an 8-bit or 16-bit (or whatever) sample. The current sample is compared with the previous sample and difference of both is used to manipulate the data to be sent.

Thus effective bandwidth required is reduced to a great extent.

Check out these links for more info.
http://www.cmlab.csie.ntu.edu.tw/cml/dsp/training/coding/dpcm/
http://www.stanford.edu/class/ee398b/handouts/01-DPCM.pdf
 
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