ISRO2015-51

Question

How many characters per sec $(7 \;\text{bits} + 1 \;\text{parity})$ can be transmitted over a $2400$ bps line if the transfer is synchronous $( 1$ start and $1$ stop bit)?

• A. $300$
• B. $240$
• C. $250$
• D. $275$

Answer 1

Ans A) 300

Total number of bits per character while transmitting is (7+1)=8 bits

No of character transmitted 2400/8=300 bps

Comments

I think it should be 300

in Synchronous transmission, we don't need start and stop bit.

on;y 8 bits are used ,so 2400/8 = 300 (A)

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U r right , it should be 300.

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The Answer is 300 according to answer key also

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ok corrected

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if it asynchronous,we need to consider start and stop bits?

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YES FOR SURE.

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Thank you

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refer question no. 19 of ISRO 2007, a slight difference,then why have you not added start and stop bit ?

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They have mentioned one start bit and one stop bit. Should we include that, or do we need to ignore

Answer 2

Awesome tricky question!

For synchronous transfer, we don't need start and stop bits.

So, $\frac{2400}{7+1}=300$ 

Option A

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For asynchronous transfer, we need start and stop bits in order to synchronise!

So, $\frac{2400}{7+1+1+1}=240$

Answer 3

Given bandwidth is 2400 bps
Each character consists of (7+1)bits = 8 bits
Synchronous transmission is a data transfer method which is characterized by a continuous stream of data in the form of signals which are accompanied by regular timing signals which are generated by some external clocking mechanism meant to ensure that both the sender and receiver are synchronized with each other.
Once sender and receiver synchronized means no need to use start and stop bits every time
Total number of characters can be transmitted per second is =bandwidth/ number of bits in each character=2400/8 = 300