transfering data

[brian873]

Hi I am trying to work out how long it will take to transfer a file over different networks.

If I have a 50mb file how long would it take to transfer using gprs @ 80kbps and edge @ 236kbps

any help would be appreciated

[Mijzelf]

I suppose that's an 50MB file? With overhead counted you need about 10 bits to transfer a byte, so you'll need 500 Mb.

@80kb/s: 500 000 000 / 80 000 = 6250 sec = 1 hour 45 minutes.

@236kb/s: 500 000 000 / 236 000 = 2119 sec = 35 minutes.

Times are slightly different when you mean MiB and Kib.

[brian873]

Thanks Mijzelf great utility !

Although I would still like to know how to calculate this, anyone help my brain is thinking too hard about it and I cant find the solution....

Any help appreciated

[Ponch]

I would still like to know how to calculate this

Mijzelf did the math for you.

Lets repeat.

1byte(B ) = 8bits(b ) (2^8=256 possibilities, enough for all characters), make it ~10 for the whole communication (sort of wrapping).

1kB = 1.000bytes and 1mB=1.000.000bytes (=~10.000.000b exchanged)

also 1KB=1024 bytes and 1MB=1024KB, but lets round it.

-80kbits/s is the speed, it's the volume per time. You want the time, so time=volume/speed but you have to use the same units for both values.

(50.000.000 x 10bits) / (80.000bits/sec) = 6250sec = ~104min =~1h44'. This is pure theory, so use 1024 (twice) instead of 1000 and also add ~20% for real world. That gives ~2hours 11'.

and so on,

1MB on 56k modem ~4min

1MB on 10Mb network ~1.2sec

10MB on 100Mb network ~1.2sec

[brian873]

Thanks Ponch ! I have got it now....

and thanks again Mijzelf

I think I have just learned somethign new today