Simple Question

EDAboard.com Forum Index -> Analog Circuit Design -> Simple Question

Author

Message

suhas_shiv

Joined: 30 Nov 2005
Posts: 139
Helped: 7

20 Jul 2006 7:22 Simple Question

I have a simple question. How do you convert MHz to Mbps?
Say for example I have a LVDS receiver operating at 400Mbps, so is the operating frequency 400MHz or 200MHz? The reason I ask is that some company products specify the working frequency as 200MHz while the data rate is 400Mbps. I am a little confused.

thanks

IanP

Joined: 05 Oct 2004
Posts: 6492
Helped: 1542
Location: West Coast

20 Jul 2006 7:31 Re: Simple Question

Quote:

(X bits * Y Mhz) / 8 = Z Mbps

...

Assuming there are 8 bits in a byte:
(megabits/second) / 8 = megabytes/second

It looks as though your numbers are not coming out correct because different busses have different number of bits/byte. Some are 8 bits/byte so you would divide by 8, others have 10 or 11 bits per byte.

Also keep in mind that for base 2 there are 1024 bits in a kilobit, while in base 10 there are 1000 bits in a kilobit. I believe that modems use the metric base 10.

Also, see: http://en.wikipedia.org/wiki/List_of_device_bandwidths

Regards,
IanP

Last edited by IanP on 20 Jul 2006 7:36; edited 1 time in total

suhas_shiv

Joined: 30 Nov 2005
Posts: 139
Helped: 7

20 Jul 2006 7:50 Simple Question

I think megabits/sec is Mbps and megabytes/sec is MBps.

Fawad Elahi

Joined: 19 Mar 2007
Posts: 64
Helped: 3
Location: Pakistan

21 Sep 2007 12:08 Simple Question

each cycle has two peaks. if the positive peak is represented by level 1. and the negative peak is represented by level 0.
then the bits rate is double than the bandwidth of the channel

Google
AdSense
Google Adsense

21 Sep 2007 12:08 Ads

Eugen_E

Joined: 29 Nov 2004
Posts: 358
Helped: 31

21 Sep 2007 21:54 Re: Simple Question

Considering it's about baseband transmission - no modulation, it depends on the coding. More exaclty, it depends on the period of the shortest signal element. The data being random, it's a bandwith, not a single frequency.

If NRZ coding is employed, for a bitrate of X bps, the signal spectrum will have a peak at X/2 Hz. The spectral energy will ocupy an theoretical unlimited - but in practice limited bandwidth, since the data is random.
For Manchester/Biphase coding, bitrate X bps, the signal spectrum will have a peak at X Hz.
For multilevel coding (rarely used, egg. fast Ethernet), the significant spectrum portion can be less than X/2 Hz, as the number of levels is increased from 2 up.