[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] USRP Tx Rate Conversion

From: Brian Padalino
Subject: Re: [Discuss-gnuradio] USRP Tx Rate Conversion
Date: Tue, 15 Apr 2008 16:03:24 -0400

On Tue, Apr 15, 2008 at 3:48 PM, Wireless Monster
<address@hidden> wrote:
> ...I understand...
> so... What needs to be done to assure data will be treated as a 270.833Ks/s
> rate?

I feel like we're in an Abbott and Costello routine.

Data is nothing until it's pumped out of a DAC at a specific rate.
Lets say it's 64Msps is the exact rate we're going to be feeding some
DACs.  We know there is an interpolating CIC filter beforehand.  We
figure we'll do a power of 2 to ensure there is no extra gain added to
the signal - so we choose 64.

Knowing this information, the stream at the output of the
interpolating CIC filter is 64Msps, and the stream going in is
64/64Msps, or 1Msps - then we know we should generate a stream of data
that is in fact a 1Msps representation of whatever data we wish.

In your case, you wish to make a 270.8333kSps (the S here means
Symbols ... also known as a baud) stream into a 1Msps sample stream.
With some quick math, I can determine that you need to interpolate by
the exact value of 48/13.  This has your data (270.8333kSymbols/sec)
at a sample rate of 1Msample/sec.

The lesson here is to never mix the terminology of sample and symbol
(or baud) rate.

Is it more clear as to what you're doing now?


reply via email to

[Prev in Thread] Current Thread [Next in Thread]