Reading carrier frequency

GNU Radio
1

Hi,
I am new to GNU radio and want to experiment. From the mailing lists, I
understood that the carrier frequency offsets change over time but that
those offsets are within +/- 20ppm of the center frequency. Suppose I
use
two USRP boards; one for transmission and another for reception of
signals.
I want to know how I can read the carrier frequency of the transmitted
signal on the receiver side through a python or C++ program. Is there
any
program to do this? Or, which library routine can I use for this
purpose?

Appreciate any kind of help you may provide on this.

Thanks.

G.

2

On Wed, Sep 10, 2008 at 11:46:26PM -0600, Gnu Radio Explorer wrote:

Thanks.

G.

This is a FAQ that needs an answer. Can someone please write
something up on carrier tracking and symbol timing recovery and post
it to the wiki?

Bottom line: there will always be a frequency offset between any two
radios and part of the receiver’s job is to handle it. There’s a ton
of literature on this as well as complete text books. In the simplest
case it’s a PLL to track the carrier, but oftentimes it’s more
complicated than that.

Eric

3

Thanks for the reply Eric. I am completely new to this field. I
understand
the receiver should be able to accomodate these differences.

But is it possible for a GNU radio program running on the receiver
computer
to be able to read the changing values of the sender’s carrier
frequency, or
is it just that the programs will only be able to read the values after
the
carrier frequency is converted to the intermediate frequency and not
directly at carrier frequency?

Another question by the way. I am having a RFX 900 board. Suppose a
transmitter program desires that the USRP should produce a signal with
center frequency f1 = 925.123456 MHz, for example. But in reality will
the
USRP be able to transmit the signal at this exact frequency f1 (at the
granularity of Hertz) by some way?

Thanks in advance.

G

4

On Thu, Sep 11, 2008 at 4:22 PM, Gnu Radio Explorer
[email protected] wrote:

center frequency f1 = 925.123456 MHz, for example. But in reality will the
USRP be able to transmit the signal at this exact frequency f1 (at the
granularity of Hertz) by some way?

You know what might be a good place to start:

http://gnuradio.org/trac/wiki/SuggestedReading

Welcome to the field! I am sure you will find it fascinating.

Brian