Re: [Discuss-gnuradio] How can we measure the frequency offsets between two USRPs?

[John Andrews]

Let me give you the details this time. sorry for the confusion.

USRP - The first version

Daughterboard - RFX2400

The signal source has the following settings.

1. Sample Rate - 1Msps

2. Waveform - Sine & Complex

3. Frequency - 100kHz

4. Amplitude - 10

5. Offset - 0

This source is connected to the USRP Sink directly. There is no other block in between and not even a throttle.

USRP sink settings:

1. Interpolation - 128

2. Frequency - 2.5GHz

3. Gain (dB) - 30

4. Side - A (Tx/Rx) The USRP is connected fine and works well with benchmark_tx/rx tests.

On the receiver side I use a GRC flowgraph with USRP sink and FFT block only.

USRP Sink:

1. Decimation - 64

2. Frequency - 2.5GHz

3. Gain (dB) - 10

FFT sink has proper settings too.

I am not using any filters as I hope the SNR is high enough.

Thanks

On Mon, May 16, 2011 at 3:47 PM, Marcus D. Leech <address@hidden> wrote:

On Mon, 2011-05-16 at 15:34 -0500, John Andrews wrote:

I am running it at 2.5GHz.

What magnitude are the samples you're feeding into the USRP sink?

--n

Also, by default the RFX2400 has a TX filter that's centered at 2.441GHz and about 85Mhz wide at the 3dB points.  So, there'll be some attenuation
 at 2.5GHz, roughly 6-8dB or so.