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.
It would be useful to see your .grc flow-graph files. Are you using
UHD, or "classic" (sorry if this has already been asked).
I'll reiterate my earlier comments. The RFX2400, by default, has a
*hardware* SAW filter with a center frequency of 2.414GHz, and a
nominal
bandwidth of 85MHz or so in the TX/RX path, so if you're running
it at 2.5GHz, you're somewhere on the skirts of the filter, which
would lead
to attenuated output. This filter can be bypassed easily by
carefully cutting the traces going to FIL1, and populating C204 with
a 30-100pF
SMD capacitor.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org