Well as you advice me, i set the --lo-offset=1M , for the following command
uhd_rx_cfile -a serial=4759a751 -N 100000 -f 2.53G --samp-rate=2M
--lo-offset=1M noise.dat -v
However the peak is still there. I give below the output of
uhd_rx_cfile.py.
As you can see the Rx DDC frequency is -2M (if I have understood
correctly, it should be 1M,right? )
Any idea what is the wrong..
linux; GNU C++ version 4.4.5; Boost_104200; UHD_003.005.002-47-g4a860d74
-- Opening a USRP1 device...
-- Using FPGA clock rate of 64.000000MHz...
Using mid-point gain of 45.0 ( 0.0 - 90.0 )
Motherboard: USRP1 (4759a751)
Daughterboard: RFX2400 (no serial, RX2, A:0)
Rx gain: 45.0
Rx baseband frequency: 2.528G
Rx DDC frequency: -2M
Rx Sample Rate: 2M
Receving 100k samples
Writing 32-bit complex floats
Output filename: noise.dat
2013/4/28 Alex Zhang <cingular.a...@gmail.com>
> I remember that some DC is manually added into the frequency point which
> can be divided by 5Mhz or 10Mhz? Besides the DC at the your central freq,
> be aware of that if the lo offset setting makes your bandwidth cover these
> frequency point, you still can see the peaks.
> Hope I am not wrong, at least It seems that I observed that thing before.
>
>
> On Fri, Apr 26, 2013 at 1:44 PM, Marcus D. Leech <mle...@ripnet.com>wrote:
>
>> On 04/26/2013 02:27 PM, vegihat vegihat wrote:
>>
>>> if i have understand i need to use the --lo-offset of uhd_rx_cfile
>>>
>>> i have gave various values to --lo-offset and only one value has moved
>>> the DC offset (--lo-offset=1G) and the plotfft gives many small spikes
>>> (maybe this is caused to aliasing, but i am not sure)
>>>
>>> which is the rule (value of --lo-offset) to set the DC offset out of my
>>> band?
>>>
>> What I do is set my LO offset to about half my bandwidth, so in your case:
>>
>> --lo-offset 1.0e6
>>
>>
>> --
>> Marcus Leech
>> Principal Investigator
>> Shirleys Bay Radio Astronomy Consortium
>> http://www.sbrac.org
>>
>>
>>
>> ______________________________**_________________
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>>
>
>
>
> --
>
> Alex,
> *Dreams can come true – just believe.*
>
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