About gr_buffer_add_reader

GNU Radio
1

Hi list,

I have a USRP N210, running on Ubuntu-10.04, when I try to use the
Gnuradio-Companion to make a fm_receiver,

I success generate the python code, but when i try to run it,

it shows

terminate called after throwing an instance of ‘std::invalid_argument’
what(): gr_buffer_add_reader: nzero_preload must be >= 0

what is that mean?

I know that I might have some problem in the flow graph or parameter
because
I use the old version example(USRP1) which I search on the internet as
the
reference, can any one help me?

PS I would like to ask an additional question: If I only have DBSRX
RFX1200
RFX1800 these three daughterboards, is that means I can’t receive the
100MHz
FM Radio Signal by my fm_receiver through the USRP N210 (bandwidth not
right)? or there is some other ways ?

thanks,

Eddie

2

On 05/24/2011 01:26 AM, Eddie Sun wrote:

what(): gr_buffer_add_reader: nzero_preload must be >= 0

what is that mean?
Not sure, would have to see your GRC flow-graph.

PS I would like to ask an additional question: If I only have DBSRX
RFX1200 RFX1800 these three daughterboards, is that means I can’t
receive the 100MHz FM Radio Signal by my fm_receiver through the USRP
N210 (bandwidth not right)? or there is some other ways ?

thanks,

The DBSRX covers about 800MHz to 2.3GHz, the RFX1200 covers 1.15GHz to
1.45GHz, the RFX1800
covers from 1.5GHz to 2.05GHz. I don’t see 100MHz anywhere in there.

If you want good coverage of the FM radio band (88MHz to 108MHz in North
America), you would
need a TV_RX2 card or WBX card.