Help on GRC to transmit at a specific frequency and width

GNU Radio
1

Hi @ all

Sorry, this stuff is new for me and therfore sorry for a possible stupid
question :wink: . I play a little with GRC and want to transmit e.g. a
cosine-wave at a specific frequency e.g. at 900MHz and width, say 2MHz.
But my problem are as following:

If i add only 2 blocks, i got nice constant transmission but the width
are too large, say more than ± 30 Mhz

| signal | | | source:
sample_rate: 1M, waveform:cosine, Frequency: 1k, Amplitude: 100
| source |--------->| usrp2 sink | usrp2 sink:
interpolation: 64, Frequency: 900 MHz, Gain: 0
|__________| |______________|

Is it possible to add a filter between the singal source and the usrp2
sink, maybe the band pass filter? Or is ist only possible with a
hardware filter behind the ursp2?
In case of the band pass filter: which values are right? I tried:
decimation=1, gain=1, samplerate=200k, lowcut=200k, highcut=200k,
transition width=200k. Or shoud the low- und highcut equals to the
frequency at 900 MHz and therfore a samplerate of 1.8 GHz?
I played a while with various values but without success.

thanks in advance
Dennis

2

The sample rate of the signal source is 1M. The sample rate of the usrp2
is 100M/64. Your rates disagree.

-Josh

3

On Fri, Aug 28, 2009 at 09:00:07AM -0700, Josh B. wrote:

e.g. a cosine-wave at a specific frequency e.g. at 900MHz and width,
say 2MHz. But my problem are as following:

If i add only 2 blocks, i got nice constant transmission but the width
are too large, say more than ± 30 Mhz

| signal | | | source:
sample_rate: 1M, waveform:cosine, Frequency: 1k, Amplitude: 100
| source |--------->| usrp2 sink | usrp2 sink:
interpolation: 64, Frequency: 900 MHz, Gain: 0
|__________| |______________|

The USRP2 expects its input to be be between 0 and 1.0. Try using
Amplitude = 0.1

Eric