[Hackrf-dev] Bandwidth control

[김상혁]

Thanks Koscher.

I got a good output. I have looked Tx FFT graph (it was not applied Osmocom bandwidth, just FFT block’s graph…).
I set osmocom Source’s bandwidth at Rx and I could check it was applied. 

> 2015. 11. 17., 오전 10:42, Karl Koscher <supersat at cs.washington.edu> 작성:
> 
> Yes. Keep in mind that this only applies a final bandwidth filter in hardware. If you are sending a signal that uses far less bandwidth than the filter's cutoff frequency, you will not notice a difference. In your case, it sounds like you're using a root-raised cosine filter block which will limit the bandwidth of the signal sent to the HackRF.
> 
> On Mon, Nov 16, 2015 at 5:25 PM, 김상혁 <tkdgur7896 at gmail.com <mailto:tkdgur7896 at gmail.com>> wrote:
> You mean I can control bandwidth using Osmocom sink’s bandwidth value ?
> 
>> 2015. 11. 17., 오전 10:21, Karl Koscher <supersat at cs.washington.edu <mailto:supersat at cs.washington.edu>> 작성:
>> 
>> When you are setting the bandwidth of the HackRF you are selecting which hardware filter is used. I believe if you specify a bandwidth, it needs to be one of the supported filter values -- 1.75, 2.5, 3.5, 5, 5.5, 6, 7, 8, 9, 10, 12, 14, 15, and 20 MHz. 
>> 
>> On Mon, Nov 16, 2015 at 5:10 PM, 김상혁 <tkdgur7896 at gmail.com <mailto:tkdgur7896 at gmail.com>> wrote:
>> I heard HackRF One support up to 20 MHz of bandwidth.
>> 
>> But, I can’t handle this value properly. I tried to adjust bandwidth on GNURadio-Companion by changing some value o
>> 
>> 1) Osmocom sink (Ch0: Bandwidth) - It was initialized by 0 and it means automatic setting. I vary this value but, never effect.
>> 2) Modulation (Excess BW) - It means Root-raised cosine filter excess bandwidth (float) and usually range of ~ 0.35. When I change this value, it was little effect on bandwidth(larger value is more bandwidth)
>> 3) Sample rate - I found that sample rate is directly related with bandwidth. I tried adjust this and it was so cool. When I use large value of amp_rate, however, the FFT plot graph was stutter. Is it computational problem?
>> 
>> I’m curious to how to control bandwidth up to 20MHz.
>> 
>> Thanks for any reply
>> 
>> Shawn.
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>> 
> 
> 

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