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Re: [Discuss-gnuradio] Observing Random Jitter in HackRF One in High Ban
From: |
Cinaed Simson |
Subject: |
Re: [Discuss-gnuradio] Observing Random Jitter in HackRF One in High Bandwidth with High Carrier Modulation |
Date: |
Thu, 6 Jul 2017 14:43:47 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux i686; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 |
Post the gnuradio flowgraph you used.
If you have a complaint with the HackRF hardware, post the complain on
the HackRF mailing list
https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
And if you're only getting 2 MSPS with the HackRF on your computer then
you just have a slow computer - or it's operator error.
See
https://greatscottgadgets.com/sdr/
for a tutorial on the HackRF.
-- Cinaed
On 07/06/2017 07:14 AM, Stack Programer wrote:
> Yet i work on DVB-T in HackRF one, in TX we can send DVB-T and we
> receive it with a hardware dongle DVB-T. but for receiving with SDR
> Based we had error: see this link for our older
> <http://blog.stackprogramer.xyz/en/2017/02/18/dvbt-project-receiver-probelm-oorestart-aquisition-d_freq_offset-5-od_freq_offset-5/>
> work or this
> <https://www.maximintegrated.com/en/app-notes/index.mvp/id/1916> link.
>
> DVBT project receiver probelm OOrestart aquisition d_freq_offset: -5
> Od_freq_offset: -5
>
> So for examine my problem i created a new issue on hackrfone github
> project see this <https://github.com/mossmann/hackrf/issues/390> link,
> every thing i found i will update there. In older our post we define
> jitter error , for more info you can see this
> <http://blog.stackprogramer.xyz/en/2017/06/18/definition-of-some-of-important-elements-of-digital-communication/>
> link.
>
> Fig1:Jitter error diagram description
>
> * *So we start examine that how we observed HackRF One has Random
> jitter errors??*
>
> my reason why HackRF One has random jitter error, In protocol like
> gr-dvbt <https://github.com/BogdanDIA/gr-dvbt>,gr-ofdm,gr-atsc that they
> are ofdm based modulation, we had not any response in receiver mode in
> dvb-t we had famous error: but frequency offset instantly from -5,3,2,7,….
>
> restart aquisition d_freq_offset: -5 Od_freq_offset: -5
>
> So we had a error in uncertianly frequency and other hand it is random,
> so we had radom jitter errror.for more info see this
> <http://www.eetimes.com/document.asp?doc_id=1204338> link.
>
> * *reason of causing HackRF One has Jitter error?*
> * Low Resolution ADC:
>
> after some search i concluded that one of reason for random jitter error
> in HackRFOne is low resolution ADC, it has 8 bit ADC,please see this
> <https://www.maximintegrated.com/en/app-notes/index.mvp/id/4466> link
> that describe how low resolution ADC can create jitter errors .
>
> * Low SNR in HackRF One:
>
> For problem long switch diode stage in RF HackRF One it is more noisy vs
> USRP. So it use long way RF, it should edited in newer version.
>
> you can see in below image and link that how bad SNR and low ADC
> resolution can caused jitter errros.
>
> for more info please seethis
> <https://www.maximintegrated.com/en/app-notes/index.mvp/id/4466> link.
>
>
>
> jitterADC
>
> Fig2:low resolution ADC can cause jitter errors
>
>
>
> So we saw that HackRF One in OFDM based modulation and high carrier or
> in high bandwidth it sucks and it has random jitter errors, so we should
> ask myself that we need new design opensource hardware SDR hardware?
>
> But some question is need to answered??
>
> *why is mention HackRFOne has bandwidth 20 MSPS…..*??
> we should define bandwidth and sps in high carrier modulation
> it has problem in high carrier modulation?.So really HackRF One have
> Bandwidth more than 2 MSPS?
>
> *but what's solution?*
>
> *
>
>
> using a external clock for hackrf one???
> *
>
> design a new hardware………?
>
> i liked hackrfone for reason that is opensource and hardware, but with
> this condition i concluded that
> we should think a new way for future sdr hardware opensource?
>
> best regards stackprogramer
>
> Fig3:HackRFOne a opensource hardware SDR hardware
>
>
>
>
>
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