[Discuss-gnuradio] Observing Random Jitter in HackRF One in High Bandwidth with High Carrier Modulation

[Stack Programer]

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

work or this
 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  link, every thing
i found i will update there. In older our post we define jitter error , for
more info you can see this

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
,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
 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
 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 see this
 link.



[image: 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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[Discuss-gnuradio] Definition of some of important elements of digital communicationDefinition of some of important elements of digital communication

[Stack Programer]

We want to discuss about elements of digital communication
 that it can be useful for
that work bettwer with SDR
 framework like
GnuRadio  or Matlab Simulink
. So we know them are for basic for study more
we should refer to references.

*Sampling:*

For Converting analog data to digital data we use sampling process.We are
limit in sampling with shannon sampling

theorem. we can do sampling with different sampling rate, for example for
audio sampling rate we can use 8000,16000,32000,44100 hz sample rate.

*Complex Sampling:*

For real data sampling  we in spectrum in a center frequency we have data
in spectrum in [fcenter,fcenter+sps/2],that sps is sample persecond that
when we has sps 10 MHZ and  center frequency 100 MHZ, in spectrum we see
data on 100Mhz to 105Mhz, but for complex sampling we has data spectrum on
[fcenter-sps/2,fcenter+sps/2], for sps 10 Mhz and  center frequency 100 Mhz
we have data spectrum on 95 Mhz to 105 Mhz. If you work with gnuradio can
see this subject in osmocom
 source and sink.

In that case, the Nyquist rate 
for a waveform with no frequencies *≥ B* can be reduced to just *B*
(complex samples/sec), instead of 2*B* (real samples/sec) .

Computing only every other sample of the output sequence reduces the
sample-rate commensurate with the reduced Nyquist rate. The result is half
as many complex-valued samples as the original number of real samples. No
information is lost, and the original s(t) waveform can be recovered, if
necessary.

[image: complex sampling]

Fig1:Complex sampling in FFT GUI WX option

*Symbol:*

A symbol may be described as either a pulse in digital baseband
transmission or a tone in passband transmission using modems, representing
an integer number of bits. A theoretical definition of a symbol is a
waveform, a state or a significant condition of the communication channel
 that persists
for a fixed period of time. A sending device places symbols on the channel
at a fixed and known symbol rate, and the receiving device has the job of
detecting the sequence of symbols in order to reconstruct the transmitted
data. There may be a direct correspondence between a symbol and a small
unit of data . For example, each symbol
may encode  one or several binary
digits or 'bits'. The data may also be represented by the transitions
between symbols, or even by a sequence of many symbols.

The *symbol duration time*, also known as unit interval
, can
be directly measured as the time between transitions by looking into an eye
diagram  of an oscilloscope
. The symbol duration time *T*s
can be calculated as:

where *f*s is the symbol rate.

[image: Inline image 1]

*A simple example*: A baud rate of 1 kBd = 1,000 Bd is synonymous to a
symbol rate of 1,000 symbols per second. In case of a modem, this
corresponds to 1,000 tones per second, and in case of a line code, this
corresponds to 1,000 pulses per second. The symbol duration time is 1/1,000
second = 1 millisecond [1 ].

Fig2:Constellation diagram for QPSK with Gray coding
. Each adjacent symbol only
differs by one bit.

You can see read more about sample rate in [2

]:

[image: Inline image 2]



A digital communications signal such as QAM can be generally written as top
equation (1)

where an are (possibly complex) amplitudes taken from a finite alphabet,
and the symbol rate is 1/T. The pulses p(t−nT) are often called "symbols".
Matlab commands that ask you to specify "samples per symbol" are asking how
many samples you want to use to define p(t)

Of course, since you know the pulse duration, specifying the samples per
symbol is an indirect way of specifying the sampling rate.

*Difference sample rate(data rate ) and buad rate:*

Bit rate is speed of data rate is expressed in Bit Per Second (bps). Data
Rate is showed with R, that is defined function of bit time, Tb:

[image: Inline image 3]

Buad Rate is number of signal pr symbels change persecond. It is more
general definition for Data Rate.

We define symbols in QAM
 based
protocols.So If the baud rate is 4800 and there are two bits per symbol,
the number of symbols is 22 = 4. The bit rate is:

R = 4800 x 3.32 log(4)

[Discuss-gnuradio] Role of Clock Recovery in communication in SDR based application?

[Stack Programer]

We in this blog post want to discuss about CDR
. In Digital Communication
Clock Role is very important in Receivers and Transmitters. we know that
any element in Digital Communication has internal or external clock that
work with it as a reference clock
. So for overcome lost data as
unsynchronization between TX and RX we sould have a solution. Even in same
Conditon is hard find two clock has same freqency. Without synchronization
we will garbage data in sampleing in Receivers.

For example you can see in below image that clock in TX and RX is not same,
so data that we sampled is incorrect in receivers.

Fig1:Unsame Clock TX and RX cause we read wrong data



So I have a question?When i want to synchronize TX and RX which parameter
of clock shoulb be same? I myself answer:

   1. Frequency Detection
   2. Phase Detection

So we should with a mechanism detect frequency incoming bit stream, that
usually first data is called recovery stream that we should use these data
stream for detection frequecy.So we may in read frequency had inaccuracy,
that most important are:



   - *Jitter:*

Jitter is a shift in the edges of a periodic signal. This breaks the
periodicity of the signal.

Fig2:Jitter in Frequency Detection

   - PPM (parts per million):

PPM is an inaccuracy of certain components (quartz crystal in case of clock
generator) in a circuit which leads to generation of a signal with
inaccurate period. PPM does not break the periodicity of a signal.

For Phase Alighment this

link related good nostalgie :

You may have seen an analog radio. There are two knobs namely coarse tune
and fine tune on analog radio. When one wants to listen to any audible
signals, coarse tune knob is used to lock onto a frequency where signals
are audible but with some disturbances. Here coarse tune is as good as
frequency detection and disturbances are jitter and PPM. To remove these
disturbances and make the voice audible, fine tune knob is used which
adjusts the pre locked frequency a little bit here and there to get a
perfect audible signals. Here fine tuning is  akin to phase alignment.

So phase alighment is important that arising edge or falling edge clock use
for reading data.With using these mechanism stimulaneously we have clock
Recovery method that is very important is communications.

we can Transmit in gnuradio with HackRF One DVB-T signal successfully, we
can see video with dongle DVB-T player in hardware base method.But for
receiving DVB-T signal with SDR based in gnuradio we have these errors:

DVBT project receiver probelm OOrestart aquisition d_freq_offset: -5
Od_freq_offset: -5

My Qeustion  is In SDR Hardware SDR should do these task or in Software
Enviroment In gnuradio we should myself do clock recovery methods? Any one
that same problem welcome to discussing for solving DVB-T signal receiving
with HackRF one.

Best regards stackprogramer

http://blog.stackprogramer.xyz/en/2017/06/09/clock-recovery-in-communication-and-optic-electronic/
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[Discuss-gnuradio] is there a SDR based software for mobile detector

[Stack Programer]

hi, i want ask for a mobile detector see more info
 http://www.instructables.com/id/simple-mobile-detector-circuit/
is there a SDR based mobile Detector?
thanks
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[Discuss-gnuradio] Warning::How can i calibrate HackRF one for frequency correction in DVB-T receiving?(Bad Receiving HackRF one reasons shared...)

[Stack Programer]

Steps to reproduce

1.I had a HackRF one TX DVB-T,and a RX-DVBT with hackRF one, in receive it
sucks .
2.with rtl-sdr and vlc it can received DVB-T signalbut with hackrf
one sucks
Expected behaviour

after some research i guess that oscillator hackrf one is not accurate .it
can should be calibrate?
how we can calibrate hackrf one for different modulation
Actual behaviour

in real world i guess it can not calibrated in frequency.
Version information

*Operating system*:
debian os , gnuradio 3.7.12,linux
why hackrf one not can received ? it has weakness in receiving? weak
receiving can be related to ppm ?
please help, any idea??? it can be related ADC?HackRFone has poor receiving
why?
i will soon share result.
best regards stackprogramer
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[Discuss-gnuradio] for sending sound from modulation digital is need syncing Tx and Rx???

[Stack Programer]

i want to use modulation digital like fsk,psk, ask for sending sound,
i have a hackrf and rtl-sdr.
for sending sound from modulation analog like fm or am everything is ok,for
sending
digital modulation from projects on githubs:

https://github.com/argilo/sdr-examples

i had not good receive sound,i had a question:

for sending digital modulation is necessary  syncing rtl-sdr and hackrf???

please help
best regards stackprogramer
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[Discuss-gnuradio] how i can enter RTP video strean as input to gnuradio grc?

[Stack Programer]

hi,i had a video rtp stream with vlc, when i send video rtp stream
protocol by upd sink my video is full noise and corrupt i heard that
we can convey rtp video stream to gnuradio from udp but it can not execute.
how i can do this work?
is there a way for entering video rtp stream to gnuradio?
please help thanks
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Re: [Discuss-gnuradio] Discuss-gnuradio Digest, Vol 169, Issue 16

[Stack Programer]

hi,how i can enter RTP video to gnuradio?

On Thu, Dec 15, 2016 at 8:30 PM,  wrote:

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> Message: 1
> Date: Wed, 14 Dec 2016 09:30:56 -0800
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> To: discuss-gnuradio@gnu.org
> Subject: Re: [Discuss-gnuradio] UHD 3.09 in Pybombs
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> Greg,
>
> glad to hear it's working overall!
>
> The PyBOMBS recipe in gr-recipes points to 'master' branch, which is
> tentatively tagged as version 3.11. I'm curious why you'd get the LTS
> version. Can you give any details on how you installed PyBOMBS and
> gr-recipes?
>
> Cheers,
> Martin
>
>
>
>
>
> On 12/13/2016 08:15 PM, Gregory Ratcliff wrote:
> > Did a fresh Pybombs install today.  Everything pybombs and gnuradio
> seems to be really working well lately.  Great work guys.
> >
> > I noticed that the UHD recipes seem to be yanking from 3.09 rather than
> the August release of 3.10.
> >
> > Not complaining; It will give me a chance to modify a recipe.
> >
> > Is ?LTS? our criteria before Pybombs recipes point at the latest
> releases for core at OOT modules?
> >
> > This caused me to look into Pybombs for a way to control the recipe
> ?ersion; looks like you get the best.  This has worked pretty well for me
> so far, but I recently flashed my N210 since macports used 3.10.
> >
> > Any plans to update core pybombs to 3.10?
> >
> > Greg
> >
> >
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> Date: Wed, 14 Dec 2016 12:37:38 -0500
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> Subject: [Discuss-gnuradio] Reminder: Dev Call Tomorrow Thu 15 Dec
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> On Wed, Dec 14, 2016 at 12:37 PM, Ben Hilburn 
> wrote:
>
> > Hi all -
> >
> > This is just a reminder that tomorrow is our monthly Dev Call! The Dev
> > Call takes place at 1700 UTC / 1300 Eastern / 1000 Pacific.
> >
> > Information about how to join or watch the livestream is available here:
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> On Wed, Dec 14, 2016 at 12:37 PM, Ben Hilburn 
> wrote:
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> > Hi all -
> >
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