Modulate Vector block and double filtration

[GNU Radio, the Free & Open-Source Toolkit for Software Radio]

Hello Community,
Recently I investigated Modulate Vector
 block and my
observations are that this block has two filtering stages - firstly in the
modulator (RRC filter) and secondly in itself (user providing the filter
taps). The simple scheme of operation looks like in the below picture.
So the question is: what is the purpose of the filter in modulate_vector_bc

 function?
Is this a bug or is there a reason for this?
[image: Modulate vector question.png]
--
BR,

Marcin Puchlik

Re: Modulate Vector block and double filtration

[Marcus Müller]

Hi Marcin,

well, that flow graph only serves the purpose of pre-modulating things, e.g. for preamble 
correlation, I'd speculate that's for when you want to e.g. simulate a channel impulse 
response, or some external band-limiting filtering on your already pulse-shaped signal.


However, you're right, neither in the GRC examples nor in any test cases we have do we 
make use of that taps vector (other than `[1]` as the perfect channel).


Cheers,
Marcus

On 04.08.22 09:43, Marcin Puchlik via GNU Radio, the Free & Open-Source Toolkit for 
Software Radio wrote:

Hello Community,
Recently I investigated Modulate Vector 
 block and my observations are 
that this block has two filtering stages - firstly in the modulator (RRC filter) and 
secondly in itself (user providing the filter taps). The simple scheme of operation looks 
like in the below picture.
So the question is: what is the purpose of the filter in modulate_vector_bc 
 function?

Is this a bug or is there a reason for this?
Modulate vector question.png
--
BR,

Marcin Puchlik

Re: Modulate Vector block and double filtration

[GNU Radio, the Free & Open-Source Toolkit for Software Radio]

Hi Marcus,
Clear for me now, thank you very much!
Have a good day,
Marcin

czw., 4 sie 2022 o 13:38 Marcus Müller  napisał(a):

> Hi Marcin,
>
> well, that flow graph only serves the purpose of pre-modulating things,
> e.g. for preamble
> correlation, I'd speculate that's for when you want to e.g. simulate a
> channel impulse
> response, or some external band-limiting filtering on your already
> pulse-shaped signal.
>
> However, you're right, neither in the GRC examples nor in any test cases
> we have do we
> make use of that taps vector (other than `[1]` as the perfect channel).
>
> Cheers,
> Marcus
>
> On 04.08.22 09:43, Marcin Puchlik via GNU Radio, the Free & Open-Source
> Toolkit for
> Software Radio wrote:
> > Hello Community,
> > Recently I investigated Modulate Vector
> >  block and
> my observations are
> > that this block has two filtering stages - firstly in the modulator (RRC
> filter) and
> > secondly in itself (user providing the filter taps). The simple scheme
> of operation looks
> > like in the below picture.
> > So the question is: what is the purpose of the filter in
> modulate_vector_bc
> > <
> https://github.com/gnuradio/gnuradio/blob/master/gr-digital/lib/modulate_vector.cc
> > function?
> > Is this a bug or is there a reason for this?
> > Modulate vector question.png
> > --
> > BR,
> >
> > Marcin Puchlik
> >
> >
>
>

Re: Ubuntu 20.04 cannot find the Hackrf board?

[George Edwards]

Hi Cinaed,
Thank you very much! Will test!
George

On Thu, Aug 4, 2022, 12:27 AM Cinaed Simson  wrote:

> Hi George - the hackrf runs under ubuntu.
>
> The latest version is
>
>   release 2021.03.1
>   https://github.com/greatscottgadgets/hackrf/release
>
> https://github.com/greatscottgadgets/hackrf/releases/download/v2021.03.1/hackrf-2021.03.1.tar.xz
>
> The current firmware version on your hackrf is 2014.
>
> You could try
>
>apt update
>apt install hackrf libhackrf-dev
>
> which may give you the 2018 version for the hackrf utils and
> libhackrf-dev.
>
> But I don't know how the firmware gets updated using apt - I've never used
> apt to install the hackrf software.
>
> The 2014 firmware may play enough well with the 2018 software - I don't
> know. It may play well enough to indicate the hackrf works on ubuntu but
> Ideally you'd like the version of firmware to match the software.
>
> -- Cinaed
>
>
> On 8/3/22 18:28, George Edwards wrote:
>
> Hello Gentlemen,
>
> I installed VirtualBox extension pack and made the USB connection in
> VirtualBox to the HackerRF board. However, in the Ubuntu Terminal when I
> execute the command hackrf_info the info that comes up is:
> hackrf_info version: unknown
> libhackrf version: unknown (0.5)
> Found HackRF
> Index: 0
> Board ID Number: 2 (HackRF One)
> Firmware Version: 2014.08.1 (API:1.00)
> Part ID Number: 0xa000cb3c 0x006e4756
>
> The above shows Ubuntu is having trouble reading the top two version
> information and as a result when I try to run the Gnuradio flowgraph, it
> gives a message that it fails to open HackRF.
>
> George
>
>
>
>
> On Wed, Aug 3, 2022 at 10:32 AM James Anderson  wrote:
>
>> You might want to try running hackrf_info with superuser privileges using
>> sudo, i.e. "sudo hackrf_info". Many/most peripherals require this in Linux
>> by default.
>>
>> Additionally, use of a VM may limit the sample rate you can achieve since
>> there is some overhead passing through the USB connection. Consider
>> installing Linux directly on your machine.
>>
>> On Aug 3, 2022, at 6:12 AM, George Edwards 
>> wrote:
>>
>> 
>> Hello GNURadio Community,
>>
>> I built a grc flowgraph in Gnuradio 3.9.5 on Ubuntu 20.04 inside
>> Microsoft VirtualBox. I have a HackRF One radio hardware. I installed the
>> hackrf drivers in Ubuntu with command: sudo apt-get install -y hackrf
>> and confirmed the installation. I connected the HackRF One board to my
>> computer and in the Terminal prompt entered the command hackrf_info and
>> received the response that it does not see the Hackrf board.
>>
>> And true to form when I ran the flowgraph, I get the following error
>> message:
>> RuntimeError: no hackrf device matches
>>
>> Why is Ubuntu 20.04 running inside MS VirtualBox not seeing the HackRf
>> board with the HackRf drivers installed. And, how do I resolve this issue?
>>
>> Will appreciate any help to resolve this issue.
>>
>> George
>>
>>
>