Hi
"The target is to generate a physical clock signal having small jitter
and
accurate phase. Hence, I need to control the frequency of some VCO based on
the information the receiver signal processing gives."
You have the option to generate the clock entirely in digital domain
because a voltage controlled clock exhibits a higher level of phase noise
as com-
pared to a free running clock, and hence injects more timing jitter
(variation
of the clock transitions around its mean value) into the system.
Cheers,
Qasim
https://wirelesspi.com
On Mon, Feb 24, 2020 at 10:02 PM <discuss-gnuradio-requ...@gnu.org> wrote:
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> Today's Topics:
>
> 1. SDR transceiver having independent mixer and ADC sampling
> clocks (Heikki Laamanen)
> 2. Re: SDR transceiver having independent mixer and ADC sampling
> clocks (Brian Padalino)
> 3. gr-fosphor on AMD RX 550 (Johannes Demel)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 24 Feb 2020 17:38:35 +0200
> From: "Heikki Laamanen" <heikki.laama...@dlc.fi>
> To: <discuss-gnuradio@gnu.org>
> Subject: SDR transceiver having independent mixer and ADC sampling
> clocks
> Message-ID: <009801d5eb28$7a78e460$6f6aad20$@dlc.fi>
> Content-Type: text/plain; charset="utf-8"
>
> Hi experts in SDR RF transceivers,
>
>
>
> I am working on a timing and synchronization system which generates a
> high-precision timing signal from a terrestrial broadcast signal. I am
> looking for a suitable SDR HW-board providing independent clocks for the RF
> mixers and the ADC.
>
>
>
> It seems that many SDR boards use transceiver chips having mixer and ADC
> clocks which are derived from a single clock. Thus, it is not feasible to
> control the ADC sampling clock frequency without affecting the mixer
> frequency. For example, some USRP products have Analog Devices AD9361
> transceiver chips providing no option to have fully independent mixer and
> ADC clocks.
>
>
>
> Why would I like to have independent mixer and ADC sampling clock?
>
>
>
> The target is to generate a physical clock signal having small jitter and
> accurate phase. Hence, I need to control the frequency of some VCO based on
> the information the receiver signal processing gives. The most
> straightforward way to do this is to control the frequency of a VCO
> wherefrom the ADC sampling clock is derived.
>
>
>
> I would appreciate any suggestions about SDR HW-platforms having the
> capability described above.
>
>
>
> Regards,
>
> Heikki
>
>
>
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>
> ------------------------------
>
> Message: 2
> Date: Mon, 24 Feb 2020 11:11:25 -0500
> From: Brian Padalino <bpadal...@gmail.com>
> To: Heikki Laamanen <heikki.laama...@dlc.fi>
> Cc: GNURadio Discussion List <discuss-gnuradio@gnu.org>
> Subject: Re: SDR transceiver having independent mixer and ADC sampling
> clocks
> Message-ID:
> <CAEXYVK4oPupGs39m=ANvSDeTpqzdpWHJ+h7U1FexyRT=
> jxu...@mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> On Mon, Feb 24, 2020 at 10:39 AM Heikki Laamanen <heikki.laama...@dlc.fi>
> wrote:
>
> > Hi experts in SDR RF transceivers,
> >
> >
> >
> > I am working on a timing and synchronization system which generates a
> > high-precision timing signal from a terrestrial broadcast signal. I am
> > looking for a suitable SDR HW-board providing independent clocks for the
> RF
> > mixers and the ADC.
> >
> >
> >
> > It seems that many SDR boards use transceiver chips having mixer and ADC
> > clocks which are derived from a single clock. Thus, it is not feasible to
> > control the ADC sampling clock frequency without affecting the mixer
> > frequency. For example, some USRP products have Analog Devices AD9361
> > transceiver chips providing no option to have fully independent mixer and
> > ADC clocks.
> >
>
> Is this assertion true? According to this document:
>
>
>
> https://ez.analog.com/wide-band-rf-transceivers/design-support/w/documents/10064/ad936x-local-oscillator-lo
>
> There exists 3 VCO's in the AD9361. One for TX, one for RX, and one for
> the baseband. Why do you believe the clocks are not independent? I agree
> the sampling clock might not be able to achieve the resolution you want,
> but I don't see why they are not fully independent already.
>
>
> >
> >
> > Why would I like to have independent mixer and ADC sampling clock?
> >
> >
> >
> > The target is to generate a physical clock signal having small jitter and
> > accurate phase. Hence, I need to control the frequency of some VCO based
> on
> > the information the receiver signal processing gives. The most
> > straightforward way to do this is to control the frequency of a VCO
> > wherefrom the ADC sampling clock is derived.
> >
>
> You need to be more specific regarding your jitter and phase requirements.
>
> Also remember that time is all completely relative. Lastly, what does
> accurate phase mean to you?
>
> Brian
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>
> ------------------------------
>
> Message: 3
> Date: Mon, 24 Feb 2020 17:30:28 +0100
> From: Johannes Demel <de...@ant.uni-bremen.de>
> To: "discuss-gnuradio@gnu.org" <discuss-gnuradio@gnu.org>
> Subject: gr-fosphor on AMD RX 550
> Message-ID: <24717603-8d02-26ea-30d8-01635c344...@ant.uni-bremen.de>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Hi all,
>
> We have some new AMD machines with RX 550 graphics. I want to run
> gr-fosphor on them. So far I've failed to make it work.
>
> It's an AMD system with RX 550 and Ubuntu 18.04 with amdgpu open source
> drivers. I work with GR 3.8-master (or 3.9.0.0-git)
> `4f53ac5a76e3ab05960a81905a570cd74d2708d7`
>
> Since it was quite tricky for me to install OpenCL and make gr-fosphor
> find it, I just document my workflow really quick.
>
> I found this website:
>
> https://einsteinathome.org/content/quick-guide-how-install-opencl-amd-gpus-linux-kubuntu-1804-and-similar-distro
>
> First, I went to amd.com and got the drivers for my GPU:
>
> https://www.amd.com/en/support/graphics/radeon-500-series/radeon-rx-500-series/radeon-rx-550
>
> Then I ran:
> ./amdgpu-pro-install --opencl=legacy,pal
> This does only install OpenCL
>
> Further, I had to install these packages on Ubuntu:
> libfreetype6-dev
> ocl-icd-opencl-dev
> libglfw3-dev
>
> Also, `clinfo` was useful because it gives you some info about your system.
>
> So finally, I could compile and install `gr-fosphor`. It appears in GRC
> and I can plug the block (Qt version) in a flowgraph.
>
> But if I run this flowgraph, I get the following error:
> ```
> [!] gl_cmap shader compilation failed (cmap_simple.glsl)
> [w] Color map shader 'simple' failed to load, will use fallback
> [!] gl_cmap shader compile log :
>
> [!] gl_cmap shader compilation failed (cmap_bicubic.glsl)
> [w] Color map shader 'bicubic' failed to load, will use fallback
> [!] gl_cmap shader compile log :
>
> [!] gl_cmap shader compilation failed (cmap_fallback.glsl)
> [!] Color map shader 'fallback' failed, aborting
> gr::log :ERROR: qt_sink_c0 - Failed to initialize fosphor
> ```
>
> I have no idea why and so far googling brought me to some macports
> threads that were related to Intel GPUs on MacOS.
>
> Did someone already succeed with gr-fosphor on this hardware? Do I have
> suitable hardware? Did I fail the installation process somewhere? Do I
> need to provide additional info?
>
> Cheers
> Johannes
>
>
>
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>
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