[TangerineSDR] Weekly Status report

Fri Jun 23 12:14:15 EDT 2023

Hi Franco,

Thank you for this investigation! I agree with you, iqplay and iqrecord
probably listens on the multicast group from the SDR interface application.
Phil, can you comment on this?

It does looks like the iq mode will create the slice of IQ data from
radiod. Phil, can you comment on this?

I also agree that there are a few sources of input to GNU Radio, and a GNU
Radio module will have to be created to join the multicast group of
interest and pipe the output to the rest of the GNU Radio processing chain.
For the time being, writing iq streams from slices or from the SDR
interface application (ie rx888d) seems like the only way to input the IQ
data into GNU Radio.

Thanks.

Jonathan
KC3EEY

On Thu, Jun 22, 2023 at 11:05 PM Franco VENTURI <fventuri at comcast.net>
wrote:

> Jonathan,
> tonight I spent some more time reading ka9q-radio source code and Phil's
> documentation (
> https://github.com/ka9q/ka9q-radio/blob/main/docs/Realtime%20Multicast%20for%20SDR%20Interconnection%20-%20Phil%20Karn.pdf),
> and I think the way the various pieces work is more or less like this:
>
> - iqrecord and iqplay work directly with the I/Q stream from the front-end
> SDR, in our case the RX888 - specifically iqplay 'plays' an I/Q recording
> file from a previous session and 'radio' can connect to it pretending it is
> connected to a live SDR; this setup would be good for testing 'radio' and
> the other programs downstream, but I don't think this is what we want to do
>
> - also I think iqrecord and iqplay deal with the whole I/Q stream (at
> 64.8Msps or 129.6Msps) before the 'magic' of Phil's fast convolution filter
> bank occurs
>
> - on the other hand in 'modes.conf' Phil defines a linear mode called 'iq'
> (https://github.com/ka9q/ka9q-radio/blob/main/modes.conf#L71-L76), with a
> sample rate of 12ksps, which I think is the I/Q stream that the Grape wants
>
> - the 'channels = 2' line at the end of that section makes me think that
> 'radio' in this case outputs a stereo PCM stream with I on the left channel
> and Q on the right channel
>
>
> I also looked at the examples of the file/wav source blocks from GNU
> Radio, and I have the impression that they can only read 'regular' files -
> the fact that on the 'File Source' wiki page (
> https://wiki.gnuradio.org/index.php?title=File_Source) they have a note
> that says "The file MUST be on the local computer" seems to also confirm
> this assumption, but I might be wrong
>
> This said, I don't think it would be that hard to create an OOT GNU Radio
> module for a source block that reads I/Q samples directly from the
> ka9q-radio 'radio' multicast stream, similar to what 'pcmcat' does; if you
> think it could be useful, I'll look into this in more detail (probably
> after this weekend, when I find some time).
>
> Franco K4VZ
>
>
> On 06/22/2023 9:59 AM EDT Jonathan <emuman100 at gmail.com> wrote:
>
>
> Hi Franco,
>
> pcmcat receives RTP streams of demodulated audio and pipes it to stdout.
> For the Grape, IQ data is needed. In this case, radiod would need to be
> configured to output only the IQ stream. Possibly iqplay can pipe IQ data
> to stdout? Can GNU Radio read from stdin? If so, that might be worth a
> shot.
>
> Jonathan
> KC3EEY
>
> On Thu, Jun 22, 2023 at 8:59 AM Franco VENTURI <fventuri at comcast.net>
> wrote:
>
> For the integration between ka9q-radio (its 'radiod' daemon, to be exact)
> and GNU Radio, you may want to look at the simple program 'pcmcat' (
> https://github.com/ka9q/ka9q-radio/blob/main/pcmcat.c) that Phil wrote to
> connect to the multicast stream, and write the PCM output to stdout.
>
> I took a quick glance at it this morning and I believe it shouln't be hard
> to write a GNU Radio OOT module starting from the code from the existing
> GNU Radio wav source module, and replace the code that reads from the wav
> file with code that reads from the multicast stream, like Phil does in
> 'pcmcat'.
>
> Franco
>
>
> On 06/22/2023 6:39 AM EDT Jonathan via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>
>
> Bill,
>
> I think he means the GNU Radio graph that takes in the Grape mixer audio
> output and then downmixes it to 10Hz carrier baseband signal in Digital RF.
> That baseband signal is then plotted in frequency to show the doppler shift
> throughout the diurnal.
>
> This can be implemented in GNU Radio processing chains using the IQ
> stream, either individual slices around each frequency or a wider bandwidth
> slice for each time station, and for AM broadcast carriers too. You would
> have to have an individual chain for each station, but probably use one IQ
> data file.
>
> Jonathan
> KC3EEY
>
> On Thu, Jun 22, 2023 at 6:22 AM Bill Liles via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>
> Nathaniel, I am not sure what exactly you mean by “the same processing
> chain.” The same as what?
>
> 1) one RX888/KA9Q acting as a grape 2 or
> 2) three RX888/KA9Q acting as three grape 1s connected together?
>
> I assume one RX888/KA9Q acting like a grape 2 but want to be clear.
>
> If using one RX888/KA9Q to receive WWV/H and CHU, why limit to three
> frequencies? Can receive all the WWV/H frequencies and CHU. And for that
> matter also the AM transmitter used by Dartmouth.
>
> Bill NQ6Z
>
> On Thu, Jun 22, 2023 at 00:23 Dr. Nathaniel A. Frissell Ph.D. via
> TangerineSDR <tangerinesdr at lists.tapr.org> wrote:
>
> Thank you, Dave and Franco. This all looks good.
>
>
>
> A brief update from me. We have a student, Rob Troy, who is tasked with
> working with the RX888 and the KA9Q software. Rob reports he now has the
> RX888/KA9Q up and running at Scranton.
>
>
>
> Rob’s next task is to make the RX888/KA9Q combination “emulate” the output
> of a Grape2. Stan Pozerski KD1LE currently has three Grape 1’s tied
> together all outputting their data into a single GNU Radio/DigitalRF
> stream. I believe this is essentially what the Grape 2 will also be doing.
> I will be having Rob work with Stan Pozerski to get this same processing
> chain running with the RX888 instead of the Grape 1s.
>
>
>
> Next week I will be on travel with a number of students to the NSF CEDAR
> conference in San Diego, CA. So, it is likely I will not be able to be on
> the Monday telecon next week.
>
>
>
> 73 Nathaniel W2NAF
>
>
>
> *From:* TangerineSDR <tangerinesdr-bounces at lists.tapr.org> *On Behalf Of *Franco
> VENTURI via TangerineSDR
> *Sent:* Monday, June 19, 2023 10:51 PM
> *To:* David Witten <wittend at wwrinc.com>; tangerinesdr at lists.tapr.org; Mr.
> Majid Mokhtari <majid.mokhtari at scranton.edu>; Rob Robinett <
> rob at robinett.us>; Tom McDermott <tom.n5eg at gmail.com>; John Ackermann <
> jra at febo.com>
> *Cc:* Franco VENTURI <fventuri at comcast.net>
> *Subject:* Re: [TangerineSDR] Weekly Status report
>
>
>
> Dave,
>
> first of all thanks for the report and kudos for all your work.
>
>
>
> A few quick comments:
>
>
>
> - regarding the maximum throughput achievable with the FX3 the best place
> to start IMHO is Cypress AN86947 (
> https://www.infineon.com/dgdl/Infineon-AN86947_Optimizing_USB_3.0_Throughput_with_EZ-USB_FX3-ApplicationNotes-v05_00-EN.pdf?fileId=8ac78c8c7cdc391c017d073e3a2e6243)
> - as you can see there the maximum throughput is achieved using an AUTO DMA
> channel with the GPIF II interface, 32bit wide, and with a clock rate of
> 100MHz (and with 4 DMA buffer of 8kB each - bulk transfer mode)
>
>
>
> - if I remember correctly, Oscar Steila IK1XPV design is based on the
> 'cyfxbulklpauto' example (you can find it in
> 'cyfx3sdk/firmware/dma_examples/cyfxbulklpauto' in the FX3 firmware SDK
> file 'fx3_firmware_linux.tar.gz'), and on a couple of very useful
> application notes from Cypress/Infineon: AN65974 "Designing with the EZ-USB
> FX3 slave FIFO interface" (
> https://www.infineon.com/dgdl/Infineon-AN65974_Designing_with_the_EZ-USB_FX3_Slave_FIFO_Interface-ApplicationNotes-v17_00-EN.pdf?fileId=8ac78c8c7cdc391c017d07396c095deb),
> and the 'ping-pong' DMA buffers approach shown in AN75779 "How to implement
> an image sensor interface using EZ-USB FX3 in a USB Video Class (UVC)
> framework" (
> https://www.infineon.com/dgdl/Infineon-AN75779_How_to_Implement_an_Image_Sensor_Interface_with_EZ-USB_FX3_in_a_USB_Video_Class_(UVC)_Framework-ApplicationNotes-v13_00-EN.pdf?fileId=8ac78c8c7cdc391c017d073ad2b85f0d)
>
>
>
> - when I looked at what he did a few years ago I didn't think it was
> exceedingly difficult; I remember the one thing to get right is the design
> of the GPIF II state machine using the program 'GPIF II Designer' (that I
> think runs only on Windows), but we can definitely look at what Oscar did
> and follow his footsteps (I think the design of his GPIF II state machine
> is in his GitHub repository too, so we can use that as a starting point)
>
>
>
> - if I have to give you one advice is to try to 'keep things as simple as
> possible'; this is what Oscar did in his design of the BBRF103, which he
> was able to design and make in a relatively short period of time. I think
> the important thing is to get a prototype out that works even if it is not
> perfect and meet all the specifications. We can always improve from that
> but at least the first step is done.
>
>
>
> - regarding the choice of the ADC I don't think 14bit or 16bit makes much
> of a difference in terms of ENOB, since I read somewhere about diminishing
> returns at those resolutions (can't find the link now); since the FX3 GPIF
> II works with 16/32 bits at a time, using a 14bit ADC would give us two
> extra bits for each sample: one could be used for the overflow bit, and the
> MSB for the PPS from the GPSDO, which I think is what Tom is doing in the
> TangerineSDR.
>
>
>
> - and finally I expect that someone will eventually come out with the
> "ClementineSDR+" that uses the LTC2208-16, since for some reason they are
> dirt cheap on AliExpress.
>
>
>
> 73,
>
> Franco K4VZ
>
>
>
>
>
> On 06/19/2023 2:36 PM EDT David Witten <wittend at wwrinc.com> wrote:
>
>
>
>
>
> Hello All,
>
>
>
> I have attached a PDF covering what I have been doing this week, and What
> else needs to be addressed.  This primarily addresses work on an
> alternative [Clementine]SDR based on USB SuperSpeed and beyond. This is a
> further derivative of the RX-888 and its predecessors.
>
>
>
> Comments Welcome!
>
>
>
> Dave Witten, KD0EAG
>
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