[TangerineSDR] Setting up DE for selected bands and sample rate
John Gibbons
jcg66 at case.edu
Mon Apr 20 13:26:53 EDT 2020
I am also looking for a C implementation of the algorithm as I will most
likely be running 4 instances if it (at the same time) and the RasPi3B+
will most likely choke on trying to do that in python.
John N8OBJ
John C. Gibbons
Director - Sears Undergraduate Design Laboratory
Dept. of Electrical Engineering and Computer Science
Case Western Reserve University
10900 Euclid Ave, Glennan 314
Cleveland, Ohio 44106-7071
Phone (216) 368-2816 <216-368-2816> FAX (216) 368-6888 <216-368-6888>
E-mail: jcg66 at case.edu
On Mon, Apr 20, 2020 at 1:12 PM Engelke, Bill via TangerineSDR <
tangerinesdr at lists.tapr.org> wrote:
> Hello Aiden & Nathaniel:
>
>
>
> I looked into working with files in fldigi – it is possible but it is not
> easily used with the type of data we will get from the TangerineSDR data
> engine. It expects wav files or mp3 files. I don’t see a way to use it with
> I/Q data. I would rather not implement an elaborate work-around involving
> creating & passing files, etc.
>
>
>
> I appreciate the Skylar is implementing something in python for the freq
> estimation algorithm, but I am hoping someone could volunteer to provide me
> this algorithm in the c language so that I can integrate it into the
> mainctl part of the TangerineSDR. (HELP!) … anyone?
>
>
>
> -73- Bill AB4EJ
>
>
>
> *From:* TangerineSDR <tangerinesdr-bounces at lists.tapr.org> *On Behalf Of *Dr.
> Nathaniel A. Frissell Ph.D. via TangerineSDR
> *Sent:* Monday, April 20, 2020 6:46 AM
> *To:* TAPR TangerineSDR Modular Software Defined Radio <
> tangerinesdr at lists.tapr.org>
> *Cc:* Dr. Nathaniel A. Frissell Ph.D. <nathaniel.frissell at scranton.edu>;
> Skylar Dannhoff <sgd24 at case.edu>; David Kazdan <dxk10 at cwru.edu>
> *Subject:* Re: [TangerineSDR] Setting up DE for selected bands and sample
> rate
>
>
>
> Thanks, Aidan.
>
>
>
> 73 de Nathaniel
>
>
>
> *From:* TangerineSDR <tangerinesdr-bounces at lists.tapr.org> *On Behalf Of *Aidan
> Montare via TangerineSDR
> *Sent:* Saturday, April 18, 2020 10:21 PM
> *To:* TAPR TangerineSDR Modular Software Defined Radio <
> tangerinesdr at lists.tapr.org>
> *Cc:* Aidan Montare <aam141 at case.edu>; Skylar Dannhoff <sgd24 at case.edu>;
> David Kazdan <dxk10 at cwru.edu>
> *Subject:* Re: [TangerineSDR] Setting up DE for selected bands and sample
> rate
>
>
>
> On the point (3a) on making frequency estimations with the IQ data: Skylar
> (KD9JPX) is working on implementing the frequency estimation algorithm in
> Python so that we can do some sensitivity analysis. The knowledge from her
> work could go into efforts to do frequency estimation from IQ signals.
>
>
>
> Nathaniel, fldigi does support reading from files, but I forget the
> specifics of this. I don't recall that it supports IQ.
>
>
>
> On Sat, Apr 18, 2020 at 6:04 PM John Gibbons via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>
> Getting the estimator is easy - you know what it's supposed to be.
>
> In our case we're 1 KHz off the beacon frequency, so it will ALWAYS be
> 1.000KHz.
>
>
>
> John N8OBJ
>
>
>
> John C. Gibbons
>
> Director - Sears Undergraduate Design Laboratory
>
> Dept. of Electrical Engineering and Computer Science
>
> Case Western Reserve University
>
> 10900 Euclid Ave, Glennan 314
>
> Cleveland, Ohio 44106-7071
> Phone (216) 368-2816 <216-368-2816> FAX (216) 368-6888 <216-368-6888>
> E-mail: jcg66 at case.edu
>
>
>
>
>
> On Sat, Apr 18, 2020 at 3:25 PM Tom McDermott via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>
> Hi Nathaniel -
>
>
>
> Responding to question 1: the requirements for the DE putting out 8
> channels sampled at 10 Hertz are similar to 8 channels
>
> sampled at higher rates. The very low sample rate requires the FPGA low
> pass filters have many more taps, but I think
>
> that's small-ish compared to other FPGA things.
>
>
>
> Responding to #2 (from the original post) The algorithm in the paper would
> probably be implemented in the Local Host as software.
>
> I'm not sure it would be easy nor useful to figure out how to compute that
> in FPGA as opposed to in CPU. But at 10 Hz sample rate,
>
> that computation is likely feasible in CPU. There will be the initial
> collection of samples to get the estimator started, then it can update
>
> frequently (i.e. 1 second rate).
>
>
>
> I can't comment on question 3.
>
>
>
> -- Tom, N5EG
>
>
>
>
>
>
>
>
>
>
>
>
>
> On Sat, Apr 18, 2020 at 3:37 AM Dr. Nathaniel A. Frissell Ph.D. <
> nathaniel.frissell at scranton.edu> wrote:
>
> Hi Bill and Tom,
>
>
>
> 1. If we run the DE in the 8 channel mode for doing these measurements, do
> we think that will max out the data engine to prevent it from doing
> anything else?
>
>
>
> 3a. I agree that we probably do not want to emulate a sound card. I would
> like to see a program like FLDigi be able to accepts files or buffers. It
> would be good not only for the PSWS, but al also for doing post-processing
> of data in general.
>
> 3b. We need the ability to collect both the raw spectrum and the derived
> frequency estimate. Exactly how to interpret and use these things is still
> an active area of research. Steve WA5FRF is actively working on this and is
> probably the best person to work with on this right now.
>
>
>
>
>
> Maybe David Kazdan can comment to address Tom’s question on needing 100
> seconds of measurements.
>
>
>
> 73 de Nathaniel W2NAF
>
>
>
> —
> Dr. Nathaniel A. Frissell, Ph.D., W2NAF
>
> HamSCI Lead
> Assistant Professor
> Department of Physics and Electrical Engineering
> University of Scranton
> (973) 787-4506
>
>
>
> On Apr 17, 2020, at 1:41 PM, Tom McDermott via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>
>
>
> Hi Bill - thanks for the link to the paper. I don't have access to the
> references in the paper, particularly
>
> [1], [2], [3], and [4], so I am missing the details of the critical first
> step. My reading of the paper indicates that
>
> the initial estimate of the frequency is needed, and that initial estimate
> has to distinguish between adjacent
>
> spectral bins, those being +/-fs/N apart. (Section 2.1, step 1.)
>
>
>
> So perhaps I'm reading this wrong, but it still seems like one needs 1000
> samples to separate
>
> out the desired bin, assuming 10 Hz sample rate and 10 milliHz resolution,
> that is 100 seconds.
>
> [ The DFT doesn't need a power-of-two sample size, it can just be a
> convenient number. ]
>
>
>
> -- Tom, N5EG
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> On Fri, Apr 17, 2020 at 8:52 AM Engelke, Bill via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>
> In yesterday’s HamSCI research telco
> <https://scranton.zoom.us/rec/play/tMd4JO39-j43H4WQ5gSDC_AtW9S_ffmsgHcd-KJZy0uzUiIAZlPwMuQSYbeIYiPAWTSPSeb1nkzcpCCR?startTime=1587063159000&_x_zm_rtaid=NMAJy4E0RWahMdU1UXtvsg.1587138515458.823452708c432bc18700b9c14edfeb54&_x_zm_rhtaid=286>,
> we discussed several ideas on how to accomplish several goals with the
> TangerineSDR; a summary is below for your review and comment.
>
>
>
> 1. We currently think that the Data Engine (DE) will have the capacity
> to simultaneously collect up to 8 channels of data for observing Doppler
> shift in carrier frequencies, i.e., WWV at 2.5, 5, 10, 15, 20 MHz plus CHU
> at 3.33, 7.335 and 14.670 MHz. We think we can do this by observing
> excursions of up to +/- 1 Hz from the carrier frequency with a *precision
> of 0.01 Hz, with measurements taken every second *(see next point).
> 2. In earlier discussions on this board, it has been stated that this
> kind of precision (10 milliHz) would require a 102.4 second sample time;
> this assumes the processing is linear. CWRU is using a non-linear method in
> the low-cost approach to extract a frequency estimate, which uses fldigi to
> achieve the 10 milliHz resolution once per second, and it was discussed
> that TangerineSDR could be set up to do this as well. (Reference here:
> http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1017.4615&rep=rep1&type=pdf
> )
> 3. I won’t try to explain the method mentioned above, as it is at the
> very limits of my understanding; however, a couple of observations…
>
>
> 1. The CWRU low-cost system uses fldigi to implement the frequency
> estimator, and in looking at fldigi I see that it requires sound card
> input. In the case of the TangerineSDR, we will have buffers of IQ data. I
> don’t think I want to use some sort of kludge to take the buffers and
> somehow emulate a sound card (do I?) – another option might be to implement
> the frequency estimator algorithm in the Small Board Computer (SBC) of the
> TangerineSDR. If we could/should do this, I would ask for a volunteer to
> code it; I fear that if I try to do it, it would take far too long for me
> to get up the learning curve. The code (C++) for the algorithm as used in
> fldigi is online (included with hundreds of other routines; see
> http://www.w1hkj.com/files/fldigi/ ). A third option might be to
> persuade the fldigi team to support buffer or file input.
> 2. As I understand, the frequency estimator outputs a single value:
> the strongest signal in the band. A downside of this is that there seems to
> be a lot of other possible information in the data (Steve Cerwin has shown
> data he has collected showing Doppler effects but with multiple structures
> including various modes in both time and frequency domain). We need some
> guidance from the science community: what data do we really need to do the
> desired science?? Maybe we need to implement/support both raw data
> collection & frequency estimation at the same time(?)
> 3. In yesterday’s call, we discussed that we should be able to
> specify an 8 ksps sample rate and a center frequency, and get the desired
> 10 milliHz resolution – frankly, I am still fuzzy on the details of this,
> so I wish someone (David Kazdan? Kristina?) would chime in and explain, for
> the record, how this works.
>
>
> 1. Channel configuration settings for the DE:
>
>
> 1. The DE will be able to tell the SBC what data rates it supports. We
> are working with 2-byte command codes; in general, a command ending in “?”
> is a query, i.e., send the DE the command “S?” and it answers “AK” , a
> simple health check. Send the DE the command “R?” – it will respond with a
> table such as the following:
>
> 1 2000 2 4000 3 8000 4 16000 etc. – where
> each entry is 2 integers: an index and a sample rate (Hz). To put a channel
> into data rate of 8000 sps, we put 3 into the channel setting.
>
>
>
> Please comment! -73- Bill, AB4EJ
>
> --
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>
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>
>
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>
>
>
> --
>
> Sincerely,
>
> Aidan Montare
> CWRU Class of 2021
> --
> TangerineSDR mailing list
> TangerineSDR at lists.tapr.org
> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>
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