Re: [Discuss-gnuradio] Gnuradio differences between mac and linux operation.

[Marcus D. Leech]

On 03/06/2018 10:32 AM, Langston, Glen wrote:

Dear Marcus,

Thanks for your efforts on spectra_radiometer.  

I’m still pursuing the issues with alias spectra and linux,
but I did see the same alias problem with spectro_radiometer under linux.
I’ll download the latest version spectro_radiometer and produce the mac and linux comparision
plots in the near future (maybe tonight).

FYI the effect I’m seeing with “NSF watch” aka (watch.py) is shown by
comparison in the two attached screen captures.  Odriod shows the problem
and mac does not.

I’ve got to gather up the strength try to get my python code into GitHub.
The current way I install is just tar -xvf the latest tar file (attached),
cd into the directory and the type:

python watch.py

I wonder if this isn't an alias issue, but rather, and RFI issue when you plug in to the Odroid?

The only way to tell is to get thee to a laboratory with a signal generator....

Are your AirSpy drivers up to date?

On Odroid I actually type

taskset -c 4,5,6,7 python watch.py

so as to use the fastest 4 of the 8 processors.
The odroid is able to eat all 6MHz bandwidth Airspy mini data

Note my major change/improvement over what happens naturally
with the WxGUI FFT is to sum all of the FFTs that are passed
as messages.  The Gnuradio Wx Spectrum GUI only processes
the first of N messages in the packet.   For radio astronomy,
I’m averaging about 1.3 Million spectra per 4 minute observation.

I appreciate the way you’ve put all the configuration arguments on
the command line of spectro_radiometer.py.   My implementation
stores the all information needed to configure the entire observation
in each observing file.   (Note a data directory is created
parallel to the “watch” directory).

I’d appreciate any suggestions you, or anyone, has. 

Best regards

Glen
Since some needed packages are not automatically installed by gnu radio
(such as ephem, I’ve added “try” code with suggestions for installing
the likely packages)

The attached plots show the observation of RFI found at 1440 MHz in
my vicinity.   The Linux gnu radio observations show the
problematic alias.  The data files have
date and time names with extensions:
.ast - astronomy
.hot - hot load calibration observations, usually pointing straight down (El = -90)
.not - configuration for observation setup.  (Notes==.not)
Occasionally I compute a cold load spectrum for full calibration:
.cld

Glen I Langston, Ph. D.
Galactic Astronomy Program Director
National Science Foundation
2415 Eisenhower Avenue
Alexandria, VA 22314
P: 703-292-4937
C: 703-470-9820
address@hidden

> On Mar 2, 2018, at 5:49 PM, Marcus D. Leech <address@hidden> wrote:
>
> I've been working on a few maint items on spectro_radiometer the last little while and committed them this morning.
>
> Here's the help blurb:
>
> Options:
>  -h, --help            show this help message and exit
>  --abw=ABW             Set Analog  bandwidth [default=4M]
>  --antenna=ANTENNA     Set Antenna [default=RX2]
>  --baseline=BASELINE   Set Baseline length [default=99.3]
>  --bbgain=BBGAIN       Set Baseband Gain [default=5]
>  --bw=BW               Set Bandwidth [default=-1M]
>  --dcg=DCG             Set Detector DC Gain [default=100]
>  --decln=DECLN         Set Observing Declination [default=0]
>  --device=DEVICE       Set SDR Device Name [default=rtl=0
>                        file=/dev/zero,rate=5e6]
>  --fftsize=FFTSIZE     Set FFT size [default=2048]
>  --frequency=FREQUENCY
>                        Set Center Frequency [default=1.42041G]
>  --gain=GAIN           Set RF Gain [default=30]
>  --ifgain=IFGAIN       Set IF Gain [default=5]
>  --longitude=LONGITUDE
>                        Set Local Longitude [default=-76.03]
>  --mode=MODE           Set Operation Mode [default=total]
>  --prefix=PREFIX       Set Data File Prefix [default=h1]
>  --rfilist=RFILIST     Set RFI Frequency List [default=]
>  --srate=SRATE         Set Sample rate [default=2.56M]
>  --zerotime=ZEROTIME   Set SIdereal time for auto baseline set [default=99.3]
>
>
> The main things to note are that antenna-selection can now be made on the command line, and the IF and BB gains can be set explicitly via the command line,
>  while the RF gain is also reflected in the GUI.
>
> The FFT sizes are now command-line selectable.
>
> The analog bandwidth is settable from the command line as well.  For some SDRs or SDR hardware configurations, this does nothing.  For some, it sets
>  the bandwidth of the analog anti-alias filters in front of the ADC.  The effects vary considerably from SDR to SDR, so some experimentation is
>  nearly always required.
>
>
>
>
>
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