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Re: [Discuss-gnuradio] Radio Astronomy GSoC 2017 group possible?

From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] Radio Astronomy GSoC 2017 group possible?
Date: Tue, 07 Feb 2017 18:38:20 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0

On 02/07/2017 05:40 PM, Glen I Langston wrote:
Hi Marcus,

I just found the problem.  My device only has one channel.  I deleted
all the 2nd channel stuff and the spectro_radiometer is working great.

I’ve got to find where the data is going, but I like the many features you’ve


I admit that documentation for spectro_radiometer is, as yet, non-existent.

However, you can get a "single channel" effect, just by being clever with the --device argument, you mentioned that you were using
  airspy, so:

--device "airpsy file=/dev/zero,rate=20e6"

Should do the trick with the "off the shelf" version of spectro_radiometer.

The non-interferometer two-input mode is a differential radiometer, so if you only have the one radio, you just substitute a sample-rate-matched stream of 0s, and you get the same results as a total-power radiometer. This was motivated by
  work that Ken Tapping (DRAO) and I did a couple of summers ago:


Of course, if you have two *real* radios, you can use them as a differential pair, or, if they are mutually coherent, for interferometry.

On Feb 7, 2017, at 5:24 PM, Glen I Langston <address@hidden> wrote:

Hi Marcus,

Thanks for your comments concerning the GSoC.   Maybe
if I more narrowly defined the features I’m after maybe
it could be made more appropriate to the group.

I appreciate your leadership in GNUradio.  It inspired me to build my
horn.   I’m writing up a full document of what I’ve done and will send it
to you.

Concerning your suggestions, that spectra_radiometer.grc is fairly amazing.

I must have some versioning issues as I get an error before it launches.
what Gnuradio regions should I have?



Here’s the text from the GRC window:

<<< Welcome to GNU Radio Companion >>>

Block paths:

Loading: "/Users/glangsto/Desktop/Research/grc/spectro_radiometer.grc"
Generating: '/Users/glangsto/Desktop/Research/grc/spectro_radiometer.py'
Warning: This flow graph contains a throttle block and another rate limiting 
block, e.g. a hardware source or sink. This is usually undesired. Consider 
removing the throttle block.
 -u /Users/glangsto/Desktop/Research/grc/spectro_radiometer.py

Mac OS; Clang version 8.0.0 (clang-800.0.42.1); Boost_105900; 

qt_mac_loadMenuNib: could not create nib directory in temp
Traceback (most recent call last):
  File "/Users/glangsto/Desktop/Research/grc/spectro_radiometer.py", line 842, in 
  File "/Users/glangsto/Desktop/Research/grc/spectro_radiometer.py", line 830, 
in main
    tb = top_block_cls(dcg=options.dcg, decln=options.decln, 
device=options.device, frequency=options.frequency, gain=options.gain, 
longitude=options.longitude, mode=options.mode, prefix=options.prefix, 
rfilist=options.rfilist, srate=options.srate, zerotime=options.zerotime)
  File "/Users/glangsto/Desktop/Research/grc/spectro_radiometer.py", line 325, 
in __init__
    self.osmosdr_source_0 = osmosdr.source( args="numchan=" + str(2) + " " + 
device )
 line 1173, in make
    return _osmosdr_swig.source_make(*args, **kwargs)
RuntimeError: Wrong device arguments specified. Missing nchan?On Feb 7, 2017, at 5:18 
PM, Marcus D. Leech <address@hidden> wrote:

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