Cheap SDR
Jim Sky
http://sdr.osmocom.org/trac/wiki/rtl-sdr#Software
Its a project to use a $20 USB stick radio range 64 - 1700 MHz. Its Linux based so far, but it might be crafted for Windows. The current software is I believe just command line, but perhaps GNU Radio has a better way to interface with it. Anyway, I would love for any input from those of you who are familiar with this type of project.
Aloha,
jim
-
-
Jim Sky
Radio-Sky Publishing
89-720 Lani Kona Rd.
Captain Cook, HI 96704
USA
http://radiosky.com
fevi bansal
i m from India. i m a recent btech graduate currently associated with some radio telescopes project under some internship in India.i m looking forward for more work experience in radio astronomy field so that it would add to my post graduation studies.can anyone guide me for same
it would be a great pleasure
Regards
fevi bansal
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Don Latham
These are all over ebay even cheaper, but they don't seem to want to
ship to the US. I'm looking into it. If it's not forbidden by some
government stupidity, we might be able to get some. Otherwise we will
have to have a nice friend in Blighty buy some and ship 'em to us as
birthday presents.
Might have something to do with ability to receive at 800 MHz?
Don
Jim Sky
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--
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
R. Bacon
"If you don't know what it is, don't poke it."
Ghost in the Shell
Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com
Marcus D. Leech
> Hi Jim:
> These are all over ebay even cheaper, but they don't seem to want to
> ship to the US. I'm looking into it. If it's not forbidden by some
> government stupidity, we might be able to get some. Otherwise we will
> have to have a nice friend in Blighty buy some and ship 'em to us as
> birthday presents.
> Might have something to do with ability to receive at 800 MHz?
> Don
>
from DealExtreme, and they
ship to U.S. and Canada.
The big questions in consumer grade electronics are whether the design
will remain relatively static.
There are at least two versions of the ezCAP DVB-T FM/DAB/DAB+ device
out there--one can easily
be turned into an SDR, while the other cannot.
The problem with "repurposing" consumer electronics in this way is that
you have no control over their
engineering/manufacturing/supply decisions, so that a "hack" that
worked six months ago no longer works,
because they've re-tooled the B.O.M. to save $0.10 on each device,
and used a completely different parts
line-up. When you're shipping thousands a month, it makes good
business sense to spend $100K in re-engineering
a device if it will save a fraction of a dollar on the B.O.M. costs.
Having said that, the "magic sauce" that they're using is based on the
RTL2832 DVB-T digital demodulator chip, which has
a "bypass" mode that bypasses the demodulated and sends the
(resampled) I/Q samples directly over the USB bus. This is
good news, since apparently a *plethora* of USB "TV in a dongle"
devices use the RTL2832 chip, paired with various I2C-based
direct-conversion/low-IF tuners, depending on the target application.
The ezCAP device uses an E4000 tuner chip, which is the
same one used in the FunCube dongle, so it covers 64MHz to 1.7GHz.
Full integration with Gnu Radio is probably a few weeks away at this
point--but that's a wild guess on my part, I have no involvement
in rtl-sdr.
Some other things to watch out for:
o the master clock on this device is a 100PPM part. That's not that
good as these things go
o its only 8-bits of I and 8-bits of Q. There may be dynamic range
issues in some cases
o the E4000 tuner is "finicky"
o the noise figure may be a lot higher than you might like--I note
that the E4000 is directly connected to the antenna port, rather than
via an LNA
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
Ray Fobes
I have recently purchased a FUN Cube SDR from AMSAT UK. Its a USB stick that operates about the same frequency as the one mentioned below.
It so happens that High Sierra Electronics sells a 5-55 MHz amplified up-converter specifically for the FUNCube. The pair make quite a combination.
The FUN Cube is open USB so any program like rf spaces SpectraVue works fine. But you do have to use one of the FUNCube GUI's to set the frequency.
I highly recommend this SDR.
Ray Fobes
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Marcus Leech
bandwidth, whereas FCD supports only 96KHz. Recall that in radio astronomy, all else being equal, bandwidth is your very good friend.
Which is why a device with greater capture bandwidth than FCD is so alluring (particularly given the price).
Oh, the other thing I don't know, having not seen a complete E4000 datasheet, is whether gain control is purely manual. If not, then
neither the FCD nor the ezCAP "serendipitous SDR" will be of general utility in radio astronomy, since AGC is rather a killer.
-Marcus
Karl-Heinz
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Marcus D. Leech
Hello Marcus,maybe you should read this test with funcube dongle and ra: http://www.britastro.org/radio/projects/An_SDR_Radio_Telescope.pdf
KH
Thanks for that.
I've actually had support for FCD in my "simple_ra" Gnu Radio software for a few months, but only have one "customer" using it right
now for Solar transit observations. So it hasn't been clear to me whether any AGC in the FCD would get in the way of low-level
observations. Clearly, it doesn't.
I've been doing SDR-based radio astronomy since around 2005, so I need to make it clear that I'm completely in favour of SDR-based
radio astronomy. It's just that sometimes these "repurposed commercial goo" projects turn out to have nasty "gotchas". I'm happy to
see that the E4000 based ones don't have the AGC gotcha.
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Kimmo
Hi
I find the FUNcube Dongle interesting because its tuning range
includes the OH
maser line at 1665 MHz. These maser lines can be very strong; in the
star
forming region W75 there has been an OH maser line with a brightness
of about
1000 Jy during a flare. See article at arxiv.org/abs/astro-ph/0501539
That brightness is about one third of the brightness of Cassiopeia A
at 1 GHz.
The maser lines are interesting because
1) They are very narrow in frequency. The article above gives about 1
km/s for
the total line width of the brightest component, which corresponds to
about 6 kHz !
Compare that to the badwidth of about 80kHz of FUNcube Dongle.
That means that a receiver does not have to be very stable, because
one is
measuring a narrow feature compared to the bandwidth.
Well, an ordinary soundcard would also work as a backend of the
receiver.
2) The brightness and velocity of the emission components changes all
the time
(on a time scale of weeks and months).
Thus, monitoring changes in OH maser emission would be an interesting
project.
The current maximum intensity of emission components of W75 may be
about 200-300 Jy ?
I do not know about the intensities of other sources.
Maybe about a 2 meter dish is enough for the strongest OH lines ?
Of course, one would have to integrate to obtain a good signal-to-
noise ratio.
cheers, Kimmo OH2GUC
----------------------------------------------------------------------------------------------------------------------------------------
Jan Lustrup LA3EQ JO28XJ_79FX
73's Jan LA3EQ
Hi
cheers, Kimmo OH2GUC
--
Jan Lustrup LA3EQ JO28XJ_79FX
Region W75....is that at RA 19:45 Dec +10.3 ?
I want to try to detect it with my Horn antenna .
I'm building a G4DDK LNA for 1665MHz and readjusting the horn's probe to get
a high return loss at 1665MHz.
Jan Lustrup LA3EQ
Norway
----- Original Message -----
From: "Kimmo" <aurinko...@gmail.com>
To: "Society of Amateur Radio Astronomers" <sara...@googlegroups.com>
Sent: Tuesday, March 27, 2012 3:36 PM
Subject: [SARA] Re: Cheap SDR
Hi
cheers, Kimmo OH2GUC
--
Tom Crowley
observed OH in comet 9P/Temple 1 during Deep Impact with the GBT. The
results showed very little water coming off the comet. Perhaps 2 cubic
meters per second.
You'll want to be +- 2 MHz in order to detect the OH +- Doppler.
Here is some info on the W75 region:
W75 N is a star-forming region containing various ultracompact H II regions
and OH, H2O, and CH3OH maser emission. Our VLBA map shows that the OH masers
are located in a thin disk rotating around an O star, the exciting star of
the ultracompact H II region VLA 1. A separate set of maser spots is
associated with the ultracompact H II region VLA 2. The radial velocity of
OH maser spots varies across the disk from 3.7 to 10.9 km s-1. The diameter
of the disk is 4000 AU. All maser spots are strongly polarized. These are
the first OH masers showing nearly 100% linear polarization in several
spots. Two maser spots seem to be Zeeman pairs, corresponding to a magnetic
field of 5.2 and 7.7 mG, and in one case we tentatively find a Zeeman pair
consisting of two linearly polarized components. The linearly polarized
maser spots are shown to be σ components, which is the case when the
magnetic field is perpendicular to the line of sight. The direction of the
magnetic field as determined from linearly polarized spots is perpendicular
to the plane of the disk, although the Galactic Faraday rotation may
significantly affect this conclusion
I can find the 3 other frequencies if you want. However this is by far the
brightest.
Cheers,
Tom Crowley
Rodney Howe
meter dish. And found nothing. And this was with a dual polarized feed
horn. There are 4 or 5 Mira maser stars at this frequency, U Her, S CrB, W
Hya, and R Cas, rated to be over 1 Jansky. It would be great if you could
detect something; perhaps looking at Srg A* ??
R.
-----Original Message-----
From: Tom Crowley
Sent: Friday, March 30, 2012 9:26 AM
To: sara...@googlegroups.com
Subject: Re: [SARA] Re: Cheap SDR
Jan, OH displays in 4 frequencies. The brightest is 1667 MHz. I've
observed OH in comet 9P/Temple 1 during Deep Impact with the GBT. The
results showed very little water coming off the comet. Perhaps 2 cubic
meters per second.
You'll want to be +- 2 MHz in order to detect the OH +- Doppler.
Here is some info on the W75 region:
W75 N is a star-forming region containing various ultracompact H II regions
and OH, H2O, and CH3OH maser emission. Our VLBA map shows that the OH masers
are located in a thin disk rotating around an O star, the exciting star of
the ultracompact H II region VLA 1. A separate set of maser spots is
associated with the ultracompact H II region VLA 2. The radial velocity of
OH maser spots varies across the disk from 3.7 to 10.9 km s-1. The diameter
of the disk is 4000 AU. All maser spots are strongly polarized. These are
the first OH masers showing nearly 100% linear polarization in several
spots. Two maser spots seem to be Zeeman pairs, corresponding to a magnetic
field of 5.2 and 7.7 mG, and in one case we tentatively find a Zeeman pair
consisting of two linearly polarized components. The linearly polarized
maser spots are shown to be οΏ½ components, which is the case when the
Bruce Rout
-Bruce
2012/3/30 Rodney Howe <ah...@frii.com>:
> maser spots are shown to be σ components, which is the case when the
Jan Lustrup LA3EQ JO28XJ_79FX
Thanks for the info guys...I will try and see if there is anything
detecteble with my horn or small dish.....
Jan Lustrup LA3EQ
Norway
Kimmo
The frequency of the OH line which showed the bright flare is
1665.4018 MHz.
The coordinates of W75 are
R.A. = 20h 38m 36s
decl. = 42d 37m 35s (J2000.0)
Two important things to note:
1) The OH emission is highly linearly polarized. Thus, you have to be
able to set your probe to different polarization angles.
2) Depending on the bandwidth of your 'backend' (spectrometer) you may
have to take into account the Doppler shift
caused by Earth's rotation around the Sun and rotation of Earth
itself.
There is a Local Standard of Rest calculator at
www.jupiterspacestation.org/software/Vlsr.html which you can use to
estimate the effect.
What kind of spectrometer you have ?
cheers, Kimmo
----------------------------------------------------------------------------------------------------------
On 30 maalis, 10:57, "Jan Lustrup LA3EQ JO28XJ_79FX" <j-
Jan Lustrup LA3EQ JO28XJ_79FX
Thanks for the info...that helps alot.
My "spectrometer" is ...: VLNA+ one (MAR-6) to a "M1G" mixer (LO is a H.P.
signalgenerator locked at 135.000MHz) feeding my ham transceiver Kenwood
"TS-2000x" tuned to1285MHz (the 23cm amateur band) with AGC "off" and in
"slow scan SSB mode". AF diode detector, op amp intergrator/level adj..
feeds a Labjack 12bit A/D converter running Radio skypipe software.
I also use a H.P. 10MHz-40GHz spectrum analyzer, using the DC vertical log
output feeding my Labjack 12 bit A/D and Radio skypipe software.this setup
does have not a precise frequency display.
The Horn antenna is horisontal polarized but I also use a 2-meter glassfiber
dish with rotable polarization feed.
I have a choice of two VLNA's ...one from "R.A.S." and a "G4DDK" kit type.
I have several transverters that I can use ...13, 9, 6 and 3cm bands. And
several "can" feeds and printboard LPA antennas-
Cheers, Jan
----- Original Message -----
From: "Kimmo" <aurinko...@gmail.com>
To: "Society of Amateur Radio Astronomers" <sara...@googlegroups.com>
Sent: Saturday, March 31, 2012 11:37 PM
Subject: [SARA] Re: Cheap SDR
Hi Jan
cheers, Kimmo
--
Jan Lustrup LA3EQ JO28XJ_79FX
Thanks for the information...I'll look it up.
Hi Kimmo....
I did a quick check for OH lines at W75 on 1665.401MHz with my Horn antenna
pointing at RA 20:38 and Dec 42 this morning with horizontal polarization.
I made three 90sec intergrated scans from 1665 to 1666MHz with
470KOhm/4.7uF RC intergration to see if anything showed up.
I think one might see some OH lines with brightness of about 0.1 dB in all
three scans...puzzling thing is that I also see three dips in noise level 50
kHz higher too...(absorption lines???)
It's all hopless drowned deep into the noise, so I will need to do som more
work on scaning slower with much longer intergration time to even out the
random noise.
My spectrum analyzer will not scan slower then 90 seconds, so I will use a
M1G mixer to down convert from1665MHz to 1265MHz and use my 23cm ham radio
in scan mode for detecting. Then I can scan for 15 minutes a time. This way
I will be able to dig deep into the noise.
Anyway, this is just a short update....might not be anything on the scan at
all in the end, just random noise, so I will have to do more work to be
shure.
This is what one gets from using a tiny horn radio telescope....wish I had a
18 meter dish ;-)
If you want to see the three 1MHz wide scans at 1665 to 1666MHz click here:
http://www.qsl.net/la3eq/radioastronomy/1665.jpg
They are stacked one above the other for easier correlation. I marked with a
blue rectangle the suspected OH line (1665.401MHz ) and the dip in
noise(1665.451MHz) with a green rectangle.
Horizontal markers are 250KHz each.
Vertical axis is in realative dB.
Jan Lustrup LA3EQ
Norway
-Bruce
> maser spots are shown to be οΏ½ components, which is the case when the
Bruce Rout
galore. I have two more on the go as well. Good luck. This is a very
difficult challenge.
-Bruce
2012/4/1 Jan Lustrup LA3EQ JO28XJ_79FX <j-lu...@online.no>:
>> maser spots are shown to be σ components, which is the case when the