SDR IQ

[Den Koawl]

Greetings All,

 

Is anyone using using the RFSPACE SDR IQ for rcvr ?  Im wondering how well it is working out ?

 

Tnx

Den

[Marcus D. Leech]

Nice device, but only designed for direct-tuning to 30Mhz, and only
190kHz of instantaneous bandwidth.

I'm not immediately aware of anyone using it for radio astronomy, but
that doesn't mean it couldn't, subject to
the above limitations.




--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

[Den Koawl]

Tnx for reply Marcus...... ok, was wondering about that..... i also checked out the Icom 1500 SDR unit and Icom says that a very broad range of spectrum can be scanned in about a second by setting the upper and lower band limits. This unit covers up to 3 GHz also.

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[Marcus D. Leech]

On 11/11/2012 03:04 AM, Den Koawl wrote:

Tnx for reply Marcus...... ok, was wondering about that..... i also checked out the Icom 1500 SDR unit and Icom says that a very broad range of spectrum can be scanned in about a second by setting the upper and lower band limits. This unit covers up to 3 GHz also.

For spectral observations, you'd really prefer something that can cover the entire spectrum simultaneously -- this gives much better
  sensitivity, which is why, for spectral observations,  you want an SDR with high instantaneous bandwidth.

Further, for continuum observations, you want more bandwidth as well, since sensitivity is proportional to bandwidth, and for an SDR
  receiver the bandwidth is directly equal to the SPS delivered to the software.

On Sat, Nov 10, 2012 at 4:29 PM, Marcus D. Leech <patchv...@gmail.com> wrote:

On 11/10/2012 08:24 PM, Den Koawl wrote:

Greetings All,
Is anyone using using the RFSPACE SDR IQ for rcvr ?  Im wondering how well it is working out ?
Tnx
Den

Nice device, but only designed for direct-tuning to 30Mhz, and only 190kHz of instantaneous bandwidth.

I'm not immediately aware of anyone using it for radio astronomy, but that doesn't mean it couldn't, subject to
  the above limitations.




--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

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[David L, N5OIQ]

Ken,

I'm using a QS1R SDR for my work, which has an instantaneous bandwidth of 2.5 MHz that is important for radio astronomy (as mentioned by Marcus below).  Additional hardware is needed to receive beyond 62 MHz and my approach toward doing this is described in detail on my website (https://sites.google.com/site/amateurradiointerferometry/file-cabinet).  

David

[Den Koawl]

David Hi, and tnx for info...... i did take a look at the QS1R, but the price is a little high for me, at the moment. For the price, that thing should cover more spectrum ( i think ), so for now i have to settle for using the Realtech USB SDR device and the associated software for it. I may end up getting that QS1R someday or the RASDR when it is available.

 

Tnx for info.

73

Den

--

[David L, N5OIQ]

Den,

I've got a RTLSDR dongle myself and they are good little radios with a large instantaneous bandwidth.  It has been a while since I've played around with my RTLSDR and I could see that it has some issues with automatic gain control that couldn't be disabled.  Perhaps someone here in the group would know if AGC can be disabled on these things?

David

[Marcus D. Leech]

On 11/13/2012 09:29 AM, David L, N5OIQ wrote:
> Den,
>
> I've got a RTLSDR dongle myself and they are good little radios with a
> large instantaneous bandwidth. It has been a while since I've played
> around with my RTLSDR and I could see that it has some issues with
> automatic gain control that couldn't be disabled. Perhaps someone
> here in the group would know if AGC can be disabled on these things?
>
> David
>

One has been able to disable AGC, via software, on the RTLSDR for
several months. I poked and prodded pretty hard to get them to
figure out how to do that, and then implement it.



Both the E4K and R820T - based dongles can have fully-manual gain
control. The FC0013/FC0012/FC2580-based dongles don't have
manual gain control. But most of them out there are E4K (rarer now)
and R820T (very common).

I'm using an RTL based dongle for my back-yard 400Mhz RT, and also the
SBRAC site will be using 14 of them to process data from the
feed.

[Den Koawl]

I see, well im not sure what software you are using with it, but i downloaded the SDRSharp pkg, and it has a tick box which disables AGC........ i cant remember the website now that i downloaded from but i can look for it again if this helps ?

[David Ocame]

Den, I found that "AGC control" in these off the shelf products is sometimes very deceptive. They say AGC on/off, but what they mean is AGC fast/slow. Icom receivers are the worst offenders for this. It took 2 years and dozens of emails before a tech at Icom finally admitted this to me!

 

Dave

 

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Dave Ocame, WS1ETI

Stony Creek Observatory
FN31og
-72.834 longitude
41.272 latitude

Member: The SETILeague, Inc. (Awards Chair),
The Society for Amateur Radio Astronomy (SARA),
The International Trumpet Guild, Shoreline Jazz Collective, and
The Connecticut Symphonic Winds

[Den Koawl]

i see, thats interesting.