Hi Hunz,
Glad you're finding RTLSDR-Scanner useful.
I think you've run into a couple of issues, firstly it appears that the
AGC isn't fully disabled on the R820T (if you remove the aerial the
noise floor increases).
Secondly RTLSDR-Scanner averages 2 chunks of bandwidth either side of
the DC point, these seem relatively quiet with an E4000 and FC0012 but I
haven't had chance to check the R820T yet. This tuner may have a very
different noise floor. I was wondering about adding a feature to allow
the user to pick their own segments (by terminating the aerial and
looking at the noise distribution).
Has anyone had a chance to test 2 different dongles with the same
tuner? I'd be interested to know if it makes a difference to the noise
floor, if there is little change, I could vary the scan based on the tuner.
Best regards,
Al
On 15/03/2013 11:00, [email protected] wrote:
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Today's Topics:
1. R820T vs. E4000 (Benedikt Heinz)
----------------------------------------------------------------------
Message: 1
Date: Fri, 15 Mar 2013 01:01:33 +0100
From: Benedikt Heinz <[email protected]>
To: [email protected]
Subject: R820T vs. E4000
Message-ID:
<CAFXU+zGq66O-nPDiPTMa-+xC1Y9_QE1sW9FrVS71Kdaa=ui...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hi everyone,
although there are some comparisons between the R820T and the E4000
already [1, 2], I also did some tests with another use-case in mind.
I'm working on a thing similar to RTLSDR-Scanner [3]. I want to
monitor a large part of the spectrum continuously.
So I compared the R820T with the E4000 using RTLSDR-Scanner w/ and w/o
an antenna.
My results are here:
https://docs.google.com/folder/d/0ByDAKwyEiyx_XzZ5ZnpRV1VZWDQ/edit?usp=sharing
There's much more spurs with the E4000 than w/ the R820T. According to
[1, 2] one also would expect a better overall sensivity compared to
the E4000.
However, the GSM900 signals for example seem to be way better with the
E4000 according to the RTLSDR-Scanner. Tuning to a certain channel w/
OsmoSDR Source in GNUradio gives about the same SNR - contrary to the
RTLSDR-Scanner output. Can anyone explain this?
Also, the DVB-T channel at 502MHz is quite weak in the R820T
RTLSDR-Scanner output when compared to the E4000. I had a closer look
at the lower limit of the channel in gnuradio. This can be seen in the
502MHz_*.png pictures. The E4000 produces a nice +20dB step while one
can hardly see the channel in the R820T spectrum. I don't understand
this as well. Is this AGC-related? Manually setting a fixed gain
didn't really help though...
Any explanations?
Thank you!
Best regards,
Hunz
[1] http://steve-m.de/projects/rtl-sdr/tuner_comparison/
[2] http://www.hamradioscience.com/rtl2832u-r820t-vs-rtl2832u-e4000/#more-1852
[3] https://github.com/EarToEarOak/RTLSDR-Scanner
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