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Hello,
right now I have exactly one prototype. But we have more PCBs and we
will populate them to fix the boards in the wild. When I have them
ready, I will post it here.
Best regards,
Christian
On 18.10.2012 06:44, Ronny Kunze wrote:
Hello ,
that are really good news. How can i get such a upgrade board ?
Best regards,
Ronny Kunze
Am 17.10.2012 18:55, schrieb Christian Daniel -- maintech GmbH:
Hello everybody,
since we found out that the Atmel SAM3U SSC interface is only
capable of transporting 500ksps worth of I/Q data, we heard a lot
of complaining because of the too narrow bandwith. Especially
compared to the rtl-sdr with about 2msps, our 500ksps was bit
contrained. The fact, that the OsmoSDR is much more sensitive to
very small signals and brings a 14bit ADC instead of 8bits did not
really compensate for the bandwidth loss.
Also the mismatch between E4000 output resistance and ADC input
brought some unwanted spectral effects.
Instead of just releasing stuff, we decided to fix both issues: I
now have a prototype with simple stack-on-board, that adds two
op-amps to decouple the E4000 from the ADC and lower the impedance
and also this board connecteds the available FPGA pins to the MCI
(SD-Card) interface of the Atmel SAM3U.
For this to get working, we had to rewrite major parts of the ARM
firmware and the FPGA VHDL code. Today this work is completed and
I can report success: The OsmoSDR now delivers up to 4msps at
14bits. Also the strange peaks around Niquist/zero frequency are
gone.
Find a screenshot of SDRangelove recording a DAB signal at 2msps
(SDRangelove needs some more love until it can cope with 4msps in
realtime - but we have verified that 4msps works without dropped
samples using the builtin FPGA test mode).
http://www.cdaniel.de/download/osmosdr-dab-2mhz.png
We will now integrate the changes into the OsmoSDR mainboard and
reroute the now free SSC pins to the pin headers instead of the
MCI interface. Also we will add the opamps.
For the already produced OsmoSDR boards, we will have more of the
prototype stack-on-top-boards.
We will keep you in the loop!
Best regards, Christian
PS: Regarding the DAB screenshot: - The horizontal lines are
correct - DAB uses a so called "pilot symbol", which only has
energy on a few carriers. That's why it looks like a pause in the
signal. - The vertical line is also correct - DAB does not use the
middle carrier to avoid I/Q offset problems on the transmitter
side.
-- - --------------------------------------------------- | maintech
# Dipl. Inf (FH) Christian Daniel | | GmbH ###
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http://www.maintech.de cd(a)maintech.de |
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- --
- ---------------------------------------------------
| maintech # Dipl. Inf (FH) Christian Daniel |
| GmbH ### Otto-Hahn-Str. 15 · D-97204 Höchberg |
- ---------------------------------------------------
| AG Würzburg, HRB 8790 Tax-ID DE242279645 |
- ---------------------------------------------------
|
http://www.maintech.de cd(a)maintech.de |
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