Hi,
Thank you everyone, very valuable advice in this thread! I will not ignore it.
Helmut, the USRP B20x variants are my main target, so be sure I'll be
testing with them, it's just not a priority now. Let me explain why
the RTL-SDR: lots of folks have this cheap dongle, and it's a very
good
As long as you look after an overload or an intermodulation condition, I
don't see a problem with the RTL-SDR. The phase noise wont matter for
low density modulation types like QPSK...
But as Helmut says, looking after the overload or intermod , SFDR
condition will be very important
8 bit is
well, 2.4 GHz (compared to 70-500 MHz), a short delay profile will be
what you are working with, but with a high likelihood of 0dB echos. The
echoes tend to get quite strong due to the large reflective surface
performance. But there tends to be alot of them, rather than 1 or two
dominant echos .
Hi Adrian,
everything better than the 8 Bit RTL-SDR improves the chance for meaningful
test results. I think all available 12 bit SDRs like Ettus B200/210, but also
your LimeSDR-Myriad (LMS7002M) or a configuration using the AD 9364 would be a
better choice.
73, Helmut
Hi Glen,
On 9/18/17, glen english wrote:
>
> It would not improve the performance in a low local multipath dominant
> two tap local delay scenario like rural/farmland.
>
I would be very curious about the dB levels vs. frequency. From my
knowledge, above 400 MHz is highly
Hi,
Do you have a particular device in mind? Anything that is supported by
Osmosdr can be tested, but I only have AD9364 and Lime Micro devices
available.
73,
Adrian
On 9/18/17, Helmut Oeller wrote:
> Hi,
>
> IMO objective and severe comparison in presence of interference can
Hi Greg
True diversity (2 x omni) receiver wont fix the long echo scenario
it is likely in that scenario both diversity branches will cop the same
(bad) delay profile .
However it would likely improve the performance if there was a very high
level of local multipath, as such decorrelating
Hi,
IMO objective and severe comparison in presence of interference can only
succeed using appropriate SDR hardware. These USB sticks are not developed
for narrow bandwidths due to very low SFDR, phase noise of LO etc.
73, Helmut
-Ursprüngliche Nachricht-
Von: Adrian Musceac
Hi Alex
so the ETSI HTx 6.2.2.4 propagation profile is specified as :
two taps, ratio 8.6dB
tap delay : 1/4 TETRA symbol (12.5uS)
In my opinion, this is completely insufficient. Any arse can pass that.
A more realistic test would be two taps 0dB, and 25uS delay. That's
reality
Their EQx
On Mon, Sep 18, 2017 at 9:14 AM, glen english wrote:
> The only real fix is slowing down the symbol rate.
A true diversity receiver is also a real fix.
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Hi ALex
well ETSI can say what they like, but unless the system is long delay
multipath tolerant, it will be a poor performer with respect to analog
if a hill gets in the way with another hill behind it...
This is not a rayleigh flat fading scenario, this is a frequency
selective fast fading
Hi,
Helmut, for me RTL-SDR support is required. I will not be testing with
another SDR hardware for reception as my application is meant to work
with the USB stick (small dynamic range or not).
Glen, have a look at
http://www.etsi.org/deliver/etsi_etr/300_399/30001/01_60/etr_30001e01p.pdf
HI Adrian
good stuff!
OK, now try the analog versus the digital, with a copy of the TX signal
at 30uS delay and -10dB with respect to the wanted signal (a common
multipath ) , and also 30uS delay and 0dB.
Let me know...
On 15/09/2017 9:10 PM, Adrian Musceac wrote:
> Hi,
>
> I present a
Adrian,
Nice video, but I would like to see the actual spectrum of ISM band causing
interference and detected with a real high performing SDR or analyzer. I doubt
that the dynamic range of the RTL-SDR is appropriate for such tests.
73, Helmut, DC6NY
Von: Adrian Musceac
Hi,
I present a three way comparison between narrow band FM (5 kHz), QPSK
Codec2 1300 (2.4 kHz) and QPSK Opus 19 kbit/s (16 kHz):
https://www.youtube.com/watch?v=vApRe6R1gnk
The comparison is taking place in the ISM band of 433 MHz with interference
present from some temperature sensors in an
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