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



-----Ursprüngliche Nachricht-----
Von: Adrian Musceac [mailto:kanto...@gmail.com] 
Gesendet: Montag, 18. September 2017 16:42
An: freetel-codec2@lists.sourceforge.net
Betreff: Re: [Freetel-codec2] Comparison between digital voice and analog 
narrowband FM on weak signals with interference

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 <dc...@gmx.de> wrote:
> 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 [mailto:kanto...@gmail.com]
> Gesendet: Montag, 18. September 2017 11:01
> An: freetel-codec2@lists.sourceforge.net
> Betreff: Re: [Freetel-codec2] Comparison between digital voice and 
> analog narrowband FM on weak signals with interference
>
> 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 specifically section 6.2.2 and below. Faces exactly the same 
> issues.
> FM is also affected by fast Rayleigh fading..
> Anyway, Doppler shift will be a bigger issue than multipath.
>
> Cheers,
> Adrian
>
>
> On 9/18/17, glen english <g...@cortexrf.com.au> wrote:
>> 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 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 adjacent 
>>> channel.
>>>
>>> Conditions: same antenna locations, same RX chain gain, varying 
>>> transmit gain (LCD like number on the top left of the screen)
>>>
>>> Results: both digital modes cope better with interference and are 
>>> more intelligible than FM. The numbers on top left of RX application 
>>> are expressed in dB of amplification in the SDR transmitter chain.
>>>
>>> Hardware: for transmit one USRP B200 with 433 MHz filter installed, 
>>> for RX one RTL-SDR filter with 433 filter installed.
>>> Software: QRadioLink running on top of Gnuradio (GNU/Linux):
>>> https://github.com/kantooon/qradiolink
>>>
>>> 73,
>>> Adrian YO8RZZ
>>>
>>>
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>>
>>
>>
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