Airspy,RTL,B200,FCDp+ with Jaero comparison/ Airpsy issue

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georgio

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Hi all !
I am putting up this quick comparison with the hope that someone will have an airspy mini to verify if the unit can actually receive "clasic aero" acars signals.
I am worried that I may have a sub-par or even faulty unit. There is also the possibility of firmware issue or hardware design issue. I am also worried that the mini, lacking in clock generator, may have other related issues that its bigger brother (Airspy R2) may not have.
Any information you may have is highly appreciated.

The test is receiving the L band Inmarsat satellite signal (1545.115 Mhz) and decoding it with the jaero utility (JAERO)
The downlink provides a continues stream of data that are packetized. The percentage of valid packets against faulty ones ("bad crc") is a good indication of healthy reception.

The units tested were :
RTL dongle with R820T2 (with SDR# v1.0.0.1466)
RTL dongle with E4000 (with SDR# v1.0.0.1466)
Funcube dongle pro plus (with SDR# v1.0.0.1466)
Airspy mini (fw v1.0.0-rc9, with SDR# v1.0.0.1466)
Ettus USRP B200 (with HDSDR v2.7)

The Jaero version was 1.0.4.4

A modified GPS patch with preamp was used.
The various parameters (gains, sampling rates, decimation etc) were optimized for apparent best reception.

After 1000 lines of messages had been gathered in the jaero utility, I copied/pasted the log into notepad++ and searched for "Bad CRC". Here's the results :

Code:
Funcube Dongle pro+ : 0 faults
Ettus B200          : 1 fault
RTL dongle, E4000   : 3 faults
RTL dongle, R820T2  : 16 faults
Airspy mini         : 256 faults
The FCD is a real winner with remarkable stability and error free reception even after hours of receiving.
I was also well impressed with the E4000 although the frequency stability is not great.
The airspy was causing the phase lock of the jaero to break every so often. There is something wrong here and I hope is it firmware fixable. It seems like a great dongle. In other parts of the spectrum is seems to perform remarkably well.
The issue can be clearly seen in the following gif captures :

Airspy mini. The phase is periodically lost. CRC errors and reception failures :
Jaero with Airspy mini - GIF on Imgur

Funcube dongle pro plus. Rock steady for hours of error free reception. Impressive :
FCDP+ with Jaero - Gif on Imgur

RTL with E4000. Remarkable for the price :
RTL-E4000 with Jaero - Gif on Imgur

Comments,ideas,questions,suggestions welcome.

Best regards
George
 
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