FlightAware Discussions

Airspy Mini - troubleshooting 6 MSPS limitation

I have a feeling that something is not OK with my Airspy mini, so I am opening a new thread instead of polluting others.
I have run a test and it looks like it can “push” only 6 not the expected 10:

airspy_rx -r NUL -t 0
Device Serial Number: 0x061C67DC2B077BA3
Stop with Ctrl-C
Streaming at 5.999 MSPS
Streaming at 6.032 MSPS
Streaming at 6.017 MSPS
Streaming at 6.008 MSPS
Streaming at 6.003 MSPS
Streaming at 5.999 MSPS
Streaming at 5.997 MSPS
Streaming at 5.995 MSPS
Streaming at 5.994 MSPS
Streaming at 5.993 MSPS
Streaming at 5.993 MSPS
Streaming at 5.993 MSPS
Streaming at 5.992 MSPS
Streaming at 6.020 MSPS
Streaming at 6.015 MSPS
Streaming at 6.007 MSPS
Streaming at 6.001 MSPS
Streaming at 5.998 MSPS
Streaming at 5.995 MSPS
Streaming at 5.994 MSPS
Streaming at 5.994 MSPS
Caught signal 0

User cancel, exiting…
Total time: 22.3123 s
Average speed 6.0014 MSPS IQ
done

OK. Time to see the info of the firmware:

airspy_info
airspy_lib_version: 1.0.9

Found AirSpy board 1
Board ID Number: 0 (AIRSPY)
Firmware Version: AirSpy MINI v1.0.0-rc10-3-g7120e77 2018-04-28
Part ID Number: 0x6906002B 0x00000030
Serial Number: 0x061C67DC2B077BA3
Supported sample rates:
6.000000 MSPS
3.000000 MSPS
Close board 1

So that made me ask… where’s the promised 10MSPS (20MHz IQ)?

  • 12bit ADC @ 20 MSPS (10.4 ENOB, 70dB SNR, 95dB SFDR)
  • 10, 6 and 3 MSPS IQ output – Optimized for portable and tablets

Have you tried using the argument to set the sample rate? From memory the 6MSPS is default because the 10MSPS is not as clean. Try:

airspy_rx -r NUL -a 10 -t 0

The firmware reports only 6 and 3!

airspy_rx -r NUL -a 10 -t 0
argument error: unsupported sample rate

It may not be supported with airspy_rx. I think you need to use debug mode to get it to work - I’m pretty sure I did try it in SDR#, but it wasn’t really worthwhile.

The specs on the website state that it can do 10… no mention of special “debug” modes. I think that the latest firmware knocked off the 10.
I’m on v1.0.0-rc10-3-g7120e77 2018-04-28

Heres mine

airspy_lib_version: 1.0.9

Found AirSpy board 1
Board ID Number: 0 (AIRSPY)
Firmware Version: AirSpy MINI v1.0.0-rc10-0-g946184a 2016-09-19
Part ID Number: 0x6906002B 0x00000030
Serial Number: 0x26A464DC28293293
Supported sample rates:
6.000000 MSPS
3.000000 MSPS
Close board 1

So the 2016.09.19 version doesn’t report 10 either…

Maybe somewhere in between did ?

BTW, I have tried to ask on airspy@groups.io but… “Your message will be sent when it’s approved by the moderators.”
Oh well…

just found this on github site

airspy_lib_version: 1.0.6

Found AirSpy board 1
Board ID Number: 0 (AIRSPY)
Firmware Version: AirSpy NOS v1.0.0-rc6-0-g035ff81 2015-07-14
Part ID Number: 0x6906002B 0x00000030
Serial Number: 0x0123456789ABCDEF
Supported sample rates:
        10.000000 MSPS
        2.500000 MSPS
Close board 1
1 Like

Hmm. I guess that won’t do stable the 12MHz samplerate…
I wish @prog was awake :grinning:

What are you trying to do?

I think it started with airspy mini only supports
Supported sample rates:
6.000000 MSPS
3.000000 MSPS
and wanted to know why there is not a 10.000000 MSPS as stated

The rates listed by the utility are supported by SDR software. The others are specific to other applications like ADSB.

But the website says that supports “10, 6 and 3 MSPS IQ output”.
Well… the firmware doesn’t agree, it says only 6 and 3. Older firmware was supporting 10.

The laptop can push 12MHz at -e 9.3 with 80% utilization of one core. MLAT is stable.
If I try anything related to 20MHz, even at -e 6, with 30% utilization of a core, MLAT drops because “unstable clock”.
I suspected that is something firmware related… and I stumbled over this.

The firmware update is right on the bottom of that page. The hardware supports much more (80MSPS).
The firmware development predate this adsb decoder. It is used by tens of thousands of people/organizations. Nothing left to optimize. If it was broken, we wouldn’t be here playing with ADSB in the first place.
Your laptop just can’t handle the data throughput, which is typical of old chipsets with the default Microsoft drivers.

That’s the one that I have.
How about adding the 10 to the firmware, beside 6 and 3, like it used to be and how it’s advertised? It would eliminate this question…

What command checks my actual MSPS on pi4

No. The design is not as simple as you would want it to be. People who understand the specs don’t even ask this question.

The sample rates with guaranteed phase noise and spectral purity are listed and can be used for narrow band scenarios with the nominal performance. The other sample rates are not listed but can be used for application specific scenarios that can tolerate spurs or other artifacts like ADSB or DAB/DAB+/TDMB.

Now my question is: What are you trying to achieve? If it is about your laptop, then we already have the answer: Old chipset running with the default Microsoft driver (ie. not the OEM driver).

Now I am only trying to understand why it says below that it can do 10MSPS, if isn’t in the firmware (because it is not possible as you stated):