Did you saw what I did to mine? And like I said, I don’t use it to supply power to the LNA, IMO is too risky.
1 Like
How about the 24MHz versus 12MHz in the R2?
The temperature reference was when i started using it for a couple of weeks … i’ve long ago change the setup … cooling is more than adequate and it has an external biast …
I had some MLAT issues a couple of weeks ago but wasn’t keen on messing with it so i just changed it to 12 MSPS … not sure i saw a difference but i’m terrain limited anyhow.
1 Like
Thank you for your valuable advice . Very interesting
Question is what you expect to be “much better”.
The number of aircraft i receive is mainly limited by the geography, because if i am comparing what i get and what is possible in theory i should be already at the max.
Maybe the message rate will go up.
Comparing other sites like ADSBx, there are not much more aircraft, only these which are out of range based on their flight level.
Moving the LNA closer to the antenna is not that easy, it would require an outdoor housing for it including cabling and connectors.
I am currently using 3 meters of cable, can’t go much shorter based on the distance to the covering roof.
I’ve meanwhile connected for testing the Uputronics to the Airsquitter.
It took almost five minutes until the system was ready and reachable.
Beside the fact that the GPS signal was lost (expected) there is no visible improvement using this combination.
I am currently back to the Raspberry with FA stick and filter/LNA
The Airspy will arrive on Monday (probably), so i can continue with my personal testing
That’s not that bad, barely any attenuation. I have my LNA at the same distance, because I didn’t have shorter cables and I didn’t want to pay extra for shorter ones.
1 Like
Same story. The ref clock in the R2 is 20 MHz, which means 20 MSPS is native and doesn’t require any extra PLL. To get any rate that is not an integer division of 20 MHz, (for eg. 24MSPS,) a PLL + dividers are required. Furthermore, an extra effort is required for packing all the data at 24MSPS to fit within the transfer budget of USB 2.0. The MCU is clocked to allow these configs to run smoothly if the host computer is fast enough, but again… more data => more current => higher temperature.
1 Like
If you can already match the AirSquitter with an RTL dongle + Preamp, then you need a preamp for your AirSquitter, or at least improve the noise figure of the antenna system.
But well, I am what you can call an “RF extremist.” A fraction of a decibel is huge for me at 1090MHz and will definitely grab it when possible.
Make sure the gain is not excessive. Is there a gain or attenuation setting in the AirSquitter?
If not, maybe add a 6 dB attenuator between the preamp and the RX to bring the signals down a bit.
Are we not all “enthusiasts” somewhere? 
I am not that technical guy on RF topics, only having fun watching aircraft.
However i’ve learned a lot from your input and from the others over the years and i would not be at this point where i am now.
I think i have to live with the 95% and let the rest 5% pass.
My wife is spinning wool at home and she goes crazy if a single fiber is not where it should be.
Unfortunately not. The device is “plug&play” without any special configuration settings for these values.
Maybe there are some tweaks available from Jetvision for maintenance, but not for the public
The device with the Uputronics works but no significant change. Maybe iit is here as it is.
Waiting for the Airspy, doing more tests then.
EDIT:
This is interesting. Right after the swap back to the Raspberry, i had a significant increase in positions reported.
Red Arrows are Airsquitter, the green one is the Raspberry with FA Stick and the LNA.
Not sure if this is a display error because there is no significant change visible on graphs1090.
EDIT: Seem to be a deviation in the data or processing on FA side. values are back to normal:
1 Like
Thank you, I didn’t know that 20 is the native for R2. I’ll keep it at 20, now that the hot days are coming here.
PS: My host has an i7-2640M CPU @ 2.80GHz, each core bogomips: 5587.03
I haven’t see someone using bogomips as a performance unit for 15 years 
1 Like
Linux does.
lscpu
For my Pi3B I get BogoMIPS: 51.20
BogoMips are not a suitable metric for anything, hence their name (bogus).
Quick sunday update, while i am still waiting for the Airspy.
I now have the Raspberry with FA stick and Uputronics filter as replacement for the airsquitter since 24 hours. Amount of messages, aircraft and positions seem to be without significant change.
In addition today i was running the Airsquitter in parallel with my spare antenna.
The antenna has a little lower value (3.8dB) than the Jetvision (5dB) but at least it give some details.
The amount of aircraft (ADS-B)was the same on both devices, also the range. On both devices the same aircraft appeared within 30 seconds in parallel.
MLAT traffic was higher on the AirSquitter as these are coming from the Jetvision Network
The message rate (frame rate) on the Airsquitter was in average 5-10% higher than the message rate displayed on te Raspberry.
Once the Airspy arrived, i will check again.
2 Likes
Please keep us posted. Once your Airspy arrived, you will be able to make a real comparison.
1 Like
My utility box has a fan blowing on the Airspy R2. So based on prog’s comments I don’t think I need to worry much about keeping my RTL SDR LNA. But, for curiosity, I switched back to the Uputronics LNA about 6 hours ago.
Sundays tend to be a bit unique for aircraft patterns. So far stats look nearly identical RTL-SDR LNA. Avg max range looks about 4 or 5 nm less so far. I can’t be certain yet, but messages & positions might be a bit less too. I’ll let it run at least another day or two to see what I can decipher.
Even before I increased the Airspy gain from 14 to 19 to keep mean signal strength the same between the two LNAs, I noticed switching to the Uputronics increased ADSB CPU utilization by a notch. Just before 12:00 in the graph.
Here we go:
But the guy responsible for packaging went way too far 
Installing it later today.
There is a small hole on one side, is this for airflow?
2 Likes
My switch was set wrong on arrival but soon sorted it
1-2 usb boot 3-4 cannot read
its a settings switch
2 Likes
I can’t resist, getting it installed immediately.
As i was running already the setup with the perfect script of @wiedehopf, i only needed to remove the FA stick, replace it with the Airspy and ran the addition to get the Airspy drivers installed.
Another restart of readsb and it works.
Thanks to @wiedehopf for his flawless setup.
But now two questions:
What is the gain range i can test for the airspy?
What gain setting is required for the adsb configuration?
Thanks
2 Likes
I get it, we all are like small children getting presents 
1 Like