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Airspy R2 SDR architecture

James Farrar
 

I'm using this excellent SDR for ADS-B and would like to find a system drawing of the gain stages in order to understand  how best to approach some fine tweaking of the system.
I did see something once, that if I recall correctly, had the input attenuation before the first gain stage. If this is so am inclined to set the first stage to maximum gain to reduce the noise floor.
Am I correct in my thinking?

Sergio Sarabia
 

If you are looking to reduce the noise by 1090 MHz, I recommend using a bandpass filter at that frequency or a rejection filter from the GSM mobile phone band.

James Farrar
 

Thank you for your reply.
I'm using a cavity filter made by a friend of mine, followed by an LNA powered by a bias-T in a housing at the top of an aluminium pole.
I did have a lot of interference from mobile telephone masts even though there is no coverage here. This was eliminated with the cavity filter.

EB4APL
 

A likely explanation is that you don't have coverage from your provider, but other provider could have strong signals there. Also the interference could be caused from another nearby source.

Regards,
Ignacio


El 20/10/2019 a las 14:53, James Farrar escribió:
Thank you for your reply.
I'm using a cavity filter made by a friend of mine, followed by an LNA powered by a bias-T in a housing at the top of an aluminium pole.
I did have a lot of interference from mobile telephone masts even though there is no coverage here. This was eliminated with the cavity filter.
_._,_._,_



Libre de virus. www.avast.com

Ian Brooks
 

Another explanation could be that if you are in a poor coverage area, mobile phones nearby will be transmitting at maximum power. Is the interference on the base station transmit frequency or the mobile transmit frequency?

Ian Brooks, former Vodafone Base Station maintenance Engineer.

prog
 

Highly recommended for ADSB receivers near base stations:

http://shop.sysmocom.de/products/cf1090-kt30

James Farrar
 

Thank you all for your replies, but this thread seems to have wandered off topic a little.
I was looking for information as to the gain, attenuator and detector adjustment capabilities within an Airspy R2. 

Sergio Sarabia
 

Sergio Sarabia
 

James Farrar
 

Thank you Sergio. That is what I couldn't find again.