Ask HN: Looking to purchase a software-defined radio, any advice?

Also like the NooElec -- the price is right.

But it took me a while to figure out I had to kalibrate it, using the GSM network.

http://www.rtl-sdr.com/how-to-calibrate-rtl-sdr-using-kalibr...

If you care I live in Berchtesgaden, which provides the unique feature of testing the Galileo System upfront http://www.gate-testbed.com/en/gate-overview.html . Anyway after learning the ESA even has a StartupIncubator here. Because of this,I decided to give it try. My first goal is to build a receiver based on the Raspberry Pi,no idea if i have a chance of doing this, I downloaded the specs and will give it a shoot and see where I get from there.

So you can start small and grow, or start large and be overwhelmed :-) The "low end" are the various DTV tuner sticks and NooElec is a good source for them. The middle of the road is the HackRF One ($300). The high end would be something from Ettus Research like the USRP.

I have one of the USB DTV receivers and it was fun for exposure but hard to do really interesting stuff with. I got the HackRF One and it has been a lot of fun, I added the Ham-it-Up so that I could easily play around in the HF and AM bands. For my bluetooth work I ended up getting an UberTooth even though the HackRF One should be able to do what I need, the Ubertooth was more compact and simpler to set up and take down.

In my case I'm interested in mesh network wireless systems for robotics and room / house localization for those robots. I also have one of the newer Crazie Fly quad copters and want to get to the point where I can manage it using software.

The important thing is to pick a unit that can operate in the frequencies you are interested in (the HackRF One goes 1Mhz to 6Ghz so its pretty wide open) and be ready to revisit a lot of math you might have considered less than useful back in school (complex numbers).

Really though maximum value per $ is probably though starting with one of the USB DTV receivers. If you find you hate it, or its too steep a learning curve, then you won't be out all that much.

A lot of people are recommending Nooelec but I'd recommend starting out with the RTL-SDR blog SDR. It'll have a low PPM receiver and an SMA connector. A lot of the cheaper RTL-SDRs you get (including Nooelec) can have high PPM, non TXCO oscillators. If you're working with weak signals it can kill. There's software to allow you to tune the SDR and eliminate the PPM error but most of the oscillators with high PPM vary by temperature so if you have the SDR in different or changing environments, your calibration can cease being accurate. The SMA connector is a huge help with antennas because the built in MCX connector on many of the SDRs can be pretty fragile (I've broken a couple by accident so far). If you do get a Nooelec anyway, get one of the 0.5PPM models (I think they call them "Mini 2+" with the "+" on the end).

If you like the RTL-SDR after playing with it a while and have a bit of money ($300) I'd strongly recommend the HackRF One. I only started with SDR a few weeks ago and the RTL-SDR was great (especially for the price) but the HackRF One is a whole other level. The amount of bandwidth you can get out of it is amazing.

If you're hoping to handle weather satellites and such, you'll need to build your own antennas. They can be kinda big and you'll need line of sight to the sky most of the time so it'll work best if you have a large open area you can frequently visit. If you own a house your back yard might be good. If you're in an apartment building the roof or parking lot is probably best.

Something else that's fun to play with is ADS-B. It allows you to pick up air traffic position/altitude/speed/heading broadcasts.

You can buy an RTL-SDR key, un upconverter to receive also the shortwave, a notch filter to cut off radio broadcasting that may saturate your receiver and a good multiband antenna. The whole kit will cost around 100€.