5 ms·
Unfortunately, we are not yet at the point where a range of frequencies anywhere near as wide as discussed in the article can be supported by a simple firmware
by pbsurf 14y ago
Unfortunately, we are not yet at the point where a range of frequencies anywhere near as wide as discussed in the article can be supported by a simple firmware upgrade. RF receivers typically include a very narrow bandpass filter as the first component after the antenna. As spectrum becomes more crowded, these filters are even more critical to prevent saturation of the low-noise amplifier and unwanted products from the downconverter/mixer.
- th0ma5 14y agoYes, yes! Sorry to over simplify it. I guess my main point was mostly the first one, there's a lot to it, heh.
- aaronblohowiak 14y agoand the bp filter isn't tunable?
- patrickyeon 14y agoA cheap one isn't. An expensive one may be, but you could trade away a lot of performance to get that feature.
- CamperBob2 14y agoRF receivers typically include a very narrow bandpass filter as the first component after the antenna Historically true, but as ADCs get better (and more important, cheaper), that will be less and less common. Software-defined radios with broadband front ends don't play by the same IMD rules as conventional radios, anyway.
- patrickyeon 14y agoIn my experience, the ADC is far from the limiting factor for linearity in an SDR receiver. The analog components up front (LNA and mixer, especially) are the limiting components. Broadband front ends make it even worse, because it's more likely you'll have an interferer passed through the filtering, even if it's nowhere near (in frequency) your signal.
- Nrsolis 14y agoDon't forget the antenna. In many cases, the antennas themselves have specific polarization and beamwidth/radiation patterns along with SWR that is directly tied to the frequency range of the antenna itself. SDR doesn't change any of this.