Thursday, 23 February 2017

Icom IC-7300 review

Icom IC-7300 is the first direct sampling SDR (software defined radio) available from one of the "big three" japanese manufacturers. This helps it bring a whole new level of performance at an accesible price point, a much more flexible configuration and a set of features only seen in top-of-the line equipment. Real-time panadapter or fully customizable filters are just the tip of the iceberg.

 Sure, amateur equipment has been using for a long time various levels of digital signal processing (DSP), but usually this was done in the last part of the receive chain, where it mostly impacted audio quality and not receiver performance. Moving to a direct-sampling SDR architecture means the signal coming from the antenna is directly transposed to the digital domain and instead of all the previously familiar receiver stages (such as mixers, filters, demodulators etc) we are using mathematical formulas applied to the data stream. The advantage of this approach is it eliminates all problems related to real-world hardware receivers (noise, distorsion, losses, imperfections, limitations etc) and opens up a new world on how you can use or visualize RF signals. Goodbye unwanted mixing products, AGC non-linearity, IF chain IMD or filter blow-by. You want a 200Hz to 2250Hz SSB filter ? Just go into the menu, customize it to that value and see how that carrier at 2260Hz simply doesn't get trough; yes, filter width and shape is just a matter of settings, leaving it all to mathematics to carry it out. Basically, the only part that limits the receiver performance is the Analog-Digital Converter (ADC) that samples the RF signal, and those are already very good.

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