n key to SDR, it is not the only technology that has and yield. Since the performance is more consistent, had to "grow up" in order to support this development. many of the factory trim and alignment issues would be Because the level planning is different in these systems, eliminated, potentially reducing a large part of the most of the analog components are stressed to a higher manufacturing and test cost. degree, and better performance is required than that found in traditional architectures. Higher gain at RF frequencies These advantages are good for providing a more consis- Analog front end tent transceiver at a lower production cost. However, as already mentioned, the level planning for an SDR is Quick conversion sufficiently different from a standard superheterodyne In order to take advantage of digital processing, an SDR that different strategies are required. seeks to convert from the RF domain to digital domain as soon as possible. This is true both for receive and Level planning transmit. In doing this, as much of the processing can In a traditional super-heterodyne transceiver, the con- be done digitally as possible. version gain is distributed throughout the signal chain. Typically, gain in the front end is balanced between high Advantages enough for a low NF but not SO high as to overdrive the If most of the processing is done digitally, then reconfi- remainder of the signal chain and cause excessive inter- guration can be quite simple. Filter coefficients can be modulation distortion. Similarly, as much gain is run after changed, and different software can be run or even, in the the channel filtering as possible SO that interfering signals case of FPGAs, completely reconfigured for the required have already been eliminated. Throughout the signal format. In the analog domain, space and resources limit chain, only enough gain is used to offset the accumulated the reconfiguration options available. losses and to prevent those elements from significantly In the analog domain, only a small number of modu