The SDR receiver FDM-S2
is similar in many areas to the FDM-1: the casing of the FDM-S2 is a bit bigger, the interfaces and connectors are nearly identical, the same SFE experimenter boards (see below) can be used.
The most important difference between FDM-S1 and FDM-S2 is the AD converter and the directly covered frequency range. Because the AD converter of the FDM-S2 is of a newer generation, it is more efficient: it scans faster and with higher resolution. Consequently the direct (without 'undersampling') covered reception range is increased, with the FDM-S2 up to 52 MHz (FDM-S1: 30 MHz). Additionally the new AD converter has a word length of 16 Bit, which allows for a finer resolution and an improved dynamic range. Another consequence of the new AD converter is the improved receiver in the VHF range (with undersampling). This way the FDM-S2 receives WFM without problems and the RDS signal is decoded as well. For better VHF support the FDM-S2 has its own, second antenna input (SMA connector). Please notice: VHF range is not available continuously, but only from 74 to 108 MHz and from 135 to 160 MHz.
Another improvement of the more efficient hardware is utilised by the included FDM-Sw2 software: It can now decode up to 4 'virtual' receivers in the same passband. Adjust every receiver independently to operating mode, filter, volume, squelch and so on.