the digitally tuned rf selectors r&s®fk20xx are plug-in modules and can be retrofitted to the transceivers/receivers r&s®xk2100l, r&s®gx2900l and r&s®ek2000. they provide the following functions:
- seven-pole lowpass (0 hz to 30 mhz) for suppressing interference >30 mhz
- five-pole lowpass (0 hz to 1.5 mhz) for suppressing strongly interfering shortwave signals
- tunable tracking bandpass filter (1.5 mhz to 30 mhz) with stopband attenuation of 20 db/40 db at 10 % frequency offset (r&s®fk2020/2040)
- automatic tracking both in reception and transmission mode
- remote control on/off (filter in rx direction can be bypassed)
- input voltage protection up to 200 v emf
the use of the digitally tuned rf selectors ¸fk 20xx is recommendedin stronglydisturbed rf environments, i.e. for collocation scenarios such as they occur on board ships. the selectors improve both the receiver input selectivity and the phase noise at the transmitter output.
the r&s®fk20xx is always active in tx direction. in rx direction, it can be bypassed (manually or via remote control). a high linearity mode can be configured for very difficult receiving conditions.
this, however, reduces the sensitivity of the transceiver/receiver by about 20 db.