For wideband FM (WFM) signals, almost the entire 192kHz is required for demodulation, and it is recommended that
that the demodulation’s carrier (the vertical red line) is set to the centre DC position. In this case, the FCHid frequency
is the same as the broadcast signal’s frequency. In radio terms, this is a single, direct conversion receiver.
For narrow band signals, such as NFM, AM, SSB and CW, typically the centre DC position is often avoided as there are
hardware artefacts such as local oscillator phase noise that can interfere with reception.
When receiving narrow band signals, avoiding the centre DC position, there is a second conversion defined by the host
software’s NCO (numerically controlled oscillator). The actual frequency of the received signal will be the first
conversion shown by FCHid, plus the Frequency shown by SDR Sharp. So, it’s much like a conventional dual conversion
receiver, except the second conversion is performed in software, and that second conversion is at a much lower
frequency than would be used in a hardware receiver.
Usually it is unnecessary to adjust the settings in the FCHid program other than the frequency, although sometimes in
extremely strong signal conditions, adjusting the LNA, Mixer or IF gain may be beneficial.
Specifications
Frequency range
150kHz-240MHz and 420MHz-1.9GHz
Sensitivity
Typically 12dB SINAD NBFM for 0.15uV at 145MHz
Reference oscillator
1.5ppm 26MHz
Sampling rate
192kHz
Bit depth
16 bits (32 bits used internally)
PC interface
USB 1.x Male A Full Speed (12Mbps)
RF interface
Standard SMA female (
not
Reverse Polarity [RP])