Calculation of sub-channels is automatically performed by the IAF TDA523x
When defining a multichannel system, the correct selection of channel spacing is
extremely important. A general rule is not possible, but following must be
• If an additional SAW filter is used, all channels including their tolerances have to be
inside the SAW filter bandwidth.
• The distance between channels has to be high enough, that no overlapping can
happen. Strong input signals may still appear as recognizable input signal in the
neighboring channel because of the limited suppression of IF Filters. Example: a
typical 280kHz IF filter has at 10.3 MHz ( 10.7 Mhz-0.4 MHz ) only 30 dB suppression.
A -70 dBm input signal appears like a -100 dBm signal, which is inside the receiver
sensitivity. In critical cases the use of two IF filters must be considered. See also
Chapter 2.4.8 Functionality of the IF Path
For Lo Side LO Injection mode operation: fRF = fLO + 10.7 MHz
For Hi Side LO Injection mode operation: fRF = fLO - 10.7 MHz
Version 4.0, 2007-06-01