CS3710 Amphion, CS3710 Datasheet - Page 5

• Manufacturer Part Number: CS3710
• Description: 32 Qam Modulator
• Manufacturer: Amphion

The SRRC (Square Root Raised Cosine) Filter consists of two
multiple-rate filters performing the shaping and filtering
function for the I-Q samples. Note that the filter is not
normalised, as this is to be considered in the hardware.
The inputs to the filter bank are:
•
Figure 5: Spectrum of Filter Output Data
Re-sampled TCM data further coded to 3-bit I-Q samples,
SRRC FILTER
The SRRC filter is a hardware specific filter, which computes
one output sample every clock (CLK) cycle using a look up
table with the coefficients specified by the coefficients selector.
The filter coefficients are obtained from a square rooted raised
cosine filter, and further decimation to two sets of polyphase
filters. The filter coefficients are quantified to 12-bits to make
full use of the fixed point dynamic range. The coefficients
selector will select coefficient set 0 whenever a new sample is
fed into the SRRC filter. The spectral shaping performance of
this filter is illustrated in Figure 5.
5
TM