FPGA Central

Hello,

I'm supposed to design a transmit chain with a root-raised cosine puls
shaping filter followed by some interpolation stages.

The RRC-filter shall interpolate by 2, and its output shall b
interpolated by 8, resulting in a total interpolation of 16.

I'm told that the total characteristics of the RRC-filter + interpolatio
chain shall resemble a root-raised cosine response.

I'm new to pulse shaping and interpolation and therefore needs some help:

1) What type of interpolation filters shall I use not to destroy the RR
shape from the pulse shaping filter, and how do I dimension them (i.e. ge
their coefficients)?

2) What kind of architecture do you suggest for implementation of th
RRC-filter and interpolation filters? I've heard about polyphase filters
are these a good choise here?

3) Can you suggest a good book that covers pulse shaping, interpolatio
and filter design?

Any help would be very appreciated!
SM

"sus" <[email protected]> wrote in message
news:[email protected] ...
> Hello,
>
> I'm supposed to design a transmit chain with a root-raised cosine pulse
> shaping filter followed by some interpolation stages.
>
> The RRC-filter shall interpolate by 2, and its output shall be
> interpolated by 8, resulting in a total interpolation of 16.
>
> I'm told that the total characteristics of the RRC-filter + interpolation
> chain shall resemble a root-raised cosine response.
>
> I'm new to pulse shaping and interpolation and therefore needs some help:
>
> 1) What type of interpolation filters shall I use not to destroy the RRC
> shape from the pulse shaping filter, and how do I dimension them (i.e. get
> their coefficients)?
>
> 2) What kind of architecture do you suggest for implementation of the
> RRC-filter and interpolation filters? I've heard about polyphase filters,
> are these a good choise here?
>
> 3) Can you suggest a good book that covers pulse shaping, interpolation
> and filter design?
>

"Multirate Signal Processing for Communication Systems" fredric j harris

When it comes to interpolation filter design, polyphase filter is ofte
used because it uses less resource (memory) compared t
direct-implementation. However, it's only different implementation, s
required specification of filter doesn't change at all, so the way o
"designing filter, calculating the coefficients" doesn't change.

So, first just design the filter (calculates the coefficients) an
implement the filter in polyphase structure with those coefficients.

About RRC, root raised cosine filter, and following interpolation filter
I guess, you need to understand what the purpose of the interpolatio
after RRC. Eventually, this upsamling is compensated by downsampling a
the receiver side, and the receiver side RRC has the same rate of TX sid
RRC, so they make Raised Cosine Channel shape, after all.

The specification of RRC filter is available in many wireless phy-laye
standard, i.e. cdma, wcdma,,, etc. And you need to implement that equatio
into your system according to your system's sampling rate.

About polyphase filter, there are many dsp text books, Discrete tim
signal processing (Oppenheim&Schaffer's) also has one section o
polyphase, and it would be a good starting point to understand polyphas
decomposition. And for the advanced understanding about polyphas
structure of filters, Multirate signal processing(?) (Vadiyanathan) woul
show you the way of how to implement all these filter banks. Eventually
these things are all related to wavelet theory.


>Hello,
>
>I'm supposed to design a transmit chain with a root-raised cosine pulse
>shaping filter followed by some interpolation stages.
>
>The RRC-filter shall interpolate by 2, and its output shall be
>interpolated by 8, resulting in a total interpolation of 16.
>
>I'm told that the total characteristics of the RRC-filter
interpolation
>chain shall resemble a root-raised cosine response.
>
>I'm new to pulse shaping and interpolation and therefore needs som
help:
>
>1) What type of interpolation filters shall I use not to destroy the RRC
>shape from the pulse shaping filter, and how do I dimension them (i.e
get
>their coefficients)?
>
>2) What kind of architecture do you suggest for implementation of the
>RRC-filter and interpolation filters? I've heard about polyphas
filters,
>are these a good choise here?
>
>3) Can you suggest a good book that covers pulse shaping, interpolation
>and filter design?
>
>Any help would be very appreciated!
>SM
>
>
>
>
>
>