[music-dsp] Video FIR filters

Alex Raider flashinc at mail.ru
Wed Jan 14 15:16:01 EST 2004


Hi.

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DO> What I'm having trouble with is a totally stable echo phenomenon in
DO> the cable. (Sharpness is actually pretty good with the FireGL 8800, 
DO> though that's part because of an adjustable filter in the monitor's 
DO> DSP.) So I figured one could throw in a FIR filter that negates the 
DO> response of the RAMDAC/cable/monitor system. One would have to tweak 
DO> the filter manually until the result is acceptable.

DO> It's just that we're talking about 300-400 MHz, three channels and 10 
DO> bit dynamic range. My first idea was to use a DSP, but where would I 
DO> found one that's anywere near the kind of performance I need? It 
DO> would have to be heavily SIMD and/or have a clock frequency in the 
DO> multiple GHz range.

[skip]

DO> How about FIR filter chips? Seen some, but they're usually all digital 
DO> (not S&H based) and 3-5 coefficients or so.
DO> I need FIR filters with a sample rate of at least 400 MHz, >60 dB SNR
DO> and at least 8 coefficients. They should preferably be programmable 
DO> during operation, for easy tweaking. If it can be done via I2C, USB, 
DO> RS-232, RS-485 or something, even better! A ton of trim pots would be 
DO> ok, though.
DO> Are there any suitable chips for something like this?

Take a closer look to  field programmable gate array chips, (FPGA) and
similar.
They often used for custom dsp processing in radars
400 Mhz is not a limit for FPGA devices. If i corect, Altera devices
can be programmed through simple byteblaster cable on LPT port.
Also, atmel/altera software contain special applications for
designing fir filters directly.
Also take a look to www.atmel.com, www.altera.com www.fpgacpu, www.opencores.org




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