SMAART capture and FIR questions

[EA Support]

EA Support

29 October 2023 at 11:33 am #724

>> I appear to be having issues with the API for SMAART. I’m able to see the measurements; however,
>> not able to bring them into the tab where a filter could be designed. Do you have a whitepaper
>> on this specific function?

On the Tutorials page, take a look at the “FIR Designer | SMAART Control” video.

FIR Filter Design Tutorials

>> Couple additional questions:
>>
>> Is the latency of a FIR filter a function of the number of taps?

No. The latency is a function of the filter coefficients themselves. Take a look at section 7 of the page

FIR Filter Guide

>> I have an extremely latency sensitive application which requires exact latency congruency
>> across a multitude of filters. The application is Analog Simulcast, all audio entering the
>> various transmitters must be precisely phase coherent. I would like to employ 7 different
>> FIR filters (installed into 7 miniDSP 2X4) in order to normalize frequency response of 7
>> transmitters. Amplitude must be maintained within .2dB, from transmitter to transmitter,
>> across 300 – 4000Hz. Overall amplitude is controlled elsewhere.

If there is significant phase differences (not time delay differences), then the FIR filters can be used to match the phase and amplitude before adding any alignment delay to some of the channels.

>> Ultimately, can I expect filters with the same number of taps across the same passband to have
>> equal latency? In this application, equal latency means exactly equal. We make delay adjustments
>> in Simulcast networks in 5us increments.

Remember the latency is a function of the filter coefficients or FIR filter design, not the overall number of taps. The number of taps is an upper limit on the latency that the FIR filter can provide. Again, take a look at section 7 of https://eclipseaudio.com/fir-filter-guide/.

Best,
EA Support