3 ms·
Q1: Do you have some BER versus SNR measurements, especially for the speaker->mic path through air? Q2: For ultrasonic: Most cheap ultrasonic transducers are v
by dbcurtis 11y ago
Q1: Do you have some BER versus SNR measurements, especially for the speaker->mic path through air?
Q2: For ultrasonic: Most cheap ultrasonic transducers are very narrow band around 40KHz. Are there barriers to moving the carrier frequency up to that range?
Q3: After a very quick look at the doc, I didn't see what kind of encoding scheme you are using?
- brian-armstrong 11y agoI don't have actual numbers. That'd be a very good thing to check. It uses convolutional codes and viterbi decoding which helps reception and decoding considerably. I suppose I should really call it nearly ultrasonic. Since I've only been able to play with standard sound hardware, and this hardware always has a low-pass filter that cuts off around 20kHz, that's the absolute highest frequency I've been able to test. When I say 44.1kHz I just mean the sampling frequency -- perhaps I should have been clearer about that, sorry :) The modulation scheme for the air path is GMSK. For cable transmission, it's OFDM + QAM1024.