re do we need the clipper for cheap security gtoal gtoal com graham toal writes can someone tell me if hardware compression is or is not needed to run digital speech down k i think it is i ve heard it s not lets say bit samples would raw data at the corresponding sampling rate be usable if not how fancy does the compression need to be a good vocoder like ours will give you bits per second locked at full rate it s a variable rate voice activity vocoder if you want less quality cut that to bps half rate at full rate variable you could put two full duplex conversations on a v bis modem this requires a dsp or asics though an rs has a cpu that could probably do it in real time because it has the add and multiply instruction and a few other dsp things if you want to do speech in real time you need about samples a second for not very good voice with your bit samples isdn is bit samples a second which is kbps you could do a fast compression on that to get it down to kbps which is just about v bis the quality at this point is very bleah but it should work now add in the time for your encryption method you re going to need sampling hardware which is no problem on a new mac an amiga or a pc with a soundblaster card just because they re so popular and cheap you could also build a simple adc the problem with the soundblaster is that it doesn t seem to be full duplex you can t sample and play backq at the same time making a two way conversation a bit tough the special hardware or a more capable sound card may be required the only thing that worries me is that compression the soundblaster can do it automatically in hardware but other than that i don t have a good feel for how processor intensive it is so i can t estimate how fast a pc you d need not all men who drink are poets some of us drink because we are not poets
