Re: [Discuss-gnuradio] Success (kinda)

[Alan Gray]

Ok, I think I've found where my problem is occurring for real time 
processing. It appears that with the MC4020 driver you are reading in data 
to a buffer, and reading straight from that same buffer to get data into 
GNU Radio. From what I can tell of the operation of the Adlink card, it 
first reads the data into a buffer, then to access this data it is copied 
to a second location in user space.

I imagine that having to move that large an amount of data around so much 
is going to have a pretty adverse effect on the performance of my system, 
however I can't see an easy way around it without access to some of the 
internals of the Adlink software (I've sent an email out, but I don't hold 
much hope)

I have had a bit of success on the non-real-time front though, I've still 
only got one disk at the moment, but with DMA enabled it gives me about 
33MB/s sustained transfer, which is enough to snag about 5 seconds of data 
which I can then process successfully to get a good quality audio stream.

When I have the chance, I'll draw up a decent schematic of the circuit I've 
used for the 4702 tuner (it's much the same as the 4937 circuit, with a few 
mods) and clean up the code a little to add to the archives

Alan