Add multichannel support

[darkstar007]

My current fork add the following things:

• Multichannel support
• Support for large files
• Antenna selection option
• Bandwidth selection option
• Long format options

This means you can do something like:

rx_sdr -d driver=lime -f 498e6 -F CS16 --gain0 50 --gain1 32 -n 200000M -A LNAL -B9M -s 10000000 -N2 dtv_ch0.ci16 dtv_lch1.ci16

This create 2 files, one per channel, with channel 0 gain set to 50 and channel 1 gain set to 32, both using their LNAL antenna port with 9e6Hz of bandwidth on the 10Ms/s sampling.

Max number of channels is compile time set (currently 8).

For the long options '--gain 10', for example, would set the gain of all channels to be 10, so something like '--gain 10 --gain2 30' would set the gain of all channels to be 10 and then set channel 2 to be 30.

Thanks,

Matt

[romeojulietthotel]

I tried your fork and it's not working correctly. With this many changes I would split them up into as many separate PRs as possible. This makes the maintainer's job easier. I like the idea of being able to specify antenna, etc.

EDIT: I got it working, I did not have command line options in the right order apparently. But the app seg faults which means there's a problem somewhere. It may be that your new options need to be optional and not cause seg faults. But maybe that's an issue without this PR.