good clocks (not using GPS) and multi-channel hw [was: sidebands of great justice]

On Thu, Nov 7, 2013 at 11:32 PM, coderman wrote:

... SDR MIMO kit leaves much to be desired, however.

let me clarify: the hardware available for SDR MIMO development leaves much to be desired. ... the blocks and implementations for OFDM coding in software are OK :) USRP N2X0 can do it, other setups require external reference clock with high fidelity. any recommendations for non-GPS clocks performing at 50-100ppb or better?