Obvious bursts, unknown modulation. Long burst heard every 5-10 seconds on average. IQQuadrature signals form the basis of complex RF signal modulation and demodulation, both in hardware and in software, as well as in complex signal analysis. file in description. First thought is some kind of trunking, as it is very close to the band where trunking radio is usually seen.
Modulation is not obvious when FMFrequency Modulation demodulated bursts viewed in Audacity.
Check http://www.sigidwiki.com/wiki/Digital_Mobile_Radio_(DMR), Half slot TDMATime Division Multiple Access sample.
EDIT: I haven't been able to get DMR to decode, and it doesn't seem as evenly spaced as slotted DMR.
EDIT : Try tetra.
Found on 405.822MHz.