A non-feedback pre-encoder for optical DQPSK modulation includes four differential encoders, two power splitters, two delay lines, one exclusive OR gate and a cross switch. The cordless cellular base station is preferably connected to a public switched telephone network and is assigned a landline number. The annular acoustic panel comprises an open framework, made from a first material, forming a plurality of cells. Hybrid maize seed, plant or plant part produced by crossing the variety PH13BP or a locus conversion of PH13BP with another maize variety. The port having the controlled data flow may have an actual usage value above a determined average shared resource usage value associated with the plurality of ports. When a cap for introducing negative pressure from the tube pump is shut off from atmosphere due to the closing operation of the valve lever, negative pressure from the tube pump can be introduced.