EM base-emitting frequency
The EM base-emitting frequency was an engineering term for measuring a phaser beam's component electromagnetic wavelengths. 

In 2366, while preparing for a battle against a Borg cube, Geordi La Forge re-tuned the phases of the  to higher EM base-emitting frequencies. La Forge hoped this adjustment would disrupt the enemy ship's subspace field. In the battle, the new phaser frequencies had no impact on the field. ()

Reports