It was similar to the beam landing systems being developed in the UK and Germany shortly thereafter, but had the added advantage that the directional signal was automatically decoded and displayed on a cockpit indicator, rather than requiring the attention of a radio operator.
The output of the aircraft radio was sent into a low-pass filter that split out the navigation signal on the way to the user's headphones, so it was not audible.
The low-frequency portion of the signal was then sent to into a panel instrument containing two vibrating-reed frequency meters, one tuned to 65 and the other to 86.7 Hz.
This was a single signal broadcast in a tightly focused beam placed at the far end of the runway that was tilted upward at an 8 degree angle and powered so it would become usable at about 8 miles (13 km).
The vertical indicator was simpler than the lateral, consisting simply of a ammeter connected to the output of the radio.
From then on, the approach of the aircraft towards the transmitter would result in the signal growing in strength according to the inverse square law.