JK Audio TAP-1 - Manual (Page 3)

6
The null adjustment allows you to manually optimize the
relationship between the hybrid in your telephone and the
hybrid in the TAP-1. In most applications, this can be left at
the factory setting, or set once and then left alone. If
however you are concerned with transmit / receive isolation
then you should follow this procedure:
1) With a telephone connected and in the off-hook
position, play a sine wave, noise source, or other
suitable signal into the TAP-1 line input jack. Be sure to
cover the microphone of the handset to prevent the
acoustical signal from traveling from the receiver to the
microphone.
2) Observe the signal on the output jack of the TAP-1
using a meter, oscilloscope, or amplifier and speaker.
3) Adjust the null control to find the minimum (the point
where the signal bottoms out, or is reduced to near
zero). The null adjust is a ten-turn control. Keep turning
in one direction or the other to find the null or until you
hear or feel a click. The click means you are at the end
of travel and you must reverse directions.
Hybrid Null Adjust (optional)
3
A single TAP-1 can be used in applications such as:
+ Phone testing and evaluation,
+ Training ASR algorithms for phone line use,
+ Simulating phone based services without actual
connection to a phone line.
Input__ __Output
Computer simulating
a central office
Applications
Service Simulator Example