Midian's VS-1000 series of inversion voice scramblers protect your voice communications against casual listeners. By mixing the frequency of the voice with an inversion tone in a balanced modulator, sum and difference frequencies are created. A low-pass filter eliminates the sum and the difference is transmitted as "inverted voice". The "inverted voice" undergoes an identical process on the receiving end that reconstructs the voice.
Midian's VS-1000 is compatible with Motorola's VPA, MX-Com's MXP-1080/1180 series, Transcrypt's SC20-400 and SC20-401, Selectone's ST-20, and others.