Midian VPU-12A User Manual

VPU-12A

16-Code Voice Inversion Scrambler

Manual Revision: 2013-04-01

Covers Software Revisions:
VPU-12A: 3.0 and higher

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SPECIFICATIONS

Operating Voltage +3.7-15 VDC
Operating Current 3.5 mA
Operating Temperature -30 - +60 C
Frequency Response – 2100 Hz 300-1700 Hz
Frequency Response – 3100 Hz 300-2500 Hz
Frequency Response – 4100 Hz 300-3600 Hz
Audio Output Impedance <10K
Input Level 150-1000 mV p-p
Input Impedance >60K
Frequency Error <0.25%
Device Gain or Loss Unity

Inversion Frequency Range 2100 – 4100 Hz
Number of Inversion Codes 16

GENERAL INFORMATION

Midian’s VPU-12A voice inversion scrambler provides an entry level of voice security for two-way radio
communications. The VPU-12A provides up to 16 different inversion frequencies that are selectable using 4-line
binary. These inversion frequencies are programmable using Midian’s KL-3. The VPU-12A is compatible with
Midian’s VPU-12, but adds the benefit of mode indications.

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PRODUCT PROGRAMMING

The VPU-12A comes preprogrammed with default inversion frequencies (see Table 1 below). By configuring the
4-line binary outputs, the desired inversion frequency can be selected. Other default features are a Power-Up
State of Clear, a Mode Select of Momentary and a Mode Polarity of Active Low. If different parameters are
needed, the KL-4 programming interface and MPS programming software will be needed.

Table 1

Grounded Wires –

Frequency Select

(A, B, C, D)

Org/Wht, Gray, Gray/Wht, Grn/Wht 0000 1 2100
Org/Wht, Gray, Gray/Wht 0001 2 2341
Org/Wht, Gray, Grn/Wht 0010 3 2423
Org/Wht & Gray 0011 4 2587
Org/Wht, Gray/Wht, Grn/Wht 0100 5 2632
Org/Wht, Gray/Wht 0101 6 2728
Org/Wht, Grn/Wht 0110 7 2868
Org/Wht 0111 8 2976
Gray, Gray/Wht, Grn/Wht 1000 9 3023
Gray, Gray/Wht 1001 10 3107
Gray, Grn/Wht 1010 11 3333
Gray 1011 12 3388
Gray/Wht, Grn/Wht 1100 13 3500
Gray/Wht 1101 14 3729
Grn/Wht 1110 15 4096
None 1111 16 3276

The VPU-12A is programmed using the KL-4 programming interface and MPS programming software. Please
reference the KL-4 manual for setup of the programming hardware and software.

Set the parameters of the software to fit the application. If any clarifications on a feature are required, move the
mouse cursor over the feature name until the question mark appears and right click, a definition of the feature will
be shown.

After entering the parameters, save the file by going to File - Save As. Enter the file name in the File Name block
and click Save. Saving the file will allow for quick and easy reprogramming of units.

KL-4 Programming: Plug the board onto the KL-4 connector labeled as “P4”. Push and hold the power button
on the KL-4 and click “Program Unit” in the MPS software. The ACK LED on the KL-4 will faintly flash if
programmed successfully.

KL-4 Reading: Plug the board onto the KL-4 connector labeled as “P4”. Push and hold the power button on the
KL-4 and click “Read Unit” in the MPS software.

Binary Code # Inversion

Frequency

(Hz)

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Switch Mode: Select whether the switch being used for mode selection is a momentary or latched switch.
Power Up State: Select the mode you wish the scrambler to go into upon power up.
Clr/Scr Polarity: If +/- is selected then the clear mode will be a positive polarity and scramble mode will be a

negative polarity. If -/+ is selected then the clear mode will be a negative polarity and scramble mode will be a
positive polarity.

Code 1-16: Set the desired inversion frequency for each code position. The table on the previous page shows
which code is selected based upon which 4-line binary inputs are selected. If only one code is being used,
program that code in Code 16 and do not connect any of the 4-line binary inputs.

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