Frequently Asked Questions About Voice Security
Do I need digital voice encryption?
Most likely not! Digital voice encryption tends to be very costly and the benefits for many systems do not outweigh this high cost. Most users only need their conversations secured for a number of minutes or hours. Once this time period has passed the information is no longer important. Examples of this would be a military commander directing troop movements during a battle, police SWAT or Narcotics operations, a taxi or towing company picking up a fare, etc. Once the troops have moved, the SWAT operation is over or the fare is picked up the information transmitted is no longer important to an eavesdropper, therefore most systems only need a tactical level of voice security such as Midian's TVS-2 or VS-1200. Digital voice encryption is typically only needed to secure conversations for a strategic time period (i.e. months or years).
Is voice inversion scrambling secure?
Voice inversion scramblers will protect conversations from a casual listener. However, someone with some technical "know how" and the desire to break it can. Many radio manufacturers are building voice inversion scramblers into the firmware of the radio and they tend to use the same or very similar inversion frequencies. If you buy a radio with the built in inversion scrambler, someone with a radio with a built in inversion scrambler could eavesdrop on your conversation if on the same channel. Adding a Midian voice inversion scrambler, such as the VPU-12A or VS-1000, on an inversion frequency away from what the radio manufacturers have built in can provide additional privacy.
What's the difference between hopping code and sweeping code type rolling code scramblers?
Midian's TVS-2 uses the hopping type of rolling code scrambling, instead of the sweeping type, for higher security. Both types of scramblers claim a certain number of hops per second. Sweepers imply a higher level of security because they "hop" hundreds of times per second. However, it is the length of the hop that is important rather than the number of hops per second. Each "hop" of a sweeper is approximately 1 Hz in length whereas each hop of a true hopping scrambler is at least 300 Hz. Therefore it would take ~300 hops of a sweeper to equal the change of a true hopper in one hop. Because of the negligible frequency change of a sweeper, sweepers are susceptible to attack by tracking the sweeping with a phase lock loop (PLL) circuit. See the diagrams below.
Is it difficult to install a voice scrambler?
Midian supports plug in modules for many popular radio manufacturers and models including Motorola, Kenwood, Vertex, Icom, Tait and HYT. For radios not supported with a plug in module, Midian offers many application notes which are instructions on how to wire in a wired module. Many of the plug in installations can be done in just a matter of minutes. Wire in installations vary in their difficulty depending on the radio, some being very easy for a radio technician and others requiring a highly skilled radio technician.
Which kinds of systems can scramblers be used in?
Midian has installed voice scramblers in simplex radio systems, as well as repeater systems, trunking systems and voted systems.
Scramblers can also be used with signaling such as CTCSS, DCS, DTMF, 5-Tone and MDC-1200. On the transmit side the scrambler scrambles the audio prior to the signaling being encoded and on the receive side the scrambler descrambles the audio after the signaling has been decoded.