VI Operating Frequencies and BrainWave

In a previous post I covered the radiowave part of the spectrum and how the frequency of a device might affect its realistic performance. A question that may have occurred to some readers is what frequency range do THS’ virtual implants (VI) work at? This is of particular interest for the Virtual Interface Implant (VII), which is nested inside the brain.
Such no operating wavelength is specified in any of the books I have read, and radio is often treated in a rather arbitrary fashion in sci-fi and general fiction, as I have discussed elsewhere. Some additional information in other books points us in a possibly fruitful direction. Broken Dreams 3e p.23 tells us “a standard AR signal, if not jammed, can typically be detected at a range of 1 mile.” Cities of the Edge 4e p.25-26 details how most of the Web traffic is via fibre-optic cables. A VI signal usually need only reach the transceivers in the nearest wall. It can also be deduced that the high-level of information being exchanged will require higher frequencies that offer better bandwidth. On the other hand, use of centimetre and millimetre bands is unlikely, since these use frequencies also utilized by microwave ovens and MADS (THS 3e p.156, 4e p.62-3) riot control. Having a device using these bands next to, or within, your brain does not seem prudent! THS 3e p.64 describes brain implants as “tiny-usually pill-sized or smaller.” Logically, VIIs, implant communicators and similar devices will need antenna of some form, but the space inside the head for these will be limited. How the VII is powered is never discussed. Replacing energy cells would not be practical. Power may be metabolic (ATP) or by wireless recharging. Whatever the system, it is probably relatively low power. Excessive heat production within the brain would need to be avoided.
Juggling all this together leads me to the conclusion that VIIs utilize UHF transmission. A range of about a mile sounds credible for a low power UHF transmission using a short aerial. A short range actually facilitates an environment where there are multiple other users. UHF works well within building interiors. UHF is the frequency used for early 21st century mobile phones. It is reasonable to assume that as use of these devices declined, the frequencies would be assigned to VI applications.
Does this mean anything in game terms? The GM and players should keep the “1 mile” range in mind. This will have little effect in a Fourth or Fifth Wave city where there are ample transceivers. Place the player out in the boonies and this becomes significant! One mile is the transmitting range. The implant may still be able to receive more powerful signals from greater distances. You may know where you are from GPS signals, but be unable to call for help. There is little point in recording a slink of climbing a mountain unless you have an external device that can boost the signal to distant receivers. Perhaps the slink is recorded instead, but for the slink to be available they have to get out alive, be rescued or their body recovered. That might be a profitable but dangerous mission. If a file you need is on a data-cube, and your AI on a brain implant, some form of hardware will be needed to read the cube and transmit the data to the implant.
Potentially, wearable devices might also utilize longer wavelengths, probably VHF. This depends on the size of the device and the practicality of using longer and/or telescopic antenna systems. This applies to wearables such as VIG and DVI (THS 3e p.142) but also to portable devices such as the hand-held/ palmscreen and book computer/ bookscreen (Broken Dreams 3e p.130). Such devices can usually read cubes or wafers without additional equipment.


“BrainWave” is an implant first encountered in 2097. Since then the technology has been widely copied.
The BrainWave is a brain implant that when triggered, emits a powerful field of centimetre-band microwave energy. This rapidly cooks the surrounding brain tissue, killing the implantee and rendering recovery of memories by brainpeel impractical. The triggering of a BrainWave is usually accompanied by wiping of a VII’s memory banks.
The BrainWave is the successor to the 20th century agent’s suicide capsule. The agent may not know they have a BrainWave implant. The BrainWave may be triggered by the agent’s companion AI when capture or interrogation seems certain, or by remote signal.