From: Eleanor email: eleanor@raven1.net
Date: Tue, 24 Sep 1996 08:21:53 +0000
Ed and others:
Had a night to 'sleep on' the voices-into-skull data from the file frey.htm.
I think a transmitter FAR less costly than the $50,000 estimate is possible. The $50,000 was based on the assumption that MICRO- WAVE carrier frequencies in the GHz range would be required. Test equipment that can reach into that frequency range is astronom- ically expensive.
Quite a few of the cases documented in the frey.htm article were at 425 MHz band, which these days is a common ham band for 'around town' repeater communication. (Limits are 420-450 MHz.)
A licensed ham (which I am no longer) could legally send short 'test' transmissions in that band. Testing in an all-metal bldg. could reduce the chances of testing being 'heard' outside the building at all.
The signal's power plays a role; to wit, the three apartments directly above mind have been kept vacant ever since the audio-into-my-skull transmissions became regular.
My guess is that a moderately powerful base station, say 200-300 watts, transmitting via a high gain (i.e. highly directional) 'yagi' (TV-style) antenna would be enough to cause in-skull audio reception. If really high power were necessary, the three empty apartments would not be enough.
Furthermore, the frey.htm article seems to indicate that although power level is critical, it is not particularly high. Rather than invest in expensive field strength meters, it may be enough to just try different transmitter power settings.
What all this means:
- Ham band = low chance of causing interference with critical radio services
- Ham band = large pool of people who are familiar with the equip- ment and signal characteristics
- Ham equipment = low cost
- Low end of UHF spectrum = lower cost than GHz ranges
- "Low" average power required = lower cost equipment AND probably no need for expensive test equipment; power trial and error will probably do the job
Depending on who may volunteer what in the way of services and equipment, the entire project might be done for less than $5,000 - a lot more encouraging.
There are two very specific needs for the project to go ahead:
- A 50 watt (or so) 420-450 MHz ham transmitter and high-gain yagi antenna
- Someone with good circuit design skills to build a modulator which can convert audio into the very low duty cycle pulses given in frey.htm
The modulator design project can go ahead on paper even though no physical equipment has been made available.
I wish I could design the modulator, but my circuit design skills are not up to that task. I could, under coaching from an expert designer, do some of the 'legwork' in the form of construction and testing.
The key feature of the modulator is that it is entirely an audio frequency device, and does not radiate a signal. In effect, it is just a special type of audio amplifier, like a PA amplifier or stereo system amplifier.
So I plan to shop around for a way to get that phase of the project started.
However, I am generally a recluse, and have only the most limited circle of contacts.
You addressees have collectively a very wide circle of contacts, and your efforts to locate either a transmitter/antenna volunteer supplier and/or a modulator circuit designer will go a very long way to getting this project underway.
I hope all concerned with this plague will put some effort into getting the first public demo weapon under construction.
Best wishes to all,
raven1