NEW
COPYRIGHT (C) 1991 BY FULL DISCLOSURE. ALL RIGHTS RESERVED.
The
The FBI's original estimate for establishing a digial voice protection system was $79.3 million.
The March 8th report indicates that "[b]ecause the FBI's estimated savings cited in the table are very preliminary and are not supported by formal field surveys or other documentation, we continue to believe that the $204.4 million and the latest $205.8 million estimate for the nationwide voice privacy program appear to be unrealistic.''
A big part of the major cost overrun was a lack of technological review of what they were getting into.
"Our
"In a follow-up discussion, a key
However, a 1984 from the Deputy Assistant Director, Technical Services
Division, the following range loss problems were described: "The Motorola
Much of the FBI's difficults seems to be from a lack of proper management.
According to the
Now, the
These radios are not
According to Transcrypt's brochure, "encryption insures that no outside party can understand radio transmissions, an encrypted radio signal has a very distinctive sound; and with the right equipment, it can be jammed, intercepted, or the source located.''
Even though their brochure claims that both the public and private sectors
outside
The idea behind frequency hopping radios is that rather than transmitting
constantly on one frequency, the frequency is changed many times per second
in a pseudo-random fashion. These radios switch from 12 to 50 times per
second, between any channels in a programmable window of the 148-174
Therefore, with a standard scanner one would not notice the existence of such transmission, nor be able to pin point them. Monitoring one of the frequencies it used in its hopping sequence would result only in a burst of noise 1/12 to 1/50 of a second in duration.
Another brochure from
Finally, the
The fact that the transmissions need or gain from having "cover'' indicates that they are not invisible.
Technical sources suggested the following as a method of detecting use of frequency hopping radios in the area. Hook a cable ready TV set to an appropriate antenna and tune it to the federal band (160-172mhz). Cable channels G, H and I. Each channel will display a 5mhz spectrum of the federal band. The complete frequency range of the radio would be cable channels A through I and 7.
The sources indicated that operation of a frequency hopping radio in the area will show a distinct pattern on the screen. To test this theory, Full Disclosure hooked up a low power programable RF oscillator to switch frequencies 15 times per second in the 160mhz range and powering the unit on showed a distinct change (unique unsynchronized horizontal lines) in the display on a TV set tuned to that frequency.
Because of the narrow window the units use, after locating the frequency of the window, jamming the unit could be accomplished with a wide bandwidth transmitter. (1.6mhz isn't real wide, compared to a 5mhz video transmitter). If a little used portion of the VHF band was selected for operation by the frequency hopping radios, jamming could be accomplished with little interference to other transmissions.
There is some dispute over the effectiveness of using a spectrum analyzer to spot the use of frequency hopping radios. One technical source aptly pointed out "why worry about whether a spectrum analyzer works when a $100 TV set does?''
As with any new surveillance technology, there is a gap between its introduction and the availablity of countermeasures. Unlike spread spectrum radios that switch frequencies over the entire RF spectrum, frequency hopping radios operate in a very small window making detection, jamming, and direction finding a much simpler task.
The following are selected specifications for the PH-26 and MH-26 radios. Figures in ()'s are for the MH-26 when different.
Frequency Programming Range: 148-174MHz. Frequency stability: .0005%.
Frequency spacing: 5, 6.25, 12.5, 15, 25 or 30KHz. Transmitter: Power Output:
1 or 5 watts (30 watts). Modulation: FM. Receiver: Sensitivity 12 db. Sinad:
.25uv. Selectivity @30Khz: 70 db. Audio Output: 500mw (5 watts). Frequency
Agil Mode: Number of channels: 4096. Frequency series: Pseudorandom (PR).
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