which acts as a terradynamic brake, leaving only the camouflaged antenna showing. The approximate detection range of this sensor is [deleted] feet for trucks and [deleted] feet for personnel-the same as the ACOUBUOY. Of course, the ranges depend on how much seismic disturbance is created and the seismic transmission qualities of the soil. ACOUSID-ADSID This device-the ACOUSID-is, as the name suggests, a combination acoustic and seismic sensor. It contains only seismic detection logic, but can transmit audio information gathered by a small microphone at the base of the antenna which can be turned on remotely to provide confirmation of a detection. Its detection ranges are the same as the ADSID. These last two sensors constitute about [deleted] percent of our sensor field in Laos. The field size today numbers over [deleted]. Since the program's inception in December 1967, over [deleted] sensors of all types have been delivered. This includes those delivered in South Vietnam in support of Army operations in country. At present, we are getting on the average [deleted] days lifetime from our latest design sensors. I have mentioned only two types of detection logic-acoustic and seismic-but we are constantly looking for better ways to find the targets we are interested in; in other words, to be more discriminating in our detection efforts. Since we are primarily looking for trucks, bulldozers, and other vehicles of that type, a [deleted] detector would be most useful. In recognition of this, we have under development the [deleted]. Senator GOLDWATER. Don't we already have that? CURRENT SENSORS-DESIGNED FOR SOUTHEAST ASIA General EVANS. We have an airborne version [deleted]. We do not have an air deliverable ground sensor. This is what we are looking for, basically the same type of logic with some refinements. As previously indicated, our current family of sensors, including [deleted], was designed specifically for use in Southeast Asia. We believe the system has demonstrated significant potential for enhancing future tactical operations worldwide, and Tactical Air Command has in fact stated a requirement for integration of IGLOO WHITE technology into TAC's worldwide operational capability. To provide this capability, improvements must be made to accommodate present sensor design to the much more severe environmental conditions to be found in many other areas of the world which are of military interest. For example, a [deleted] which will work in the temperate latitudes must be developed. Considerable effort is being devoted to this problem and we think the solution is a [deleted]. The overcrowded radio frequency environment of Central Europe presents another problem; a place in the frequency spectrum must be found in which we can operate and not interfere with other communications systems and vice-versa. We are working on this problem, also. SENSOR COST Before we leave the sensors, I would like to say a few words about their cost. To really evaluate sensor cost, we must look not only at the basic price of the sensor, but also examine its reliability, useability, and useful life. A meaningful measurement of cost would be how much it costs us to maintain a sensor in the field for one day. I know that General Deane used this approach by illustrating the change in cost of a hand-emplaced sensor. I would like to show you a comparison of factors between 1967 and 1970 which produces a cost-per-sensor day for an air-delivered sensor, the ADSID. I have chosen the ADSID which was our most popular sensor at the start of the sensor program and which is still the mainstay of our field today, with over [deleted] of them now in the ground. The basic cost of the ADSID in 1967 was $2,145. With improvements in design and production techniques, we have reduced that basic cost to about $975. This design and production experience also has moved our reliability figure from [deleted] percent in 1967 to [deleted] percent now and, as I will point out shortly, more accurate delivery of the sensors putting them where we intend so they can be used to full advantage has increased their usability from [deleted] percent to [deleted] percent. Improved battery design has lengthened sensor life from [deleted] to [deleted] days. When you consider all of these factors, the cost-per-sensor day in 1967 was $100, whereas now it costs under $15. LIFE OF SENSOR Senator CANNON. Is the life of the sensor dependent on the battery? Is that the limiting factor? General EVANS. Yes, sir; the life of a sensor is determined by the battery and, of course, the useful battery life is determined by how many activations that sensor has to transmit. [Deleted] days is a good figure for the ADSID today whereas our acoustic sensors use more power when they transmit the type of information that we heard earlier on the tape, so their lifetime is not nearly as long as the seismic sensor. How do we deliver these sensors? At first, delivery was accomplished visually. Of course, this requires good weather and easily identifiable terrain features, conditions which frequently do not exist in Southeast Asia. Also, we did not have a high-speed capability and the vulnerability of our slower moving delivery vehicles to antiaircraft fire forced high-delivery altitudes from which large implant errors were induced, as indicated by the Navy witness this morning as far as the OP-2 was concerned. Since those early days, we have developed a high-speed, nonvisual delivery capability in the form of [deleted]-equipped F-4 aircraft. [Deleted.] This slide shows the SUU-42 delivery pod mounted on an |