AN-PRC-64_report_AD813297_1967.pdf

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1、Co 0 (V) cJ 0) 0 Co 0 0 cJ TECHNICAL REPORT NO. 67-01 RADIO SET, AN/PRC-64 *Development and Test Program FINAL REPORT by STANLEY D. PEIRCE April 1967 DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED U. S. ARMY LIMITED WAR LABORATORY Aberdeen Proving Ground, Maryland 21005 0 -4 4J 00) ow 0j *I- 4 *4 I- 0)

2、0 tu .0 S TECHNICAL REPORT 67-01 April 1967 Radio Set AN/PRC-64 Development and Test Program By Stanley D. Peirce U. S. ARMY LIMITED WAR LABORATORY Aberdeen Proving Ground, Maryland 21005 iii ABSTRACT This report describes a lightweight man-pack radio for use by long range jungle patrols. It covers

3、the development program and the many different tests given the AN/PRC-64 Radio which lead to its acceptance for use by A Detachments of the U. S. Army Special Forces. v FOREWORD The purpose of this project was to develop a lightweight, man-pack radio set in the low HF band for use by long range jung

4、le patrols. This development was based on the PRC-52 radio made for the U. S. Army Electronic Development Laboratory under contract to Delco Radio Division of General Motors Corporation, who also produced all the AN/PRC-64 radios. The radio underwent many tests by different agencies and governments

5、in diverse parts of the world. The following paper prepared by W. B. Fegan, Major, Royal Australian Signals, would normally be an appendix to this report. However, since it so vividly explains the problem of jungle communications we took the liberty of placing it in the Foreword, feeling it would gi

6、ve the reader a much better understanding of the report. COUNTER-INSURGENCY C01UNICATIONS FOR JUNGLE OPERATIONS 1. Counter-insurgency operations generally follow a definite pattern, which is developed to counter the efforts of insurgents as they progress through the regular phases of a guerrilla for

7、ce build-up. In brief, a commander, charged with combating guerrillas and extending control over an area, must move his forces into the area and establish local bases of oper- ation. 2. These bases must be of sufficient size to dominate their local area. The primary task will be to control the civil

8、 population and isolate it from the guerrillas. Once this is achieved then the security forces must conduct offensive action against local guerrilla units. Bold, aggres- sive patrol action must then be maintained to ensure that the enemy does not effect a come-back. In some cases it may be necessary

9、 to arm friendly elements of the local population as village guards and police auxiliaries. These will require quick support by the military if they are to be effective. They can be invaluable in gaining time for the deployment of the regular forces if reliable communications and mutual confidence e

10、xist. 3. The gaining, analysis and dissemination of intelligence data is always a major effort in counter-insurgency operations. The requirements for communications facilities by intelligence officers are very heavy. In this respect, communications to civil police are very important and the military

11、 must be prepared to provide communication support to local civil authorities. 4. Another major communications requirement comes from the extensive use of air support for counter-insurgency forces. To offset the mobility of guerrilla forces in difficult terrain every possible use is made of air- mob

12、ile forces. Aerial re-supply of patrols, casualty evacuation as well as offensive air support require communications facilities. vi 5. There are many sub-divisions of the communication system which will be employed to meet these requirements. However, for the purposes of exam- ination of communicati

13、on problems peculiar to counter-insurgency operations, it is proposed to divide the system into only two categories. These may be classified as In Jungle and Out of Jungle communications. 6. Where both ends of a communication link are located outside the jungle there is no particular problem in prov

14、iding the required scale and grade of service. When one or both ends of a link are located in the Jungle there are a number of specific problems which are capable of solution, pro- viding that the problems are recognised. These problems are: a. Portable radio equipment cannot generate sufficient pow

15、er to bull-doze a signal directly through the jungle vegetation. b. Mobile groups within the jungle have to be combat ready at all times. They cannot carry large amounts of radio gear or put up elaborate antennas. They require maximum assistance from communication equipment based outside the jungle.

16、 c. There is a distinct difference in the communication require- ments of short range and long range jungle patrols operating in counter- insurgency roles. d. A means of alerting security forces when civilians are menaced by guerrillas is a most important requirement of the communications system. To

17、 obtain timely, secure and accurate information of this nature is a major problem. 7. The problems outlined above are all capable of solution. However, it must be realized that the solutions will not be achieved by producing some hardware which can be issued to combat troops as the answer to all jun

18、gle communication problems. We certainly can improve some items of equipment, to make them more suitable for this environment, but the answers come through adaptation of the available equipment, to meet the requirements of the mission, the terrain and the local enemy situation. 8. To examine the fir

19、st problem. Here is a table showing the loss at radio frequencies owing to jungle foliage: Loss per 0.1 Mile in Frequency in Megacycles Dense Jungle Foliage 2 12.6 db 3 15.4 5 20 10 28 30 48 50 63 100 86 vii 9. These figures bring out the point that low power radio sets cannot push a signal THROUGH

20、the jungle. So we are forced to accept this and look elsewhere for the solution. If both ends of a radio link can raise their antenna ABOVE the jungle there is no problem. However, we know this is an unacceptable requirement for the mobile patrols. So we have to examine the communication arrangement

21、s at the local base. The aim will be to have the base equipment as efficient as possible to compensate for the inherent inefficiency of the jungle equipment. If we can achieve this we will have the answer to problems a and b, above. 10. If we analyse the difference in communication requirements betw

22、een the types of jungle patrols we may then design the base radio installation to cater for three of our basic problems, and perhaps also provide a solu- tion for the fourth. We have already placed these patrols in two categories. These may be defined as: a. Short Range Patrols. Those patrols operat

23、ing within a 15 mile radius of the local base. b. Long Range Patrols. Those operating at ranges in excess of 15 miles. 11. The short range patrol is generally operating within the range of artillery and mortar support weapons of the local base. The requirement is principally for voice communication

24、with some telegraphy. There is a need for 24 hour reliable circuits for close supervision and coordination by the base commander. The ideal communications would be VHF (FM) radio with whisper facilities and morse capability to provide constant, noise free, high quality links. 12. The long range patr

25、ol of necessity operates beyond the immediate close support area of the local base. It must be self-sufficient in all aspects and able to stay out for extended periods. The distance factor, coupled with the high attenuation of the jungle foliage, dictates the use of radio sets operating in the HF ba

26、nd and using horizontal wire antenna. Communication is impossible when the patrol is moving but is required at any time when the patrol is halted. The patrol base must have a high efficiency antenna and maintain ceaseless listening watch to compensate for the difficulty of operation experienced by t

27、he patrol. The use of such antennas as the Shirley Array of phased and spaced dipoles has been found to be very effective. The use of high speed keyers to give burst transmission is desirable for long range patrols. 13. The problem of communicating between civilian communities and the local military

28、 base requires a new approach in communication methods. The need is for some type of fire alarm to be distributed to each community which may be concealed and triggered surreptitiously. Construction of such a device appears to be well within the state of the art at the present time. viii 14. Now tha

29、t we have examined the problems we might consider more solutions. It appears mandatory to elevate the base end of all radio links well above the jungle canopy. The most convenient way to do this would be to situate the base on high ground which overlooks the operational area. This will seldom be pos

30、sible. To put up masts is seldom a practical solu- tion as the height required for effective range is about 500 feet. The best solution appears to be the use of balloons. 15. In counter-insurgency operations there is no requirement to con- ceal the location of the static operational bases. In fact,

31、the opposite is true, as the aim is to dominate the area by a show of overwhelming military strength. Therefore, the use of large balloons anchored over the bases would be acceptable and, as they would have to be equipped with air- craft warning lights on the cables and balloon body, there might be

32、a bonus gained from the moral effect on the civilian population. In some cases these devices would also be very useful as navigation markers for jungle patrols and light aircraft who may be in a position to obtain a visual fix on the balloon warning lights. 16. The balloon equipment including gas ge

33、nerators, cables, winches, anchors, etc., should be available in easily transported packages. Normal transportation would be by truck but it would be advantageous to have the packages of convenient size and weight for transportation by light aircraft or helicopter. From investigations carried out to

34、 date, it appears that there would be no difficulty in obtaining commercial balloon equipment capable of lifting payloads of 70 to 80 pounds up to heights of 500 feet. This greatly exceeds the payload requirements for communication balloons which could vary from about 25 pounds to a maximum of about

35、 40 pounds. To obtain a relatively stable platform for the radio equipment, the balloon would require aerodynamic shaping to give lift under heavy wind conditions. The KYTOON type equipment commercially available from a number of sources in the USA would appear to be very suitable. 17. Every effort

36、should be made to use only the normal current field radio equipment for this requirement. For short range patrols the existing FM equipment would be ideal for this purpose, as the performance, size and weight characteristics of such FM radio sets as AN/PRC-25 would ensure adequate short range covera

37、ge. It may be necessary to develop a set of connectors from existing lightweight cables and plugs to operate the equip- ment by remote control. However, it should first be tried with existing remote control equipment, such as AN/GRA-6, to eliminate any time-consuming development not strictly necessa

38、ry. 18. With the addition of the balloon equipment the short range patrol communication problem will be greatly simplified and may well be completely solved in many areas. If the balloon also carries the receiver for village alarm transmitters located in the surrounding countryside it would be a lar

39、ge step forward in providing constant surveillance of the area. With the development of a suitable alarm system, the problem of alerting security forces to guerrilla action will be considerably reduced. ix MANPACK RADIO FOR LONG RANGE PATROLS IN JUNGLE WARFARE 1. The most important item of equipment

40、 in a manpack radio station is the man. He is often forgotten in studying the problem of providing optimum communications, in an environment which is very restrictive to radio propa- gation. General speaking, the approach to date has been to provide a radio set which is quite easy to carry and opera

41、te, in a temperate climate. This usually produces an equipment which can be used in the jungle but does impose severe tactical limitations, which could probably have been avoided if designers were really aware of the limitations imposed by the jungle on men at war. 2. From the moment a soldier arriv

42、es in a tropical theatre of war, he is subjected to a set of conditions that tend to undermine his resistance and lower his physical and mental efficiency. Even in areas where compara- tively good road conditions exist, it will not always be possible to make full use of the transport available, and

43、consequently the soldier will often be forced to move on foot, carrying on his back what he requires for himself and for the fighting efficiency of his unit. 3. Movement under tropical conditions is seldom easy; the ground is difficult underfoot, and is made progressively worse when a number of men

44、are forced, as they are on most occasions, to move along one track. In open country, the lack of shade and the heat from the ground increases fatigue, so that the advantages the soldier would normally expect to gain by being able to move away from the rain forest, are thereby minimized. 4. A great d

45、eal of the movement is up or down steep slopes, and the distances which can be covered in a given period, and the time during which the soldier can keep moving, are therefore much less than would be the case under non-tropical conditions, while the physical and mental strain is con- siderably greate

46、r. The basic load carried by the soldier, to enable sur- vival in the jungle, exceeds the minimum load for comfortable movement. In addition the requirement for personal weapons, ammunition, etc., adds to the burden. Communications equipment will always be additional to these basic requirements. The

47、 soldier will be overloaded before he picks up the radio set. 5. Apart from their normal role, all troops will be required to do a number of manual tasks, such as unloading landing craft, recovering air dropped supplies, digging weapon pits and numerous other tasks involving heavy physical labour. T

48、he tropical climate tends to produce lassitude even when there is no physical exertion, and strength and energy is there- fore, slowly but surely sapped. As a result, troops are continually sub- jected to conditions that tend towards excessive fatigue, and with it, a lowered resistance to disease. I

49、n addition, mental strain engendered by operations will also take its toll. In most areas it is impossible to maintain communications to troops moving in the jungle. So the radio operator is expected to do his communicating during halts when most other troops are resting. This means that the manpack radio set in jungle warfare x is often operated by an exhausted man who has to hurry in order to complete his task before the order to march is given. 6. To say that a manpack radio needs to be as light as possible is meaningless. However, we can arrive a