MXPA96005484A - Class e amplifier of linear phase for satellite communication unaterminal that communicated a satellite of orbit terrestrial b - Google Patents

Abstract

The present invention relates to a terminal for establishing communication with a low-Earth orbit satellite consisting of: means generating data signal to generate a data signal for transmission to a low-earth orbit satellite; modulation means, having a input and output, said input electrically connected to said data signal generating means for converting the data signal into a modulated phase data signal; a class E interruption amplifier, having an input and an output, said input of said class e interruption amplifier is electrically connected to said output of said modulation means, said class E interruption amplifier amplifying the phase modulated data signal in a phase modulated signal at frequencies between 148 and 150 MHz, and an antenna, electrically connected to said output of said class E interruption amplifier, to transmit the signals of f It is modulated at frequencies between 148 and 150 MHz towards the satellite deorbit terretre ba

Description

CLASS E LINEAR PHASE AMPLIFIER FOR A SATELLITE COMMUNICATION TERMINAL COMMUNICATING WITH AN ORBIT SATELLITE LOW TERRAIN FIELD OF THE INVENTION The invention relates to satellite communication systems and particularly to communication systems "with satellites." BACKGROUND OF THE INVENTION Satellite communication services are widely used in civil applications. a l? Most civil communication satellites have an orbit < jeoes + ac? onar? a a,) b, B80 lin u) land. They receive sera from a first terrestrial ation, to a terminal by ~ tat.il, and then they amplify and they adduce l? In order to transmit the signal to a second station (1 station or towers), it is used effectively to make use of the pandas of iiueioondas of anger without requiring towers. Most common microwaves used by civil communication elites are carrier bands of!), < L) 2! 3 b 111-1 a (5,425 MHz in the upper links P and 3,700 MHz to 4,700 1111 / (in the lower links) r, jn oml> «? L, l use" lo "bands The waves in a higher link, requires more complicated circuits due to the high frequencies involved, due to the fact that the geostationary satellites are stationed in a high orbit with respect to other satellites, b a high power output is required. In this way, the size of the portable terminal, the circuits and the cost when operating in microwave bands can be increased, rather than when operating in 0 An alternative satellite communication system, known as 0RLBC0I1M, has been proposed by Orbital Communications Corporation of FAi rt? , Virginia. The ORBC? MM system is described in a catalog published by 'OrbitaL Coimnum cat? Ons Corporat i on, entitled "ORBOOIIISM, Vital 5 Communications flbsolut ely flnyplace on f-IarthSM" (1 92). FL system 0RBC0HI1 is designed for Carry communications of data and position determination to a multitude of portable mobile torminals. Network 0RBC0I1Í1 provides low speed VHF digital data communications using 0 low earth orbit satellites that have a very high availability. (Jomo is shown in Figure 1, the basic system of ORLIC0HI1 uses a network of satellites 111, a network control station 112, and a base station 113 par 'communicate with portable terminals 110 .. The terminals b port ai Les they can not be pocket sized with user input and display, and can operate for long periods with battery "." A typical message of about 100 bytes or characters is transmitted from a portable terminal to a mobile device. io <- »through the satellite III and the network control center 112. The data is then stored in the network control center 112 and a user can have - at his convenience, access in a similar way" to the electronic mail. A user in a base station 113, which could be a portable computer with a HODEM, can then share the network control center 112 t > for messages through a normal telephone line 11? "A portable terminal element is an amplifier stage. The output of an amplifier in an amplifier stage is usually classified into a class commonly recognized depending on the driving characteristics of those active amplifier devices. One of the most common amplifier classes is the class amplifier. C. high power amplifiers and ba o vol Conventional (I mean-, class C), however, typically have a poor aggregative power efficiency. This is true, in part, because of the conduction losses of the relatively large currents required to develop sufficient RF output power from a low voltage source (e.g., 7 V). Or the problem associated with the Mase 0 of amplifiers that tend to be non-linear phase. Fn other words, the amplitude variation of 1 A signal of "-olue induces a phase change in the output signal, for example, when? n amplifier-class C is limited in hard. Due to the fact that class C amplifiers tend to be limited in hard, and therefore non-linear phase, class C amplifiers tend to cause spectral regrowth or problems of temperature. FL spectral regrowth occurs when lateral frequency lobes of modulated phase signals undergo non-linear phase conditions and then mix together, which can potentially cause interference in the same channel. This In this way, spectral regrowth can prevent reception in modulated phase systems. Class 0 amplifiers are also more sensitive to design parameters. For example, the ansistores can not be easily substituted even if their data sheet characteristics are similar.

Fsla sensitivity can make class 0 amplifiers in more complicated stages. These characteristics of Class C amplifiers make them bad selections for "Portable terminals when communicating with a satellite of low Earth orbit.

BRIEF DESCRIPTION OF THE INVENTION It is therefore an object of the present invention to provide an improved satellite communication system. It is another object of the present invention to provide an improved terminal for communication with low Earth orbit satellites.

Another object of the present invention will provide a high efficiency, low power amplifier pair to a satellite communications terminal which is also line phase l. These and other objects according to the invention are provided using a Class E interruption plifier for a terminal communicating with a low-order satellite. As is well known to those skilled in the art, an F-class interrupt amplifier has a voltage across the active switch device when the device is turned off and a current flow to the device's tr-fuses. when it's on In addition, the current is reset to zero before an increase in voltage, and the voltage is reduced to zero before an increase in current, when the states change at the transition points between on and off In this way, the VL power losses are kept at a minimum, and ideally at cer, the voltage and the current isolated to different states, which results in increases in efficiency., Fl amplifier Class E is described in the North American patent No. 1, 919, FJ5F-, entitled High-Ffi ciency T? ned -jwitching Power A pliier, the full description of which is incorporated herein by reference. The high efficiency amplification was achieved using an interruption amplifier that, ideally, does not dissipate energy in the circuit breaker, "you have well the whole power dissipates in the load. "*" in ideal class E terruption device does not dissipate power because it does not have voltage to s? It does not work when it is turned on and there is no current flowing through it when it is off. By operating the transistor-switch, the instantaneous power is almost zero with respect to time, so, the average power loss is almost cer-o as well. Patent F) 56, however, does not indicate the type of transistor or other specific amplifier necessary for high VHF operation, low power efficiency and low voltage, if not only mention npn transistors in gener-al. In this way, the patent ft56 does not describe circuit operation characteristics even at different frequency scales. Assumptions that are valid for HF (3 Ml-l - 30 MHz) are not applicable to the VHF band (30 MH - 300 MI-I?). 5 For more information related to class C amplifiers see-, U.S. Patent No. 4,733, 194 to Roehrs et al., entitled "Apparatus and Mehod for Parallel 1 ig Power field Fffect Transí s ors in High Frequeney í pl pliers"; "Firoadband Power Efficient Class F Ainplí fiers with fl non-Linear 0 COD Model Of The Active MO Deviee", CJ.K.n. Everard and A.J.

King, "Journal Of The Institute of Electronic And Radio Fngineers", Vol. 67, No. 7, pp. 52-58 (March / April 1 1987): and "Class F it ching-Mode RF Power flmpl i fiers - Low Powers Dissipation, Low ^ onsitivi Component Toleranes (Tncluding 5 Transist ors), and Well - Di f er end Operatio ", Nathan 0, l al and Alan D "okal, JI-FF Flectro Conference, New York, NY .. U..r, .H.

-, 'April 5, 1979). Section 73. It has been verified, in accordance with the invention, that the high efficiency of class E amplifiers can be used in a terminal pair-to communication with satellites. Thus, a terminal according to the invention includes a data signal generator, a modulator, and a class E interruption amplifier. The data signal generator may include a keypad to the fan-signal that is sensitive to the actuation. of the user to accept the input of a user's message and generate a data signal for transmission to a satellite of low Earth orbit. The modulator converts the data signal into a modulated phase signal that is then amplified by the class E interruption amplifier. In a preferred embodiment, the modulator converts the data signal into a differential phase deviation encoded data signal ISPSK. ), The class I interruption amplifier amplifies the modulated phase lane at frequencies between 14B and 150 MHz. An antenna is connected to the output of the class F deflection amplifier to transmit the phase modulated signals to the amplifier. low Earth orbit satellite. In addition, a batopa energy source can be used to produce a portable terminal. In accordance with another aspect of the invention, it has been verified that a charged amplifier for Class F operation has a characteristic linear phase transfer on predefined frequencies. Fn other words,? N amplifier - "" - l E is linear phase on predetermined frequencies. In particular, a class-F deviation amplifier according to the invention includes an interruption transistor, an input network, an E-class load network, a DC polarized network and a balanced output network. The input equalizing network connects the input signal to the interruption transistor and provides an adequate input impedance balance to ensure that the transistor is operated between cut-off and saturation. The class F load network is electrically connected to the transistor of interruption and load to the transistor for the operation class E of phase 1 meal by a predetermined bandwidth. The output balanced network connects the load network E electrically to the load and provides adequate balance of output resistance. As mentioned above, the interruption transistor opet to a predetermined interruption frequency of between 148 and 150 MHz "In accordance with another aspect of the invention, it has been verified that a transistor designed for use in wide cell phone band "can be used successfully in a satellite terminal medium." In particular, the Ciase interrupter amplifier includes a transistor that is designed to operate at a first frequency | >I will change nothing and a first predetermined voltage, < However, the transistor operates preferably below these predetermined designed levels. A power source provides a second voltage - * - "redetermined which is smaller - than the first-voltage predetermined transistor, For example, the first predetermined voltage can be 12.5 V and the second predetermined voltage can be * between 4 to 8 V. Sirily, a class F load network loads the transistor for linear phase E-class operation at a second predetermined frequency which is less than the first predetermined frequency, for example, the interruption transistor can to be a cellular transistor designed to operate at frequencies between 806 to 960 MH / In this way, the first predetermined frequencies would be between 006 MHz to 960 Ml-lz, and the load rod would then load the transistor operation by second predetermined frequencies of at 148 and 150 MHz. In other words, the second predetermined frequencies are approximately 15% of the first predetermined frequencies, the invention results in an operation of high efficiency in -line phase (that is, 00 '~~ * •%) with a low voltage supply (for example 7 V) on the VHF band. Such performance is not possible with conventional serial transistors for class C operation of typical voltage or voltage, increased efficiency allows for prolonged use of the battery, increased reliability, lower temperature of the transistor, lower cost, decreased weight, and small size for the satellite communications terminal ,, - * - BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of the ORBCOMM communications r-ed of the prior art. Figure 7 is a step diagram of a module according to the invention, which communicates with a satellite of a terrestrial orbit. Figure 1. Figure 3 is a step diagram of portions of the terminal. illustrated in Fig. 2. Fig. 4 is a stepped diagram of the class-E amplifier according to the invention for use in the terminal illustrated in Fig. 7. Fig. 5 is a circuit diagram of the class-F amplifier. illustrated in Fig. 4. Fig. 6 is a circuit diagram of an alternative embodiment of the class F amplifier illustrated in Fig. 4.

DESCRIPTION OF THE PREFERRED MODALITIES Now the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which the preferred embodiments of the invention are shown. However, this invention can be formulated in many different forms and the modalities set forth in the foregoing should not be perceived or limited; rather, modalities are provided for this description to be thorough and complete and to lead completely to the scope of the invention to those experts in the field. Similar numbers refer to similar elements in all respects. Referring now to Figure 2, a preferred embodiment of portable terminal 110 'is shown. A microprocessor 119 controls a radio frequency (RF) switch 118 and drives a light transmission mode or torminal reception. After the receiver 120 receives a lower link signal from the antenna 179 through the RF switch 118, it amplifies and mixes the signal at the correct power and frequency level for a '12 L demodulator and a Doppler frequency counter. 122. A frequency generator 125 provides local oscillator frequencies to the receiver-120 which is required to mix the received frequency at the intermediate frequency. The demodulator '121 extracts the digital data from the received signal and sends the data to the microprocessor 119. This data may contain satellite deposition information so that the microprocessor 119 can send the terminal position using an algorithm of position determination and the measured Doppler frequency. Alternatively, the data may be displayed with a message on an indicator 126, such as an LCD indicator. The portals 110 'can be pocket-sized, they can operate for a long period with a L27 battery, and can have a simple circular antenna of length of 50 cm.

"The processor 119 also controls a modulator 173 and a transmitter 124. The modulator 123 uses digitally encoded information, received from the microprocessor 119, to modulate the carrier frequency supplied from the frequency generator 125. The modulator 123 converts the data signal into a phase-shifted encoded data signal, and preferably into a symmetric differential phase-encoded data signal. The transmitter 124 then receives a modulated signal from the modulator 123. An amplified RF signal can then be transmitted from the antenna 129 to a low-earth orbit satellite III. Referring now to Fig. 3, it more fully illustrates a preferred embodiment of the transmitter 124 of the portable terminal 110 '. The croproosser 119 can provide a data signal to be transmitted, or you can monitor a message from a user device 135, as a key pad to the fan. As you know for those experts on the subject, a data message can also be provided by an RS-732 port or other well-known user inputs. After modulation with the modulator 123, a modulated data signal passes to the transmitter 124. The modulated data signal is preferably filtered by a filter 136, which may be a digital signal processor, and then pass over? digital-analogue converter 137. The analog-digital converter 137 supplies two analogous orthogonal components of the signal, namely the in-phase component and the quadrature component. The orthogonal components are then provided to a second filter 138, which is preferably a cosine vector raised to the root, also known as a Nyquist filter. As is well known to those skilled in the art, an RF signal is produces by applying the in-phase and quadrature components of the analog signal to a first and second mixers 139, L40, the outputs of which are applied to a power converter, .142. The mixers 139, 140 receive the frequency of transmission from the frequency generator 125 90 ° out of phase with each other to a phase deviator 141. The methods and circuits for providing an RF output are well known to those who have experience in the matter and therefore will not be discussed further in the present. The RF output can then be passed through a twist (liter 150, which is preferably a band filter, prior to the stages of the amplification or, depending on several factor-s, including <The size of the RF-signal from the combiner 142, the intended output power, etc., is used by a cascade of amplifier stages 151, 152, 153, 154 to evade the RF signal at its transmit level. i n. For example, four amplifier stages may be used, as shown, for 10-watt output power. The three amplifier stages may include two amplifier-class stages a, 151, 152, and one amp amplifier stage AB 153. Class A amplifiers are preferred -51, 152 as the first and second stages because because they can easily amplify small signals, however, class A amplifiers have low overall efficiency because they are turned on during the entire operating period and there is both voltage and current through their collector-emitter junctions. Even though the operating efficiency may be globally poor, they do not dissipate excessive amounts of energy because they are amplifying a small signal with respect to the stages, otherwise a class AB 153 amplifier provides better efficiency than an amplifier. Class A amplifier, but neither is amplifying the largest signal, it is the last stage that raises the RF signal to its transmission level that tends to dissipate most of the energy, and of In this way, it is the last stage whose efficiency effects the energy consumption of a portable terminal in a large amount. The operation uses a linear phase high efficiency Mase F amplifier 154 as the last stage. According to this, the input 130 of the class E amplifier 154 is connected to the output of the class amplifier AB 153, and the output 131 of the class F amplifier 154 is connected to the RF switch 118. The output signal passes then through fourth filter 155, which is preferably a low pass filter, before being transmitted from ul antenna 179. As illustrated in Figure k, the amplifier Mase E includes an interrupt transistor 160, a network If the input signal is an I / R input, it has a polarization DC 15 ?, it has a load rod, and it has an output network 164. Preferably, the interruption transistor 160 operates at a predetermined interruption frequency between 148 and 150 MHz. The DC 16 polarization r-ed? provides DC power to interrupting transistor 160 and preferably includes a battery 127. In addition to providing a polarization from DC to L interrupt transistor 160, DC bias network 162 also isolates the class E 163 charge r-ed from adverse effects, from DC. The input balanced input network 161 electrically connects the data modulated carrier signal to the interruption transistor 160. The class E load network 163 loads the interruption transistor 160 for linear phase E-class operation, preferably by a width bandwidth of 140 to 150 MHz. Applicant has found that linear phase amplifiers do not cause spectral regrowth problems associated with other amplifiers. In particular, the applicant has determined that the amplifier is an upper linear phase amplifier, and in this way is an ideal candidate for systems with a odd phase, such as SDPSK modulation. As used herein, does the linearity of f conform? The invention is a phase shift of less than about 20 ° from the output power instant to the power of the instant instantaneous. The output equalizing network 164 connects the charging network class F 163 and the antenna 129 logically. A class E interruption amplifier of-* conformity to the invention has a very short interruption time. However, in the preferred embodiment only one of the two interruption times, the shutdown time, is particularly significant. The shutdown timeout is dominated by the storage time (Taus), that is, the time (Tauß) necessary to neutralize the space charge region of a transistor.,, The storage time must be short so that no current flows, preferably "minimum" through the transistor when the next one starts? turned off). Preferably, a shutdown time suitable for the invention is approximately 10% of i / f0, where f0 is the operating frequency. In this way, for 150 Mllz, the storage time (Ta? S) is approximately 700 ps. Conventional FETs do not suffer from the typical time effects of other transistors because they are primarily carrier devices. Their output capacitances, however, are higher than bipolar transistors, which decreases efficiency. In addition, the resistance in the on state (saturation) for a conventional l- "lr is as high as that of a similar bipolar transistor, which also decreases the efficiency.Therefore, a bipolar transistor is preferred for the In this invention, the storage time (Ta? B) of a device is not specified in data sheets describing the device, however, the storage time (d) of a device is a function of fT, the common emitter unit of current gain bandwidth of the transistor, which is typically specified in data sheets of the device In the preferred embodiment, a suitable transistor has a high f "t with respect to its frequency of operation . Preferably the f "t must be at least 15 times", the operating frequency par-at a particular frequency of operation.Thus, for an operating frequency of 150 MHz, the ft must be at least Approximately 2.2 b GHz or more The rate of the invention is based on a current in the on state of 2000 rnA RMS, however, the ft of a device varies with the peak value of the current in the on state . Therefore, the variation in current in the on state varies to a suitable f "t In accordance with another aspect of the invention, a transistor can be used which this serialized to operate at a predetermined first frequency and a predetermined voltage pinner. adored; However, the tiansistor is preferably operated below these predefined designed levels. A power source 127, co, or a battery may be used to supply a second predetermined voltage to the transistor, whichever is less than the first predetermined voltage p. In addition, the loading rod class E 163 preferably loads the transistor for the linear phase operation class E at the second predetermined frequency, which is less than the first froeuenc i p r and i-m i nothing.

^ A transistor-presently preferred is MOTOROLA MRF 873 (without internal balance), which is a cellular transistor designed to operate at predetermined first frequencies between almost 806 to 960 MHz with a supply of 12.5 V. In the low power application of the invention, the transistor it can have a voltage supply of 4-8 V with the load class r-ed E 163 charging the transistor operation at second predetermined frequencies of ont re almost 148 and 150 ^, MI-lz "In other words, a second frequency default is almost 15% of the first predetermined frequency. The f? The MRF 873 is almost 2.5 GHz ((? 2000 mA RMS), which is within the theoretical minimum of 2.25 GHz referred to above, and the other suitable transistors can To be compared with its designed operating frequencies, a suitable voltage is typically found in transistors whose operating frequencies are about 750 Ml-lz.This way, the transistors designed for use within of cellulose devices, with a frequency scale in the US of 800-900 Ml-lz (European scale 890-960 MHz), are candidates for a potential replacement with MRF 073. Others are potential candidates for substitution, thanks to the interruption moments, they are the laterally diffused MOSFFIs (LDMOSFFTs) A modality of a class F interruption amplifier according to the invention is illustrated in Figure 5. An angiotensing bipolar-160 connected in a common emitting device with its emitter cone electrically connected to reference voltage (ie, ground). The re < 1 equ i input impedance librator 161, which connects i > electrically an RF input 130 to the interruption transistor 160 preferably consists of two capacitors Ci, 2 and an inductor l_? . The first capacitor Ci is electrically connected to the tripods of the base of the bipolar transistor and the voltage of the terminal. The first inductor Li is also connected electrically to the base, with the second capacitor C2 connected electrically through the inductor pr.rner l.i and the referenced voltage. The class E 163 load network, which loads the transistor 1.60 pair-to the linear phase operation class F, can use two capacitors O3, C4 and two inductors 1.2, I 4. The third and fourth capacitors O3, O4 are connected to the collector, with the third capacitor O3 connected electrically through the collector and the reference voltage. The second inductor L2 is connected electrically to the fourth capacitor- C4. f the fourth inductor- I 4 is electrically connected to the collector- of the transistor 160. Furthermore, the charging network 163 'must take into account the bait; which is the output capacitance 1 mea rizada of the interruption sensor 160. If Vcc - 6.8 6V, the output power P0 'I: 10 W, and the voltage across the collector-emitter junction of transistor 160 (Vce) to saturation is equal to zero, then: V? = 0 5768--2.1 & where Rc 'is The effective load resistance of the output impedance balancing network. If The frequency of operation, F0, is 150 MH, and it is assumed that Cs is - at 0 pF, and QL ~ 10 for a sufficient harmonic suppression, then. _, - - - - = 29 nH; 2pfn 1. 110 1 + - = 44p; And 2pf0QLRc '0, -1.7879 With C3 cone ci o, e nt o n ce < -. 10 - S nH. { 21. fn) 2RÍ C2 In this way, the nominal values for a class E power amplifier according to the invention are: 03 70 pF, 1.2 = 79 nH C «44 pF, 1.4 -" 51 nM * These nominal values are a point of departure for a later release, which may include computer simulation and experimentation. The r-ed eq? I i orr of output nnpedance 164, which electrically connects the RF output signal to a load, can also use two capacitors Cs, Ce and an inductor L3. The fifth capacitor Cs and the third inductor L3 are both electrically connected to the second inductor l_2, with the fifth capacitor C5 connected electrically and through the second inductor 12 and the reference volt .. The sixth capacitor Ce is electrically connected to through the third connector- L3 and the reference voltage., With a value for Rc ', then I 3 and Cs can be determined in a well known manner using a S ith Chart; L3 .-. 10 nH and Cs-100? F "Those skilled in the art will recognize that the elements of the output rn.rc.rn.rn.nn.sub.npector 164 can be combined with elements of the class E 163 load network [FIG. reduction of parts in general, but achieving the same results, as shown in Figure 6 on block 1 0. Using the first and second frequencies mentioned above, a set of values optimized for Cu, O12, Le. and C13 can be on the order of Cu-18 pF (power factor), O12 = 300 pF, Le-12 nH, and C13 = 75 pF. Those skilled in the art will further recognize that the specific component values for the output and input impedance signaling networks 1 and 164 will vary depending on the required gain and power output.

The latching network t) C 167, which biases the transistor 160 with a DC voltage, can include two capacitors 0? , Ca and? N inductor Ls. The seventh capacitor C7 and the fifth inductor L5 are electrically connected to the fourth inductor L4, with the seventh capacitor C7 electrically connected through the fourth inductor L4 and the reference voltage. The eighth capacitor- Ce is electrically connected through the fifth inductor Ls and the reference voltage. A set of ". values for C? , Ce, and Ls can be in the order of C7 = 1200 pF, C8 - 112000 pF, and L5 = 33 nl-l. As indicated in Figure 5, an RF input signal 130 can be applied to the transistor 160 via a DC blocking capacitor O9 electrically connected to the second capacitor C2 and the first inductor Li. similarly, an RF output signal from another blocking capacitor CIO can be received, which is connected to the third inductor L3 and to the sixth capacitor-Ce of the first output equi-bractometer 164. One second reference voltage Vcc, is preferably a DC supply voltage supplied by- [\ battery 127 to the transistor of 1 Rotation 160, the < which can est < -u connected to transient 160. \ t 1 birds of the DC polarization network 162. The arrival of satellite l - advanced small lil and the rockets of ba or cost with which they are launched, has facilitated the operation of the terminal of communication with satellite IOL 'of the present invention. The invention is intended to be linked to the ORBCOMM network described above, and the following design considerations are compatible with the needs of both systems. Satellites in low Earth orbit can operate on VHF. For example, the satellite transmission frequency band can be 137-139 MH, while the terminal transmission band can be 148-150 MHz. uses a symmetric differential phase shift coding, and - By programming the output data rate at 4800 bps and the input speed at 2400 bps, the narrowband VHF channels can be used, the data stream can then be transmitted to satellite 111 in a wide channel of 5 KHz in the band 148-150 MHz. The VHF of the narrow band also reduces costs, since it not only reduces the mass and cost of the satellites, but also reduces the cost of portable terminals 110 '. The cost of a portable terminal is currently estimated at or less than 400 dollars. The present invention gives you this less expensive way than the geostationary satellite systems and the inferred orbit voice services. The invention is also comparable with tower-based data services, but does not present the geographical limitation of any terrestrial network. In satellite 111, messages can be separated and trans- mitted downwards into one of a number of wide channels of 10 KHz in the 137-139 MHz band. Each satellite can additionally transmit time signals and other signals. data "in a UHF channel designated a, eg, 400.1 MHz. Satellites 111 may typically be in a circular orbit at an altitude of approximately 888 kilometers above the earth. In this way, half the beam width can be close to 60 degrees, and the coverage pattern will be almost 5,319 kilometers in diameter. The antenna pattern of the satellite III can be designed to produce an increased gain outside the viewing beam to compensate for longer path lengths at portable terminals 110 'near the edge of the coverage pattern. A constellation of Earth orbiting satellites ba lll produces a continuously changing coverage pattern, with the uncovered areas moving constantly as well. Preferably, the satellites III do not have extensive memories and thus can not operate in a forward or full storage mode. In this way, the availability of a satellite link requires that one of the satellites 111 have a simultaneous view of the portable terminal 110 '., and it is either the r-ed 112 control center or a relay station (not shown). In any case, it is contemplated that many regions would have availability times in excess of 95%. By way of example, an availability to a certain remote terminal location of 98% would mean that, on average, there would be an interruption of communications in that location of 7% of the Lempo, or 29 minutes in each 24-hour period. This is not 75 It dignifies, without embarrassment, that there would be only one interruption each day that lasted about one hour. On the contrary, the interruptions would be frequent, short and almost uniformly distributed over time. It is estimated that with a contour of 95%, 90% of the i terruptions would last less than two minutes.

The global communication terminal 110 'in accordance with the present invention is not damaged by interruptions of this type. Instead, these interruptions allow a - • effective and low-cost global satellite communication terminal. In the drawings and specification typical preferred embodiments of the invention have been described and, although specific terms are used, they are used in a generic and descriptive sense only, and not for limitation purposes, the scope being established of the invention in Las si? Lenses rei in ications.

Claims (2)

2b NOVELTY OF THE INVENTION CLAIMS

1. - A terminal to establish communication with a low Earth orbit satellite that consists of: means generating data signal to generate a signal data pair-a s? transmission to a satellite of low Earth orbit; - modulation means, having an input and an output, said input electrically connected to said data signal generating means to convert the data serial to a modulated phase data signal; a Mase F interruption amplifier, having an input and an output, said input of said class E interruption amplifier is electrically connected to said output of said modulation means, said class F interruption amplifier amplifying the modulated phase data signal in a phase modulated signal at frequencies between 1 and 150 MHz; and an antenna, electrically connected to said output of said Ciase interrupter amplifier E, for transmitting the modulated phase signals at frequencies between 148 and 150 Ml-lz to the low Earth orbiting satellite.

2. A torminal according to claim 1, further characterized in that said modulation means convert said data signal into a ser! of encoded data of phase deviation, and because said amplifier or interruption Maso E is a class E linear phase interruption amplifier on? n bandwidth between 148 and 1 0 MHz. 3.- A terminal in accordance with the claim 2, further characterized in that said modulation means converts said data signal into a data signal encoded by differential symmetric phase deviation. 4.- A terminal of conformity with the claim "M, further characterized in that said means" the generation of data signal consist of input means for the user, which respond to the activation of the user, to accept the input of a message from the user. 5.- A terminal in accordance with the claim 1 which also consists of a battery power source connected electrically to both the data signal generation means and the class E interruption amplifier, in order to produce a portable terminal. 6. A terminal according to claim 1 in combination with a terrestrial satellite orb satellite, which receives the phase-modulated sera from between? 148 and 150 MHz. 7. A torminal according to claim 1, further characterized in that said class F interruption amplifier consists of: an interruption transthat operates at a predetermined interrupting frequency between 148 and 150 MHz; DC power source means for supplying DC power to said interruption transistor; an input balancing network, which electrically connects said data signal generation means to said interruption transistor; a load class R-ed E, electrically connected to said interruption transistor, which loads said interruption transistor to a class F operation; and an output equalizing network, electrically connected between said class F load network and said antenna. 8. A terminal in accordance with claim 7, fell furthermore because said class E load network is a linear phase load buster, which loads said interrupt an- choresor for an operation of linear phase class F over a bandwidth of between 148 and 150 MHz. 9. - A class-U interruption amplifier to amplify an input signal and drive a load over a predetermined bandwidth, said class interruption amplifier E consists of: a t ansistor, which is designed to operate at a predetermined first frequency, which is greater than 800 MHz, and at a predetermined first voltage; power source means for substituting a second predetermined voltage to said transistor, said second predetermined voltage being less than said predetermined vortex pprner; an incoming charging network, electrically connecting the input signal to said transistor "; an E-class charging network, electrically connected to said transistor, which charges said transistor to a transistor; ) linear phase ration Mase F at a second predetermined frequency, which is between 148 to 150 MHz; and an equi 1 output grid, electrically connected between said class E load r-ed and the load. 10. An E-class interruption amplifier according to claim 9, further characterized in that said second predetermined frequency is 15% of said first predefined frequency. 11. An interruption amplifier cia and F according to claim 9, further characterized in that said first predetermined voltage is 12.5 V, and because said second predetermined voltage is between 4 to 8 V. 12.- An amplifier- Class E interrupt according to claim 11, further characterized in that said transistor is a cellular transistor - designed to operate at first frequencies p? What are the frequencies on the 806 to 960 MHz, and why does said charging network load said transistor-to operate at predetermined second frequencies? my swimmers between 148 and 150 MHz. 13.- A Mase F terruption amplifier conformed with the claim 9, which also consists of an input signal, electrically connected to said input equi input network. , said input field is a coded input signal of phase deviation and said class E-interrupt amplifier is a linear phase amplifier of class F phase to second frequency. e 148 and 150 MHz. 14. An E-class interruption amplifier according to claim 13, further characterized in that said input signal is an input signal.