DE2438433C3

DE2438433C3 - Satellite communication method

Info

Publication number: DE2438433C3
Application number: DE19742438433
Authority: DE
Inventors: Jochen Dipl.-Ing. 8000 München ZiIg
Original assignee: Siemens AG
Current assignee: Siemens AG
Filing date: 1974-08-09
Publication date: 1977-04-07

Description

quenzversatz von 4,4 · 10~⁸, bezogen auf die Rahmen- System nach F i g. 1 zustande kommt, ist im ersten frequenz der Rsferenzstation. Ein beispielsweise beim Zeitdiagrammm nach Fig. 2 angegeben. Der Burst Intelsat-System spezifizierter Wert von maximal der Bodenstation BStr markiert den Rahmenbeginn 2-ΙΟ"⁷, der außerdem nur bei eingelaufenen Genera- und stellt den Referenzburst r dar. Die Bursts der toren, nämlich dem Generator der Referenzstation 5 Bodenstationen BSr 1.. .BSt 4 sind mit 1 bis 4 be- und dem von jeweils einer Bodenstation, erreicht zeichnet. Der Referenzburst r und die Bursts I bis 4 wird, wird somit beträchtlich unterschritten. Die er- der Bodenstationen bilden dabei jeweils den Empzielbare Erstzugriffsgenauigkeit, die sich aus der fangsrahmen. Von dem Referenzburst r wird jeweils eigentlichen Meßgenauigkeit sowie der Abdrift ergibt, ein Impuls abgeleitet (vgl. Diagramm n) zur Synchrodie sich aus der Frequenzgenauigkeit des Taktgenera- io nisierung der Taktgeneratoren, von denen die Sendetors während der Phasenkorrekturoperation ergibt, phase des ErstzugriSssignals abgeleitet wird. Es werkann somit ebenfalls erheblich verbessert werden. den dabei die Taktgeneratoren der Nichtreferenz-frequency offset of 4.4 · 10 ~ ⁸ , based on the frame system according to FIG. 1 comes about is in the first frequency of the reference station. For example, given in the time diagram m of FIG. The burst Intelsat system specified value of a maximum of the ground station BStr marks the beginning of the frame 2-ΙΟ " ⁷ , which also only occurs when the genera- and represents the reference burst r . The bursts of the gates, namely the generator of the reference station 5 ground stations BSr 1. .BSt 4 are denoted by 1 to 4. The reference burst r and the bursts I to 4 are thus significantly undershot The actual measurement accuracy and the drift are obtained from the reference burst r , a pulse is derived (see diagram n) for synchronization results from the frequency accuracy of the clock generation of the clock generators from which the transmitter gates result during the phase correction operation, phase of the first access signal is derived. It can thus also be considerably improved erators of non-reference

In vorteilhafter Weise kann diese Synchronisierung Stationen innerhalb der Bodenstationen durch den der Taktgeneratoren auch bei der weiteren Burstaus- empfangenen Referenzburst der Referenzstation vor sendung, d. h. also nach der Erstzugriffsoperation, 15 und zumindest während der Erstzugriffsoperation synfortgeführt werden. chronisiert. Diese Synchronisierung der Taktgenerato-Advantageously, this synchronization can be carried out by the stations within the ground stations of the clock generators also in the case of the further burst from the reference burst received by the reference station shipment, d. H. that is, continued after the first access operation, 15 and at least during the first access operation will. chronized. This synchronization of the clock generator

Anhand eines in der Zeichnung dargestellten Aus- ren kann aber auch in vorteilhafter Weise noch bei führungsbeispiels soll die Erfindung im folgenden der weiteren Burstaussendung, also nach Beendigung noch näher erläutert werden. In der Zeichnung be- der Erstzugriffsoperation, fortgeführt werden. Im deuten 20 Diagramm ο ist mit St jeweils der Start des Erstzu-With the aid of an Ausren shown in the drawing, however, the invention can also be explained in more detail in the following with reference to the further burst transmission, that is to say after completion, in the exemplary embodiment. In the drawing, the first access operation can be continued. In the interpret 20 diagram ο , St is the start of the first entry

Fig. 1 die schematische Darstellung eines Satel- griffssignals innerhalb eines Empfangsrahmens beliten-Nachrichtenübertragungsverfahrens, zeichnet. Die Erstzugriffsoperation erfolgt also in der1 shows the schematic representation of a satellite handle signal within a reception frame beliten message transmission method, draws. The first access operation takes place in the

F i g. 2 ein einen Erstzugriff einer Bodenstation Weise, daß zunächst der TDMA-Rahmen empfangen näher erläuterndes Zeitdiagramm und wird, danach in der vorstehend beschriebenen WeiseF i g. 2 an initial access of a ground station way that first received the TDMA frame Explanatory timing diagram and will, thereafter in the manner described above

Fig. 3 in einem Blockschaltbild eine Synchroni- 25 eine Synchronisierung des Taktgenerators der betrefsierungseinrichtung. fenden Bodenstation über den Referenzsynchronisie-3 shows a block diagram of a synchronization of the clock generator of the control device. ground station via the reference synchronization

In F i g. 1 ist der über der Erdoberfläche in seiner rungsburst der Referenzstation durchgeführt und da-Umlaufbahn synchron mit der Erdumdrehung sich nach das Erstzugriffssignal ausgesendet wird. Nach bewegende Satellit mit Sa bezeichnet. Er ist mit einer Beendigung der Erstzugriffsoperation erfolgt dann die Relaisstation ausgerüstet. Die Bodenstationen BStr, 30 Aussendung der Burstpräambel und der weiteren BSt 1... BSt 4 stehen alle über den Satelliten 5a mit- Bursts.In Fig. 1 is carried out above the earth's surface in its rungsburst of the reference station and because the orbit is synchronized with the earth's rotation after the first access signal is sent out. After moving satellite labeled Sa. It is then equipped with a termination of the first access operation the relay station. The ground stations BStr, 30 transmission of the burst preamble and the other BSt 1 ... BSt 4 are all over the satellite 5a with bursts.

einander in Verbindung. Jede Bodenstation, sofern Anhand des Blockschaltbildes nach Fig. 3 wirdconnected to each other. Each ground station, provided that it is based on the block diagram of FIG

sie in Betrieb ist, sendet im Rhythmus der Rahmen- die Synchronisierung noch näher erläutert. Die vom periode τ einen aus einer Präambel und sich daran Referenzsynchronisierungsburst abgeleiteten Refeanschließenden Signalkanälen bestehenden Burst zum 35 renzsynchronisierungsimpulse bzw. Spikes werden Satelliten. Innerhalb einer Rahmenperiode senden die einem Phasendiskriminator 10 zugeführt, der zugleich einzelnen Bodenstationen ihre Bursts in gegeneinan- mit dem Grundtaktgenerator 11 mit nachgeschaltetem der durch Schutzabstände getrennten Zeitintervallen, Frequenzteiler 12 verbunden ist. Der Ausgang des um sicherzustellen, daß die alle vom gleichen Träger Phasendiskriminators 10 und des Frequenzteilers 12 Gebrauch machenden Bodenstationen sich mit ihren 40 sind zur Phasensynchronisierung bzw. zur Synchroni-Bursts zeitlich nicht überlappen. sierung der Wiederholungsfrequenz des Erstzugriffs-it is in operation, sends in the rhythm of the frame - the synchronization will be explained in more detail. The ones from period τ a reference derived from a preamble and a reference synchronization burst Signal channels existing burst for 35 reference synchronization pulses or spikes Satellites. Within a frame period the send to a phase discriminator 10, which at the same time individual ground stations their bursts in relation to one another with the basic clock generator 11 with a downstream the time intervals separated by protective distances, frequency divider 12 is connected. The outcome of the to ensure that all of the same carrier phase discriminator 10 and the frequency divider 12 Ground stations making use of their 40 are for phase synchronization or for synchronizing bursts do not overlap in time. the repetition frequency of the first access

Ein Rahmen, wie er satellitenseitig bei einem signals mit der Erstzugriffseinheit 13 verbunden.A frame of the kind that is connected to the first access unit 13 on the satellite side in the event of a signal.

Hierzu 1 Blatt Zeichnungen1 sheet of drawings

Claims

i 2 can, the transmit phase generator circuit briefly with patent claims: its intrinsic value must continue to run, which results here from the basic clock frequency

1. Satellite communication method, short-term failure of the synchronization circuit - without which the time-multiplexed arrangement combined with the risk of image overlap - bridgeable volume-based Si time provided with a preamble, the longer the more precise the basic clock channels (burst) of different ground stations frequency adapted to the local requirements, it is staggered on the satellite side and, based on the fact that in practice the reference long-term frequency accuracies of about 10 ~ ⁷ realiburst marking the start of the frame can be realiburst realiburst at the beginning of the frame and can be re-ioed, they must also be transmitted in stationary operation (TDMA), in which, further to the state, the effects of any remaining implementation of an initial access to a ground frequency differences by the phase synchronization station are regulated by this device emitting an initial access signal. This happens both and its position, based on the reception, for example, through the use of frequency dividers, to set the target phase position for 15 with a variable division ratio.

the burst to be sent by the accessing ground In the interest of increased operational reliability Stations is evaluated, thereby striving to characterize the frequency accuracy of the basic clock, that the transmission phase or generators to improve or to approximate to the daily repetition frequency of the first access signal fluctuating setpoint values. Derived from the time of day will result from the setpoint fluctuations borrowed from the reference station a ° at geostationäüber the receiving side synchronized clocks from the inevitable satellites, as is well known generator and that the clock generators of the non-residual movements of the satellite, based on the earth reference stations within the surface of the ground stations.

by the received burst signals of the reference To solve this problem has already been

station before and at least during the first ace, in addition to the phase synchronization device

access operation can be synchronized. a frequency control loop of the basic clock generation

2. Satellite communication method tor to introduce their control criteria from the time Claim 1, characterized in that borrowed density s and the sign of the Syndiese Synchronization of the clock generators also causes phase control steps to be synchronized the further burst transmission is continued. 30 are directed. This circuit arrangement, which

has proven very well in steady-state operation, it also allows the aging effects of the basic

to regulate the clock generator.

The invention is based on the object for a

35 TDMA system to specify a solution with the one

Improvement of the frequency accuracy of the basic

The invention relates to a satellite clock generator already during the first access.

Direction transmission method in which the is reached in a timely or immediately afterwards,

multiplex arrangement combined with a This task is carried out with a satellite

Signal channels (burst) provided with a preamble of different directional transmission methods, in which the

These ground staiionen on the satellite side in a time-staggered multiplex arrangement combined, with a

time and, based on the signal channels (burst) providing the start of the frame mar-

kizing reference burst, combined into a frame of the earth stations on the satellite side, staggered in time

and in turn are sent out (TDMA), in which and, based on the mark the start of the frame-

furthermore, to carry out an initial access of a 45, the reference burst, combined to form a frame, and

Ground station from this a first access signal can be sent out in turn (TDMA), and at the

sent and its location, based on the recipient, to carry out an initial access of a

catching frame, for setting the target phase position for the ground station from this an initial access signal

the burst to be sent by the accessing ground and its position, based on the

station is evaluated. 50 catch frame, for setting the target phase position for

In TDMA systems, the partial bursts to be transmitted by the accessing ground-receiving ground stations require that the station is evaluated, according to the invention, in the transmission phases of its burst sequences in such a way that the transmission phase or again these burst sequences are resolved accordingly an organizational fetch frequency of the first access signal is derived from a predetermined scheme, interleaved in time at the input 55 from which the reference station is applied via the reception path of the satellite transponder. In order to ensure that the clock generator is synchronized to the side, clock generators of the non-reference stations within speaking synchronizing devices are required in each TDMA terminal to control the ground stations through the received burst of the transmit phase generator circuit. The signals of the reference station before and at least during the basic clock supply of the transmit phase generator circuit 60 are synchronized at the end of the first access operation, takes place by the TDMA basic clock generator. The method according to the invention has the advantage that the frequency accuracy of this basic clock generator has the fact that the frame frequency with which the first access significant repercussions on the conception and signal is sent only to the influence of the design of the synchronization _{device and the Doppler effects D 0} on the satellite link of the overall conception of a TDMA system. This is due essentially to the fact that in the case of a short-term non-frequency station of the frame frequency, the failure of the synchronization device, as distinguishes it from the reference station, is the reference station and D _{n on the satellite link.} In the case of the orbit data example if the reference status fails from Intelsat IV, this corresponds to a maximum fre-