Method for the interference-resistant transmission of communications

The invention relates to a method for radio transmission, resistant to disturbances, ι

j of vocal signals processed by vocoder, with! ........ ....... ............ ~ "..................

the use of expanded frequency bands (SSMA) or a rapid change of radiofrequency. To remedy [the consequent danger of an own disturbance,

I j that occurs when many stations use i

I simultaneously the same frequency band or '' ........... ".......... ........

ì the same collection of radio frequency channels, it is proposed to activate the transmitter (SR) and! the receiver (ER) with the rhythm of the frame rate inside the system (RT), during a period of frame rate, only when useful information is also present. In this way, about 40% of the time of urasmx sxone can be averaged xn links to alternating communication in the two directions and more than 60% of the transmission time in the duplex service, correspondingly mitigating

· X * - *

-PlacezzaCastello, the disturbance of the system

Description

The invention refers to a method for a radio transmission, resistant to disturbances, of vocal signals processed by vocoder, with the use of expanded frequency bands (SSMA) or of a rapid change of radio frequency (EH).

'l ·'

For the use of tactical radio devices in the military field, high resistance against intentional disturbances of any kind is of decisive importance. For this purpose, transmission procedures must be adopted, in which the transmitted signals can not be easily compromised by potential disturbance transmitters. Such a transmission procedure is offered, for example, by the so-called SSMA technique. This phrase derives from the esprps.

English Spread-Spectrum-Multiple-Technique

Access-Modulation ". An application of this procedure is indicated for example in the Germanic patent; western 21 21 117. In this case, the frequency band of the useful signal to be transmitted is j

I 1! strongly expanded by means of a characteristic modulation and this expansion is again revoked in the receiving section by a correlator. In₍ I 'this way, strong disturbances in the form of singles

BRETCTTT JAUMANN CONSULTING STUDIO

MILAN-Piazza Castello, 2

- 5 spectral irigas are considerably attenuated with respect to the useful signal. Another procedure with; ! isiste in adopting a rapid change of radiofre- I

..

during transmission, so that it is difficult for a powerful transmitter to switch to the radio channel quickly enough.

The frequency currently used. Radio systems, which use a radiofrequency blowing method, are known, for example, from the patents in the region 4 </ 37 159 · resistance to signal disturbances to be transmitted is much higher, the smaller the bandwidth may be. useful of the signal with respect to the bandwidth transmitted.

For this reason it is advisable that in voice transmission, to increase the resistance to disturbances, in addition to adopting the described techniques, vocoders are also used. In this case, in the transmitting section, by means of a vocoder analyzer, the speech signal is attenuated with respect to its specific parameters of the voice and only these parameters are transmitted in coded form to the receiving section. In the vocoder synthesizer of the receiving section, through these parameters and together with an impulsive excitation function and a noise excitation function the segija is synthesized^{r, az}'^{it's at} Castello, f the original vowel. In addition to a reduction in the useful bandwidth, the coded form

......... Н delusegliele transmitted also allows encryption with a high degree of secrecy, which is normally also required for military use in addition to the already

mentioned resistance to disturbances. 'j

As can be seen in practice, the above mentioned ί

procedures for a transmission of rendered messages ί

suffering from disturbances can cause their own disturbances. When adopting the SSMA technique, many stations simultaneously use the same fréί band_; quence.For a given receiver, which with the aid of its correlator receives the signal ί

I only need a signal determined by the modula .......................................... ................................................. " "................................................. ... ions, all the useful signals transmes, at the same time, for other stations, they behave as disturbance or noise signals at the input * of the receiver. In other words, with reference to 'i

to the assigned frequency band, the number of! stations that are simultaneously in serious trouble must remain limited to such an extent that a

ί ....... "......................................... ............................... ................... .................................................. ...... .. j ......

! receiver can still receive the j perfectly; signal that is destined to him, separating it from the noise.

; ............................ ..................... ....... .......................... ί ......

Similar considerations apply when i!

adopt a rapid change of radiofrequency. In this

STUDIO CONStltfWA frRtVETfl JAUMANN

I LANO-Piazza Castello, t base, it should be borne in mind that in total there is only a limited number of radiofrequencies

I whose order of magnitude is about 5> Q0. These are the · »

500 radiofrequencies can, for example, be set to

The arrangement of one of the various radio links one;

I! r

Assortment of about 120 radiofrequencies. For various j! ,. ..... ............. the motives it is practically impossible to foresee a superior command, which controls a plurality of radio-

I!

links to carry out a jumped procedure '....... ................................... ............ | synchronous Since the available frequencies are limited},] it is also excluded that a reserved channel bundle can be assigned to each radioI. · Since X radios or connections are not synchronous neither in the jump phase nor in the jump frequency program}.

----------- j.

the isi will therefore have, with probable probability, so-}]

Variable widths of information blocks of equal frequency transmitted by v

The radio sets of the various radio links.

I j With the aforementioned MEI I voice transmission

Ί ................................................. .................. .........!

by means of a vocoder, which reduces redundancy, it is obtained

I maintains an acceptable quality of the voice 'in practice, if less than 2% of all the blocks are interrupted, quit, if the duration of the blocks is sufficient. ...................... "• shortly and the vocal synthesizer has knowledge of the disturbance For a collection of 128 radJo1 studio consulehu smn« umann MILAN-Piazza Castle, 2 blowing frequencies, this amount of disturbance ver!. '"' Ì pebbe already exceeded when in the troubled sector« pet! ..... - simultaneously create more than 3 radio links. j¹ J

For a procedure of the kind described, at the beginning, the invention poses the problem of indicating another solution which substantially reduces ι ... ì

The kl disturbs its own and therefore, being assigned the {'~ ..................................... ...... the transmitted frequency band or the collection of

I!

trivial radiofrequency, allow-to raise sensi-;

ί ...... .............!

if necessary, the admissible number of j ί .... ........

I (stations in contemporary function.

Starting from a procedure for a radio transmission, resistance to disturbances, of vocal signals processed by vocoder, with the use of (expanded frequency bands or a rapid change of! .......... ...............-............-.......... I · tcadiofrequency, said problem is solved according to {l invention for the fact that with the processing of ί ..............-.................... f .. ...

voice signal to be transmitted, carried out in the vocoder analyzer of the transmitting section, a signal criterion is obtained referring to caj! ........-......... ----... ........................; --------------------..... .. | (plot dance within the system, by which! .......... ....... '.................... ...........ⁿ'™' makes the transmitter or the final stage of the transmitter, whether it is present or not present in the respective element is switched on or off, secondly a time signal of a period of the frame rate,

STUDIO CONSUIEMA PATENTS JAUMANN

MILAN-Piazza Castello. 1Ì, as well as for the fact that the signal segments, referred to the frame rate internal to the system and digitized for their transmission to the receiving section, are equipped, where necessary, with data protection information, for the recognition of errors, and furthermore, due to the fact that, in the receiving section, with the decoding of the incoming signal segments, the signal criterion is reconstructed when necessary by the data protection information and, with reference to the period of the frame rate, it is used for switch the vocoder synthesizer on or off at the receiver output depending on a signal present or not present.

The invention is based on the notion that, also for links to alternating communications in the two directions, medial about 40% of the transmission time is useless, if we save even small fractions (lasting 20 ms and up). In these; conditions, the sparing time for duplex connections can even exceed 60%.

Ϊ;

jThis saving contributes entirely to reducing "i ί

'their own trouble. For example, in simplex jsi service it can almost double and in duplex service it is almost possible to triple the number of stations opeSTUDIO CONSULENZA PATENT JAUMANN

I LANO-Piazza Castello, 2 at the same time in the same area of ​​radiocommunication, having to respect the residual error index still tolerated in known systems. In this regard it is also very advantageous that this saving in transmission time also entails an increase in EOI resistance, because the receivers are inserted only if a signal is present in the time intervals determined by the internal frame rate.

If a rapid change of radiofrequency is adopted, then in order to best exploit the reduction of the proper disturbances, made possible by the solution according to the invention, it is necessary that the frequency drop interval corresponds exactly to 1, 2, ... , n frame periods of the vocoder and is synchronized on the frame rate or on. • one of its multiple.

To prevent the vocoder synthesizer of the receiving channel from being switched off when the indication "no signal" is caused by a disturbance of the reception, it is advisable that the criterion, of reconstructed signal in the receiving section, be; value in a signal hour, at whose second center the received signal is received. In particular. the signal evaluator provides a command signal to switch off the voice synthesizer only if at the instant in which a "no signal" signal appears, there is no signal interruption due to a disturbance.

The invention is explained in greater detail below, taking into consideration examples of embodiment represented in the drawing.

In the drawing:

fig. 1 shows the block diagram of the transmission and reception sections of a radio station, which belongs to a radiocommunication system, which employs the frequency skip technique, and operates with the insertion and disconnection of the transmitter and of the receiver according to the invention, FIG. 2 shows the block diagram of the transmission and reception sections of a radio station, which belongs to a radiocommunication system 5, which uses the SSLLA technique, ie it works with the insertion and disconnection of the 1 '' ';

transmitter and receiver according to the invention; fig. 5 shows the block diagram, mag; detailed, of a vocoder analyzer of the transmitting section according to FIGS. 1 and 2,

JAUMANN PATENT CONSULTANCY STUDIO

I LANO-Piazza Castello, 2 fig. 4 shows the more detailed block diagram of the vocoder synthesizer of the receiving section according to FIGS. 1 and 2.

The transmitting section of the block diagram of a radio station, shown in fig. 1, presents the VOS vocoder analyzer, which is excited at the input by the microphone output signal Mi. The VOS vocoder analyzer has two outputs. The output provides the representative parameters of the entry, which are coded with redundancy in the CO encoder in order to be able to detect transmission errors, and are then fed to the SR transmitter. In the exemplary embodiment according to FIG. 1, the SR transmitter is provided with an RS device for a rapid frequency change. I se; codified signals are transformed into the transmitter;

SR in radiofrequency signals and are irradiated by the antenna As radio frequency signals, received by the antenna A and of the receiving section, are; transposed into the baseband in the ER receiver, which is similar to the SR transmitter with uni f

RS device for rapid frequency change;

. synchron.9, and are then examined in the decoder DE to detect any transmission errors.

JAUMANN PATENT CONSULTANCY STUDIO

MILAN-Piazza Castello, 2

The decoder DE has two outputs, which are connected with the two inputs of the VOE vocoder synthesizer of the receiving section. On an entry, the vocoder synthesizer receives from the decoder

LE the specific parameters of the voice, analyzed in the vocoder analyzer of the transmitting section, by means of which the synthesizer reconstructs for / intended the original signal, which is irradiated through the receiving capsule H.

According to the invention, the VOS vocoder analyzer of the transmitting section provides on its second output a signal criterion if, which indicates whether, with reference to the internal frame rate, a useful signal is or is not present, during a period deli, plot. This signal is obtained in the course of the analysis and is fed, through a delay element ί, to a second input of the transmitter SR, where it is used to insert and disarm the transmitter according to whether a signal is present or not present. In other words, the SR transmitter comes

I always unplugged during the exercise, with the rhythm '

Ϊ the internal frame rate of the VOS vocoder analyzer, if no signal is present in the time frame of a period of the frame. In

DBDIO CONSULTING PATENTS JAUMANk

MI LANO-Piazza Castello, 2.

In this case, the RS device provided for the rapid change of function is also referred to the frame rate and precisely in such a way as to effect a radio frequency change at each passage from one signal segment to the other.

In order that in the receiver section the receiver can be switched on and off in the same way, depending on whether or not a signal is present, the receiver or the vocoder synthesizer (VOE must be able to distinguish a signal from a noise. the specific samples of the entry at the input of the coder CO, which each represent a segment of signal and are obtained in a period of the frame, in

: of a signal are provided in the cross-section_:

... and the sender of a data protection information, which allows, in the decoder DE, a reconciliation or even a correction of transfer errors: on its second output, the decoder sends a corresponding signal. , in the form ((of the signal criterion if ', at the second input, of the VOE vocoder synthesizer.) In the VOE vocoder synthesizer, the signal criterion¹ otrJ 'held in this way is used to insert

I and switch off the vocoder synthesizer.

PATENT CONSULTANCY iAUMANN

MlLANO-Piazza Castello, 2

- 15 A variant of the radio station according to fig. 1 is illustrated by the block diagram according to fig. 2, which represents a radio station in a radiocommunication network operating with the SSHA technique. In this case, in the transmitting section, the signal segments at the output of the VOS vocoder analyzer are fed to a modulator M, in which a characteristic modulation provided by a quasi-thermal generator is impressed on each individual bit of these signal segments. random QZ. The expansion of the useful frequency band obtained in this way is revoked in the same way in the receiving section, by means of a characteristic modulation produced therein in an identical quasi-random generator QZ, in the modulator following the output of the receiver ER, and the signal obtained in this way is fed to an evaluation circuit. The evaluation circuitry AS supplies, on the. its first output, the signal bits, which represent the useful transmission, at the first entry of the

VOE vocoder synthesizers. On the second output of the evaluation circuit a signal appears only in the absence of signal bits or in the presence of noise. Signal bed is integrated into the I-host for the duration of a signal segment.

SriiDIO CONSULENZA PATENTS JÀUMÀNN

MILAN-Piazza Castello, Γ

Ί4 The "yes" signal that appears at the output of integrator I is fed into a decision loop ES, which at the input of a signal segment produces!

I the signal criterion if * and gives it to the second input of the VOE vocoder synthesizer to engage and disarm the latter depending on the presence or absence of a signal segment.

! To better understand how the transmitter and receiver are switched on and off: according to the invention in radio stations according to ifigg. 1 and 2, in FIGS. 5 and 4 are respectively ι

more detailed block diagrams are shown, which illustrate the vocoder analyzer

VOS of the transmitteme section and ± 1 sxnteOj-zzabore ì

The VOE vocoder idi of the receiving section. The analysis section of the delvaooder section of the transmitting section! · '.......

isecond the fig. 5 has SK1 spectral channels,

ÌSK2, ..., SKn connected in parallel to the output of j ...... ----- ....

Mi mi microphone These spectral channels divide r

The vocal band, by means of band filters, in various [partial bands, which at the output are equalized and, by means of a low pass, are freed from unwanted components at a higher frequency. Subsequently these output signals of the spectral channels, which are also called partial signals

JAUMANN PATENT CONSULTANCY STUDIO

I LA AIO-Piazza Castello, 2

- 15 envelopes are sampled and converted into coded signals in an analog-digital A / D converter.

In order to be able to synthesize in the receiving section the vocaòhe appears at the microphone output, one must also obtain a signal indicating the fundamental vocal frequency, ie a so-called pitch signal, and a signal indicating the quality of the sounds. In the analysis section of the "vocoder according to Fig. 3, two further channels are provided for, namely a SGP channel with a filter for the fundamental speech frequency and an LB channel with a circuit to determine the sound quality. from the SGP and LB channels, they are also coded by means of an analog-digital A / D converter and are combined with the digital outputs of the SK1 ... SKn spectral channels, in the multiplexer MUX, to form a pulse frame having a duration of about 20 ms The signal criterion sc required to engage and disengage the SR transmitter, is obtained by the adder-amplifier SU, and the following threshold circuit SW. The UP amplifier adds up the signals, which appear at the inputs of the analog-to-digital A / D converters of the spectral channels. Secondly, the sum exceeds or

- 16 MtLANO-Piazza Castello, does not exceed the threshold of the SW threshold circuit, the signal at the output of the threshold circuit SW indicates the criterion "signal present" or "signal not present".

The synthesis section of the side-ribbed vocoder presents the intermediate memory as input ^!SP, to which the switch U1 follows. The switch-!

ir ι

! the U1 has three switching positions; in the ροη: the switching condition shown in the drawing,!

'I: ι it directly forwards the input signal to the following LE-MUX demultiplexer, bypassing the intermediate memory SP. In the interimedia switching position, the LE-MUX demultiplex input is connected to the intermediate memory output SP and, in; ...........-....... ....... i

The upper switching position, it is connected: t / with the output of the device R, which in the more general case provides a combination of pulses, which characterizes the state of rest.

is

To each of the outputs of the mixer! follows a digital-analogue L / A converter. A f

; these converters follow the spectral channels SK1, SK2, ___, SKn. The signal containing the fundamental vocal frequency is fed to the output; of the corresponding digital-analogue D / A converter ί

} towards the command entrance of the phonic height of

PATENT CONSULTANCY IAUMAHH

MlLANO-Piazza Castello.2

- 17 a TG phonic generator. The signal indicating the quality of the sound, in turn, commands the switch U2, which, according to the speech signal, is:

I present a sweet or sour sound, adduces to all ',!

second inputs of the spectral channels the signal of;

uscita TG generator output or the RG noise generator output signal. The synthesized logic signals of the original voice signal;

; they appear at the output of the spectral channels!

The SKn, ì: SK1, SK2, ..., / are added to the amplifier-ί on-board SU 'and are fed into the output of the receiver • on the receiver H.

ι As can be deduced from fig. 4, the VOE vocoder syntaxer also presents, in en!

[a signal evaluator SB, in which the first is [

the incoming signal is also given,

Ϊ .'while at the second entry is given the!

signal criterion if it is obtained in the decoders i

DE according to fig. 1 or in the integrator I according to fig. 2. The signal evaluator SB comprises a computer, which examines the signal that is given to it on the first input to detect whether a signal pause is relevant to the voice or was caused by a signal disturbance on the transmission path. Only if in the instant in

STUDIO CONSULENZA PATENT MEfMÀNN

MtLANO-Piazza Castello, 2

- 18 to which the signal criterion "signal not present" appears, the signal evaluator does not detect a disturbance of the signal, the switch U1 is brought by the signal evaluator in the upper position, which establishes the connection with the device

E. Otherwise, the signal evaluator SB brings the switch U1 to the intermediate switching position, in which, instead of the disturbed signal segment, a signal segment temporarily stored in the intermediate memory SP is fed to the demultiplexer DE-I1UX.

Resell cations

Proced.-Proceptor for a radio transmission, resistant to disturbances, of vocal signals processed by vocoder, with the use of expanded frequency bands (SSHA) or a rapid change of radiofrequency (PH), characterized by the fact that processing of the voice signal to be transmitted, carried out in the vocoder analyzer of the transmitting section (VOS), a signal criterion is obtained (if) referred to the frame rate inside the system (RI), by means of which the transmitter (SH) or the final stage of the transmitter is switched on or off, as long as a signal is present or not present in the respective time element

STUDIO CONSUim BREVEITÌ MUMANN

MI LANO-Piazza Castello, £

15 »of a period of the frame rate, as well as of the fact that the signal segments, referred to the internal frame rate and digitized for their⁽transmission to the receiving section, are given, where necessary, information protection of data, for the recognition of errors, and also by the fact that, in the receiving section, the tji

signal criterion (if ') is reconstructed at the end of the data protection information, with reference to the frame rate period,

it is used to switch the sin4 vocoder (VOE) on or off when receiving the receive! The value depends on a signal present or not on I t

'here I'm. ί

^ .- Procedure according to claim 1 with the im!

The use of a rapid change of radiofrequency, characterized by the fact that the jump interval of frer

THE'

I! quenza corresponds exactly to 1, 2, ..., n frame periods of the vocoder and is synchronized on the frame rate (RT) or on a multiple thereof.

5. A method according to claim 1 or 2, characterized in that the signal criterion (s) reconstructed in the receiving section is evaluated in a signal evaluator (SB), at whose second input the signal received is received.

JAUMANN PATENT CONSULTANCY MIMO

MILAN-PTA_Z2a Castle, as well as by the fact that the signal evaluation provides a command signal for the switching off of the vocoder synthesizer (VOE) only if at the instant in which a signal criterion appears (if *) indicating "no signal" there is a signal interruption due to a disturbance.

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STUDY CONSULTANCY BREVTNI

MILAN-Piazza Castello, 2

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