FIELD OF THE INVENTION

The exemplary and non-limiting embodiments of the invention relate generally to communications.

BACKGROUND OF THE INVENTION

Long-range communication, especially long-range communication in space presents major technical challenges. Beside communication issues common in any wireless communication such as throughput and efficiency, issues arising from large distances between a transmitter and receiver present some additional problems. Error detection, correction, confirmation of packet reception, retransmissions are difficult and sometimes impossible to realise due to long delays between transmission and reception. Conventional transmission methods cannot reliably realize very long-range communication solutions.

BRIEF DESCRIPTIONOF THE INVENTION

According to an aspect of the present invention, there are provided apparatuses of claims 1 and 11.

According to an aspect of the present invention, there is provided a method of claim 12.

According to an aspect of the present invention, there is provided a computer program of claim 17.

One or more examples of implementations are set forth in more detail in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. The embodiments and or examples and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached [accompanying] drawings, in which

Figure 1 illustrates an example of long range communication;

Figure 2 is a flowchart illustrating a communication method in an apparatus;

Figure 3 illustrates an example of possible structure of transmission; Figure 4 illustrates an example of usage of frequencies; Figure 5 illustrates an example of pulses used in transmission;

Figure 6 illustrates an example of transmission of a hailing message; Figure 7 illustrates an example of transmission of a coding matrix; Figures 8A and 8B illustrate examples of transmission of data messages; Figures 9A and 9B illustrates examples of an apparatus of an embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Interstellar or long-range communication between objects in the outer space is a challenging topic. In the design of terrestrial communication systems two factors play a large role, namely throughput and communication efficiency. Additional issues related to long-range communication are related to the long delays between a transmitter and potential receiver.

Some multinational programs have been developed to study long-range communications in outer space. One of these programs is Messaging to Extra- Terrestrial Intelligence, or METI. Indeed, when transmitting to outer space there is always a possibility that the signal may be received by an unknown recipient that is not necessarily familiar with communication methods used on Earth. If such a message is intended to be received and understood by such a recipient, the signal should be designed in such a manner that receiving the message and decoding the content of the message is possible.

As for example, Long term evolution, LTE, or 5G standard might be considered for the outer space communication. Any potential recipient, which is not authorized recipient may detect signal pattern, including frequencies, signal modulation scheme and number of pulses. This may help the recipient to determine the source of transmission, but the message content may still remain unknown. Some security related properties of these systems, such as encryption or coding rules and many other, may prevent decoding and understanding the content of the transmission. Another problem is achievable transmission throughput. In case of LTE,

5G and other terrestrial standards, higher throughput requires channel synchronisation, error detection and correction, encryption and confirmation of packet reception. For this purpose, additional control signals need to be also included in transmissions. In some cases, retransmission may be needed to minimize errors, but it affects throughput. Considering very long communication range, proposed solutions typical for Earth wireless communication standards may not be applicable.

Fig. 1 illustrates an example of long range communication. A transmitter 100 is transmitting 102 a signal to outer space. There may be known receivers 104 and also unknown receivers 106 which may capture and receive the transmission 102. In this context it is considered to make it possible that any potential recipient whether being known or unknown may receive and decode the transmission. Thus, the purpose is not to hide and protect the transmission but to enable the reception and decoding the transmission without any prior knowledge of the transmission parameters and transmitter. Thus it should be possible for any potential recipient capable of receiving radio frequency transmissions.

In an embodiment, the communicating apparatuses may be non terrestrial base stations, satellites, probes, space ships. The proposed method may also be applied when either one or both of the communicating apparatuses are located the Moon.

Fig.2 is a flowchart illustrating a communication method in an apparatus. In an embodiment, the apparatus is a transmitter or a part of a transmitter configured to transmit a long range signal.

In step 200, the apparatus is configured to utilise a plurality of frequencies of a set of substantially equally spaced frequencies for transmission, transmissions on the frequencies comprising a header pulse and a number of data pulses, where pulses are separated from one another by a gap. In an embodiment, transmissions on frequencies comprise a header pulse and a number of data pulses. In an embodiment, each transmission on each frequency comprises a header pulse and a number of data pulses. The number of frequencies is a selectable parameter. In an embodiment, the number of frequencies is ten illustrating a decimal character of the transmission.

In step 202, the apparatus is configured to utilise a transmission comprising a hailing message, and a data message. In an embodiment, the transmission comprises a coding matrix between the hailing message and the data message, where the coding matrix comprising information on the size and type of the data message.

In step 204, the apparatus is configured to transmit the hailing message on the plurality of frequencies, one frequency at a time, the message comprising a given number of numbers of the value of Pi. The given numbers are indicated by the number of data pulses on a frequency of the plurality of frequencies. In an embodiment, numbers being indicated by the number of data pulses on a frequency of the plurality of frequencies. In an embodiment, each number is indicated by the number of data pulses on a frequency of the plurality of frequencies.

Figure 3 illustrates an example of possible structure of transmission. In an embodiment, a message 300 transmitted by the transmitter 100 may comprise three parts, a hailing message 302, a coding matrix 304 and a data message 306.

In an embodiment, the hailing message may be used for message detection improvement and to assure that the message context will be correctly understood. The coding matrix may be used to define size and type of the data message. In some situations, the coding matrix is not included in the message. The data message may be used for provision of binary coded data, radioglyphs or other kinds of data.

In an embodiment, the proposed transmission method and message structure utilises an universal mathematical or physical constant which may safely be assumed to be the same everywhere. The mathematical or physical constant to be used maybe selected or predetermined when designing the transmission. Examples of possible mathematical constants include

- Pi « 3.14159 26535 89793 23846 26433 83279 50288...

- Euler e « 2.71828 18284 59045 23536 02874 71352 66249...

- Square root of 2 2 * 1.41421 35623 73095 04880 16887 24209

69807...

- Golden ratio phi * 1.61803 39887 49894 84820 45868 34365

63811...

Examples of physical constants include

- Electron mass me = 9.1093837015(28)xl0-31 kg

- Planck constant h = 6.62607015x10-34 J-s

- Elementary charge e = 1.602176634x10-19 C

- Speed of light in vacuum c = 299792458 m/s.

Above constants are merely an example of possible values. Also other constants may be used as one skilled in the art is well aware. The values of physical constants are dependent on the units using which they are expressed. However, it can be assumed that they may be also used as universal constants as these physical constants may be recognized assuming the same physical rules applies.

In following, as a non-limiting numerical example, the universal mathematical constant Pi, p , which is defined as the ratio of a circle's circumference to its diameter, is used as the predetermined constant. As a mathematical equation, Pi or p may be defined as c p = - r [Eq. 1] where C is the circumference of a circle and r is the diameter of the circle. At present, the value of Pi is known with accuracy to more than 22 trillion digits.

Pi (or other universal mathematical or physical constant) may be used in the coding of the message to indicate that the transmission is not a random transmission or noise, but originated from an intelligent source understanding mathematics.

Further, the transmission is based on a set of substantially equally spaced frequencies, of which a plurality of frequencies is selected for use in the transmission. In an embodiment, the frequencies may comprise ten relatively closely spaced and organized in incremental character frequencies F0-F9, which has intuitive character for humans.

In an embodiment, the hailing message, one of the purposes of which is to enable a possible recipient to notice the transmission, is transmitted on the plurality of frequencies, in a serial format one frequency at a time, where the message comprises a given number of decimals of the value of Pi, each decimal indicated by the number of data pulses on a frequency of the plurality of frequencies. The usage of Pi value as universal means for message coding creates an universal communication interface, which may be crucial when a first communication between unknown recipients is exchanged.

In an embodiment, of the proposed solution for long-range communication where due to interferences error correction or encryption may not be effective, quality of transmission may be increased by usage of encoded pictograms (radioglyphs), which may be resistant for some transmission losses and still be able to convey a desired message.

Let us study in more detail the proposed solution for transmission of long range messages.

As mentioned, a given number of substantially equally spaced frequencies is used in the transmission. In an embodiment, a group of ten substantially equally spaced frequencies, denoted as F0-F9, is selected in incremental order to emphasis decimal character of interface and transmitted message.

The carrier frequencies may be interpreted to correspond with digits 0- 9, which are common for humans and may be easier understood with reference to binary number representation. This simplification is especially important, if a response for initial transmission will be received, as it allows better understanding of recipient intentions.

Fig. 4 illustrates an example of frequencies F0, FI, ..., F9. As a non limiting numerical example, F0 = 2000 MHz, FI = 2010 MHz, ..., F9 = 2090 MHz, which means an inter-frequency separation is 10 MHz. These numerical values are for illustrative purposes only. The numerical values may be selected depending on the application and may be transmitter specific, for example. Of this set of frequencies a plurality of frequencies may be used for communication. The plurality of frequencies may comprise all frequencies or a sub set of frequencies.

The proposed multi frequency transmission may be easier to detect by a recipient with respect to a single frequency transmission. Additionally, due to stabile pattern in terms of frequency spacing and repetition period, the artificial character of transmissions may be easily determined.

In an embodiment as illustrated in Fig. 5, transmissions at each selected frequency comprise the use of pulses of two groups, namely header pulses 500 and data pulses 502, 504. In the example of Fig. 5, there further data pulses of two types: a short data pulse 502 and a long data pulse 504. Further, there are gaps 506, 508 between the pulses and the length of the gap may vary.

In an embodiment, the decimal convention or character of the transmission system may be enhanced by applying at each selected frequency a transmission method where up to nine pulses are transmitted, which together with a no transmission gap, i.e. zero, form basis for communication interface used in decimal convention. Consistency with 0-9 digits is maintained.

In an embodiment, header pulses 500 may have different modulation (amplitude, frequency or phase) than data pulses 502, 504 to indicate different meaning of the pulses. In an embodiment, the data pulses 502, 504 may have different length but modulation may be the same. The pulse shapes, lengths, spacing and frequencies may be configurable with respect to technical equipment capabilities. In an embodiment, timing and frequency values may reflect decimal character of metrics and relation to seconds. As a non-limiting numerical example, the pulse lengths might be 100 ms for header pulses 500, 50 ms for short data pulses 502, 100 ms for long data pulses 504 and 100 ms for gaps 506, 508.

In an embodiment, longer pulse lengths or gap lengths may be used in order to ease signal pattern generation at recipient site, which may not be prepared for demanding signal timing requirements.

In an embodiment, the used modulation pattern may be simple. An efficient modulation method provides a better throughput but increases complexity required in the demodulation. In this case, it is important to maintain simplicity of the transmitted signal pattern, which at reception should be well distinguished from noise and easy to reproduce.

In an embodiment, three closely spaced header pulses 500 or triplets are used as a discriminator for a new radio frame transmitted on a given frequency. The gap between the header pulses might be 100 ms, for example. However, this may depend on the system and may vary. In this example, the total header length of three pulses with inter pulse gaps could have the length of 600 ms, for example.

The length of data message segment may be determined by the lengths of the maximum number of pulses and gaps, transmitted on a given frequency. This maximum number is a system variable. If decimal character of convention is emphasised, there may be nine pulses on the given frequency.

In an embodiment, when transmitting short data pulses 502, a gap of 50 ms might be used between pulses and when transmitting long data pulses no gap is used. In this example thus both short and long data pulses have the same timing in a frame.

Therefore, in this example using the pulse lengths given above, a total data segment length for nine long data pulses 504 or short data pulses 502 might be equal to 900 ms. A frame comprising header pulses and data pulses on a given frequency F0-F9 may have the length of 1500 ms.

The next transmission, containing another frame, on the same or another frequency may start after another 500 ms in order to emphasis a separate context of the next transmission.

Thus in this example, 2000 ms, one transmission block may be sent on a given frequency, and the next transmission block may be expected after this period on the same or other frequency from F0-F9.

As mentioned above in connection with Fig. 3, an entire message may be divided in three groups 300, 302, 304, groups having a different purpose. In an embodiment, transmission pattern used in the transmission of a group may differ. For example, when transmitting hailing message 300, the transmission pattern may be serial, where specified a number of pulses may be serially transmitted on one frequency following a number of pulses on another frequency and so on. Further, in the transmission of the hailing message on the plurality of frequencies, one frequency at a time, the message may comprise a given number of decimals of the value of Pi, each number indicated by the number of data pulses on a frequency of the plurality of frequencies. The plurality of frequencies may be transmitted in such an order that first is transmitted a frequency indicating the integer part of the value Pi, 3 and then frequency having one data pulse , following a frequency having four pulses and so on, so that the value of Pi 3,14... is indicated with a desired amount of decimals.

In an embodiment, the coding matrix 302 may be transmitted in serial or parallel form (one frequency at a time or all frequencies at the same time.

In an embodiment, the data message 304 may be transmitted in serial or parallel form.

Later on examples these transmissions are illustrated.

The data throughput of the proposed transmission system may be denoted with following equation:

T[t ) - Nfx N _P x Nv x Ct [Eq. 2] where:

T - data throughput, t - Frame total length (ms),

Ct - pulse length compression factor,

Nf - maximum number of frequencies used,

N _P - maximum number of pulses per frequency,

Nv - maximum number of basic pulses variation per frequency: short pulse, long pulse, gap.

In an embodiment, header pulses are not be used for carrying data context but they may be needed to attract recipient attention. Triplets of header pulses may also confirm the artificial character of the transmission and also refer to Earth, which is a third planet in Solar system.

It is anticipated that the throughput T would be greater if advanced coding rules were be applied. However, the purpose is to keep transmission simple and to enable reception for any potential recipient. A simple message structure and radio transmission parameters enable easy detection and decoding of transmitted signals even from recipients with moderate scientific background.

In an embodiment, throughput may be improved by pulse length compression factor Ct.

For example, let us assume that for basic frame length, which in this example is 2000 ms, Ct equals 1.

When a recipient receives Pi value-based transmission it may respond to such transmission including encoded in Data Message (radioglyph or other way) quality indicator, which may indicate a percentage of losses information. In an embodiment, quality estimation may be done at transmitter site by analysing quality of received response with respect to a percentage of losses information, with the assumption that channel quality is the same for uplink and downlink direction, which in case of interstellar or long-range communication will probably be the case. Quality indicator may be proportional to Ct factor and may be defined per message or per given frequency.

In an embodiment, a quality indicator may be determined based on received known message (e. g. radioglyph). Any missing or interfered pulses with respect to required message pattern may indicate quality of communication channel.

If obtained quality indicator confirms good quality connection, a total frame length for a specified frequency or for entire set of F0-F9 frequencies (depending on the system) may be reduced by a factor of Ct factor, which may be expressed by following equation; T frame base T frame base

Ct = [Eq. 3] T frame new T frame base T reduce where Ct - pulse length compression factor,

T frame base - basic frame length, i.e. 2000 ms,

T frame new - new frame length, i.e. 1000 ms,

Treduce indicates, in ms, the size of frame length reduction (Treduce < Tframe base)

For example, if Tframe base = 2000 ms, and Treduce = 1000 ms, then Ct = 2. Thus, the same time period the throughput may be doubled if new total frame length Tframe new will be reduced to 1000 ms.

In another example, if Tframe base = 2000 ms, and Treduce = 100 ms, then Ct = 2000/1900 = 1.05. A throughput may be improved by a factor 1.05 if total frame length Tframe new will be equal 1900 ms.

In an embodiment, a change of total frame length may have proportional impact on every pulse used in the transmission. Ct may be also used for further extension of total frame length, if needed i.e. Ct < 1.

The correction factor may be indicated for the recipient in the coding matrix.

It may be pointed out again that the purpose is not to maximise throughput but ensure safe reception of messages when the potential recipient is not a priori aware of transmission and may need to detect the presence of such transmission from the noise floor.

In an embodiment, a frequency offset compression factor Cf may be considered. The frequency offset compression factor may on the similar basis as Ct be applied based on whether inter-frequency separation is adequate to transmission, as inter channel interferences may have impact on transmission quality. The same algorithm as for Ct may be applied.

As mentioned, in an embodiment the mathematical constant Pi may be used a coding key in the proposed transmission method.

Pi p value has more than 22 trillion digits, but for the purpose of this Method it may be truncated. First one hundred (100) decimal places are:

3.14159265358979323846264338327950288419716939937510582 09749445923078164062862089986280348253421170679 ...

In the decimals, the first instance of each digit from 0 to 9 is denoted with italics and underline.

In an embodiment, in the transmission of the hailing message 302 the position of digits may be related to transmission order of the plurality of frequencies used in the transmission. In other words, during transmission of the hailing message, on the plurality of frequencies one frequency at a time, the order of used frequencies may be selected based on the decimals of Pi. Digit 1 is on the first place followed by digit 4. Then the digit 5 can be found on fourth decimal place followed by 9, 2 and 6. And so on. The last digit to be found is 0 which is on the 32th decimal place. Thus, for complete presentation of each digit from 0 to 9, the set of substantially equally spaced frequencies from which a plurality of frequencies is selected for use, at least 32 substantially equally spaced frequencies should be used. However, considering redundancy issues, first 50 digits after coma could be considered, or even 100 digits, especially if only the hailing message part is transmitted or broadcasted or if more of Pi p places should be sent.

However, in the first ten decimals places after comma, there are already seven unique digits, which may be placed on seven different frequencies according to the proposed convention. It means that potential recipient will have 70% of coding key and 70% of frequencies distribution. If the number of plurality of frequencies selected for use is ten, they may be numbered as F0, FI, F2, ..., F9, and they may be substantially equally spaced in the frequency domain. The order in which they are used in the serial transmission of the mailing message is determined based on when the corresponding the location of the digit in decimals of Pi.

Missing number 7, on frequency F7 and number 8, on F8 may be easily interpreted as a gap between frequencies F6 and F9, which may be received, especially when frequencies were substantially equally spaced in frequency domain. It means that potential recipient may anticipate, that frequencies F7 and F8 may also carry some signals, but intentionally no pulses were present there (due to nature of Pi p value). This may improve understanding to 90%.

It may be noted that digit 0 may present some problems as this number should be allocated to the lowest frequency from the selected frequencies F0-F9. It should be noted that even for humans idea of zero value (0) created some problems at some point of time. For example, Romans had no number for 0. Nevertheless, it may be assumed, that due to Pi p value concept a presence of additional 0 number should be also anticipated by potential recipient. Therefore, for message keying, a truncated Pi p value may be used as a base for proposed radio interface, namely:

3.1415926535

Another benefit of such constructed radio interface is that truncated Pi p value intuitively suggests a potential response, which may be Pi p value with additional places, i.e.:

3.1415926535 8979323846

Thus, the underlined part may be provided by recipient in the response, which unambiguously may confirm, that the message was successfully received, its context has been properly understood, and what is the most important, a recipient intention may be to establish contact using the proposed transmission system.

Fig. 6 illustrates an example of a possible scheme for transmitting the hailing message 302. A plurality of substantially equally spaced frequencies F0, FI, ... , F9 are selected for transmission. In this example, the transmission comprises eleven serial transmissions.

In the beginning, frequency F3 is used, where the transmission consists of a triplet of header pulses followed by three long data pulses to reflect the integer part of the value of Pi.

Next, frequency FI is used for transmission, again starting with a triplet of header pulses followed by a short pulse denoting the first decimal 1 of the value of Pi.

Then, frequency F4 is used for transmission, again starting with a triplet of header pulses followed by four short pulses denoting the second decimal 4 of the value of Pi.

This process continues until frequency F5 is used to transmit with a triplet of header pulses followed by five short pulses to denote the tenth decimal 5 of the value of Pi.

In the hailing message transmission of the example of Fig. 6, frequencies and number of pulses may be descripted using proposed naming convention as presented below:

3 F3/3H3L

1 F1/3H1S

4 F4/3H4S

1 F1/3H1S

5 F5/3H5S

9 F9/3H9S

2 F2/3H2S

6 F6/3H6S

5 F5/3H5S

3 F3/3H3S

5 F5/3H5S

Above, "H" denotes a header pulse, "L" denotes a long data pulse and "S" a short data pulse. For coding matrix and data message part, different number of pulses may be present on the given frequencies. Additionally, different type of pulses or gaps may be also described according to proposed convention.

The main objective of the hailing message 300 may be to present Pi value context in decimal representation and use it as a coding key for the message.

In an embodiment, the total length of the hailing Message may be equal to 6600 ms for header pulses and 4400 ms for data pulses. In total, the hailing message part in basic form may last 11000 ms.

In an embodiment, the hailing message part proposed in this transmission system may also be used as separate broadcast emitted by any Earth- originated object operated in the outer space. For example, it may be used as a beacon or transponder, which enables object positioning, especially in emergency positioning. It may be utilised as an universal communication converter, as it enables signalling interception, recording and familiarization with human technology.

In an embodiment, the hailing message is included in all radio transmissions used in the proposed transmission system.

Fig. 7 illustrates an example of a possible scheme for transmitting the coding matrix 304. A plurality of substantially equally spaced frequencies F0, FI, ... , F9 are selected for transmission. In this example, the transmission of the coding matrix comprises transmissions on ten frequencies F0, FI, ..., F9, starting in this example from the lowest frequency F0.

At a frequency the maximum number of pulses (long or short) may be transmitted, which in this example case is nine pulses. On a frequency, the transmission begins with a triplet of header pulses followed by the data pulses. In an embodiment, the coding matrix may indicate usage of different kind of pulses, as specified by Equation 2. Further, the coding matrix may also contain information about factor Cf for frequencies distribution and factor Ct for total frame length compression.

The coding matrix may comprise information on pulse lengths and changes in the pulse lengths. A pulse length for each group of pulses (long, short, gap) may be indicated separately.

The coding matrix may further comprise information on carrier frequencies and any changes in frequency selection or inter-frequency separation within receiver bandpass filter spectrum to enable detection of new carrier frequencies F0-F9.

The coding matrix may further code frequency Nf - time N _P , two- dimensional plain canvas (or frame), [part of Equation 2], for data provided in data message part.

As graphical data representation (such as radioglyphs, pictograms, Barco code) may be used in data messages, the coding matrix may include a set of pulse types or shapes, which may be used for data transmission, which number corresponds to N .

The basic length of the coding matrix for above proposed exemplary pulses or frame lengths may be equal to 10 frequencies x 2000 ms, which is 20000 ms. For example, with total frame length compression factor Ct = 2, the coding matrix part length may be 10000 ms. The same compression factor may be used also in the transmission of the data message following the coding matrix.

Figs. 8A and 8B illustrate examples of a possible scheme for transmitting data message 306. In this example, the transmission of the data message comprises transmissions on ten frequencies F0, FI, ..., F9, staring in this example from the lowest frequency FO.In the figures the data message transmission utilises radioglyph presentation. In Fig. 8A digit "1" is transmitted and in Fig. 8B word "OK". In an embodiment, any kind of coding may be applied in the transmission of the data pulses.

Efficiency of transmission may be determined based on Equation2, with additional meaning for N , which provide information about allowed pulse shape variations, which may also convey some information.

The data pulses may have been modulated in amplitude, frequency, phase or combination of above.

Using radioglyphs in the transmission may provide a visual meaning but they may also carry additional information. For example, "OK" on Fig. 8B may code also overall status of an object operated in the outer space. If some parts of the transmission will be interfered or garbled, which may mean that information carried on some specified frequencies cannot be received, a meaning may be retrieved by analysing of radioglyph shape.

Additional data may be transmitted using for instance random or pseudo-random phase shifting, where number of phase changes or its values may carry useful information.

When considering interstellar or long-range communication requests for retransmission may not be effective but received radioglyphs from few messages may be integrated to form a common message, which apart from binary coded information may provide overall message meaning.

As illustrated in Figs. 8A and 8B, printed diagrams consisting of ordered frequencies and number of pulses may form canvas, which may be used for further or during physical communication. Again, simplicity is a significant benefit of this method as such printouts may be very helpful for establishing initial communication. Also, drawings may be translated into radio frequency transmissions if required. This feature is useful if initial contact is established between unprepared parties (average people - no scientist) as it may reduce communication barriers.

In an embodiment, the proposed data structure may be used for communication between earth devices operated in the outer space, for example for noncritical communication. The number of frequencies and the efficiency of pulse coding (or modulation) may selected on the basis of application. The transmission of the data message may be parallel on a frequency or serial, which may depend on transmitter maximum power. The configuration may be indicated in the coding matrix.

In an embodiment, the assumption is that a potential recipient may be able to detect transmission pattern based on the presence of a triplet of header pulses, which then indicate additional presence of data pulses (short or long) on the same frequency. Recipient may be able to recognize the triples as artificial due to the characteristic pattern and repetitions on specified frequencies.

In an embodiment, the frequencies F0-F9 may be relatively close to each other. Thus, detection of all signals may be also assumed. A recipient may be able to distinguish that triplets have always the same context, therefore they may not contain data, whereas changing number of data pulses are likely to carry information.

A recipient may be able to distinguish the short and long data pulses due to different pulse length. It can safely be considered that geometric rules apply everywhere. Thus Pi value expressed as a ratio (Equation 1) has universal meaning. Thus, it may be assumed that any potential recipient, who is able to detect and process a radio frequency signal is familiar with Pi.

Thus, a recipient may detect transmission as 31415926535

On the basis of different pulses used in the transmission of the integer value (the first three pulses), a recipient may assume a special meaning and determine that the received transmission is in fact 3.1415926535.

A natural and intuitive reaction may be usage of the next places of Pi value as a response to confirm, that transmission was received and understand:

3.1415926535 8979323846

Thus, potential response for transmission

3 F3/3H3L

1 F1/3H1S

4 F4/3H4S

1 F1/3H1S

5 F5/3H5S

9 F9/3H9S

2 F2/3H2S

6 F6/3H6S

5 F5/3H5S

3 F3/3H3S

5 F5/3H5S might be following: 8 F8/3H8S

9 F9/3H9S

7 F7/3H7S

9 F9/3H9S

3 F3/3H3S

2 F2/3H2S

3 F3/3H3S

8 F8/3H8S

4 F4/3H4S

6 F6/3H6S

Reception of the response message may confirm that the hailing message was received by the recipient, that the message and radio interface convention was understood, Pi value concept may be known, decimal transmission may be understood and that the recipient may be willing to establish contact using proposed radio interface. In addition, confirmation of transmission location or origin may indicate area of interest, which should be intensively monitored. In this case positioning is not a technical problem.

The transmission method proposed here may be applied to any modern transmitters as frequency changing is not an issue. However, ability to build a transmitter, which may output the given signal pattern similar to the received in the message or hailing message broadcast may not be considered obvious depending on the technology level of a potential recipient. Thus, frequencies used, transmission pattern pulses modulation and timing criteria should be purposefully relaxed, especially for hailing message transmission. The purpose is to keep the transmission method simple to enable construction of such transmitter in simple manner. Simplicity also means that such concept may be used as emergency beacon, as it may be relatively easily to construct such a transmitter for enabling emergency broadcast.

Figs. 9A and 9B illustrates examples of the basic structure of an apparatus 900, which is capable of transmitting a signal described above. The apparatus may be used on the transmitting side on Earth and also by a potential recipient in order to generate response for received Pi value-based transmission.

It may be assumed that potential recipient already a has receiver capable for message reception.

In the example of Fig 9A, the apparatus may consist of a frequency generation unit 902, which is configured to generate frequencies used in the transmission, such as the frequencies F0, FI, ..., F9, for example, and apply suitable modulation, amplitude, frequency, phase or a combination of above. In keying unit 904, the radiofrequency signal may be then keyed or coded to form pulses of the given shape or length. Frequency selection and keying may be done by user of the apparatus or it may be automated.

The apparatus may further comprise an amplifier unit, where coded signal (pulses on the given frequency) may be amplified and finally emitted by the antenna system 908.

Thus, the proposed apparatus may be very simple. As no sophisticated pulse shapes, frequency patterns or timing constraint are needed, a response transmission may be elicited practically by any recipient, which may have access to relatively basic radio equipment.

Fig. 9B illustrates an example embodiment. The figure illustrates another simplified example of an apparatus 900 applying embodiments of the invention. It should be understood that the apparatus is depicted herein as an example illustrating some embodiments. It is apparent to a person skilled in the art that the apparatus may also comprise other functions and/or structures and not all described functions and structures are required. Although the apparatus has been depicted as one entity, different modules and memory may be implemented in one or more physical or logical entities.

The apparatus 900 of the example includes a control circuitry 910 configured to control at least part of the operation of the apparatus.

The apparatus may comprise a memory 912 for storing data. Furthermore, the memory may store software 914 executable by the control circuitry 910. The memory may be integrated in the control circuitry.

The apparatus may comprise one or more interface circuitries 916, 918. One of the interfaces may be a transmitter or a transceiver 916 configured to transmit a signal. The transmitter or transceiver may be connected to an antenna arrangement (not shown). Other interface (s) 918 may connect the apparatus to other elements of a communication system. The interface may provide a wired or wireless connection to the communication system. The interface may also be user interface. The interfaces may be operationally connected to the control circuitry 910.

The software 914 may comprise a computer program comprising program code means adapted to cause the control circuitry 910 of the apparatus to perform the embodiments described above and in the claims.

As the proposed transmission method is intended for interstellar or long-range communication, number of false transmissions may be naturally reduced as there are not many such transmitters in the outer space. Additionally, any received transmission may be deeply analysed in order to determine its origin, which in this case may reflect the given quadrant of the space. Any other origin (i.e. Earth based) may be considered as spurious.

In general, the proposed transmission method may be considered as a bridge for establishing communication between a sender and recipient in a situation, where the recipient may not be initially familiar with a radio interface (frequencies, pattern, signals) used by the sender. An intuitive and simple character of proposed radio interface and usage of Pi value concept as a common ground for interface explanation will provide the potential recipient clues for detecting and decoding the transmission. What is also important, proposed transmission method may be well recognized also by an average human, who has elementary mathematical background only.

The proposed radio interface requires no additional signalling. In fact, this may be beneficial for throughput consideration, especially when considering control overhead in the message structure. Using radioglyphs of known meaning it may be possible to provide some information even if part of transmission was interfered or lost. This is significant benefit for interstellar or long-range communication. Binary transmission may be sensitive for this problem, whereas a meaning of radioglyphs still may be retrieved from interfered or part of radioglyph included in transmission.

The proposed transmission method is suitable also for non-critical communication due to lack of encryption or coding. A protection may be provided by password - response convention, where the true meaning of the transmitted radioglyphs or data may be known only for authorized recipient. Justification is that in the outer space may be relatively low number of intentional or unintentional recipients, which means there may be no need for advance encryption algorithms typical for LTE or 5G.

In some embodiments, other technical solutions or technologies can be also implemented and used either on top of or with the above described embodiments. Thus, other frequencies related to other technologies, for example, could be also implemented and used in the same device as the above described embodiments.

In an embodiment, the apparatus applying embodiments of the invention comprises means for utilising a plurality of frequencies of a set of substantially equally spaced frequencies for transmission, transmissions on frequencies comprising a header pulse and a number of data pulses, where pulses are separated from one another by a gap, means for a transmission comprising a hailing message, and a data message and means for transmitting the hailing message on the plurality of frequencies, one frequency at a time, the message comprising a given number of decimals of the value of a predetermined mathematical or physical constant, numbers being indicated by the number of data pulses on a frequency of the plurality of frequencies.

In an embodiment, a computer program comprises instructions for causing an apparatus to perform at least the following: utilising a plurality of frequencies of a set of substantially equally spaced frequencies for transmission, transmissions on frequencies comprising a header pulse and a number of data pulses, where pulses are separated from one another by a gap; a transmission comprising a hailing message, and a data message, transmitting the hailing message on the plurality of frequencies, one frequency at a time, the message comprising a given number of decimals of the value of a predetermined mathematical or physical constant, numbers being indicated by the number of data pulses on a frequency of the plurality of frequencies.

In an embodiment, a computer readable medium comprises program instructions for causing an apparatus to perform at least the following: utilising a plurality of frequencies of a set of substantially equally spaced frequencies for transmission, transmissions on frequencies comprising a header pulse and a number of data pulses, where pulses are separated from one another by a gap; a transmission comprising a hailing message, and a data message, transmitting the hailing message on the plurality of frequencies, one frequency at a time, the message comprising a given number of decimals of the value of a predetermined mathematical or physical constant, numbers being indicated by the number of data pulses on a frequency of the plurality of frequencies.

In an embodiment, a non-transitory computer readable medium comprises program instructions for causing an apparatus to perform at least the following: utilising a plurality of frequencies of a set of substantially equally spaced frequencies for transmission, transmissions on frequencies comprising a header pulse and a number of data pulses, where pulses are separated from one another by a gap; a transmission comprising a hailing message, and a data message, transmitting the hailing message on the plurality of frequencies, one frequency at a time, the message comprising a given number of decimals of the value of a predetermined mathematical or physical constant, numbers being indicated by the number of data pulses on a frequency of the plurality of frequencies.

In an embodiment, a communication system for communication between non-terrestrial base stations, satellites, probes, space ships or Moon based apparatuses is provided, wherein the communicating apparatuses are configured to utilise a plurality of frequencies of a set of substantially equally spaced frequencies for transmission, transmissions on frequencies comprising a header pulse and a number of data pulses, where pulses are separated from each other by a gap; a transmission comprising a hailing message, and a data message, the communicating apparatuses being configured to transmit the hailing message on the plurality of frequencies, one frequency at a time, the message comprising a given number of decimals of the value of a predetermined mathematical or physical constant, numbers being indicated by the number of data pulses on a frequency of the plurality of frequencies.

In an embodiment, the processes or methods described in above figures may also be carried out in the form of one or more computer processes defined by one or more computer program. A separate computer program maybe provided in one or more apparatuses that execute functions of the processes described in connection with the figures. The computer program(s) may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. Such carriers include transitory and/or non-transitory computer media, e.g. a record medium, computer memory, read-only memory, and software distribution package. Depending on the processing power needed, the computer program may be executed in a single electronic digital processing unit or it may be distributed amongst a number of processing units.

The steps and related functions described in the above and attached figures are in no absolute chronological order, and some of the steps may be performed simultaneously or in an order differing from the given one. Other functions can also be executed between the steps or within the steps. Some of the steps can also be left out or replaced with a corresponding step.

The apparatuses or controllers able to perform the above-described steps may be implemented as an electronic digital computer, which may comprise a working memory (RAM), a central processing unit (CPU), and a system clock. The CPU may comprise a set of registers, an arithmetic logic unit, and a controller. The controller is controlled by a sequence of program instructions transferred to the CPU from the RAM. The controller may contain a number of microinstructions for basic operations. The implementation of microinstructions may vary depending on the CPU design. The program instructions may be coded by a programming language, which may be a high-level programming language, such as C, Java, etc., or a low-level programming language, such as a machine language, or an assembler. The electronic digital computer may also have an operating system, which may provide system services to a computer program written with the program instructions.

As used in this application, the term 'circuitry' refers to all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of circuits and software (and/or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s)/software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of 'circuitry' applies to all uses of this term in this application. As a further example, as used in this application, the term 'circuitry' would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and/or firmware. The term 'circuitry' would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or another network device.

The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read-only memory, and a software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers. The apparatus may also be implemented as one or more integrated circuits, such as application-specific integrated circuits ASIC. Other hardware embodiments are also feasible, such as a circuit built of separate logic components. A hybrid of these different implementations is also feasible. When selecting the method of implementation, a person skilled in the art will consider the requirements set for the size and power consumption of the apparatus, the necessary processing capacity, production costs, and production volumes, for example.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.