JPH1022877A - Communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a data transfer rate in the case of mainly transmitting/ receiving the data of images, etc., by decreasing the number of times of frequency hopping in communication, using the frequency hopping technique. SOLUTION: The error rate of data demodulated by a reception side demodulator 34 is stored in an error rate detection storage part 24 and compared with a 1st reference value by a comparative discrimination part 23 and when that error rate is higher, a spreading code outputted by a spreading code system generator 26 is changed. When the error rate is lower, the spreading code is not changed. Corresponding to the spreading code, the frequency of transmission/reception, to be performed by a frequency synthesizer 28, is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication apparatus using spread spectrum, in particular, a frequency hopping system.

[0002]

2. Description of the Related Art Conventionally, as a communication system in a communication system using the above spread spectrum communication system, a frequency hopping system (hereinafter, referred to as an FH system) used for effective use of frequency and for enhancing confidentiality. There is. In the FH method, a carrier is spread by hopping according to a rule predetermined by a spreading code sequence. A conventional two-way communication system using the spread spectrum communication system based on the FH system was configured as shown in FIG.

[0003] First, a transmitter will be described. According to the spreading code sequence output from the spreading code sequence generator 5, a signal of a random frequency is output from the frequency synthesizer 6. The primary modulation signal is input to the transmission data input terminal. The output frequency of the primary modulation signal supplied to the transmission data input terminal 1 is determined by the up-converter 3 based on the output from the frequency synthesizer 6. Upconverter 3
The transmission data frequency-converted by the above is amplified by the amplifier 8, and then transmitted and output from the antenna 11 via the duplexer 10.

Next, a receiver will be described. Antenna 1
The signal received at 1 is separated from the transmission wave by the duplexer 10,
After being amplified by the amplifier 9, it is input to the down-converter 7, frequency-converted by the down-converter 7 based on the signal designating the frequency from the frequency synthesizer 6, demodulated by the demodulator 12, and becomes reception data.

[0005] The received data is output to a data operation circuit (not shown) and also to a synchronization circuit 4. The synchronization circuit 4 detects the phase of the hopping frequency from the received signal, and outputs a synchronization signal from the synchronization circuit 4 to the spread code sequence generator 5. The spreading code sequence generator 5 outputs a spreading code sequence according to the input synchronization signal. The spread code sequence output from the spread code sequence generator 5 is supplied to a frequency synthesizer 6. The frequency synthesizer 6 generates a random frequency output according to the input spread code sequence. Down converter 7 multiplies the received signal by the output from frequency synthesizer 6 to despread the received signal. The despread signal despread in the down-converter 7 is demodulated in the demodulator 12 to obtain received data in the demodulator 12, and the demodulated received data is output from the received data output terminal 2.

In order to perform two-way communication with such a transceiver, these transmitters and receivers operate simultaneously. Note that the random frequency means that a spread code output every time a synchronization signal is input from the spread code generator 5 is randomly changed, and the sequence of the spread code (frequency change pattern is Is transmitted and received by sharing a set of communication devices with each other.

[0007]

However, the above F
In the communication system using the H system, a time period in which the frequency generated by the frequency synthesizer is stabilized immediately after hopping (hereinafter, referred to as an occupation time) is required.
In the communication based on the frequency hopping method, an upper limit is set for the communication time on the same frequency in order to keep the communication confidential and increase the number of channels. Hopping is performed every hour). As shown in FIG. 11, a certain frequency band (for example, f1)
Therefore, when the frequency shifts to another frequency band (for example, f2), an unstable time (t2) of the frequency is the occupation time.
Normal communication cannot be performed during this occupation time, and there is a waiting time in the entire system until the frequency is stabilized. As a result, the transmission speed is reduced in principle as compared with the communication in which the carrier frequency is normally used for the amateur radio or the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is possible to increase the transfer rate by reducing the occupation time during frequency hopping. Another object of the present invention is to provide a communication device suitable for transmitting and receiving image data having a large data amount.

[0009]

In order to achieve the above object, a communication apparatus according to the present invention comprises a detecting means for detecting an error rate of a received signal, a storing means for storing a reference value of the error rate, Error rate determining means for determining whether the error rate of the received signal detected by the detecting means is greater than the reference value, and frequency changing means for hopping the frequency based on the error rate determination result. ing. The error rate of the received signal is detected by the detecting means, and the error rate determining means determines whether the detected error rate is higher than the reference value stored in the storage means, and changes the frequency based on the determination result. Means make the frequency hop.

According to a second aspect of the present invention, there is provided a communication device, comprising: measuring means for measuring an elapsed time from when the frequency is hopped; and determining whether or not the elapsed time measured by the measuring means has reached a predetermined time. And a time determining means for performing the determination. The frequency changing unit changes the frequency at the earlier timing of the determination of the error rate exceeding the reference value of the error rate by the error rate determining unit and the timing of determining the predetermined time by the time determining unit. The communication is performed by limiting the communication time on the same frequency.

Further, in the communication apparatus according to the third aspect, the frequency changing means has a table storing a change pattern of the frequency to be hopped, and determines the frequency to be changed according to the table. By preparing a table in which the frequency to be hopped is determined in advance, there is no time to calculate the hopping frequency when determining the carrier frequency to be used, and the communication can be speeded up.

Further, the communication apparatus according to the present invention further comprises a high error rate frequency discriminating means for detecting a frequency determined by the error rate discriminating means to have a high error rate,
The frequency detected by the high error rate frequency discriminating means is excluded from the hopping frequency. As a method of calculating the error rate, the carrier frequency determined as having a high error rate is excluded from the hopping table, or the hopping table is changed to a hopping frequency determined as having a low error rate by the high error rate determining means. I do. Alternatively, when the hopping frequency is calculated, the frequency is used as the hopping frequency before that, and at that time, when it is determined that the error rate is high, the carrier frequency is not used, and the next calculated carrier frequency is used. Use frequency. By doing so, it is possible to remove a frequency that is easily disturbed in communication, and it is possible to perform communication smoothly.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the block diagram of FIG. 1 and the transmission data diagram of FIG. The format of data when transmitting from the communication device having the configuration shown in FIG. 1 is a format as shown in FIG. In this format, a transmission time slot and a reception time slot are respectively formed. Note that the data information in FIG. 9 is a signal originally intended to be sent, the error correction data indicates an error correction signal for determining whether the data information is correct, and the hop information is , Signals for judging the level of the error rate. Here, a known Reed-Solomon code or the like can be adopted as the error correction data, which is added to data information indicating transmission contents.

First, in FIG. 1, the frequency synthesizer 2
8, up-converter 22, amplifier 30, duplexer 32,
The antenna 33, the amplifier 31, the down-converter 29, and the demodulator 34 are the same as those in the prior art shown in FIG.

The synchronizing circuit 25 is configured to output a synchronizing signal having a constant frequency to a control unit 38 described later.

The spread code sequence generator 26 reads a command signal from the control unit 38 in response to the synchronization signal, and if it is a transition command signal for commanding a frequency transition, the spread code sequence next to the spread code sequence. Is output to the frequency synthesizer 28. On the other hand, if the received signal is not a transition command signal, no frequency transition is performed and a new spread code is not output.

The control section 38 operates in response to the synchronization signal, and has an input side connected to a demodulator 34 connected between the reception data output terminal 21 and the down converter 29, and an output side thereof. It is connected to a data redundancy device 36 via a primary modulator 37. The data redundancy unit 36 is connected between the transmission data input terminal and the up-converter 22, so that the transmission data input from the transmission data input terminal 20 and the data from the control unit 38 are redundant.

Based on the received data input from the demodulator 34, the control section 38 stores the error rate in a known error rate using an RS (Reed-Solomon code) code or the like in the error rate detection storage section 24 as detecting means. Computation is performed using a correction technique, and a comparison reference unit 23 serving as an error rate determination unit compares a preset first reference error rate value for frequency transition determination with the calculated error rate of received data. When the error rate is larger than the first reference error rate value, it is determined that good communication is impossible, and the transition command signal is sent to the spreading code sequence generator 2.
6 when the calculated error rate is smaller than the first reference error rate value, the communication is still good and the frequency maintenance signal is output to the spreading code sequence generator 26. . The control unit 3
8 outputs the transition command signal and the frequency maintenance signal to the primary modulator 37 in the transmission time slot, modulates them, and adds them as hop information to the data redundancy unit 36 after the error correction data.

On the other hand, the control unit 38 receives the hop information of the received signal in the reception time slot, and if it is a transition command signal, generates a spread code sequence so as to hop the frequency in the next transmission time slot. A transition command signal is output to the device 26.

In this way, the communication device (A) that detects that the error rate has become larger than the first reference value
And the communication device (B) instructed to change the frequency based on the hop information is simultaneously switched to the next hopping frequency. That is, as shown in FIG. 2, hopping is not performed at regular time intervals as in the related art,
Since hopping is performed only when the error rate is deteriorated due to communication interruption, the total occupation time is reduced. The communication device (A) is provided with a reception time slot after the transmission time slot, and repeats the operation. The communication device (B) performs the reception time slot when the communication device (A) is in the transmission time slot. When the communication device (A) is in the reception time slot, the communication device (B) is set to be the transmission time slot, so that multiplex communication is performed. When the time slot is 1 frame,
An integral multiple of the frame is the hopping residence time. This residence time differs for each hop.

FIG. 3 shows a second embodiment in which the time discriminating means according to claim 2 is taken into consideration. Frequency synthesizer 28, upconverter 22, amplifier 30, duplexer 3
2, antenna 33, amplifier 31, down converter 2
9, demodulator 34, synchronization circuit 25, spreading code generator 26,
The primary modulator 37 is the same as that shown in FIG. 1, and therefore detailed description is omitted, and only different parts will be described.

A timer 27a as a measuring means is provided in the control section 38, and starts counting when a transition command signal is output from the control section 38 to the spread code sequence generator 26, and again executes the transition command. When a signal is output, the counter is reset after zero reset is performed.

The time discriminating section 27 as time discriminating means includes
It is provided in the control unit 38 and is configured to determine whether or not the time counted by the timer 27a is longer than a predetermined reference residence time, and to generate a time-up signal when it becomes longer. .

On the other hand, the comparison / determination section 23 generates a communication failure (NG) signal when the error rate of the received signal detected by the error rate detection section 24 becomes larger than the first reference value. It is configured.

When a transition is instructed based on the hop information in the reception time slot, the control unit 38 outputs a transition instruction signal to the spread code sequence generator 26 at the time of the next transmission time slot. Primary modulator 37
Also output to At this time, the count of the timer 27a is restarted after being reset.

Further, the control unit 38, when one of the communication failure signal and the time-up signal is generated,
A transition command signal is output to the spread code sequence generator 26 at the time of the next transmission time slot. This functional part corresponds to the frequency changing means of claim 2.

The flow of the entire system will be described with reference to FIGS. 5 and 6, which are flow charts when the configuration of FIG. 3 is adopted for two transceivers. The counters 1 and 2 in FIG. 5 are counters stored in the memory in the transceiver 1, and the counters 3 and 4 in FIG. 6 are counters stored in the memory in the transceiver 2. All counter values are the same. The spread code sequence generator 26 has a built-in table in which hopping frequencies are stored.
Different frequencies are set corresponding to the addresses, and one cycle of a hopping pattern is stored. The contents of the counter specify the address of this table.

First, the transmission / reception initial carrier frequency is set to
Is determined by the transceiver 2 (s1). The transceiver 1 receives the data sent from the transceiver 2 (s2 to s2).
s4). The received hop information (flag) is separated from the data, and the value of the counter 2 serving as a pointer for determining the carrier frequency at the next communication is changed according to the state of the hop information (s5, s6). When the signal indicates that the hop information satisfies the error rate criterion (hereinafter referred to as an OK maintenance signal), the counter 2 is not changed and the carrier frequency is not changed. When the hop information does not satisfy the error rate standard (hereinafter referred to as NG transition signal), the counter 2 is updated and the carrier frequency of the transceiver 1 is changed.

If the hop information sent from the transceiver 2 is OK
At the time of the maintenance signal, the time determination unit 27 determines whether or not the reference time has elapsed (s7). If the reference time has elapsed, the counter 2 is updated (s8, s9). Time discriminator 2
7, when it is determined that the reference time has not elapsed, data information and error correction data to be transmitted to the transceiver 2 are created (s10), and the transmission data (data information, error correction data) from the transceiver 2 are generated. The error rate comparison is performed using the error rate obtained in (1) (s11). At this time, if the error rate criterion is satisfied, the hop information is set as an OK maintenance signal (s12, s13), and all created transmission data is transmitted to the transceiver 2 (s14, s1).
5). When the error rate criterion is not satisfied, the counter 2 is updated (s9), an NG transition signal is created as hop information, and all created transmission data is transmitted to the transceiver 2.

When the hop information transmitted from the transceiver 2 is an NG transition signal, the counter 2 is updated to change the carrier frequency at the next transmission (s6). Transmission data (data information and error correction data) to be transmitted to the transceiver 2 and hop information (OK maintenance signal in this case) are created (s17), and the value of the counter 2 is substituted into the counter 1 (s18), The created transmission data is sent to the transceiver 2 at the hopping frequency corresponding to the counter 1 (s14, s15).
At this time, the transceiver 2 performs communication at the hopping frequency corresponding to the counter 3 (t2, t3).

The transmitter / receiver 2 receiving the transmission data changes the value of the counter 4 serving as a pointer for determining the carrier frequency for the next communication depending on the state according to the hop information of the data received from the transmitter / receiver 1. When the hop information is the OK maintenance signal (t5), the counter 4 is not changed and the carrier frequency is not changed. If the hop information is N
At the time of the G transition signal, the counter 4 is updated (t6), and the carrier frequency of the transceiver 2 is changed.

If the hop information sent from the transceiver 1 is OK
At the time of the maintenance signal, the time discrimination section judges whether the reference time has elapsed (t7), and if the reference time has elapsed, updates the counter 4 (t8, t9). When it is determined by the time determination unit that the reference time has not elapsed, data information to be transmitted to the transceiver 1 and error correction data are created (t10), and the transmission data (data information, error correction) from the transceiver 1 are generated. The error rate is compared with the error rate obtained from the data for use (t12). At that time,
If the error rate standard is satisfied, hop information is OK
As a maintenance signal (t13), all created transmission data is transmitted to the transceiver 1 (t14, t15).

When the error rate criterion is not satisfied, the counter 4 is updated (t9), an NG signal is created as hop information, and all created transmission data is transmitted to the transceiver 1 (t14, t15).

At time t5, when the hop information transmitted from the transceiver 1 is an NG signal, the counter 4 is updated to change the carrier frequency for the next transmission (t6). Transmission data (data information and error correction data) to be transmitted to the transceiver 1 and hop information (OK maintenance signal in this case) are created (t17), and the value of the counter 4 is converted to the value of the counter 3
(T18), and sends the created transmission data to the transceiver 2 at the hopping frequency according to the counter 3 (t14, t)
15). At that time, the transceiver 1 performs communication at the hopping frequency corresponding to the counter 1.

By performing communication in such a flow, the communication device of the present invention can be substantially operated.

FIG. 4 is a block diagram showing a third embodiment having a high error rate discriminating means. Frequency synthesizer 28, upconverter 22, amplifier 3
0, the duplexer 32, the antenna 33, the amplifier 31, the down converter 29, the demodulator 34, the synchronization circuit 25, the spread code generator 26, and the primary modulator 37 are the same as those in FIG. Hopping table 3 in section 38
5. The role of the high error rate determination unit 39 will be mainly described.

The hopping table 35 is stored in the comparing
Receiving the frequency transition signal generated in step 3
6 is a table in which a new spreading code generated by No. 6 is stored in advance as a hopping frequency change pattern.

The high error rate discriminating section 39 determines that the error rate calculated by the error rate detecting and storing section 24 is the second error rate.
Is determined to be higher than the reference value (a value higher than the first reference value), and the carrier frequency when it is determined to be higher is excluded from the hopping table 35 or the error rate is set to the second reference value. The hopping table is changed to a hopping frequency determined to be lower than the value. Or
When calculating the hopping frequency, the frequency is used as the hopping frequency before that, and at that time, if it is determined that the error rate is high, the carrier frequency is not used, and the next calculated carrier frequency is used. Is configured. Further, when the change of the hopping table 35 occurs more than a certain reference number, or when the frequency used of the hopping table 35 is reduced by more than a certain reference number, the state of the hopping table 35 can be returned to the initial state. It is configured as follows.

That is, similarly to the second embodiment, the control unit 38 generates a time-up signal generated by the time discrimination unit 27 and a transition signal at the earlier timing of the occurrence timing of the communication failure signal. 26 and output to the hopping table 35. In addition, the high error rate determination section 39 generates a table change signal when the error rate of the received signal detected by the error rate detection storage section 24 becomes higher than the second reference value.

The control unit 3 responds to the table change signal.
8 excludes the hopping frequency used when the error rate becomes higher than the second reference value from the frequency use table of the hopping table 35 as a spare area, and sets the spare frequency to It moves to the storage address of the excluded frequency.

Thus, the frequency having a high error rate in the next hopping cycle is not used. From the hopping table 35 included in the spread code generator 26, the carrier frequency with a high error rate is removed using the signal from the comparison and determination unit 23,
The data transfer rate can be improved. Furthermore,
After confirming that the frequency usable as the carrier frequency has decreased to a certain reference, the hopping table 35 is returned to the initial state, and the hopping pattern is returned to the original state.
By performing this repetition, a confidential communication system having a double structure results, and the confidentiality and confidentiality of the conventional FH spread spectrum communication apparatus can also be improved. Also, the generation pattern can be stored without mounting a spread code generation means such as a PN code on the terminal.

In addition to those described above, the following modifications are also possible. That is, in one communication device, it is possible not to include the error rate detection storage unit 24 and the comparison determination unit 23 for simplification of the system. Since the time required to calculate the error rate eventually limits the data transfer rate, when it is desired to further increase the data transfer rate, FIG. 10 of the conventional communication device can be used as one of the communication devices. The flow of the entire system at that time is shown in the flowcharts of FIGS.

The transceiver 1 is the same as described above. The transmitter / receiver 2 in FIG. 8 separates the data received from the transmitter / receiver 1 into hop information and data information (p1, p2). Further, the data information and the error correction data created by the transceiver 2 are sent to the transceiver 1, and the hop information is sent back to the transceiver 1 as it is (p3, p
4). The hopping frequency at the next reception is changed according to the result of the hop information transmitted from the transceiver 1 (p
5, p6). Communication can be performed according to this flow.

In this embodiment, the format of the transmission data is configured as shown in FIG. 9. However, this communication is not impaired regardless of the order of the data information, error correction data, and hop information. Needless to say.

The control unit 38 is shown in block diagrams 1, 3 and 4 collectively. The control means can be operated by hardware such as a circuit and software such as a program.

[0046]

As described in detail above, the communication device according to the first aspect of the present invention includes a detecting unit for detecting an error rate of a received signal, a storing unit for storing a reference value of the error rate,
Error rate determining means for determining whether the error rate of the received signal detected by the detecting means is greater than the reference value, and frequency changing means for hopping the frequency based on the error rate determination result. Accordingly, the frequency of hopping the frequency in the conventional data communication is substantially reduced, and the occupation time required for each fixed time can be reduced, and as a result, the data transfer rate can be improved.

The communication device according to the second aspect of the present invention can limit the time occupying a certain carrier frequency band by providing a frequency hopping time measuring means and a time discriminating means. Since an upper limit is set for the communication time at the same frequency, communication conditions can be satisfied within the range of the restriction.

The communication device according to the third aspect of the present invention includes a table storing the hopping change pattern, so that the time for calculating the hopping frequency every time the carrier frequency is determined can be omitted, and the communication can be speeded up.

In the communication apparatus according to the present invention, the hopping frequency can be limited by providing a means for excluding a carrier frequency having a high error rate, and the occupation time can be reduced by limiting the hopping frequency. Therefore, the data transfer rate can be improved accordingly.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment to which a system of the present invention is applied.

FIG. 2 is a time chart showing a change in a carrier frequency to which the present invention is applied.

FIG. 3 is a block diagram showing a configuration of another embodiment (especially claim 2).

FIG. 4 is a block diagram showing a configuration of another embodiment (especially claims 3 and 4).

FIG. 5 is a flowchart of a control operation in the configuration of FIG. 3;

FIG. 6 is a flowchart of a control operation in the configuration of FIG. 3;

FIG. 7 is a flowchart of the control operation when the configuration of FIG. 3 is used for one transceiver and the configuration of FIG. 5 is used for the other transceiver.

FIG. 8 is a flowchart of a control operation when the configuration of FIG. 3 is used for one transceiver and the configuration of FIG. 5 is used for the other transceiver.

FIG. 9 is a format of transmission / reception data in the configurations of FIGS. 1, 3, and 4;

FIG. 10 is a block diagram showing a configuration of a communication device using a conventional FH spread spectrum communication system.

FIG. 11 is a time chart of a carrier frequency change in the conventional FH spread spectrum communication system.

[Explanation of symbols]

 Reference Signs List 20 transmission data input terminal 21 data output terminal 22 up-converter 23 comparison / determination unit 24 error rate detection storage unit 25 synchronization circuit 26 spreading code sequence generator 27 time discrimination unit 27a timer 28 frequency synthesizer 29 down converter 30 amplifier 31 amplifier 32 duplexer 33 antenna 34 demodulator 35 hopping table 36 data redundant unit 37 primary modulator 38 control unit 39 high error rate discriminating unit

Claims (4)

[Claims] 1. A communication apparatus for performing two-way communication while hopping a frequency, a detecting means for detecting an error rate of a received signal, a storing means for storing a reference value of the error rate, and a detecting means for detecting an error rate of the received signal. Error rate determination means for determining whether the error rate of the received signal is greater than the reference value, and frequency changing means for hopping the frequency based on the error rate determination result, Communication device. 2. A measuring means for measuring an elapsed time from when the frequency is hopped by the frequency changing means, and a time determining means for determining whether or not the elapsed time measured by the measuring means has reached a predetermined time. And the frequency change means, the error rate determination means by the error rate reference value exceeding the reference value is determined timing,
2. The communication device according to claim 1, wherein the frequency is changed at a timing earlier than the timing of the determination of the predetermined time by the time determination unit. 3. The communication according to claim 1, wherein the frequency changing unit has a table storing a change pattern of a frequency to be hopped, and determines a frequency to be changed according to the table. apparatus. 4. A high error rate frequency discriminating means for detecting a frequency judged to have a high error rate by said error rate discriminating means, and excluding or changing the frequency detected by said high error rate frequency discriminating means from a hopping frequency. The communication device according to claim 1, further comprising: