JPH0473820B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a frequency hopping multilevel frequency shift keying (FH-MFSK) receiving apparatus.

[Conventional technology]

Conventionally, a frequency hopping multilevel frequency shift keying (FH-MFSK) receiving device uses, for example, a specific user's FH address sequence.
Decoding a received signal of length L by selecting one or more of 2 ^k levels with a maximum value less than or equal to a predetermined absolute value to convert it into a received signal desired by the user. There is a ^2K level frequency shift keying receiver capable of.

Figure 5 shows the configuration of a conventional receiving device.
In the figure, 30 is a receiving device, 32 is a receiving antenna, 34 is a down converter for down-converting the received signal to a selected frequency band if necessary (the dotted line indicates an option), and 36 is a receiving signal or a receiving antenna. a spectral analyzer and detector that processes the downconverted signal and determines which of the 2 ^k frequencies are present; 3;
8 is a frequency hopping address generator that generates a user-specific address sequence; 40 is a pulse generator that provides data determination timing; 42 is a modulo ^2k subtracter that subtracts the address level from the detected level of the received signal; 44 a detection and majority logic decider to determine which of the 2 ^k levels has the maximum length or maximum value; and 4
Reference numeral 6 denotes a ^2k level decoder that decodes ^2k levels according to the reception format required by the user.

FIG. 3 shows a spectral analyzer and detector 36 in a conventional receiving device. In the figure, 50 is a band filter that separates 2 ^k frequencies, 52 is an energy detector that detects the energy of the output signal of each band filter, and 54 is a thread that detects the energy level detected by the energy detector 52. A threshold detector converts the detected energy level into a binary "1" or "0" depending on whether the threshold level is exceeded or not, or an energy level detector 54 converts the detected energy level into a multi-bit binary output signal. , 56 is a threshold or energy level detector 54 when it is desired to temporarily store the detected signal.
A multiplexer which serially sends each of the output signals obtained from the spectral matrix to a receive spectral matrix store 57, or a threshold or energy level detector 56 when it is desired to send the detected signals directly to a modulo ^2k subtractor. 2 ^k gates responsive to pulses from the synchronized pulse generator 40 to simultaneously transmit the output signals obtained from the modulo 2 ^k subtracter 42, 57 a receive spectral matrix storage, and 58 a receive spectral matrix. A lead connecting the memory 57 and the modulo ^2k subtractor 42 is shown, and 59 represents a lead connecting the gate 56 and the modulo ^2k subtracter 42.

FIG. 4 shows a system diagram of a typical frequency hopping multilevel frequency shift keying (FH-MFSK) transmitter.

In the figure, 10 is a transmitting device, 12 is a ^2K level encoder, 14 is a code word buffer that temporarily stores the levels obtained by the ^2K level encoder 12 as words of L elements having the same code level for each element, and 16 18 is a frequency hopping address generator that generates a unique frequency hopping address code word that is different for each system user; 18 generates synchronization pulses from an internal clock and generates the corresponding chips of the code word and address word; A synchronous pulse generator that simultaneously sends both of the modulo 2 ^k adders 20, 20 is the modulo
2 ^k adder, 22 is a frequency generator that transmits one of 2 ^k frequencies by the transmit spectrum matrix every τ seconds, 24 is an up converter (the dotted line indicates that it is optional), and , 26 indicate transmitting antennas.

Next, the operation will be explained. ^2k of transmitting device 10
Level encoder 12 periodically samples an analog input signal, for example from a particular user, and converts the amplitude level of each sample to an equivalent level of a ^2k level code. On the other hand, if the input signal is in binary form, the ^2k level encoder 12 converts each group of K consecutive bits to an equivalent level of a ^2k level code. In either case, the resulting code equivalent level is buffered in the code word buffer 14 as a word of L elements with the same code level for each element. This is called a chip and has a time width of τ seconds. An example of a code word is shown in a matrix below code word buffer 14 in FIG.

Here the code word consists of 5 chips, L=5
It is.

Each chip represents the fifth of eight possible levels, K=8.

Frequency hopping address generator 16 operates to generate unique frequency hopping address words that are different for each system user within the same zone or cell. The address code word is a sequence of L chips, each chip having τ
It has a time width of seconds and consists of one of 2 ^k levels of codes, and the code may be different for each chip of the same address word. For example, as shown in the matrix labeled "Address" below frequency hopping address generator 16 in FIG.
The address word for a user of a particular system is L=
5 consists of 5 chips, with chips 1-5 having code levels 1-5 of the 2 ^k possible code levels that each chip can have.

Synchronization pulse generator 18 generates pulses from an internal clock to cause corresponding chips of the code word and address word to be transmitted simultaneously to modulo ^2k adder 20. Adder 20 adds the corresponding chips of the code and address word modulo 2 ^k to produce a new code word of length L, as shown, for example, in the matrix shown under "Transmit Spectrum" in FIG.
The new codewords thus obtained are sent to the frequency generator 22, and the system It operates to generate 2 ^k specific ones within the total bandwidth. For example, for the "transmit spectrum" matrix of FIG.
For a time span of seconds, 2 ^k −2, 2 ^k −1, 2 ^k , 1,
A frequency corresponding to level 2 is transmitted. This sequence of L tones or frequencies is still the correct system transmit frequency if the frequency generator 2
2, it is converted to the correct system transmission frequency by an optional upconverter 24 and transmitted by a transmitting antenna 26. The operation of the receiving device 30 that can receive and decode the FH-MFSK signal transmitted by the transmitting device 10 of FIG. 4 in this way will be explained next. The FH-MFSK signal is received by receive antenna 32 and, if necessary, downconverted to the appropriate frequency band by optional downconverter 34 before further processing. The received and downconverted signal is processed by spectrum analyzer and detector 36 to determine which of the 2 ^k frequencies or tones are present. The spectral analysis and detector 36 is
Contains ^2k tone detectors to determine which of ^2k tones is present. Each of the tone detectors determines which of the 2 ^k frequencies contains the energy of the received signal every τ seconds. The received energy matrix of FIG. 5 shows the transmitted tones of FIG. 4 and the tones indicated by the O's received from other links. Figure 3 shows the spectrum analysis and detection circuit 3.
6 is illustrated. The signal received from receive antenna 32 or optional downconverter 34 is applied to 2 ^k bandpass filters 50, each filter capable of separating the 2 ^k tones shown in the "Receive Spectrum" matrix of FIG. It is synchronized. The signal passing through each bandpass filter 50 is provided to an individual energy detector 52, which operates to detect the energy of the signal passing through each. The output signal from each of the energy detectors 52 is provided to a separate threshold or energy level detector 54, which
When this detector operates as a threshold detector, the energy level detected by ” Convert to ”. Instead of this, the detector 54
also operates as an energy level detector, in which case the detector converts the detected energy into a multi-bit binary output signal.

When it is desired to temporarily store the signals detected in response to pulses from the synchronous pulse generator 40, a multiplexer 56 is used to connect the 2 ^k threshold or energy level detectors 54.
Each ^of the output signals obtained from
Subtractor 42 may be temporarily stored prior to transmission through lead 58. If instead it is desired to send the detected output signals directly to the modulo ^2k subtractor 42, the circuit 56 is configured to simultaneously send the ^2k detected output signals to the modulo ^2k subtractor 42 through leads 59. It will consist of ^2k gates responsive to pulses from generator 40. In either case, the receive spectral matrix consists of FH-MFSK signals from multiple uses that are simultaneously received on the receive antenna 32 and processed as shown in FIG. 5 by the spectrum analyzer and detector 36. Ru.

In FIG. 5, a frequency hopping address generator 38 can receive the signal and generate the desired user-specific address code word to be decoded. As shown in the address matrix of FIG. 5, this is the same address code word generated in the transmitter of FIG. A synchronization pulse generator 40 generates pulses corresponding to the received FH-MFSK signal, and the address code word is simultaneously applied to a modulo 2 ^k subtracter 42 where the address level is modulo 2 ^k from the detected level of the received signal.
A determination matrix as shown in FIG. 5 is generated. In the decision matrix, the elements obtained from the user in Fig. 4 are indicated by ×, and the elements from other links are indicated by O, but these are based on received tones, that is, frequency components from other links. It is obtained by subtracting the same address elements.

The output from ^modulo2k subtractor 42 is sent to detection and majority logic decision circuit 44 for processing. Detection and majority logic decision circuit 44 examines the decision matrix to determine which of the 2 ^k levels has the maximum length or value. If only one level has such a maximum length or value, its level indication is sent to a ^2K level decoder 46, which decodes the level indicated to the user according to the desired form of reception. It is converted into a K-bit binary message or an analog signal with an amplitude corresponding to the displayed level.

[Problem that the invention seeks to solve]

Since the conventional frequency hopping multilevel frequency shift keying (FH-MFSK) receiving device is configured as described above, it is necessary to provide 2 ^k band filters in the spectrum analyzer and detector, which requires a large amount of hardware. There were problems such as the difficulty of making the wear smaller.

This invention was made to solve the above-mentioned problems, and aims to provide a frequency hopping multilevel frequency shift keying (FH-MFSK) receiving device that can reduce the size and cost of hardware. purpose.

[Means for solving problems]

The frequency hopping/multilevel frequency shift keying (FH-MFSK) receiving apparatus according to the present invention uses a frequency discriminator in its constituent components, spectral analysis and detector.

[Effect]

In the spectrum analysis and detector of the present invention, the energy detector after the bandpass filter is configured with a frequency discriminator, and not only energy level information but also frequency information is used to detect 2 ^k frequencies.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 50 is a band filter, 51
54 is a threshold or energy level detector; 56 is a multiplexer or gate; 57 is a reception spectrum matrix storage; and 58, 59. indicates lead. In other respects, the configuration of the receiving device is the same as that of the prior art.

FIG. 2 shows an example of the characteristics of the frequency discriminator 51.

Next, the operation will be explained. Signals received from receive antenna 32 or optional down converter 34 are applied to 2 ^k-1 bandpass filters 51 . Each filter carries two of ^{the 2k} tones shown in the “Receive Spectrum” matrix in Figure 4.
It is tuned so that it can be separated into 2k ^-1 pieces. The signal passing through each bandpass filter 50 is applied to an individual frequency discriminator 51. The frequency discriminator 51 outputs a voltage according to the frequency of the output signal of the bandpass filter 50 (FIG. 2), and can separate 2 ^k tones in total. The output signal from each frequency discriminator 51 is provided to a separate threshold or energy level detector 54. The subsequent operations are similar to those of the prior art.

In the above embodiment, two frequencies are discriminated by the frequency discriminator 51, but even if two or more frequencies are discriminated, the same effect as in the above embodiment can be obtained. However, if signals from other links are present, increasing the number of frequencies identified by one frequency discriminator 51 makes it difficult to separate the desired wave from the interference wave.

〔Effect of the invention〕

As described above, according to the present invention, frequency hopping multilevel frequency shift keying (FH-
MFSK) type receiving device is configured to use a frequency discriminator for spectrum analysis and the energy detector of the detector, so the number of band filters required can be halved, the device can be made cheaper, and the device can be made smaller and lighter. There is.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a spectrum analysis and a detector of a frequency hopping multilevel frequency shift keying receiver according to an embodiment of the present invention;
Fig. 2 is a characteristic diagram of the frequency discriminator shown in Fig. 1, Fig. 3 is a system diagram showing a conventional spectrum analyzer and detector, and Fig. 4 shows a conventional frequency hopping multilevel frequency shift keying transmitter. System diagram,
FIG. 5 is a system diagram showing a conventional frequency hopping multi-level frequency shift keying receiving apparatus. In the figure, 10 is a transmitter, 12 is a ^2k level encoder, 14 is a code word buffer, 16 is a frequency hopping address generator, 18 is a synchronization pulse generator, 20 is a modulo ^2k adder, and 22 is a frequency generator. , 24 is an up converter, 26 is a transmitting antenna, 30 is a receiving device, 32 is a receiving antenna, 34
is a down converter, 36 is a spectrum analyzer and detector, 38 is a frequency hopping address generator, 40 is a synchronization pulse generator, 42 is a modulo ^2k
subtractor, 44 detection and majority logic decision, 46
is a ^2k level decoder, 50 is a bandpass filter, 51 is a frequency discriminator, 52 is an energy detector, 54 is a threshold or energy level detector,
56 is a multiplexer or gate, 57 is a reception spectrum matrix storage device, and 58 and 59 are leads. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1 The information signal from each user is encoded as one of 2 ^k frequencies, and each signal has a length L.
In a frequency hopping/multi-level frequency shift keying type receiving device that modulates with ^{a frequency} hopping/address sequence of a frequency hopping address generator that receives the pulses from the pulse generator and generates a desired user-specific address sequence;
a modulo ^2k subtracter that generates a decision matrix by subtracting the address level from the output level from the spectrum ^analysis and detector in response to the pulses from the pulse generator; a detection and logic decider for determining which of the levels has a maximum length or maximum value;
The spectrum analyzer ^and detector includes a level decoder to which the output from the determiner is supplied and decodes it according to the reception form required by the user. The signals that have passed through these band filters are supplied to a plurality of frequency discriminators that discriminate between two or more frequencies, and the output signals from each frequency discriminator are respectively supplied to detect whether the threshold is exceeded. and a multiplexer to serially send the output signal from the detector to the receive spectral matrix storage or a gate to send the output signal from the detector to the modulo ^2k subtractor. A receiving device characterized by: