JPS6336696B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiving device using a communication system that transmits information to be transmitted by changing a plurality of frequencies corresponding to the information.

This type of communication method is called a spread spectrum communication method, and one of them is the frequency hopping method (FH method).
Hopping System). In this method, for example, as shown in FIG. 1a, for each bit of time-series digital information to be transmitted, N center frequencies ₁ , ₂ , ₃ , . , _N , and assign the bit information to the positive or negative frequency deviation Δ for each center frequency.
This is repeatedly transmitted every N bits. On the other hand, on the receiving side, since the above frequency arrangement and frequency deviation are known, after receiving the transmitted signal and establishing synchronization, the direction of frequency deviation from the center frequency (positive or negative side) is detected. Restore digital information by However, conventionally, this type of communication system transmits digitized information using N irregularly changing frequencies, so the transmission frequency changes irregularly over a wide band.
Therefore, the receiving filter had to have a wide bandwidth, and had the disadvantage of being susceptible to interference.

The present invention provides a receiving device that effectively eliminates the above-mentioned drawbacks (communication interference), interference, etc. that occur in a communication system that transmits information by changing a plurality of frequencies.

In order to achieve this object, the receiving device according to the present invention has a wide bandwidth filter and a plurality of narrow bandwidth filters, and when asynchronous, reception is performed through the wide bandwidth filters, and when synchronization is established, transmission is performed. The plurality of narrow bandwidth filters are switched in accordance with changes in the side frequency for reception.

Next, an embodiment of the present invention will be described with reference to FIG.

The receiving device according to the present invention includes an antenna 1 that captures incoming radio waves, and a high frequency bypass switch 3 that connects the high frequency input from the antenna 1 to a control section 6 and a demodulation section 7 through a wideband filter 2 during asynchronous operation, and cuts off this connection during synchronization. , a narrowband filter switching device 5 that switches a plurality of narrowband filters 4 under the control of the control section 6 , a control section 6 that controls the high frequency bypass switch 3 and the narrowband filter switching device 5 , a bottom band filter 2 , and a plurality of bottom band filters 2 . a demodulator 7 that demodulates the output of the narrow band filter 4;
includes an output terminal 8.

Next, the operation of the receiving apparatus according to the present invention will be explained.
Incoming radio waves enter the receiving device from the antenna 1 and are not synchronized in the initial state of reception, so the high frequency bypass switch 3 becomes conductive, and the high frequency input passes through the wide band filter 2 and is input to the control section 6 and the demodulation section 7. When synchronization is established in the control section 6, the high frequency bypass switch 3 becomes non-conductive, and at the same time, the narrowband filter switch 5 switches to the control section 6.
The narrow band filters 4 are switched to a plurality of narrow band filters 4 according to the receiving frequency under the control of. The demodulator 7 is configured to select one of the broadband filters 2 or a plurality of narrowband filters 4 selected by the narrowband filter switch 5.
The outputs of two narrowband filters are input, and the demodulated output is output to the output terminal 8.

As explained above, the present invention is configured to switch the reception band limiting filter in accordance with the frequency of the reception high frequency, thereby achieving a broadband reception frequency that is characteristic of a communication system that transmits information using a plurality of frequencies. At a certain moment, it cuts out unnecessary frequencies, eliminates receiver mixer spurious noise, external interference, interference, etc., and greatly improves reception conditions.

[Brief explanation of the drawing]

FIGS. 1a and 1b are diagrams illustrating a method of transmitting digital information by changing a plurality of frequencies, and FIG. 2 is a block diagram showing an embodiment of the present invention. 1...Antenna, 2...Broadband filter, 3
... High frequency bypass switch, 4 ... Multiple narrowband filters, 5 ... Narrowband filter switching device,
6...Control unit, 7...Demodulation unit, 8...Output terminal.

Claims (1)

[Claims] 1. A receiving device for a signal in which information is transmitted by changing a plurality of predetermined frequencies, including a first filter with a wide bandwidth that passes the plurality of frequency components, and a band whose center frequency is predetermined. A plurality of narrow-width filters, a synchronization means for synchronizing with the changes in the plurality of frequencies, and when out of synchronization, the signal is received through the first filter with a wide bandwidth, and from the time when synchronization is established, synchronization means synchronizes with the changes in the frequency of the plurality of frequencies. and control means for controlling the plurality of narrow bandwidth filters to switch and receive data.