JPH0591094A - Fm transmitter-receiver - Google Patents

Abstract

PURPOSE:To facilitate cordless operation of an OA equipment and radio LAN by providing an AM modulation means and a frequency mixer to a reception section, applying FM demodulation to an intermediate frequency signal of an output of the frequency mixer to obtain reception data. CONSTITUTION:An AM modulation means 1 receives a low level reception signal f1+ or -DELTAf around a radio frequency f and uses an output of a local signal generator whose frequency is F1 lower than the frequency f1 and larger than an FM modulation signal band width B of a reception signal as a modulation signal thereby implementing amplitude modulation. Side band components f1+ or -DELTAf+f and f1DELTA-F are generated by the modulation and outputted to a frequency mixer 2. The mixer 2 mixes the side band outputs f1+ or -DELTA+f and f1+ or -DELTA-F of the means 1 and an output of a radio frequency f of a voltage controlled oscillator VCO of a transmission section and outputs a signal F+ or -DELTAf having an intermediate frequency of the difference frequency F. Then the amplitude is controlled by a limiter through a BPF and the result is demodulated by a discriminator to obtain a reception data DR. Thus, the cost of the transmitter- receiver is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention divides the use time of one radio frequency into transmission and reception in an office or the like, and FM-modulates transmission data to perform bidirectional communication.
sion Duplex) type FM transceiver.

[0002]

2. Description of the Related Art Demand for simple wireless communication on the premises of high-speed and large-capacity data such as cordless operation of OA equipment in offices and construction of wireless LAN is rapidly increasing.

By the way, in order to perform high-speed and large-capacity data wireless communication, it is suitable to use a quasi-millimeter wave band or a millimeter wave band having a high frequency. However, circuit components in these high frequency bands are expensive. Therefore, it is necessary to simplify the circuit in those radio communication devices in the high frequency band. FIG. 5 shows a configuration example of a conventional quasi-millimeter wave band or millimeter wave band FM transceiver. The transmission unit uses the low-pass filter LP for the input transmission data D _T.
A so-called voltage controlled oscillator VCO whose output is band-limited by F and whose oscillation frequency is determined by a control voltage and which is subjected to FM modulation. A predetermined frequency deviation Δf with a predetermined radio frequency f1 as the center frequency.
The FM-modulated transmission signal f1 ± Δf is generated, the power is amplified to the specified transmission power by the power amplifier PA, and is transmitted from the antenna ANT to the communication partner via the transmission / reception changeover switch SW. The receiving unit uses the antenna ANT to receive the FM-modulated radio signal f1 ± Δf of the predetermined radio frequency f1 from the communication partner.
At the transmission / reception changeover switch SW, amplified by the preamplifier AMP, and then mixed by the frequency mixer MIX with the output of the local oscillator RLOC having the radio frequency f2, and the difference between them. The frequency is converted to fi ± Δf = │f1−f2│ ± Δf, passed through the bandpass filter BPF of the passband B (= 2Δf) at the intermediate frequency fi, the amplitude is limited by the limiter, and the FM demodulator discretizes. Then, demodulation is performed and the received data D _R is obtained.

[0004]

As described above, in the configuration of the conventional FM transmitter / receiver, the reception signal of the FM frequency-modulated radio frequency f1 ± Δf of the signal received by the receiving section at the antenna ANT is the intermediate frequency fi = │. In order to perform frequency conversion into f1−f2│ ± Δf, the oscillation frequency of the transmission signal of the transmitter is at the radio frequency f1 and the oscillation frequency is almost the same as that of the voltage controlled oscillator VCO with a certain output level. Since the oscillator RLO is required, two expensive high frequency oscillators are required, and the FM
There has been a problem that the cost of circuit components of the transmitter / receiver increases. An object of the present invention is a device that does not require a local oscillator RLO of a radio frequency f2 having substantially the same configuration as a voltage controlled oscillator VCO that outputs a transmission signal of a radio frequency f1 on the transmission side to a receiving unit, and has a high frequency. Is to realize a low-cost TDD FM transmitter / receiver by a circuit that handles low-level received signals and high-level but relatively low-frequency signals.

[0005]

The basic configuration of the present invention for achieving this object is shown in the principle diagram of FIG. 1 is a high-frequency radio frequency but low-level received signal f1 ± Δf is input, and a local signal having a frequency F lower than the radio frequency f1 and larger than the FM modulation signal bandwidth B of the received signal is input. Amplitude modulation AM is used as the modulation signal, and its sideband component f1 ± Δ
The AM modulation means outputs f + F and f1 ± Δf-F. 2 is
Output of voltage controlled oscillator VCO for generating signal of radio frequency f1 ± Δf of transmitter and output f1 ± Δf + of AM modulation means 1
It is a frequency mixer which mixes F and f1 ± Δf−F and outputs a signal F ± Δf having a center frequency of an intermediate frequency equal to the frequency F of the modulated signal of the frequency difference between the two outputs.

[0006]

In the present invention, the AM modulation means 1 provided in the receiving section
However, the low-level received signal f1 ± Δf centered on the high frequency radio frequency f1 from the antenna ANT is input, and the frequency is lower than the radio frequency f1 and the FM modulated signal bandwidth B (= 2Δf) of the received signal Amplitude modulation AM is performed by using the output of the local signal generator having a larger frequency F as the modulation signal. Then, the sideband wave components f1 ± Δf + F and f1 ± Δf−F are generated by the modulation and output to the frequency mixer 2. The frequency mixer 2 mixes the sideband output f1 ± Δf + F, f1 ± Δf-F of the AM modulation means 1 with the output of the radio frequency f1 of the voltage controlled oscillator VCO of the transmitter,
It outputs the signal F ± Δf of the intermediate frequency of the difference frequency F. Below is the conventional band pass filter BPF of the intermediate frequency F.
, The amplitude is limited by a limiter, and demodulated by the FM demodulator in a discrete manner to obtain received data D _R. Therefore, in the present invention, the receiver controls the voltage controlled oscillator VC of the radio frequency f1 on the transmission side.
The AM modulation means 1 does not require a local oscillator RLO having the same radio frequency f2 as that of O and compares the received signal f1 ± Δf at a high radio frequency but at a low level with the radio frequency f1 at a high level. Since it is a circuit that amplitude-modulates with a low frequency F modulation signal, the transmitter / receiver is low in cost and the purpose is achieved.

[0007]

2 is a block diagram showing the configuration of an FM transmitter / receiver of an embodiment corresponding to claim 1 of the present invention, and FIG. 3 is a block diagram of an FM transmitter / receiver of an embodiment corresponding to claim 2 of the present invention. The configuration is shown. 4 is a signal waveform diagram of each point for explaining the operation of the embodiment of FIG.

In the FM transmitter / receiver of the embodiment shown in FIG. 2, the AM modulating means 1 of the receiving section has a PIN for turning on / off the received signal f1 ± Δf at a low level although it has a high radio frequency in its modulation element. Diode, so-called HEMT, GaAsF
A high frequency semiconductor element such as ET is used, and its frequency is lower than the radio frequency f1 and the amplitude modulation AM is performed by the modulation signal of the frequency F that is larger than the FM modulation signal bandwidth B of the received signal, and the sideband component f1 ± Δf + F , f1 ± Δf- F, and frequency mixer
Output to 2. The frequency mixer 2 outputs the output f1 ± Δf + F, f1 ± Δf-F of the AM modulator 1 and the voltage controlled oscillator VCO FM-modulated by the frequency deviation Δf at the radio frequency f1 at the output of the transmitter. The output f1 ± Δf is mixed, and the signal F ± Δf of the intermediate frequency of the difference frequency F is output.The following is the band pass filter BPF of the intermediate frequency F, the amplitude is limited by the limiter, and the FM demodulator It demodulates in a discreet manner to obtain received data D _R. In the present invention, the frequency for AM modulation received by the antenna ANT with respect to the received signal f1 ± Δf
For example, since it is possible to use the VHF band as the F modulation signal, only one of the voltage-controlled oscillators VCO on the transmission side is required as an expensive high-frequency oscillation source in the quasi-millimeter wave band or millimeter wave band. Therefore, the cost of the FM transmitter / receiver can be reduced.

In the embodiment shown in FIG. 3, a transmission / reception switch is used.
Oscillation frequency F for AM modulation for SW switching signal (Fig. 4) and received signal f1 ± Δf received by antenna ANT
In the multiplier 3 which multiplies with the output of the local signal oscillator of FIG. 4 (of FIG. 4), a modulated signal of the intermittent frequency F 1 is created as shown in FIG. 4 and is added to the AM modulating means 1. With this circuit configuration, the switching signal of the transmission / reception switch SW (of FIG. 4) is used as the switching signal for the output (of FIG. 4) of the local signal oscillator of the oscillation frequency F for AM-modulating the reception signal f1 ± Δf. Also, the circuit of the receiving unit can be simplified.

[0010]

As described above, according to the present invention, the cost of the FM transmitter / receiver for data transmission can be reduced. Therefore, the cordless operation of the OA equipment in the office and the wireless L function can be realized.
The effect of facilitating the construction of the AN is obtained.

[Brief description of drawings]

FIG. 1 is a principle diagram showing a basic configuration of an FM transceiver according to the present invention.

FIG. 2 is a block diagram of an FM transmitter / receiver according to an embodiment corresponding to claim 1 of the present invention.

FIG. 3 is a block diagram of an FM transceiver according to an embodiment corresponding to claim 2 of the present invention.

FIG. 4 is a signal waveform diagram of each point for explaining the operation of the embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional FM transceiver.

[Explanation of symbols]

Reference numeral 1 is an AM modulator, 2 is a frequency mixer, and 3 is a multiplier.

Front page continuation (72) Inventor Yoji Ohashi 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited (72) Inventor Teruhisa Ninomiya 1015, Kamedota, Nakahara-ku, Kawasaki, Kanagawa

Claims (2)

[Claims] 1. A TDD-type FM transmitter / receiver which divides the use time of one radio frequency (f1) into a transmitter and a receiver and FM-modulates transmission data (D _T ) to perform two-way communication. In the receiving unit of the preceding station device, the reception signal (f1 ± Δf) received by the antenna of the signal transmitted by the transmitter of the preceding station apparatus by FM-modulating the signal of the radio frequency (f1) is lower than the radio frequency. Amplitude modulation (AM) using a local signal with a frequency (F) larger than the FM modulation signal bandwidth (B) of the received signal as the modulation signal
And output the sidebands (f1 ± Δf + F, f1 ± Δf-F) A
M modulation means (1) and the radio frequency of the transmitter of the own station device
The output of the voltage controlled oscillator (VCO) that has sent the signal of (f1) and the output (f1 ± Δf + F, f1 ± Δf-F) of the AM modulation means are mixed, and the modulation is performed by the frequency difference between the two outputs. Signal frequency
A frequency mixer (2) that outputs an intermediate frequency signal (F ± Δf) equal to (F), and FM demodulates the intermediate frequency signal (F ± Δf) output from the frequency mixer to receive data (D). FM transmitter / receiver characterized by obtaining _R ). 2. An A provided in a receiving portion of the FM transceiver.
The modulation signal of the M modulation means (1) is a switching signal that drives a switch (SW) that switches between a transmission signal output from the transmission unit of the own transmission / reception device to the antenna (ANT) and a reception signal input from the antenna to the reception unit. And the output of the multiplier (3) that multiplies the output of the local signal generator that continuously outputs a frequency (F) lower than the radio frequency (f1) of the received signal and higher than the FM modulation signal bandwidth (B) The FM transmitter / receiver according to claim 1, wherein