Telecommunications – Transmitter – Carrier frequency stabilization
Patent
1981-05-27
1983-07-26
Ng, Jin F.
Telecommunications
Transmitter
Carrier frequency stabilization
455 76, 455113, H04B 104
Patent
active
043957765
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a transmitter used in FM radio equipment for a multichannel simultaneous transmitting and receiving system, of the type used mainly in VHF and UHF bands.
BACKGROUND ART OF THE INVENTION
In a mobile communication system using VHF or UHF band frequencies, it is common for the frequencies to be multichannel and wide band. In this case, there is a strong requirement to decrease the transmission strength of spurious waves and to decrease noises in sideband, especially in the transmitting output signal in order not to disturb other communication systems.
On the other hand, due to the multichannel requirement of the communication system, the "phase synchronizing type digital frequency synthesizers" being easily obtainable, a very large number of frequencies are increasingly used as the signal source of the local oscillation frequency of the transmitter and the receiver. For such purpose, derives the local oscillation frequency signal source for the transmitter and for the receiver from a single phase synchronizing type frequency synthesizer widens the frequency bandwidth.
Such a device is basically constructed to have a phase synchronizing type of digital frequency synthesizer, a transmitter, a receiver, an antenna duplexer, and an antenna terminal. Further, in more detail, the transmitter comprises a side step oscillator, a phase or frequency modulator, a transmitting buffer amplifier, a frequency mixer, a bandpass filter, a preamplifier and a power amplifier. The receiver comprises, in more detail a receiving buffer amplifier, a receiving high frequency portion, an intermediate frequency converter, an intermediate frequency bandpass filter and a demodulator.
In this formation or arrangement of the transmitter, it is difficult to obtain a good signal having low noises and sufficiently suppressed spurious waves over a wide band at the transmitter output so that it has disadvantages of many technical and manufacturing problems.
SUMMARY OF THE INVENTION
The present invention is directed to solving the aforementioned problems. The main feature thereof may be summarized as follows: A phase synchronizing system having its reference frequency taken from an output signal of the bandpass filter is inserted between the bandpass filter and the preamplifier of the transmitter, and by this means the suppression or decrease of the aforementioned spurious waves and the sideband noises in the output of the transmitter is achieved.
According to the present invention, a high quality, wide band transmitter for FM radio equipment of the type having a multichannel simultaneous transmission and receiving system can easily be obtained in a miniaturized form and at low cost.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of conventional FM radio equipment for a multichannel simultaneous transmission and receiving system;
FIG. 2 is a block diagram of a digital frequency synthesizer of a phase synchronization type;
FIG. 3 is a block diagram of a transmitter according to the present invention;
FIG. 4 is a block diagram for an improved embodiment of the transmitter shown in FIG. 3;
FIG. 5 is a block diagram for an improved embodiment of the transmitter shown in FIG. 4;
FIG. 6 is a block diagram for a further improved embodiment of the transmitter shown in FIG. 5;
FIG. 7 is a block diagram showing the inside of an antenna duplexer;
FIG. 8 is a block diagram showing an improvement in the transmitter of FIG. 6 relating particularly to the modulator;
FIG. 9 is a block diagram showing further improvement of the transmitter of FIG. 8;
FIG. 10 is a practical embodiment of FM radio equipment for a multichannel simultaneous transmission and receiving system of the type using the transmitting system of the present invention; and
FIG. 11 is a more practical embodiment of the block diagram shown in FIG. 9 .
Hereinafter, a transmitter using the transmitting phase synchronization system of the present invention will be explained by referring to the accompanying drawings.
A
REFERENCES:
patent: 3644831 (1972-02-01), Latker et al.
patent: 4231116 (1980-10-01), Sekiguchi et al.
patent: 4259744 (1981-03-01), Junod et al.
Naito Yukio
Takahashi Shigeo
Tamura Masahide
Ng Jin F.
Toyo Communication Equipment Co., Ltd.
LandOfFree
Transmitter having a phase synchronizing system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Transmitter having a phase synchronizing system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transmitter having a phase synchronizing system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2224897