JPH01218189A - Transmitter - Google Patents

Abstract

PURPOSE:To transmit a voice signal and a data signal with high definition by multiplexing the voice signal and the data signal independently with a frequency-modulated video signal. CONSTITUTION:Assuming the frequency band occupied by a base band video signal is defined from DC to fv, a voice signal inputted to a phase modulator 10 whose carrier wave is in fa (fa>fv) is phase-modulated therein and inputted to a frequency multiplexer 30. A base band data signal inputted to an FS modulator 20 whose carrier wave is in fd (fd>fv) is FS modulated therein and inputted in the multiplexer 30. In the meantime, a base band video signal is frequency modulated in a band outside the frequency band occupied by an output signal from the multiplexer 30 by a frequency modulator 40 whose carrier wave is in fp. The frequency band occupied by an output signal from this modulator 40 is a carrier wave fp as a center and is within fp+ or -fa. In such a way, phase- modulated voice signal and FS modulated data signal are multiplexed independently of a video signal frequency modulated at the time of transmission, therefore, high-definition voice data signal and data signal can be transmitted at high transmission speed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to devices for transmitting video, audio, and data.

BACKGROUND OF THE INVENTION A conventional example of a device for transmitting video, audio, and data will be explained with reference to FIG. A PCM encoded audio signal inputted to the phase modulator 11 as a carrier wave fsa is phase modulated and inputted to the frequency multiplexer 31. Carrier wave f lId (f l
Id> f @a) The data manually input to the FS modulator 21 is FS-modulated and input to the frequency multiplexer 31. The frequency multiplexer 31 converts the baseband video signal 11, the phase-modulated audio signal, and the FS The modulated data signal is frequency multiplexed and output.

The power spectrum of the output of the frequency multiplexer 31 is shown in Figure 5 (
Shown in a). This multiplexed signal is input to a frequency modulator 40 which uses it as a carrier wave fp and is frequency modulated. The discriminator 50 performs binary discrimination on the output signal of the frequency modulator 40 based on the DC zero level of this signal, and transmits the resultant signal. The power spectrum of this signal is shown in FIG. 5(b).

The output signal of the discriminator 50 is input to the frequency demodulator 91 of the receiving section via the transmission line 100. This frequency demodulator 9
1 reproduces a multiplexed signal of a baseband video signal, a phase-modulated PCM encoded audio signal as a carrier wave fea, and an FS-modulated data signal as a carrier wave fgd. This multiplexed signal is filtered by a low-pass filter 63 for the baseband video signal band and a band-pass filter 64 for the center frequency faa.
, a baseband video signal, a phase-modulated PCM encoded audio signal with a carrier wave f@a, and a carrier wave F with a carrier wave fsd, respectively, through a band-pass filter 65 with a center frequency fsd.
The signal is separated into S-modulated data signals. A phase demodulator 71 connected to the bandpass filter 64 reproduces a PCM encoded audio signal from the phase modulated PCM encoded audio signal, which is the carrier wave fea.

Also, an FS demodulator 8 connected to a bandpass filter 65
1 is the carrier wave f[! A baseband data signal is reproduced from the FS modulated data signal d.

Now, as the transmission speed of audio data increases, the frequency band occupied by the output modulated wave of the phase modulator 11 widens. Therefore, the carrier wave flIa of the phase modulator 11 needs to be high in consideration of frequency multiplexing with the baseband video signal. At this time, in the frequency demodulator 91 of the receiving section, the higher the frequency of the carrier wave fna of the phase modulator 11 is, the worse the C/N becomes due to triangular noise. The same applies to FS modulated data signals.

Problems to be Solved by the Invention As explained above, in conventional devices, as the transmission speed of audio data or data signals increases, the frequency of the carrier wave of the phase modulator or FS modulator must be increased. This has resulted in a drawback that the C/N of the audio signal or data signal becomes poor.

The present invention has been made in view of this point, and an object of the present invention is to provide a transmission device that improves the C/N ratio between an audio signal and a data signal.

Means for Solving the Problems In order to solve the above problems, the present invention provides a phase modulator with a carrier wave fa outside the occupied frequency band of the baseband video signal, and a phase modulator with a carrier wave fd outside the occupied frequency band of the baseband video signal. FS modulator, the output of the phase modulator and the F
a frequency multiplexer that frequency-multiplexes the output of the S modulator; the baseband video signal is transferred to a frequency band other than the occupied frequency band of the output signal of the frequency multiplexer, and the occupied frequency band is a carrier wave fP (fp>2-fa and t p >2- f d)
a frequency modulator that performs frequency modulation within fa and fv around , and binary identification of the output signal of the frequency modulator with the output signal of the frequency multiplexer centered on the zero level of the output signal of the frequency modulator; a transmitter comprising a discriminator; a first unit that separates the transmitted output of the discriminator into an output signal of the phase modulator, an output signal of the FS modulator, and an output signal of the frequency modulator; , second and third bandpass filters, said first, second and third bandpass filters;
a phase demodulator that demodulates the output signal of the phase modulator, an FS demodulator that demodulates the output signal of the FS modulator, and a frequency demodulator that demodulates the output signal of the frequency modulator. A transmission device is constituted by a receiving section comprising:

Effect of the Invention The present invention can improve the C/N ratio between the audio signal and the data signal by independently multiplexing the audio signal and the data signal onto the frequency-modulated video signal using the above-described configuration.

Example An embodiment of the present invention will be described with reference to FIG.

Now, assuming that the occupied frequency band of the baseband video signal is from DC to fv, in the transmitting section, the carrier wave f a
A PCM-encoded audio signal input to the phase modulator 10 (f a > f v) is phase-shifted and input to the frequency multiplexer 30 . A baseband data signal input to the FS modulator 20 as a carrier wave fd (fd>fv) is FS-modulated and input to the frequency multiplexer 30. Here, it is assumed that fd>fa. The frequency multiplexer 30 frequency-multiplexes the phase-modulated audio signal and the FS-modulated data signal, and outputs the signal. This multiplexed signal is input to the discriminator 50. The power spectrum of the output of the frequency multiplexer 30 is shown in second g(a). On the other hand, the baseband video signal is transmitted to a frequency multiplexer 30 by a frequency modulator 40 having a carrier wave fρ.
The output signal is frequency modulated outside the occupied frequency band. The occupied frequency band of the output signal of the frequency modulator 40 is centered on the carrier wave fp and is within fa above and below fa. Frequency modulator 4
The power spectrum of the 0 output is shown in FIG. 2(b). This output of the frequency modulator 40 is input to the discriminator 50.

The discriminator 50 performs binary discrimination on the output signal of the frequency modulator 40 based on the output signal of the frequency multiplexer 30 centered on the zero level of this signal. Here, when the output voltage of the phase modulator IO and the output voltage of the FS modulator 20 with respect to the output voltage of the frequency multiplexer 30 are ma and md, respectively, it is assumed that mail and md<1. The power spectrum of this signal is shown in FIG. 2(C).

This power spectrum includes the power spectrum of the phase-modulated audio signal as carrier wave fa, the FS-modulated data signal as carrier wave fd, and the frequency-modulated video signal as carrier wave fρ, as well as the power spectrum of the frequency-modulated video signal as carrier wave fd. A power spectrum is generated at frequencies higher and lower than the carrier wave fa of the audio signal and the carrier wave fd of the data signal around the carrier wave fp, but the carrier wave f of the frequency modulator 40
By setting p to a frequency higher than 2·fd, their power spectra do not overlap.

The output signal of the discriminator 50 is manually inputted to a bandpass filter 60 with a center frequency fa, a bandpass filter 61 with a center frequency fd, and a bandpass filter 62 with a center frequency fp in the receiving section via a transmission line 100, and each of them is converted into a carrier wave. f
a phase modulated PCM encoded audio signal, carrier f
The signal is separated into an FS modulated data signal called d and a frequency modulated video signal called a carrier wave fp. A phase demodulator 70 connected to the bandpass filter 60 reproduces a PCM encoded audio signal from the phase modulated PCM encoded audio signal, which is the carrier wave fa. Further, an FS demodulator 8θζ connected to the bandpass filter 61 reproduces a baseband data signal from the FS modulated data signal, which is a carrier wave fd. Frequency demodulator 90 connected to bandpass filter 62
reproduces the baseband video signal.

In this way, since the phase-modulated audio signal and the FS-modulated data signal are multiplexed independently of the frequency-modulated video signal during transmission, they can be demodulated independently when received. Therefore, the phase modulated audio signal and the FS modulated data signal are transmitted through the phase modulator and the FS modulated data signal.
Even if the carrier wave frequency of the modulator becomes higher, the C/N ratio of the audio and data signals does not deteriorate due to the influence of triangular noise in the frequency modulation of the video signal, and the audio and data signals are transmitted with high quality and high transmission speed. becomes possible.

In addition, since the video signal, audio signal, and data signal are independent of each other, it is only necessary to demodulate the signal to be received in a transmission system as shown in Figure 3, and the circuit configuration of the receiver is simplified. Even if there is an addition, only the demodulation system part of the signal needs to be added. In this way, it is extremely flexible in system construction.

Effects of the Invention As described above, according to the present invention, voice signals and data signals can be transmitted with high quality. In addition, video signals,
Since the audio and data signals are independent of each other, system construction is extremely flexible.
It is extremely useful in practical terms.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a transmission device according to an embodiment of the present invention, FIG. 2 is a spectrum diagram showing the operation of the same device, and FIG.
4 is a block diagram of a conventional transmission device, and FIG. 5 is a spectrum diagram showing the operation of the conventional transmission device. 10.11... Phase modulator, 20, 21...
-F S modulator, 30.31... Frequency multiplexer, 40... Frequency modulator, 50... Discriminator, 60-64... Band Pass filter, 65
...Low pass filter, 70.71...
・Phase demodulator, 80, 81...FS demodulator, 9
0,91... Frequency demodulator, 100...
・Transmission line. Name of agent: Patent attorney Toshio Nakao

Claims (1)

[Claims] Carrier wave fa outside the occupied frequency band of the baseband video signal
a phase modulator with a carrier fd outside the occupied frequency band of the baseband video signal; a frequency multiplexer with which the output of the phase modulator and the output of the FS modulator are frequency-multiplexed; The occupied frequency band is a carrier wave fp (fp>2・fa and fp>2・
a frequency modulator that performs frequency modulation within fa and fv around fd), and converts the output signal of the frequency modulator into a binary value with the output signal of the frequency multiplexer centered around the zero level of the output signal of the frequency modulator. a transmitter comprising a discriminator for identifying, and separating the transmitted output of the discriminator into an output signal of the phase modulator, an output signal of the FS modulator, and an output signal of the frequency modulator, respectively; first, second and third bandpass filters, a phase demodulator connected to the first, second and third bandpass filters respectively and demodulating the output signal of the phase modulator; 1. A transmission device comprising: a receiving section comprising an FS demodulator that demodulates an output signal and a frequency demodulator that demodulates an output signal of the frequency modulator.