JP2000287099A - Analog fpu device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit video and audio signals with superior channel quality by providing a main line signal conversion means, a signal conversion means, and a multiplier means that multiplies an intermediate frequency signal for send-back into a multiple frequency signal to a high frequency section, so as to eliminate the need for complicating a configuration of a distributor. SOLUTION: A high frequency section 20 has distributors 21, 29, a main line that modulates the frequency of an intermediate frequency signal(IF signal) into a signal having the frequency of the SHF band, and a unit on a send-back line that modulates the frequency of the SHF signal into a send-back purpose intermediate frequency (IFR signal). The send-back line has a low noise amplifier(LNA) 30, band-pass filters(BPF) 31, 34, mixers 32, 35, local oscillators (BVO) 33, 36 and a multiplier 37. Then the multiplier 37, e.g. doubles the frequency of an IFR 2 signal, whose original frequency has been converted into 100 MHz by the mixer 35, into a frequency of 200 MHz and outputs the resulting signal as an IFR signal(multiple frequency signal).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FPU (Field P) used as a repeater of a television broadcast signal.
More specifically, the present invention relates to a portable analog FPU device in which the functions of a transmitter and a receiver are mounted in one housing of a high-frequency unit.

[0002]

2. Description of the Related Art Conventionally, an analog FP having a bidirectional transmission function used as a repeater of a television broadcast signal.
The U device is configured by connecting a high frequency unit and a control unit with a coaxial cable.

The high-frequency section includes a main line for processing a main line signal received from the control unit via a coaxial cable, a return line for processing a return signal received from the outside, a main line signal and a return line. It includes a distributor that separates and combines a signal and a distributor that separates and combines a received SHF signal and a transmitted SHF. In the high frequency section, a main line signal having a predetermined intermediate frequency (usually 130 MHz or 70 MHz is used) is converted into an SHF band frequency and output to the outside. In the high-frequency section, the signal for returning the SHF band frequency is a predetermined intermediate frequency for return (normally 2).
00 MHz) and output to the control unit via a coaxial cable.

The control section includes a modulation section for modulating the video and audio signals into main line signals, a demodulation section for demodulating the return signal transmitted from the high frequency section to video and audio signals,
And a distributor that separates and combines the main line signal and the return signal. In the control unit, the main line signal modulated by the modulation unit is output to the high frequency unit via the coaxial cable. In the control unit, the return signal received via the coaxial cable is demodulated into a video and audio signal by the demodulation unit.

[0005]

By the way, in the analog type FPU device having the above-mentioned transmission / reception function, the return signal is configured to have the same quality as the main line signal regardless of the length of the coaxial cable. Is preferred.

In order to solve the above-mentioned problem, there is a method in which an intermediate frequency of a return signal is made closer to an intermediate frequency of a main line signal to transmit and receive a signal through a coaxial cable, thereby reducing a loss difference due to a cable length. However, there is a problem that the configuration of a distributor for separating and synthesizing the signal for the main line and the signal for returning is complicated because the main line is likely to have an adverse effect such as spurious noise.

Further, there is a method in which a transmission level on a frequency side having a large loss is increased in consideration of a loss difference caused by a coaxial cable. However, if the coaxial cable
When the length is too short, cross-modulation due to excessive input to the coaxial cable is caused, so that the sending level cannot be extremely increased, and there is a problem that the length of the coaxial cable is limited.

The present invention solves the above-mentioned problems and provides an analog FPU device capable of transmitting a return signal having the same quality as that of the main line system regardless of the length of the coaxial cable without complicating the structure of the distributor. The purpose is to do.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a high-frequency section and a control section connected to the high-frequency section by a coaxial cable, for transmitting and receiving television video signals and audio signals. In the analog type FPU device for performing the above, the high frequency section comprises a main line signal converting means for converting a main line intermediate frequency signal transmitted from the control section into an SHF signal, and a signal conversion for converting a return SHF signal to a return intermediate frequency signal. And a multiplying means for multiplying the return intermediate frequency signal to convert it into a multiplied frequency signal.

[0010] With the above configuration, a return signal having the same quality as that of the main line system can be transmitted regardless of the length of the coaxial cable without complicating the configuration of the distributor.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a configuration of an FPU device 10 of the present example. The FPU device 10 includes a high-frequency unit 20, a control unit 40, a high-frequency unit 20 and a control unit 4.
0 and a coaxial cable 50 for connecting to

The high-frequency section 20 FM-modulates the dividers 21 and 29 and an intermediate frequency signal (hereinafter, referred to as an "IF signal") to convert the signal into an SHF band signal (hereinafter, referred to as an "SHF signal"). It has a main line and a return line for FM-modulating the SHF signal and converting it to an intermediate frequency signal for return (hereinafter referred to as an "IFR signal"). The main line includes mixers 22 and 25, VCOs (local oscillators) 23 and 26 connected to mixers 22 and 25, respectively, and B
PF (band pass filter) 24, 27 and SHFPA
(SHF power amplifier). The return line is
LNA (low noise amplifier) 30 and BPF 31, 34
, Mixers 32 and 35, VCOs 33 and 36 respectively connected to the mixers 32 and 35, and a multiplier 37. The intermediate frequency of the IF signal is mainly 70 MHz.
Although a frequency of z or 130 MHz is used, in this example, an IF frequency of 130 MHz widely used in Japan is used. Since the intermediate frequency of the IFR signal is usually around 200 MHz, in this example, the intermediate frequency is 200 MHz.
Hz IFR frequency shall be used.

The distributor 21 separates the IF signal transmitted from the control unit 40 via the coaxial cable 50 and outputs the separated IF signal to the main line. The distributor 21 combines the IFR signal processed by the return line to form a coaxial cable. And a synthesizing unit 21b that outputs the signal to the control unit 40 via the control unit 50. In this case, the separation unit 21a and the synthesis unit 21b
It consists of.

The mixer 22 constituting the main line transmits a first intermediate frequency signal of 130 MHz (hereinafter referred to as “IF1 signal”) transmitted from the control unit 40 to 1024 in this example.
It is configured to perform processing for converting to a second intermediate frequency signal of MHz (hereinafter, referred to as “IF2 signal”). Also, BPF
24 is configured to select and output the frequency component of the IF2 signal, and the SHF band mixer 25 converts the IF2 signal to a desired SH2 signal.
It is configured to convert to an F signal. Furthermore, the transmission BPF
27 is configured to select and output a desired frequency component of the SHF signal, and SHFPA 28 is configured to amplify the input SHF signal to a predetermined power and output the amplified signal. In this example, an AGC amplifier (automatic gain control amplifier), not shown, is provided in the preceding stage of the mixer 22, and the IF signal whose signal level is kept constant by the AGC amplifier is output from the mixer 2
2 is input.

The LNA 30 constituting the return line is:
It is configured to amplify the input SHF, and the reception SHFBPF
Reference numeral 31 is configured to selectively output a signal in a predetermined frequency band. In addition, the mixer 32 converts the return signal to the first intermediate frequency signal for return at 994 MHz (hereinafter, referred to as “the first intermediate frequency signal”).
(Referred to as "IFR1 signal").
F34 is configured to select and output the frequency band of the IFR1 signal. Further, the mixer 35 is configured to convert the frequency of the IFR1 signal into a 100 MHz second return intermediate frequency signal (hereinafter, referred to as an “IFR2 signal”) in the present example and to output the same.
In this example, the IFR2 signal converted to
It is configured to output as an IFR signal (multiplied frequency signal) of MHz. In this case, in this example, since the FM modulation method is used, the frequency and the frequency shift amount of the signal multiplied by R (R is a positive real number) by the multiplier 37 are multiplied by R.

The divider 29 separates the SHF signal input from the high-frequency input / output terminal a and outputs it to the return line. The distributor 29 combines the SHF signal input from the main line and outputs the synthesized signal from the high-frequency input / output terminal a. And a synthesizing unit 29b. In this case, the separation unit 29a and the synthesis unit 29b
It is composed of BPF.

The control unit 40 includes a distributor 41 for separating and synthesizing the IF signal and the IFR signal, and a video and audio signal for the IF1 and IF1.
It includes a modulator 42 for modulating a signal and a demodulator 43 for demodulating an IFR signal into a video and audio signal.

The divider 41 receives an input IF from the modulator 42.
One signal is synthesized, and a high-frequency part 2
It has a synthesizing unit 41a that outputs the signal to 0 and a separating unit 41b that separates the IFR signal transmitted from the high frequency unit 20 via the coaxial cable 50 and outputs the IFR signal to the demodulator 43. Note that the combining unit 41a and the separating unit 41b are configured by a BPF.

As the coaxial cable 50, for example, one equivalent to 5D-2W is used. The coaxial cable equivalent to 5D-2W is generally used in consideration of portability.

Next, the operation of the FPU device 10 will be described with reference to FIG. First, the video signal and the audio signal are subjected to predetermined signal processing in the control unit 40, and then are FM-modulated by the modulation unit 42, and are converted into an IF1 signal having a frequency of 130 MHz and an electric field strength of, for example, +15 dBm. The IF1 signal is synthesized by the distributor 41 so as not to affect other signals, and transmitted to the high frequency unit 20 via the coaxial cable 50.

The level reached when the IF1 signal is transmitted to the high frequency section 20 via the coaxial cable 50 is determined by the distribution
When the loss at 1, 21 is not considered, the cable length is 1 m
Is +15 dBm when the cable length is 500 m, and -35 dBm when the cable length is 500 m. I received by the high frequency unit 20
The F1 signal is input to the mixer 22 after the signal level is kept constant by an AGC amplifier (not shown) in the high-frequency unit 20, and is subjected to processing on the main line, such as being sequentially frequency-converted by the mixers 22 and 25. Is output from the high frequency input / output terminal a. When the cable length is 500 m, the C / N of the IF1 signal is, as shown in FIG.
Expressed as −35−X using the noise level X in the device 10.

On the other hand, the return SHF signal received by the high-frequency section 20 from the high-frequency input / output terminal a is subjected to frequency conversion processing by the mixers 32 and 35 in processing on the return line, and in this example, the 100 MHz IFR2 signal is used. It is said. The IFR2 signal output from the mixer 35 is further multiplied by 2 by a multiplier 37 in processing on a return line, and
It is converted to an IFR signal whose frequency shift is doubled at 00 MHz. The frequency output from the multiplier 37 is 200 MH
For example, an IFR signal having an electric field strength of +15 dBm at z is input to the distributor 21. This IFR signal is synthesized by the distributor 21 so as not to affect other signals, and the coaxial cable 5
0 to the control unit 40.

When the IFR signal is transmitted via the coaxial cable 50, the level reached by the control unit 40 is determined by the distributor 2
If the loss at 1, 41 is not considered, the cable length is 1 m
Is +15 dBm when the cable length is 500 m, and -48 dBm when the cable length is 500 m. The in-device noise level of the IFR signal is the demodulation BPF of the FPU device 10 (the BPF in the demodulator 43) and the demodulation BPF of another device with which the FPU device 10 communicates via the high frequency input / output terminal a. (FPU device 1
When the bandwidth of the IF1 signal is substantially the same as that of the demodulator 43, the internal noise level X of the IF1 signal is the same. Since both the FPU device 10 and the other devices use the FM modulation method, the bandwidths of the demodulation BPFs are substantially the same. Therefore, when the cable length is 500 m, as shown in FIG.
/ N is expressed as -48-X using the noise level X in the device. The difference between the C / N of the IF signal and the C / N of the IFR signal is 13 dB.

The S / N in the FM modulation method is (C / N) +
(S / N improvement coefficient). In the case of a television broadcast signal, the S / N improvement coefficient is obtained by 10 log (3 · video frequency shift ² · (reception intermediate frequency bandwidth / maximum modulation frequency ³ )). Since the reception intermediate frequency bandwidth and the like of the main line signal and the return signal are generally the same, the S / F of the 200 MHz IFR signal that has not been multiplied is generally used.
As shown in FIG. 2, the N improvement coefficient has substantially the same value as the S / N improvement coefficient Y of the IF signal, and the C / N difference of 13 dB directly appears as the S / N difference. However, in this example, since the IFR signal is doubled, the frequency shift is doubled. Therefore, the SFR of the IFR signal
/ N improvement factor becomes Y + 10log2 ² and the value of S / N improvement amount of about 6dB is added to the S / N improvement factor Y of the IF1 signal. Therefore, the doubled IFR signal and I
The S / N difference from the F1 signal is close to 7 dB.

As described above, by adopting a configuration in which the doubled IFR signal is transmitted by the coaxial cable 50,
The frequency shift amount of the transmitted IFR signal is doubled and the IF
Since the S / N difference from one signal can be set to a close value, the configuration of the distributor is not complicated, and even when the coaxial cable length is long, the line quality is almost the same as that of the IF1 signal. Video signals and audio signals can be transmitted. Therefore, the IFR signal can be satisfactorily demodulated on the control unit side.

In the above-described embodiment, the configuration is such that an intermediate frequency signal of 130 MHz is used for the IF signal and a 200 MHz is used for the IFR signal, but an intermediate frequency signal of another frequency may be used. In this case, each unit constituting the device may determine the frequency of the signal processed by each unit in correspondence with the determined frequency.

In the above-described embodiment, the multiplication is performed by the multiplier 37. However, the multiplication may be performed by another multiplication amount. In this case, the multiplication amount is determined so that the difference in S / N between the IFR signal and the IF1 signal becomes closer in accordance with the length of the coaxial cable used, such as increasing the multiplication value as the cable becomes longer. Good. With this configuration, the frequency shift amount of the transmitted IFR signal can be converted to a desired value, and
Since the S / N difference between the FR signal and the IF1 signal can be made close to each other, the line quality is almost the same as that of the IF1 signal without complicating the configuration of the distributor and irrespective of the coaxial cable length. Can transmit a video signal and an audio signal.

As described above, according to the present invention, an analog FPU device configured to include a high-frequency section and a control section connected to the high-frequency section by a coaxial cable and transmit and receive a television video signal and an audio signal. , A high-frequency unit includes: a main line signal conversion unit that converts a main line intermediate frequency signal transmitted from the control unit to an SHF signal; a signal conversion unit that converts a return SHF signal to a return intermediate frequency signal; Multiplying means for multiplying the frequency signal and converting it to a multiplied frequency signal,
The multiplied frequency signal can be transmitted as an IFR signal through a coaxial cable, and the S / N ratio between the IFR signal and the IF1 signal can be increased.
Can be made close to each other, so that the video signal and the audio signal are transmitted with substantially the same line quality as the IF1 signal without complicating the configuration of the distributor and irrespective of the coaxial cable length. be able to.

The signal conversion means converts the return SHF signal into a return first intermediate frequency signal, and converts the return first intermediate frequency signal into a return second intermediate frequency signal. In the case where the signal is constituted by the second signal conversion means, the multiplied frequency signal can be transmitted as an IFR signal through a coaxial cable, and the S / N difference between the IFR signal and the IF1 signal can be reduced to a value close to each other. Because, without complicating the configuration of the distributor,
In addition, video signals and audio signals can be transmitted with substantially the same line quality as the IF1 signal regardless of the coaxial cable length.

The multiplying means, if the coaxial cable length is longer, the multiplication amount is set to a higher multiplication amount. If the multiplication amount is set to, for example, the IFR signal and the IF1 signal in accordance with the coaxial cable length to be used. And the S / N difference between the IFR signal and the IF1 signal can be converted to a desired value, and the S / N difference between the IFR signal and the IF1 signal can be converted to a desired value. The difference can be a close value. Therefore, the video signal and the audio signal can be transmitted with substantially the same line quality as the IF1 signal without complicating the configuration of the distributor and regardless of the coaxial cable length.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a configuration of an FPU device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of an improved state of an S / N difference between an IF1 signal and a doubled IFR signal according to the first embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 FPU apparatus 20 High frequency part 21, 29 Distributor 22, 25, 32, 35 Mixer 23, 26, 33, 36 VCO (Local oscillator) 24, 27, 31, 34 BPF (Band pass filter) 28 SHFPA (SHF power amplifier) ) 30 LNA (Low Noise Amplifier) 37 Multiplier 40 Controller 41 Divider 42 Modulator 43 Demodulator 50 Coaxial Cable

Claims (3)

[Claims] 1. An analog FPU device comprising a high-frequency unit and a control unit connected to the high-frequency unit by a coaxial cable and transmitting and receiving a television video signal and an audio signal, wherein the high-frequency unit includes the control unit Main line signal conversion means for converting the main line intermediate frequency signal transmitted from the main line into an SHF signal;
An analog FPU device comprising: signal conversion means for converting a return SHF signal to a return intermediate frequency signal; and multiplying means for multiplying the return intermediate frequency signal to convert it to a multiplied frequency signal. 2. The signal conversion means includes: first signal conversion means for converting a return SHF signal into a return first intermediate frequency signal; and transmitting the return first intermediate frequency signal signal to a return second intermediate frequency signal. 2. The analog FPU device according to claim 1, wherein said analog FPU device comprises a second signal conversion means for converting the signal into a signal. 3. The multiplying means, as the coaxial cable length is longer,
3. The analog FPU device according to claim 1, wherein the multiplication is performed by a multiplication amount determined to be a high multiplication.