CN2230995Y - NICAM-728 digital audio signal receiver for satellite broadcast - Google Patents
NICAM-728 digital audio signal receiver for satellite broadcast Download PDFInfo
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- CN2230995Y CN2230995Y CN 94206500 CN94206500U CN2230995Y CN 2230995 Y CN2230995 Y CN 2230995Y CN 94206500 CN94206500 CN 94206500 CN 94206500 U CN94206500 U CN 94206500U CN 2230995 Y CN2230995 Y CN 2230995Y
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Abstract
The utility model relates to an nicam-728 digital audio signal receiver for satellite broadcast, comprising a band-pass filter (141), a preamplifier (142), a DQPSK demodulator (143), an NICAM-728 decoder (144), a digital/ analogue converter (145), an amplifying de-weight filtering stage (146), a balanced output driving stage (147), and a CPU (148). The nicam-728 digital audio signal receiver for satellite broadcast is characterized in that the output terminal of the DQPSK demodulator (143) is connected with the input terminal of the NICAM-728 decoder (144); the output terminal of the NICAM-728 is connected with the input terminal of the digital/ analogue converter (145); the output terminal of the digital/ analogue converter (145) is connected with the input terminal of the amplifying de-weight filtering stage (146); the output terminal of the amplifying de-weight filtering stage (146) is connected with the input terminal of the balanced output driving stage (147).
Description
The utility model is that the name that the applicant applies for is called the application of uniting of " system that transmits digitized voice and data in satellite TV system ", the utility model relates to the digital sound receiver that is used to receive sound radio in the said system.
The NICAM-728 system is the two sound accompaniment broadcast modes that are used for ground TV broadcast by Britain BBC research.It is applicable to terrestrial television PAL-B/G, PAL-I, SECAM-D/K standard, and a typical terrestrial television NICAM-728 receiver block diagram as shown in Figure 2.Tuner circuit changes to intermediate frequency with under the receiving channels, carries out Filtering Processing.The traditional circuit demodulation is adopted in image and monophony sound accompaniment.The NICAM carrier wave together enters the intercarrier frequency mixer with image and monophone sound accompaniment, and in frequency mixer, NICAM signal transformation becomes a carrier frequency beat (the B/6 system is 5.85MHZ, and the I system is 6.552MHZ).Before the demodulation, the NICAM carrier wave is fed to the DQPSK demodulator then through the shaping of cosine filter network.The output of DQPSK demodulator is fed to the NICAM-728 decoder, in decoder, and the decoded digital audio signal that is treated to of NICAM-728 signal, D/A converter is transformed to analoging sound signal with digital audio signal, exports left and right two-way sound.
The purpose of this utility model provides a kind of NICAM-728 digital sound receiver that is applied to receive satellite sound broadcasting.This receiver is used for said system, it is applied to China Satecom's television transmission system with the NICAM-728 technology, can be in transfer circuit image and sound accompaniment, the transmission carrier frequency is 7.28MHZ, the two cover monophone broadcast programs or of encoding in the NICAM-728 mode overlap stereophonic program.
According to the NICAM-728 digital sound receiver that is used to receive satellite sound broadcasting of the present utility model, it comprises band pass filter, preamplifier, the DQPSK demodulator, the NICAM-728 decoder, D/A, amplify and go heavy filtering stage, balance out drive stage and CPU, it is characterized in that: band pass filter extracts the NICAM-728 signal from the satellite television base-band signal spectrum, the output of band pass filter is connected with the input of preamplifier, the output of preamplifier is connected with the input of DQPSK demodulator, demodulating carrier frequency by the DQPSK demodulator is 7.28MHz, the DQPSK mode is modulated, the cosine roll off coefficient is 100% NICAM-728 signal, the output of DQPSK demodulator is connected with the input of NICAM-728 demodulator, the NICAM-728 decoder is a digital audio signal with above-mentioned signal decoding, the output of NICAM-728 is connected with the input of D/A converter, D/A converter is transformed to analoging sound signal with digital audio signal, the output of D/A converter is connected with the input that amplifies the filtering stage of postemphasising, in postemphasising filtering stage, amplification amplifies, postemphasis, audio frequency filtering and uneven to balanced transformation, the output that amplifies the filtering stage of postemphasising is connected with the input of balance out drive stage, at last by balance out drive stage output two-way voice signal; CPU is connected with NICAM-728 digital sound receiver, carries out I
2Operations such as C Bus simulator, decoding chip initialization, Error detection.
Below in conjunction with accompanying drawing specific embodiment of the utility model is elaborated.
Fig. 1 is a block diagram of the present utility model.
Fig. 2 is a main channel of the present utility model circuit diagram.
Fig. 3 is a control section circuit diagram of the present utility model.
Fig. 4 is a software flow pattern of the present utility model.
Fig. 5 is band pass filter circuit figure of the present utility model.
Fig. 6 is tone filter of the present utility model and output circuit figure.
Fig. 7 is warning circuit figure of the present utility model.
Fig. 8 is a power circuit diagram of the present utility model.
Fig. 9 is band pass filter amplitude-frequency characteristic figure of the present utility model.
Figure 10 is band pass filter group delay characteristic figure of the present utility model.
Referring to Fig. 1, band pass filter (141) extracts the NICAM-728 signal from the satellite baseband signal frequency spectrum, after preamplifier (142) amplifies, demodulating carrier frequency by DQPSK demodulator (143) is 7.28HZ, the DQPSK mode is modulated, the cosine roll off coefficient is 100% NICAM-728 signal, NICAM-728 decoder (144) is a digital audio signal with above-mentioned signal decoding, D/A converter (145) is transformed to analoging sound signal with digital audio signal, amplify through the amplification filtering stage (146) of postemphasising, postemphasis, audio frequency filtering and uneven to balanced transformation, deliver to balance out drive stage (147), export the two-way voice signal at last.Computer and display control section (148,149) are finished I2C Bus simulator, decoding stamen sheet initialization, Error detection and outputting alarm signal under specific software is supported.
The electrical schematic diagram of professional NICAM-728 digital sound receiver such as Fig. 2 are to shown in Figure 9, and each element circuit formation is described as follows:
The physical circuit of band pass filter (141) unit constitutes sees Fig. 5.Its effect is the FM carrier wave (transmitting the carrier wave of television field frame) that decay closes on, and it is one six a rank LC band pass filter, centre frequency 7.28MHZ, impedance 470 Ω, the variable inductor L of four high Q values of employing
1, L
2, L
3, L
4, so that adjust and obtain low insertion loss.
Preamplifier (142) is by V
1, V
2, W
1Deng composition, physical circuit figure sees Fig. 2, wherein potentiometer W
1Be used to adjust amplifier gain, to satisfy the requirement of DQPSK demodulation (143) to signal level.
DQPSK demodulation (143) element circuit constitutes and sees Fig. 2, and it is by IC
1TDA8732 and peripheral circuit thereof are formed.The effect of Unit 143 is to finish in the DQPSK mode to modulate, and transmits the DQPSK demodulation of the input signal of NICAM coding, for NICAM-728 decoder (144) provides NICAM encoded data stream and synchronous with it 728MHZ clock signal.
IC
1Constitute IC by Costas loop quadrature demodulator, data clock recovery circuit and the differential decoding circuit that closes parallel/serial conversion
1The formation and the characteristics of peripheral circuit are as follows:
1, pulse shaping filter
The DQPSK signal is handled by the 3rd pin input the carrying out quadrature demodulation of TDA8732 stamen sheet after filtering, amplification, and sine (quadrature) that demodulation produces and cosine (homophase) signal are exported through the 7th, 8 pin of TDA8732 stamen sheet respectively, via IC
1Peripheral cell L
1, L
2, C
12, C
13, R
10, R
11, C
10, C
11After the pulse shaping filter circuit of forming is handled, import by the 8th, 5 pin of TDA8732 stamen sheet respectively.The characteristics of pulse shaping filter are:
A) leach the higher harmonic components that produces by quadrature demodulation.
B) satisfying at receiving terminal base band shaping filter amplitude-frequency response is 100% cosine roll off characteristic.
2, carrier phase-locked loop
The effect on carrier phase-locked loop road is to produce the required oscillator signal of demodulation process, this oscillator signal two frequencys multiplication input DQPSK signal frequency, and phase-locked with the DQPSK modulation signal.Carrier phase-locked loop adopts single crystal oscillator G
1, crystal frequency is 14.56MHZ, load capacitance is by variable capacitance diode VD
3And C
16Constitute variable capacitance diode VD
3Capacitance change according to the external low-pass filter output signal of the 9th pin of TDA8732 stamen sheet, this low pass filter is (by R
12, C
14, C
15Constitute) leach the high fdrequency component in the inner phase-detection output signal of TDA8732, be variable capacitance diode VD
3One DC control voltage is provided.
3, monostable peripheral circuit
In TDA8732 stamen sheet,, handle sine and cosine signal by monostable circuit in order to obtain the 364KHZ signal.The time constant of monostable circuit is by IC
1Peripheral cell R
15, C
17, R
16, C
19Determine.
4, clock phase-locked loop low pass filter
The 728KHZ oscillation frequency clock also is by outside direct voltage adjustment.TDA8732 stamen sheet pin 1 output one clock phase error detection signal, through outside low pass filter (by C
23, c
24, C
25, R
22Constitute) leach high fdrequency component, its DC component is as variable capacitance diode VD
4Control voltage, utilize VD
4The 17.472MHZ oscillation frequency clock of SAA7280 is adjusted in the variation of capacitance.
NICAM-728 decoder (144) physical circuit constitutes as shown in Figure 2.It is by IC
2SAA7280 stamen sheet and peripheral circuit are formed.Its effect is to finish the whole digital decoding functions of NICAM-728 system.It will deliver to D/A converter (145) after will crossing processing such as sampling filtering from the demodulated signal decoding of TDA8732, error detection, three times.
D/A converter IC
3Adopt the integrated circuit TDA1543 of PhiLiPs company, TDA1543 is one 16 bit D/A converter, and it finishes the conversion of the digital audio signal of decoding processing to analoging sound signal.
The output of steering D/A conversion is delivered to amplification, is postemphasised, filtering, uneven to balanced transformation and output driving circuit (146,147).Its physical circuit is seen Fig. 6.The effect of output driving circuit (146,147) is the current source of TDA1543 to be exported convert the audio frequency output voltage to, realizes following three functions:
(CCITTJ17) postemphasises
Low-pass filtering is to remove three times of sampling mirror pictures of crossing the number of samples character filter.
Power amplification and uneven conversion to balance.
Output driving circuit (146,147) uses five dual operational amplifiers (NE5532) to realize the above-mentioned functions of two passages altogether, first amplifier finished first rank of postemphasising with third-order low-pass filter, second amplifier realizes a second order joint of third-order low-pass filter, third and fourth, five amplifiers finish power amplification and uneven conversion to balance.
Warning circuit as shown in Figure 7, its function provides aural warning.When receiving error rates of data, receiver is higher than 2 * 10
-3The time, providing the alarm control signal by CPU (148), warning circuit receives the alarm control signal, through V
5, V
6The monostable that constitutes drives buzzer B
1Produce warning tone, the work of prompting user receiving system is undesired.
Power circuit is shown in Fig. 8, and it finishes AC rectification, voltage stabilizing, filter function, provide+12V ,-12V, two-way+5V DC circuit.Circuit is mainly by bridge rectifier VD
1, VD
2, three terminal regulator 7912,7812,7805 and electric capacity constitutes.
The receiver control section is seen Fig. 3, and the control section circuit core is 8031 chip microprocessors, IC
62764 is memory under program, IC
574LS373 is the 8D trigger, is used for address latch, IC
7, IC
8All adopt 74LS273 tape erasure end 8D trigger, for light-emitting diode display latchs shows signal.LED adopts eight sections light emitting diode indicators.The 1st, 2 pin of single-chip microcomputer 8031 are used for the I of emulation Philips
2The C bus, 8031 tripod links to each other with the SAA7280 reset terminal, and SAA7280 resets by software control.8031 by the 1st, 2 pin emulation I
2The C bus is provided with the state of SA7280, and visits the internal storage location to SAA7280 in real time, acquisition state error code information, and 8031 analyze the data of gathering, calculate, and provide report and alarm signals such as receiving the error rate to the user.System controlling software adopts the MCS-51 assembler language to write.
The design original creation part of NICAM-728 digital sound receiver is:
1, design specialized 7.28MHZ bandpass filtering and input circuit (band pass filter circuit figure sees shown in Figure 5).
2, because Fei Lipu NICAM demodulation stamen sheet is only applicable to ground PAL-I, B/G standard, its restituted signal frequency is up to 6.7MHZ.It is 7.28MHZ that the utility model requires the demodulation operating frequency.For this reason, the utility model redesigns G to the peripheral circuit of former Philips NICAM demodulation stamen sheet TDA8732
1Be revised as 14.56MHZ by 13.104MHZ, C
16By 1
nBe revised as the 150P variable capacitance, by adjusting C
16Capacitance realize the expansion of frequency, demodulation frequency and guarantee that the shop of phase-locked loop catches scope (referring to Fig. 2).
3, because Fei Lipu NICAM reception application-specific integrated circuit (ASIC) is to be designed for household appliances, its output audio signal 12KHZ～15KHZ part can not satisfy specification requirement of the present utility model.Use equipment, the utility model to design special audio frequency filtering and output circuit as the broadcasting specialty, can guarantee that audio signal satisfies the special-purpose requirement of broadcasting in 20KHZ～15KHZ bandwidth, and be equipped with balance output, monitor new functions such as output.
4, the input/output port of using single-chip microcomputer 8031 is realized I by the software support
2The C Bus simulator.
5, exploitation special-purpose software control system work.
Claims (1)
1, a kind of NICAM-728 digital sound receiver that is used to receive satellite sound broadcasting, it comprises band pass filter (141), preamplifier (142), DQPSK demodulator (143), NICAM-728 decoder (144), D/A (145), amplify and go heavy filtering stage (146), balance out drive stage (147) and CPU (148), it is characterized in that: band pass filter (141) extracts the NICAM-728 signal from the satellite television base-band signal spectrum, the output of band pass filter (141) is connected with the input of preamplifier (142), the output of preamplifier (142) is connected with the input of DQPSK demodulator, demodulating carrier frequency by DQPSK demodulator (143) is 7.28MHz, the DQPSK mode is modulated, the cosine roll off coefficient is 100% NICAM-728 signal, the output of DQPSK demodulator (143) is connected with the input of NICAM-728 demodulator (144), NICAM-728 decoder (144) is a digital audio signal with above-mentioned signal decoding, the output of NICAM-728 is connected with the input of D/A converter (145), D/A converter (145) is exchanged for analoging sound signal with digital audio signal, the postemphasis input of filtering stage (146) of the output of D/A converter (145) and amplification is connected, in postemphasising filtering stage (146), amplification amplifies, postemphasis, audio frequency filtering and uneven to balanced transformation, the output that amplifies the filtering stage (146) of postemphasising is connected with the input of balance out drive stage (147), at last by balance out drive stage (147) output two-way voice signal; CPU (148) is connected with NICAM-728 digital sound receiver, carries out I
2Operations such as C Bus simulator, decoding chip initialization, Error detection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94206500 CN2230995Y (en) | 1994-03-10 | 1994-03-10 | NICAM-728 digital audio signal receiver for satellite broadcast |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94206500 CN2230995Y (en) | 1994-03-10 | 1994-03-10 | NICAM-728 digital audio signal receiver for satellite broadcast |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2230995Y true CN2230995Y (en) | 1996-07-10 |
Family
ID=33825094
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 94206500 Expired - Fee Related CN2230995Y (en) | 1994-03-10 | 1994-03-10 | NICAM-728 digital audio signal receiver for satellite broadcast |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2230995Y (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101164239B (en) * | 2005-04-29 | 2010-08-18 | 飞思卡尔半导体公司 | NICAM encoder with a front-end |
| CN104658322A (en) * | 2013-11-25 | 2015-05-27 | 上海航空电器有限公司 | Voice warning circuit for ground proximity warning system |
-
1994
- 1994-03-10 CN CN 94206500 patent/CN2230995Y/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101164239B (en) * | 2005-04-29 | 2010-08-18 | 飞思卡尔半导体公司 | NICAM encoder with a front-end |
| CN104658322A (en) * | 2013-11-25 | 2015-05-27 | 上海航空电器有限公司 | Voice warning circuit for ground proximity warning system |
| CN104658322B (en) * | 2013-11-25 | 2018-09-11 | 上海航空电器有限公司 | A kind of ground proximity warning system voice alarm circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |