CN2489526Y

CN2489526Y - Digital integral tuner for direct broadcasting satellite television

Info

Publication number: CN2489526Y
Application number: CN01244841U
Authority: CN
Inventors: 宋波; 陆士良; 曹金鹏; 鲁道云; 倪晓清; 洪建荣
Original assignee: Anhui Sun Create Electronic Co Ltd
Current assignee: Anhui Sun Create Electronic Co Ltd
Priority date: 2001-07-13
Filing date: 2001-07-13
Publication date: 2002-05-01
Anticipated expiration: 2011-07-13

Abstract

A digital integral tuner for direct broadcasting satellite television is characterized in that a zero intermediate frequency QPSK tune integrate circuit is adopted and a STV0299 QPSK demodulation/tandem type forward error correction integrate circuit is arranged. The local frequency of the orthogonal mixer in the zero intermediate frequency QPSK tune integrate circuit is provided by a frequency phase-locked loop formed of combination of a TSA5059(A) frequency synthesizer circuit, a voltage control oscillator and a lowpass LPF. The I/Q signal outputted by a baseband buffer amplifier is sent into the input end of the STV0299 QPSK demodulation/tandem type forward error correction integrate circuit after filtering, buffering and magnifying. The MPEG-2 cluster/parallel data stream, data stream clock, isochronous signal and error indicating signal are outputted from an energy dispersive descramble unit of a manifold block STV0299. The utility model has simple structure, strong function, and high price performance.

Description

The digital integral tuner that is used for the direct broadcasting satellite TV

Technical field:

The utility model relates to tuner.More particularly, be a kind of digital tuner that is used for the direct broadcasting satellite TV.

Background technology:

Digital satellite television receiving system indoor unit critical piece is Integrated Receive Decoder (IRD-S) or set-top box (STB-S), its basic function is L-band (950-2150MHz) signal that receives outdoor unit low noise conversion fast (LNB) output, this signal imports in the tuner through feeder line, tuner is controlled by receiver, from the signal in this broadband, select an individual passage, by processes such as frequency translations, carry out signal processing by the motherboard in the set-top box again, final output simulation video/audio signal uses for the user.

In the prior art, the digital tuner of direct broadcasting satellite TV has two kinds of forms, and the first is come work with following form.As shown in Figure 2, by the next L-band signal of outdoor unit low noise transform block (LNB), in input 18 feed-in tuners.In tuner, through high pass filter 19 filtering interference signals, amplify through first order RF amplifier 20 again, carry out level adjustment by adjustable attenuator 21.Afterwards, be with logical the adjusting by tunable bandpass filters (BPF) 22, then by frequency mixer 23 mixing, the frequency phase lock loop circuit that the local frequency of frequency mixer 23 is made up of frequency synthesizer circuit 27 and low pass filter 26, voltage controlled oscillator 25 provides, by frequency mixer 23 the RF signal that receives is moved down into intermediate frequency 479.5MHz, this signal amplifies through intermediate frequency amplifier 24 again, and the signal after the amplification is exported needed television channel signal at last by surface acoustic wave (SAW) filter 28.Though this tuner circuit structure is simple, its function is simple too, only input rf signal is made single-conversion, is output as intermediate-freuqncy signal, and the motherboard that the work of back all meets in the set-top box is handled.

The another kind of form of direct broadcasting satellite Television Digital tuner of the prior art is with following form work: see Fig. 3, by the next L-band signal of outdoor unit low noise transform block (LNB), F type plug 18 feed-in tuners on tuner, this RF signal is after high pass filter 19 filtering, entering amplifier 20 amplifies, carry out the level adjustment through adjustable attenuator 21 again, this adjustable attenuator is subjected to AGC testing circuit 52 controls of back, adjusted RF signal is by tunable bandpass filters 22 filtering, enter frequency mixer 23 mixing, the local frequency of frequency mixer is by frequency synthesizer circuit 27 and low pass filter 26, the frequency phase lock ring that voltage controlled oscillator 25 is formed provides, frequency mixer 23 is isolated the TV signal that needs from the signal of input, this television channel signal frequency is 479.5MHz, after the intermediate frequency amplifier 24 of back amplifies, enter Surface Acoustic Wave Filter 28, enter i/q signal conversion integrated circuit 501 at last, this is comprising preamplifier 51, AGC testing circuit 52, orthogonal mixer 53 and 54, dual-stage amplifier 55,57, with 56,58, two low pass filters 59 and 60, base band buffer amplifier 61 and 62.Last tuner is output as two-way I/Q baseband signal.In this version, carried out double conversion, i.e. frequency mixer 23, orthogonal mixer 53 and 54.Thereby middle relative set amplifier 24 and the intermediate frequency Surface Acoustic Wave Filter 28 of needing.Thereby increased the complexity of product, cost is improved.Simultaneously, the final output of this tuner also is i/q signal.Still handle as for QPSK demodulation, the work of cascade decoding FEC by the set-top box motherboard of back.

Summary of the invention:

Technical problem to be solved in the utility model provide a kind of simple in structure, have the zero intermediate frequency characteristic, and can directly export the digital integral tuner that is used for the direct broadcasting satellite TV of the serial/parallel data flow of MPEG-2, data flow clock, synchronizing signal and wrong indication.

The technical scheme that the utility model technical solution problem is adopted is: from L-band (950-2150MHZ) signal of outdoor unit low noise transform block, go up feed-in at F type plug (18), through high-pass filtering (19), first order RF amplifier (20), access second level RF amplifier (32) amplification after adjustable RF attenuator (21) level adjustment again.Design feature of the present utility model is that follow-up circuit adopts the tuning integrated circuit of zero intermediate frequency QPSK (701), and STV0299 QPSK demodulation/cascade forward error correction (FEC) decoding integrated circuit (901) is set; The local frequency of orthogonal mixer (73), (74) is provided by the frequency phase lock ring that TSA5059 (A) frequency (PLL) condensating synthesizering circuit (37), voltage controlled oscillator (81) and low pass filter LPF (36) form in the tuning integrated circuit of described zero intermediate frequency QPSK (701), the i/q signal of base band buffer amplifier 75,76 outputs inserts the signal input part of the A/D conversion (91) of STV0299 QPSK demodulation/cascade forward error correction (FEC) decoding integrated circuit (901) through low pass filter 33,34 filtering, buffer amplifier 77,78; And directly export the serial/parallel line data stream of MPEG-2, data flow clock, synchronizing signal and error indication signal in the energy dissipation descrambling unit of integrated package STV0299.

Compared with the prior art, the beneficial effects of the utility model are embodied in: the utility model adopts the integrated circuit preferred embodiment, has high integration, and discrete component is few, and is simple in structure, and cost is low.As high-performance is complete in the digital satellite television set-top box L-band fore-end to base band, this digital integrated tuner on the ratio of performance to price as compared with the past tuner have greatly improved.

Description of drawings:

Fig. 1 is the utility model electrical schematic diagram.

Fig. 2 is the prior art electrical schematic diagram.

Fig. 3 is another prior art electrical schematic diagram.

Embodiment:

Referring to Fig. 1, from L-band 950-2150MHZ signal feed-in on F type plug 18 of outdoor unit low noise transform block (LNB), through high-pass filtering 19, first order RF amplifier 20, after adjustable RF attenuator 21 level adjustment, connect second level RF amplifier 32 again.

Present embodiment is based upon on the preferred version of three main integrated circuits, this comprises the tuning integrated circuit 701 of employing SL1925 zero intermediate frequency QPSK, adopt STV0299B QPSK demodulation/cascade forward error correction fec decoder integrated circuit 901, and adopt TSA5059 (A) frequency synthesizer integrated circuit 37.

Shown in Figure 1, after RF amplifies by second level RF amplifier 32, enter the tuning integrated circuit 701 of SL1925 satellite zero intermediate frequency QPSK, this is comprising preamplifier 71, AGC amplifier 72,90-degree phase shifter 79,1/2 frequency divider 80, compacting controlled oscillator Vcoh Vcol 81.Wherein, AGC amplifier 72 is by 35 controls of AGC control circuit, the local frequency of orthogonal mixer 73,74 is provided by the frequency phase lock ring that TSA5059 (A) frequency synthesizer circuit 37, voltage controlled oscillator 81 and low pass filter LPF36 form, the i/q signal of base band buffer amplifier 75,76 outputs enters base band buffer amplifier 77,78 after low pass filter 33,34 filtering.Export final baseband I/Q signal this moment.This baseband I/Q signal enters STV0299 QPSK demodulation/cascade forward error correction fec decoder integrated circuit 901, this is comprising 6 bit A/D conversion 91, calibration filters 92, matched filter 95, carrier loop control 93, timing loop control 94, output control 96, AGC level 97, internal bus controller 98, Viterbi decoding 99, Reed-Solomon synchronous 100, convolution descrambling 101, Reed-Solomon decoding 102, energy dissipation descrambling 103, the serial/parallel line data stream of last tuner output MPEG-2, the data flow clock, synchronizing signal and error indication signal.

Claims

1, the digital integral tuner that is used for the direct broadcasting satellite TV, L-band (950-2150MHZ) signal from outdoor unit low noise transform block (LNB), go up feed-in at F type plug (18), amplify (20), access second level RF amplifier (32) amplification after adjustable RF attenuator (21) level adjustment again through high-pass filtering (19), first order RF, it is characterized in that follow-up circuit adopts the tuning integrated circuit of zero intermediate frequency QPSK (701), and STV0299 QPSK demodulation/cascade forward error correction (FEC) decoding integrated circuit (901) is set; The local frequency of orthogonal mixer (73), (74) is provided by the frequency phase lock ring that TSA5059 (A) frequency synthesizer circuit (37), voltage controlled oscillator (81) and low pass filter LPF (36) form in the tuning integrated circuit of described zero intermediate frequency QPSK (701), the i/q signal of base band buffer amplifier 75,76 outputs inserts the signal input part of the A/D conversion (91) of STV0299 QPSK demodulation/cascade forward error correction (FEC) decoding integrated circuit (901) through low pass filter 33,34 filtering, buffer amplifier 77,78; And directly export the serial/parallel line data stream of MPEG-2, data flow clock, synchronizing signal and error indication signal in the energy dissipation descrambling unit of integrated package STV0299.