CN1417962A - L-band tuner for satellite digital audio and multimedia broadcast - Google Patents
L-band tuner for satellite digital audio and multimedia broadcast Download PDFInfo
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- CN1417962A CN1417962A CN 01140565 CN01140565A CN1417962A CN 1417962 A CN1417962 A CN 1417962A CN 01140565 CN01140565 CN 01140565 CN 01140565 A CN01140565 A CN 01140565A CN 1417962 A CN1417962 A CN 1417962A
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- frequency
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- noise amplifier
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Abstract
In the L-band turner for satellite digital audio and multimedia broadcast, RF signal is processed successively in high-pass filter HPF1 of cut-off frequency of 900 MHz, low-noise amplifier LNA1, microwave ceramic filter F4 and gain-adjustable low-noise amplifier LNA2 in IC Module U4, and through twice down frequency varying to become required second MF signal with central frequency of 1.84 MHz and bandwidth of 2.5 MHz. The ceramic filter is one band-pass filter and in the BPF2 position a surface acoustic wave filter is used. The present invention has high indexes of receiving bandwidth, out-of-band inhibition, etc.
Description
This product is a kind of novel satellite digital audio and multimedia broadcasting tuner, is mainly used in receiving satellite word audio frequency and multimedia broadcast signal, is extremely important front-end receiver spare.
Satellite digital audio and multimedia broadcasting are a kind of advanced person's technological systems, and the wide group of generation (WORLD SPACE) has released digitized audio and multimedia live broadcast system.The international standard that the wide satellite technology system of the United Nations's itu recommendation generation is the digital satellite audio broadcasting.The advantage of satellite digital audio radio shows: tonequality is pure, can reach the CD quality; Area coverage is big; Greatly expand the deficiency of broadcasting frequency quantity in the past.
And there is shortcomings such as receiving bandwidth relative narrower, the outer inhibition of band weak effect in existing satellite reception with tuner.
The objective of the invention is to design a kind of novel satellite digital audio radio tuner, make it on bandwidth and Anti-Jamming Technique index, to do corresponding the improvement and raising.
The objective of the invention is to realize by following means.
At first through a high pass filter HPF1, its cut-off frequency is about 900MHz for L-band satellite digital audio and multimedia broadcasting tuner, RF radiofrequency signal; Amplify through one-level low noise amplifier LNA1, through a Microwave Ceramic Filter F4, enter integrated circuit modules U4 then again, the low noise amplifier LNA2 through the one-level Gain Adjustable amplifies once more, and low noise amplifier at the corresponding levels is integrated among the U4; After this RF radiofrequency signal need be through twice down-conversion, and becoming the second required intermediate frequency is that centre frequency is 1.84MHz, and bandwidth is the intermediate-freuqncy signal of 2.5MHz; To achieve the object of the present invention, behind HPF1 and LNA1, adopt the better ceramic filter of filtering performance; Adopt Surface Acoustic Wave Filter in the BPF2 position.
Adopt structure of the present invention, receive bandwidth, obtained tangible improvement and raising on the Anti-Jamming Technique indexs such as the outer inhibition of band.
Description of drawings is as follows:
Fig. 1 is a work block diagram of the present invention.
Fig. 2 (A) is the filtering performance curve chart of band pass filter in the present invention and the prior art.
Fig. 2 (B) is the filtering performance curve chart of Surface Acoustic Wave Filter in the present invention and the prior art.
Below in conjunction with accompanying drawing structure of the present invention is described in further detail.
Can be seen that by Fig. 1 the RF radiofrequency signal enters tuner, at first through a high pass filter HPF1, its cut-off frequency is about 900MHz.Amplify through one-level low noise amplifier LNA1 again, the about 10dB of low noise amplifier gain at the corresponding levels, again through a Microwave Ceramic Filter F4, select useful radiofrequency signal, suppress and the image frequency inhibition to guarantee that enough bands are outer, enter integrated circuit modules U4 then, the low noise amplifier LNA2 through the one-level Gain Adjustable amplifies once more, low noise amplifier at the corresponding levels is integrated among the U4, enters follow-up down-conversion part.
After this RF radiofrequency signal need be through twice down-conversion, and becoming the second required intermediate frequency is that centre frequency is 1.84MHz, and bandwidth is the intermediate-freuqncy signal of 2.5MHz.In accompanying drawing 1, LNA2, MIXER1, AMP1, MIXER2, AMP2, RFVCO, IFVCO, PLL1, PLL2 are integrated among the integrated circuit U4.
Down-conversion for the first time, the tuning range of RFVCO is 1338.14～1375.4MHz, it with in MIXER1, carry out mixing from the RF radiofrequency signal of prime, produce first intermediate-freuqncy signal, leave U4.The signal of this frequency is through the Surface Acoustic Wave Filter F3 of a special use, and this Surface Acoustic Wave Filter has extraordinary squareness factor, and it is better to suppress index outside frequency response flatness and the band in the band, thereby selects useful signal, returns U4.This signal through the amplifier AMP2 by AGC control, carries out the down-conversion second time again.
Down-conversion for the second time, IFVCO adopts fixing frequency of oscillation 117.08MHz, and it is 115.24MHz first intermediate-freuqncy signal with frequency from prime, carry out mixing in MIXER2, produce second intermediate-freuqncy signal, the second intermediate-freuqncy signal centre frequency is 1.84MHz, bandwidth is 2.5MHz, is exported by U4.
RFVCO and IFVCO all adopt the frequency synthesis mode, and (PLL1 PLL2), and passes through I
2The C bus is controlled by the CPU of peripheral control circuit.
From the AGC control voltage of peripheral control circuit, can control the gain of AMP1.The AGC controlling depth is 54dB, makes that when the RF signal level changed, second intermediate-freuqncy signal all had constant output level, so that follow-up decoding circuit uses.
This tuner receive frequency is L-band: 1452～1492MHz, and it is 1.84MHz that the RF radiofrequency signal that receives is become centre frequency, and bandwidth is the intermediate-freuqncy signal of 2.5MHz.
Use electronic tuning unit for common satellite reception, behind HPF1 and LNA1, the general employing by electric capacity, inductance etc. separated the band pass filter that set of devices becomes, and filtering energy property is also bad.Its filtering performance is seen the curve B in the accompanying drawing 2 (A).
And this product adopts the better ceramic filter of filtering performance, its performance index:
Centre frequency: 1472 ± 2MHz
Passband: 1452～1492MHz
1dB bandwidth: 60 ± 2MHz
Decay: 1262～1380MHz 〉=25dB
1381～1400MHz≥15dB
Its filtering performance of 1600MHz 〉=30dB is seen the curve A in the accompanying drawing 2 (A).
Obviously, use this band pass filter, it is better that outer inhibition of band and image frequency suppress index.
Use electronic tuning unit for common satellite reception, generally do not adopt the Surface Acoustic Wave Filter (as 20MHz, 40MHz etc.) of Surface Acoustic Wave Filter or employing broader bandwidth in the BPF2 position, its filtering performance is seen the curve B in the accompanying drawing 2 (B).And this product adopts the better Surface Acoustic Wave Filter of filtering performance, its performance index:
Centre frequency: 115.24 ± 0.5MHz
1.5dB bandwidth: 2.9 ± 0.5MHz
15dB bandwidth: 3.9 ± 0.5MHz
30dB bandwidth: 4.4 ± 0.5MHz
Its filtering performance is seen the curve A in the accompanying drawing 2 (B).
As can be seen, this filter, squareness factor are good especially, and the outer inhibition of band index is very good, has satisfied the signal bandwidth requirement of satellite digital audio and multimedia broadcasting.
All functions circuit as herein described is all packed in the metal framework and above lower cover (crown cap) shields, and can effectively prevent all kinds of interference.This product has the characteristics that significantly reduce cost and conveniently use.
Though this product is described, but obviously this programme can be made amendment by many modes, all such modifications are conspicuous for those skilled in the art, and these modifications can not be considered to break away from the spirit and scope of this programme, also should include within the scope of claim.
Claims (2)
1, a kind of L-band satellite digital audio and multimedia broadcasting tuner, at first through a high pass filter HPF1, its cut-off frequency is about 900MHz to the RF radiofrequency signal; LNA1 amplifies through the one-level low noise amplifier, through a Microwave Ceramic Filter F4, enters integrated circuit modules U4 then again, and the low noise amplifier LNA2 through the one-level Gain Adjustable amplifies once more, and low noise amplifier at the corresponding levels is integrated among the U4; After this RF radiofrequency signal need be through twice down-conversion, and becoming the second required intermediate frequency is that centre frequency is 1.84MHz, and bandwidth is the intermediate-freuqncy signal of 2.5MHz; It is characterized in that behind HPF1 and LNA1, band pass filter adopts ceramic filter; Adopt Surface Acoustic Wave Filter in the BPF2 position.
2, according to claim 1 described L-band satellite digital audio and multimedia broadcasting tuner, it is characterized in that described all functions circuit all shields in a metal enclosed cavity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 01140565 CN1417962A (en) | 2001-11-06 | 2001-11-06 | L-band tuner for satellite digital audio and multimedia broadcast |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 01140565 CN1417962A (en) | 2001-11-06 | 2001-11-06 | L-band tuner for satellite digital audio and multimedia broadcast |
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| Publication Number | Publication Date |
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| CN1417962A true CN1417962A (en) | 2003-05-14 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 01140565 Pending CN1417962A (en) | 2001-11-06 | 2001-11-06 | L-band tuner for satellite digital audio and multimedia broadcast |
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| CN (1) | CN1417962A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101790129B (en) * | 2004-08-05 | 2013-04-24 | Lg电子株式会社 | Frequency selection method for multi-media broadcasting/multicasting service and mobile terminal thereof |
-
2001
- 2001-11-06 CN CN 01140565 patent/CN1417962A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101790129B (en) * | 2004-08-05 | 2013-04-24 | Lg电子株式会社 | Frequency selection method for multi-media broadcasting/multicasting service and mobile terminal thereof |
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