JPH04105777U - satellite receiver - Google Patents

Abstract

(57) [Summary] [Purpose] To automatically correct disparities in input signal levels for each satellite channel. [Configuration] Regarding the individual intermediate frequencies of the satellite channel group input to the satellite tuner 12, the control circuit 14 controls the slope attenuator 13, which amplifies the signal with a certain difference between adjacent channels, between the low channel and the satellite channel group. The advantages of the IF transmission method can be maximized by determining the level difference between adjacent channels from the input signal level of the high channel and working to correct the level difference by varying the amplification difference of the slope attenuator 13. Enables satellite reception.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention can automatically correct disparities in input signal levels for each satellite channel. This article relates to a satellite receiver designed to

0002

[Conventional technology]

BS-3a was launched as a successor to the broadcasting satellite BS-2b, and the current NHK One commercial channel will be added in addition to the two channels. On the other hand, Heisei In 1999, programs were already distributed to CATV all over the country using communication satellites (CS). "Space Cable Net" has appeared, and currently JCSAT-1, JCS Three satellites, AT-2 and Superbird A, are in operation, leading to an era of multi-stationing ahead of BS. is welcoming. The frequency of radio waves transmitted from CS for program distribution is Ku band. 12.25 GHz to 12.75 GHz, which also uses the Ku band. A slightly higher frequency band is used compared to BS's 11.7GHz to 12.2GHz. It will be done. Additionally, the BS-IF band is already in the 1,035 to 1,335 MHz band. Since the CS-IF band is used, Space Cable Net uses the CS-IF band as the The frequency range is 1,335 to 1,770 MHz. The frequency array of CS-IF is The differences between when using JCSAT and when using Superbird are shown in Figures 5 and 6, respectively. So, in JCSAT, 1,380-1,770MHz is also used as Super Bird. 1,360-1,770 MHz is used, and these bands overlap each other. Therefore, it is not possible to simultaneously transmit all channels using one cable. do not have.

0003 As for the transmission method of CS signals in joint reception, as in the case of BS, the basic AM (VHF) transmission, AM (MID, SHB) transmission, AM (UHF), CS - There are four types of IF transmission, but when considering the signal transmission quality, the CS antenna CS-IF that transmits the 1GHz band FM signal as it is after frequency conversion using an inverter. The transmission method is optimal, especially for many small-scale communal reception facilities such as apartments. Adopts BS-IF/CS-IF transmission method. However, the transmission frequency is high. Transmission loss is also large, so coaxial cables, distributors, branchers, series units, etc. It is mandatory to use a CS-IF compatible type of duplexer that can transmit up to 1,770MHz. In the case of CS-IF transmission method, horizontal polarization (H) and vertical polarization are transmitted from one CS. Since two directly polarized (V) waves are transmitted simultaneously, for example, JCSAT-2 and When receiving two CSs of Super Bird A, overlap the CS-IF bands. In order to avoid this, measures such as switching channels for transmission are necessary.

0004 The satellite receiver 1 shown in FIG. 4 is a joint reception equipment for BS-IF/CS-IF transmission system. It is provided in each apartment building with It has a built-in satellite tuner 2 called a BS/CS tuner. B.S. Antenna 3 and CS antenna 4 capture radio waves coming from satellites, and are attached to each Converters 3a and 4a convert the frequency to intermediate frequency, mix it in the mixer 5, and then The signal is supplied to the satellite tuner 2 in the satellite receiver 1 via a coaxial cable.

[0005]

[Problem that the idea aims to solve]

The conventional satellite receiver 1 above uses the BS-IF/CS-IF transmission system. Therefore, it is possible to receive multiple satellite channels in high quality, but coaxial cable Since the transmission loss at the IF frequency varies depending on the IF frequency, the longer the signal transmission distance The problem is the difference in signal attenuation between channels. For example, as shown in Figure 7, TV JIS cable (TVE), which is well known as a coaxial cable for general households. FCX), the signal attenuation is 1,300 dB/Km at 770 MHz. At MHz, there is a signal attenuation of 374 dB/Km, and it is not suitable for outdoor use for communal reception. With coaxial cable S-5C-HFL, 160dB/Km at 770MHz signal attenuation of 220 dB/Km at 1,300 MHz. As such, signal attenuation becomes noticeable almost in proportion to the IF frequency. For this reason, B Distance between satellite antennas such as S antenna 3 and CS antenna 4 and satellite tuner 2 The longer the signal transmission distance by intermediate frequency becomes, the more the satellite channel becomes There are large differences in signal attenuation between channels, which makes it difficult to share satellite antennas. For joint reception facilities such as satellite antennas, the best option is to Even though all channels can be viewed in the same quality in the apartments on the upper floors, the satellite antenna If you live on the first floor, where there is a significant distance from the BS channel and signal attenuation is significant, all BS channels or The CS low channel can be viewed normally, but the CS high channel is input. There were times when I was unable to watch properly due to insufficient signal level.

[0006] On the other hand, to address this issue of disparity in reception, conventional methods have been used, for example, as shown in Figure 6. A slope attenuator 6 is interposed in front of the star receiver 1, and a specialist engineer specifies the Based on input signal levels of all channels measured using Tram Analyzer 7 Then, the slope characteristics of the slope attenuator 6, that is, the amplification difference for each frequency, are Manually correct it and send all channels to satellite tuner 2 as a signal at a constant level. I had adjusted it so that it would be entered. However, making these adjustments requires considerable expertise. requires knowledge and special measuring equipment, is nearly impossible for ordinary users, and requires Since it has to be carried out individually for each unit, in apartment complexes with a large number of units, It takes a lot of work to finish adjusting everything, and even once the adjustments are done, , changes in signal attenuation of coaxial cables due to aging, and changes in broadcasting conditions at broadcasting stations. We anticipate cases where the slope characteristics will need to be readjusted due to changes, etc. They were faced with issues such as being exposed.

[0006]

[Means to solve the problem]

This idea solves the above problem and uses satellite signals sent as an intermediate frequency. A satellite tuner that selects and demodulates star channels, and a satellite tuner that is input to the satellite tuner. For each intermediate frequency of the star channel group, a certain disparity is maintained between adjacent channels. a slope attenuator for amplifying the signal, and a low channel for the satellite channel group. The level difference between adjacent channels can be calculated from the input signal level of the channel and high channel. and correct the level difference by varying the amplification difference of the slope attenuator. The invention is characterized in that it is equipped with a control circuit for correcting the problem.

[0007]

[Effect] This idea is based on the individual intermediate frequencies of the satellite channels that are input to the satellite tuner. Slope attenuation is used to amplify signals with a certain level of disparity between adjacent channels. The control circuit controls the low channel and high channel of the satellite channel group. The level difference between adjacent channels is determined from the input signal level of the input channel, and the slope working to correct the level disparity by varying the amplification disparity of the attenuator; This enables satellite reception that takes full advantage of the advantages of the IF transmission method. Ru.

[0008]

【Example】

Examples of this invention will be described below with reference to FIGS. 1 to 3. Figure 1 2 is a schematic circuit diagram showing an embodiment of the satellite receiver of this invention, and FIG. To explain the averaging operation of the input signal level by the slope attenuator, 3 are flowcharts for explaining the operation of the control circuit shown in FIG. Ru.

[0009] The satellite receiver 11 shown in FIG. 1 receives a satellite channel sent as an intermediate frequency. Satellite tuner 12 for demodulating tuning and satellite channel input to satellite tuner 12 For each intermediate frequency of a group of channels, the signal is increased with a certain difference between adjacent channels. The slope attenuator 13 that controls the width, and the low channel and high channel of the satellite channel group. Determine the level difference between adjacent channels from the input signal level of the same channel, Control for correcting the level difference by varying the amplification difference of the slope attenuator 13 It has a memory 15 for storing data required by the circuit 14 and the control circuit 14. The slope attenuator 13 sets the amplification difference for each frequency as a slope degree. As shown in Figure 2, the signal levels of the BS-IF signal and CS-IF signal are changed. amplification with a certain disparity between channels. However, in Figure 2, the dotted line is a slow This is the input signal level of the IF frequency seen just before the attenuator 13, and is indicated by the dashed-dotted line. is a slope attenuator that has exactly the opposite characteristics to the input signal level of this IF frequency. It shows the slope characteristics of the slope attenuator 13, and it shows the slope characteristics of the slope attenuator 13. By providing a suitable slope characteristic, the input I of multiple channels can be adjusted as shown by the solid line. The signal level of the F signal can be averaged.

0010 The operation of determining the degree of amplification by the control circuit 14 will be explained below with reference to FIG. Ru. First, in step (101), when the satellite receiver 11 is powered on, the control In the following step (102), the control circuit 14 selects a channel for the satellite tuner 12. Issue a command to receive the CS low channel (for example, CS13 channel) Ru. Then, the AGC output voltage Vl of the satellite tuner 12 at this time becomes step ( 103), the data is stored in the memory 15. Next, in step (104) , issues a channel selection command to the satellite tuner 12, and selects the CS high channel (for example, AGC output of satellite tuner 12 at that time Voltage Vh is stored in memory 15 in step (105). Next, from the AGC output voltages Vl and Vh obtained in this way, step (106) , the low channel (L MHz) and high channel (H MHz) is calculated as (Vh-Vl)/(H-L). Finally, for the slope attenuator 13, it is necessary to correct the above reception disparity. The degree of amplification is determined by the slope degree, that is, the slope of -(Vh-Vl)/(H-L). Set. By setting the amplification degree in this step (107), the adjacent channel The reception disparity between channels is corrected, and the input signal level of multiple channel groups is is averaged. However, until now, the operation was performed within a short time after the power was turned on, and the viewer This poses almost no hindrance to the selection of channels that users actually want to watch.

[0011] In this way, according to the satellite receiver 11, small-scale communal reception such as in apartments, etc. In the BS-IF/CS-IF transmission system used in equipment, from BS to CS Signal transmission from the satellite antenna to the satellite tuner 12 for multiple channel groups There is a difference in signal attenuation between channels due to different transmission distances, and this difference Even if the difference differs from residence to residence, control can be performed at the reception point of the satellite tuner 12. The slope attenuator 13 is adjusted based on the difference in signal attenuation determined by the circuit 14. To vary the amplification difference between channels and correct the signal level difference between channels. , optimal reception is possible automatically without relying on frequency analysis by experts. It is. Also, when the satellite tuner 12 is powered on, the slope attenuator By adjusting the amplification degree for 13, it is possible to always adjust the amplification degree to It is possible to average the signal level in response to the environment, and is suitable for the era of multi-channels. A satellite reception system can be constructed.

0012 In the above embodiment, the slope attenuation is performed each time the satellite receiver 11 is powered on. The configuration was configured to adjust the amplification level of Neta 13, but I made a note of the details of what was done once. 15, and increase according to the same implementation content until the next implementation order is issued. It may be configured to repeat the width adjustment.

[0013]

[Effect of the idea]

As explained above, this invention is based on the satellite channel input to the satellite tuner. Signal amplification with constant disparity between adjacent channels for each intermediate frequency of the group In contrast to the slope attenuator that performs slope attenuation, the control circuit The level difference between adjacent channels can be calculated from the input signal level of the channel and high channel. Correct the level difference by varying the amplification difference of the slope attenuator. For example, since the structure is designed to encourage In the BS-IF/CS-IF transmission system used for For the group of channels, the signal transmission distance from the satellite antenna to the satellite tuner is This difference causes a difference in signal attenuation between channels, and this difference is Even if it differs from case to case, the control circuit at the receiving point of the satellite tuner The amplification difference between channels of the slope attenuator is calculated based on the difference in signal attenuation. frequency by experts to adjust the signal level disparity between channels. Optimum reception is possible automatically without relying on analysis, and satellite tuning is also possible. The amplification level for the slope attenuator is adjusted when the power is turned on. By making sure that the To build a satellite reception system that is possible and suitable for the era of multi-channels. It has excellent effects such as:

[Brief explanation of drawings]

FIG. 1 is a schematic circuit diagram showing an embodiment of a satellite receiver of the present invention.

FIG. 2 is a diagram for explaining an input signal level averaging operation by the slope attenuator shown in FIG. 1;

FIG. 3 is a flowchart for explaining the operation of the control circuit shown in FIG. 1;

FIG. 4 is a schematic circuit configuration diagram showing an example of a conventional satellite receiver.

FIG. 5 is a diagram showing IF frequency arrays of BS and JCSAT.

FIG. 6 is a diagram showing IF frequency arrays of BS and Superbird.

FIG. 7 is a diagram showing the relationship between the IF frequency and the amount of signal attenuation due to the signal cable.

[Explanation of symbols]

11 Satellite receiver 12 Satellite tuner 13 Slope attenuator 14 Control circuit

──────────────────────────────────────────────── ─── Continued from front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location H04N 5/44 H 7037-5C

Claims (1)

[Scope of utility model registration request] 1. A satellite tuner that selects and demodulates a satellite channel sent as an intermediate frequency, and a signal that has a certain difference between adjacent channels for each intermediate frequency of a group of satellite channels that is input to the satellite tuner. A slope attenuator that performs amplification, and a control circuit that determines a level difference between adjacent channels from input signal levels of a low channel and a high channel of the satellite channel group, and corrects the level difference by varying the amplification difference of the slope attenuator. A satellite receiver comprising: