CN201774606U

CN201774606U - Digital tuner

Info

Publication number: CN201774606U
Application number: CN2010205130992U
Authority: CN
Inventors: 方全民; 朱丽云
Original assignee: SHANGHAI JINXIN ELECTRONICS Ltd
Current assignee: SHANGHAI JINXIN ELECTRONICS Ltd
Priority date: 2010-09-01
Filing date: 2010-09-01
Publication date: 2011-03-23
Anticipated expiration: 2020-09-01

Abstract

The utility model relates to a digital tuner used for a digital set-top box, which comprises an active distributor connected between radio frequency input and radio frequency output. A passive loop-through circuit is arranged between the radio frequency input and the active distributor, and a filter circuit which can separate desired signals and restrain undesired signals is used as the passive loop-through circuit. When the set-top box is not powered on, the active distributor of the tuner of the digital set-top box can keep working as usual, and the passive loop-through circuit can enable other equipments to use signals simultaneously; and when the set-top box is powered on, the passive loop-through circuit does not work and not affect the use of other equipments.

Description

Digital tuner

Technical field

The utility model relates to a kind of digital tuner, specifically is used for the digital tuner of top box of digital machine.

Background technology

Top box of digital machine is a kind of multimedia terminal, and the hardware architecture and special-purpose real time operating system and the application software that are similar to household PC are arranged.Its operation principle is: each module of set-top box in the high speed of Internet inserts, collaborative work.The user is at first by sending URL of command request.In a process of exchange that uses the PPP point-to-point protocol, on the modulator-demodulator common frame of the final arrival of this order Internet service supplier.By the dynamic assignment method, this user obtains the IP address of use in this transaction then, and Internet is sent in request.After the content of Internet is found, then it is delivered to Internet service supplier (ISP) there, be responsible for it is delivered to cable television network by the router of ISP again, get back to user's set-top box at last.In the set-top box of cable TV, the information content is intercepted and captured.Set-top box is finished the task of a gateway between television set and cable system.Its task is the communication flows of managing I P, in case have the ability IP bag arrival set-top box that the control user passes in and out network, vision signal is separated from this bag, data are wherein deciphered, it is delivered to prepare in the browser on television set, to show then.

Could surf the Net because Cable Modem requires the user will dispose a computer, influence the expansion of client layer, use set-top box then not need computer, it is enough for a television set, thereby the market prospects of set-top box may be had an optimistic view of.Information user from enterprise to family's transition, the network bandwidth from the arrowband to the broadband transition, user-network access equipment is from the TV transition of PC to band set-top box (STB), use the interface from Windows to TV remote key interfaces transition, the information content from for enterprises service to serve transition for people's lives, be the general orientation of network service development, set-top box (STB) obviously is a stage on this general orientation.

At present the tuner that uses of the world and domestic top box of digital machine is to have active distributor function all, and the RF input signal is distributed, and makes that inserting multiple devices on the signal uses.But only under the situation of set-top box energising, distributor just can have effect.The user is in set-top box no power situation, and other equipment can not use signal.

Summary of the invention

The utility model purpose is to overcome the deficiency of above-mentioned prior art and a kind of digital tuner is provided, and still can use under the situation that this digital tuner does not have to switch in set-top box, and other equipment also can use signal.

Realize that the technical scheme that the utility model purpose adopts is: a kind of digital tuner, comprise the active distributor that is connected between radio frequency input and the radio frequency output, between radio frequency input and active distributor, be provided with the passive loops circuit passband.The filter circuit that described passive loops circuit passband suppresses unwanted signal for the signal that can isolate needs.

As a kind of preferred version of the present utility model, used passive loops circuit passband is the RC filter circuit that 3 electric capacity and inductance are formed.

The utility model digital tuner is to increase the passive loops circuit passband between radio frequency input and active distributor, make set-top box under the situation that does not have energising, the RF output of top box of digital machine tuner can be worked as usual, can make other equipment use signal equally.And under the state of energising, this passive loops circuit passband is then inoperative, and does not influence the use of other equipment.

Description of drawings

Fig. 1 is the utility model circuit diagram.

Fig. 2 is the circuit diagram of passive loops circuit passband among Fig. 1.

Embodiment

As shown in Figure 1, digital tuner comprises the active distributor that is connected between radio frequency input and the radio frequency output, is provided with the passive loops circuit passband between radio frequency input and the active distributor.The passive loops circuit passband is that T shape frequency selection circuit that 3 electric capacity and inductance are formed can be isolated the signal that needs and filter circuit that unwanted signal is suppressed, as shown in Figure 2.The circuit that the wideband switch field effect transistor of 1 1GHz is formed does not have under the situation of energising set-top box, and RF output can be worked as usual.VC=0V, RFIN and RFOUT are in conducting state; Make during VC=5V to disconnect between RFIN and the RFOUT, be in cut-off state.Realized that promptly RFIN and RFOUT do not have under the situation of energising in set-top box, the RF output of top box of digital machine tuner can be worked as usual, can make other equipment use signal equally.And under the state of energising, this passive loops circuit passband is then inoperative.Therefore no matter top box of digital machine energized whether, other equipment all can normally use signal.

More than show and described basic principle of the present utility model and principal character and advantage of the present utility model.The technical staff of the industry should understand; the utility model is not restricted to the described embodiments; that describes in the foregoing description and the specification just illustrates principle of the present utility model; under the prerequisite that does not break away from the utility model spirit and scope; the utility model also has various changes and modifications, and these changes and improvements all fall in claimed the utility model scope.The claimed scope of the utility model is defined by appending claims and equivalent thereof.

Claims

1. a digital tuner comprises the active distributor that is connected between radio frequency input and the radio frequency output, it is characterized in that: be provided with the passive loops circuit passband between radio frequency input and the active distributor.

2. digital tuner according to claim 1 is characterized in that: the filter circuit that described passive loops circuit passband suppresses unwanted signal for the signal that can isolate needs.

3. digital tuner according to claim 1 and 2 is characterized in that: described passive loops circuit passband is the RC filter circuit that 3 electric capacity and inductance are formed.