CN201887926U - Wireless headphone applicable to listening test - Google Patents
Wireless headphone applicable to listening test Download PDFInfo
- Publication number
- CN201887926U CN201887926U CN2010206405600U CN201020640560U CN201887926U CN 201887926 U CN201887926 U CN 201887926U CN 2010206405600 U CN2010206405600 U CN 2010206405600U CN 201020640560 U CN201020640560 U CN 201020640560U CN 201887926 U CN201887926 U CN 201887926U
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- wireless headphone
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Abstract
The utility model discloses a wireless headphone applicable to listening test, which is capable of solving the problems of signal interference and signal intensity change. The wireless headphone comprises an earflap-type headphone, a rod antenna, a radio circuit and a power supply, wherein the radio circuit includes a local oscillating circuit, an amplification circuit and a power amplifier circuit. The wireless headphone is characterized in that the radio circuit further includes a medium-frequency circuit, the amplification circuit includes a preamplifier circuit and a secondary amplifier circuit, and the preamplifier circuit and the medium-frequency circuit form a short and medium wave receiving circuit. Compared with the prior art, the wireless headphone respectively amplifies sound volume and power, improves receiving sensitiveness, and overcomes same-frequency interference.
Description
[technical field]
The utility model relates to a kind of wireless headset, particularly a kind of wireless headset that is applicable to foreign language listening examination usefulness.
[background technology]
In the examination of present English, hearing has become an indispensable substance, and along with the going deep into of educational reform, hearing mark shared proportion in total examination mark also increases year by year.Hearing examination pattern is the earliest carried out the broadcast of hearing content in each examination hall a cassette player being set all, but the danger that the as easy as rolling off a log generation examination paper of this kind mode are revealed is not easy to carrying out synchronously of each examination hall examination again.And then, many schools just change and use f-m broadcast station to play examination content, and the student wears earphone and listens to examination content and answer, and the method has solved the problem of synchronous examination, but still have the following disadvantages: 1. because electronic products such as mobile phone are popularized, the wave interference that causes is increasing; What 2. common broadcast receiver used is 1019 family chips, and its intermediate frequency is 10.7 million, thereby can produce the phenomenon that mirror image disturbs, and influence is listened to; 3. small-power frequency modulation transmitting station power and frequency are fixed, and campus-wide is big, classroom situation difference separately, and signal is difficult to accomplish homogeneous.
[summary of the invention]
Technical assignment of the present utility model is at above the deficiencies in the prior art, and a kind of wireless headset that is applicable to hearing examination usefulness is provided, and can solve the strong and weak variation issue of signal interference and signal.
The technical scheme in the invention for solving the technical problem is: a kind of wireless headset that is applicable to hearing examination usefulness, comprise circumaural earphone, telescopic antenna, radio reception circuit, power supply, described radio reception circuit comprises local oscillation circuit, amplifying circuit and power amplifier, it is characterized in that: described radio reception circuit also comprises intermediate-frequency circuit, described amplifying circuit comprises pre-amplification circuit and second amplifying circuit, during pre-amplification circuit and intermediate-frequency circuit constitute, the short-wave reception circuit.
Above-mentioned intermediate-frequency circuit comprises 7021 frequency modulation chips, and this chip is provided with common modulation frequency and special-purpose IF-FRE, and IF-FRE is 76KHz.
Between above-mentioned pre-amplification circuit and the second amplifying circuit filter circuit is arranged.
Above-mentioned filter circuit adopts the C-L-C pi type filter.
Compared with prior art, the utlity model has following outstanding beneficial effect:
1, described amplifying circuit comprises pre-amplification circuit and second amplifying circuit, amplifies respectively on volume and power, has improved receiving sensitivity;
2, IF-FRE be during the 7021 frequency modulation special chips of 76KHz receive, shortwave, receiving sensitivity height, good, the bandwidth of selectivity;
3, filter circuit is overcome co-channel interference.
[description of drawings]
Fig. 1 is the schematic block circuit diagram of the utility model radio reception circuit.
[embodiment]
Below in conjunction with specification drawings and specific embodiments the utility model is further specified.
The utility model comprises circumaural earphone, telescopic antenna, radio reception circuit, power supply.
As shown in Figure 1, described radio reception circuit comprises local oscillation circuit, amplifying circuit, power amplifier, intermediate-frequency circuit, and described amplifying circuit comprises pre-amplification circuit and second amplifying circuit, during pre-amplification circuit and intermediate-frequency circuit constitute, the short-wave reception circuit.Described intermediate-frequency circuit adopts 7021 frequency modulation chips, and this chip is provided with common modulation frequency and special-purpose IF-FRE, and IF-FRE is 76KHz.Between described pre-amplification circuit and the second amplifying circuit filter circuit is arranged, filter circuit adopts the C-L-C pi type filter.
During examination, open localpower earlier, local oscillation circuit produces 68～88,000,000 frequencies, through intermediate-frequency circuit 7021 frequency modulation chip internal processing of circuit frequency modulation, makes local frequency be transferred to the frequency of playing with the examination hall, place generation resonance when consistent, and taking frequent rate is 76KHz.The micropower rectified signal of receiving enters pre-amplification circuit and carries out the volume amplification, enters filter circuit then and carries out the filtering noise reduction, enters second amplifying circuit and carries out power amplification, and amplifying signal enters power amplifier, drives playback.
Need to prove; particular of the present utility model is described in detail the utility model; for a person skilled in the art, in the various conspicuous change of under the situation that does not deviate from spirit and scope of the present utility model it being carried out all within protection range of the present utility model.
Claims (4)
1. wireless headset that is applicable to hearing examination usefulness, comprise circumaural earphone, telescopic antenna, radio reception circuit, power supply, described radio reception circuit comprises local oscillation circuit, amplifying circuit and power amplifier, it is characterized in that: described radio reception circuit also comprises intermediate-frequency circuit, described amplifying circuit comprises pre-amplification circuit and second amplifying circuit, during pre-amplification circuit and intermediate-frequency circuit constitute, the short-wave reception circuit.
2. the wireless headset that is applicable to hearing examination usefulness according to claim 1 is characterized in that described intermediate-frequency circuit comprises 7021 frequency modulation chips, and this chip is provided with common modulation frequency and special-purpose IF-FRE, and IF-FRE is 76KHz.
3. the wireless headset that is applicable to hearing examination usefulness according to claim 1 is characterized in that between described pre-amplification circuit and the second amplifying circuit filter circuit being arranged.
4. the wireless headset that is applicable to hearing examination usefulness according to claim 3 is characterized in that described filter circuit adopts the C-L-C pi type filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206405600U CN201887926U (en) | 2010-11-26 | 2010-11-26 | Wireless headphone applicable to listening test |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206405600U CN201887926U (en) | 2010-11-26 | 2010-11-26 | Wireless headphone applicable to listening test |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201887926U true CN201887926U (en) | 2011-06-29 |
Family
ID=44185468
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010206405600U Expired - Fee Related CN201887926U (en) | 2010-11-26 | 2010-11-26 | Wireless headphone applicable to listening test |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201887926U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102538952A (en) * | 2012-01-12 | 2012-07-04 | 中国人民解放军理工大学 | High-sensitivity thunder test circuit |
| CN103533487A (en) * | 2013-09-27 | 2014-01-22 | 潍坊歌尔电子有限公司 | Wired earphone circuit with function of suppressing 217Hz noise interference |
-
2010
- 2010-11-26 CN CN2010206405600U patent/CN201887926U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102538952A (en) * | 2012-01-12 | 2012-07-04 | 中国人民解放军理工大学 | High-sensitivity thunder test circuit |
| CN103533487A (en) * | 2013-09-27 | 2014-01-22 | 潍坊歌尔电子有限公司 | Wired earphone circuit with function of suppressing 217Hz noise interference |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110629 Termination date: 20111126 |