Receiver
The receiver (じゅしんき) receives a signal among communication machines and is the device which regains the health, and restores information. In addition, the sending out side of the signal is a transmitter. I am called radio receiver, receiver, tuner, RX.
The reason of "the receiver" is "a receiver", but I include it to the sound reproduction device including the speaker when I say a receiver and it is Japanese and is usually often equivalent to "a radio" (there is the meaning called the receiver of the radiobroadcast in English radio). I may say a receiver referring to headphones to tie to the receiver. On the other hand, it may be the meaning such as "the tuner" which does not include speakers when I say a receiver and often points to the device receiving a device more full-scale than a radio, an electric wave except the general radiobroadcast again.
I refer to the radio # receiver.
Table of contents
Constitution of the receiver
The basic constitution of the receiver consists of the following. At first I receive an electric wave with an antenna (and I ground it) and take out an objective electric wave signal by a tuning circuit. Radio Frequency abbreviates here and says RF. I get a voice signal by the recovery (detect) from a signal of RF. It is said for RF for short with AF Audio Frequency. I output a signal of AF to speakers and get a sound.
The ore radio is a receiver only by this basic constitution. I pick up the amplification with the practical receiver appropriately.
The figure is constitution of the orthodox receiver of the analog era. Even problems of 無線技士試験 are seen with a thing of the I.F. two steps amplification in one step of high frequency, super-heterodyne system. It is mainly designation ぜられた with "2 in high 1" for the vacuum tube era.
- High frequency amplifier
- It is choice and a low noise amplifier to amplify with an input signal. When a signal is feeble, it can be assumed that I make a stage for the first grade at a good device of the SN ratio (SN ratio). Transistors such as the HEMT of the low noise are used now in the UHF zones. With the receivers more than a UHF zone, I am often called LNA (Low Noise Amplifier). Depending on a case and the demand specifications that an input signal has a big enough, the high frequency stage of the front end is omissible. In addition, LNA is not used with the car telephone in the 1980s because an equal receiving sensitivity is provided if I put transistor which is a low noise and small BPF of the loss together and design the mixer when there is LNA. Unwanted radio wave emission (there is a duty to hold part oscillator (local )→ mixer → high frequency amplifier → antenna) in check.from an antenna called the leak local as a secret duty of the high frequency amplifier The amplifier has a gain in the order direction, but it becomes the negative gain for the opposite direction and damps a country signal flowing backward.
- Frequency changer
- I am comprised of a part oscillator and a mixed container (I say a mixer or the mixer). It is the circuit which converts a reception signal into constant low frequency (there is much intermediate frequency of 455kHz in the case of medium frequency Zone (531-1602kHz) of the figure in question intermediate frequency) regardless of the frequency. The reasons to frequency-convert here are as follows and have a particularly important meaning in a reception circuit.
- When I am going to amplify it to the level that it can demodulate as the frequency of the signal targeted for the reception, positive feedback occurs and oscillates it, and an amplifier is easy to become unstable.
- The saturation of interference and the latter half amplifier occurs when I do not damp the signal except the signal targeted for the reception by a narrow-band filter, but it is necessary for the thing that is not easy, low frequency to convert that variableness does the tuning frequency of the narrowband filter of the high selectivity into a signal of the constant low frequency (= intermediate frequency) from making of narrowband filter and Suiko of the high selectivity.
- Because low frequency is easy to make the circuit to receive and process of the latter half to some extent, it is necessary to convert it into constant low frequency (= intermediate frequency).
- I call this a superheterodyne (it is said that it is super with a thing of once to have been abbreviated, and to frequency-convert commonly with a single supermarket.as for the thing of the twice a double supermarket) method. In 1918, it was invented by Edwin Armstrong. The frequency is converted into the frequency of differences between input signal and part oscillator output (intermediate frequency may be higher than reception frequency recently, and, in that case, the constitution of the frequency of the sum is possible, too). In addition, in the super-heterodyne system, I receive the image frequency other than frequency for the reception (image interference). It is necessary to damp image frequency by a filter enough before entering the mixer not to receive a signal of the image frequency, but an image rejection-shaped mixer comes to be used by the reception circuit of recent receiver, e.g., Bluetooth;; is not necessary.
- I.F. amplifier
- Variableness does an amplification rate by the strength and weakness of the input signal, and, as for the purpose of this amplifier, 1 keeps a fixed input signal level to a demodulator filter function, 3 to remove an unnecessary signal of the frequency that amplification, 2 to the level that can recover were next to; is gain control (AGC) functions automatically.
- Demodulator
- I include a necessary recovery function by a communication method to receive. I assumed an envelope curve wave detector here.
- Low frequency amplifier
- I power-amplify the audio frequency signal which is the output of the wave detector to a level to be able to sound a speaker.
Circuit method except the superheterodyne
The circuit method except the superheterodyne includes next. The current mainstream is double super-heterodyne system and a direct conversion method in the field of radio. As for AM, the FM receiver, super-heterodyne system is still mainstream.
- Straight
- I input to a wave detector after the amplification without frequency-converting the high frequency signal which I received without or amplifying it and get a low frequency signal. In practice, I am hardly used. I am seen in the AM radios of the electronic work kit now.
- Reflex
- After amplifying a high frequency signal with one vacuum tube, transistor, and having detected it, it goes back up for the input of the same vacuum tube, transistor again and amplifies the low frequency. The constitution that was seen in the receiver of the times when a vacuum tube and a transistor were expensive well. I am seen in the AM radios of the electronic work kit now.
- Reproduction
- A method to return a part of the high frequency signal to the input side (positive feedback). There is the fault that I oscillate when quantity of return is too strong while a high amplification degree is provided by a brief circuit. There is the method that dispensed with adjustment of the quantity of return by letting an oscillation make an intermittent continuation (quenching) intentionally and is called superregeneration. I am hardly used now. The constitution (regular three, regular four) not to have a high frequency stage becomes the unnecessary radiation that a signal is released as an electric wave by an antenna when quantity of return is excessive and oscillates it. In 1947 after the World War II defeat, the Japanese Government prohibited the production sale of the regenerative radio by the company by an advice of GHQ [1].
- High frequency tuning (TRF)
- A method to have a tuning circuit in front and behind a high frequency stage (and sometimes plurally), and to go along with in each. With the double tuning.
- Double superheterodyne
- After the IF amplifier of the superheterodyne, I prepare for a mixer and from station one more and am a method to frequency-convert already once. It is said that 1st is local by 1stIF, from station in first IF, and 2nd is local by 2ndIF, from station in the second IF. There is the merit that image interference can strengthen by the RF filter that it is easy that it is possible at 1stIF frequency highly to divide it into twice, and to cut down on frequency and can keep image frequency away. It is a method spreading most with radio machines now. In addition, in the reason top, a mixer and from station can evade image interference so as to increase it if it increases numbers, and there are triple (three times), the thing of the hoe gong pull (four times) by the number of the steps, too, but, actually, is very special enough by an RF filter now because I can drop an image. The pentapull (five times) has not yet appeared. There were the times when it was ever evaluated simply if triple is higher-performance than a double, a double than a single, but it is at the present when a filter and a semiconductor, a design technology developed, and such an evaluation does not have a meaning. 455kHz was ever often used for 2ndIF, but 450kHz may be used recently to use a standard oscillator of PLL and an oscillator of the 2nd country in common. In addition, I may compose 2ndIF filter of the active filter in the IC, and in this case lower frequency is used.
- Direct conversion
- A method to get audio frequency directly without making the frequency of the part oscillator approximately same as reception frequency, and using intermediate frequency. It is old and was used for single sideband (SSB), the reception of telegraphic communication (CW) by the amplitude modulation, but in late years the adoption with the cell-phone is prosperous to be able to lose big, expensive IF filter.
Example of the classic receiver
- A receiver to receive radio receiver (radio) - radiobroadcast. The signal which regained its health converts it into sound vibration with a speaker and the earphone which are a voice signal (audio system signal) and listens.
The chart below is constitution of five pitches of supermarket radios (radio with the transformer using early miniature (MT) pipe) of (about 1955) for the vacuum tube era.
- Vacuum tube example of five pitches of supermarket radios
| Use | ST pipe | GT pipe (*) | With MT tube transformer | MT tube transformer reply | Remarks |
|---|---|---|---|---|---|
| Amplification of high frequency | (UZ) 6D6 | 6SK7 | 6BA6 6BD6 | (**) | Only in the high-quality plane six pitches supermarket |
| Intermediate frequency conversion | 6WC5 | 6SA7 | 6BE6 | 12BE6 | |
| The intermediate frequency amplification | (UZ) 6D6 | 6SK7 | 6BA6 6BD6 | 12BA6 | |
| Detection, the low frequency amplification | 6ZDH3A | 6SQ7 | 6AV6 | 12AV6 | |
| Power amplification | (UZ) 42 6ZP1 | 6F6 6V6 | 6AR5 6AQ5 | 30A5 35C5 | |
| Rectify | (KX) 80 (KX) 12F | 6X5 5Y3 | 5MK9 6X4 | 35W4 |
- (*) The GT pipe was not common in Japan.
- (**) When reduction in cost was given priority to over the MT tube transformer reply as a product of the last years of vacuum tube from about 1958, there is not most of the amplification of high frequency from circuital limitation.
- A receiver to receive TV receiver (television receiver or merely TV) - television transmission. I have the sound reception functions such as a display unit and radios such as a cathode-ray tube, a liquid crystal display, the plasma display.
General coverage receiver (wideband receiver)
The radio having the plural RF part was called outcome "all-frequency" before the war when the use of the radio spread with a long wave, medium frequency, a short wave to cover those all bands. Such radio which even the possibility that could intercept the information from the foreign countries and sometimes military communication was was regulated in wartime (by the political situation, it is similar now depending on a country).
I set intermediate frequency well and, by a technological change, did it using PLL synthesizer as a part oscillator not an analog oscillation circuit and was able to receive ultra high frequency from a long wave continually (depending on a design without a band change). General coverage (ゼネカバ) receiver or a wideband receiver means this. There are an expensive receiver for business use and the small handy receiver which in late years is consumer as a reception function of the amateur radio communications machine supporting many bands in the early days.
RZ-1 of Kenwood, FRG-965 of YAESU MUSEN, standard (Marantz Japan) AX700 convert a tuner for the CATV for foreign countries made in SHARP. I take 1stIF near frequency of the personal radio communications service with part oscillatory frequency as approximately 1-2GHz, and SR001 (a reception frequency range: 25-1000MHz) of the Nobukazu communication machine converts the reception circuit of the personal radio communications service machine. This receiver was able to receive the circuitry top from a long wave, but it is said that I wore a mask because I cannot guarantee performance.
Receiver of the new method
Direct or, in the 2000s, input the signal which I received into analog - digital conversion circuit after frequency conversion, and I calculate it, and the DSP method with the output is put to practical use, too. Such a receiver is called a software receiver or a software radio, abbreviated designation SDR (Software Defined Radio).
Software receiver using the PC
After having done down-converting (I frequency-convert) to the frequency that the sound card of the PC can handle, I input the reception signal which I caught with an antenna into the sound card of the PC, and the experiment of the method that selects it, and processes the recovery is performed by software.
Footnote
- For ^ well edge Kazumasa (いばたかずまさ) "story "CQ ham radio" April, 2009 issue of a breast or the series intermediate frequency", CQ publishing company, 2,009 years, it is 144-145 pages.
Allied item
- Transmitter (transmitter)
- Transceiver (transceiver)
- Set top box
- Radio
- Ore radio
- Transistor radio
- Digital tuner
- Reproduction receiver
- Superheterodyne receiver
- Direct conversion receiver
Outside link
- SDR: Software radio (Japanese) to make in Software Defined Radio Pure Data
- The patches for Patches for HAM Radio amateur radio communications (Japanese)
This article is taken from the Japanese Wikipedia Receiver
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