FamilyMart: Deploying Beverage Refilling AI Robots to 300 Stores
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Store employees wear location information transmitters, and receivers installed in the store recognize location data, making it possible to visualize and analyze work hours for each time period.
Family Mart announced on August 8 that the AI robot "TX SCARA" developed by Telexistence, the store ... → Continue reading
Wikipedia related words
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Receiving machine(Jushinki) isCommunication deviceOfsignalReceiveddemodulationdo it情报It is a device that restoresAlso, the sending side of the signal isTransmitter.Radio receiver,receiver,tuner,RXAlso called.
"Bluetooth receivers" and "receivers" sold as general products may also transmit, but are generally called receivers.
Usually, the translation of "receiver" is "receiver", but if you say "receiver"speakerIncluding voice playback devices such as, in Japanese, "radio” (the English word “radio” also means a receiver for radio broadcasting).connect to receiverHeadphonesIt is even said to refer to the receiver.On the other hand, when we say a receiver, we do not include speakers, etc.tuner”, and often refers to a device that is more serious than a radio, or a device that receives radio waves other than general radio broadcasting.
radio # receiverSee also
The basic configuration of the receiver consists of the following.first,antenna(andGround)soRadio waveReceivetuningTarget radio wave by circuitsignaltake out.The process up to this point is also called the Radio Frequency stage, or RF stage for short. from RF signalsdemodulationby (detection)voiceget the signal.From here onwards, the RF stage is referred to as the Audio Frequency stage, or abbreviated as the AF stage. AF signalspeakeretc. to obtain audio.
The figure shows the configuration of an orthodox receiver in the analog era.High frequency 1 stage,superheterodyneIt is a method of intermediate frequency two-stage amplification,Wireless workersYou can also find it in exam questions.mainlyVacuum tubeIn the era, it was also called "high 1 middle 2".
- high frequency amplifier
- It is a low noise amplifier that selects and amplifies the input signal.If the signal is weak, the signal-to-noise ratio (SN ratio) can be a good device.Currently, in the UHF band, etc., low-noiseHEMTsSuch asTransistoris used. For receivers in the UHF band and above, it is often called an LNA (Low Noise Amplifier).If the input signal is large enough or depending on the required specifications,front endcan be omitted.By designing a mixer that combines a low-noise transistor and a low-loss BPF, it is possible to obtain the same reception sensitivity as with an LNA.As a hidden role of the high-frequency amplifier, unnecessary radio wave radiation from the antenna called local leak (local oscillator(local) → mixer → high frequency amplifier → antenna).The amplifier has gain in the forward direction, but has negative gain in the reverse direction, attenuating the local signal flowing backward.
- frequency converter
- with local oscillatormixer(also called mixer or mixer).Transmit the received signal to a constant low frequency (Intermediate frequency, IF.In the case of the medium wave band (531 - 1602kHz) in the example of the figure, it is a circuit that converts to 455kHz intermediate frequency).The reason for the frequency conversion is as follows, and it has a particularly important meaning in the receiving circuit.
- of the signal to be receivedfrequencyWhen trying to amplify to a level that can be demodulated withpositive feedbackThe amplifier tends to become unstable, such as oscillation due to
- If signals other than the signal to be received are not attenuated by a narrow-band filter, interference and saturation of the post-stage amplifier will occur. Since it is easier to create a narrow band filter with high selectivity, it is necessary to convert the signal to a constant low frequency (=intermediate frequency).
- Since it is easier to create a reception processing circuit at a later stage with a somewhat lower frequency, it is necessary to convert the frequency to a constant low frequency (=intermediate frequency).
- thissuperheterodyne(Commonly abbreviated as super. One frequency conversion is called single super, and two is double super).1918,Edwin Armstrong invented byThe frequency is converted to the difference frequency between the input signal and the local oscillator output (nowadays the intermediate frequency may be higher than the receive frequency, in which case a sum frequency configuration is possible).Note that in the superheterodyne system, image frequencies are received in addition to the frequencies to be received (image interference).In order not to receive the image frequency signal, it is necessary to sufficiently attenuate the image frequency with a filter before entering the mixer.Bluetoothimage-rejection-type mixers have come to be used in the receiving circuits of , and the need for such mixers is disappearing.
- intermediate frequency amplifier
- The purpose of this amplifier is 1. Amplification to a level that can be demodulated, 2. Filter function to remove unwanted signals of adjacent frequencies, 3. Input to the demodulator by varying the amplification factor depending on the strength of the input signal. keep the signal level constantAutomatic gain control (AGC) function, etc.
- It has the necessary demodulation function depending on the communication system to be received.An envelope detector is assumed here.
- low frequency amplifier
- Let the audio frequency signal, which is the output of the detector, bespeakerAmplify the power to a level where you can hear the sound.
Circuit system other than superheterodyne
Circuit methods other than superheterodyne include the following.The current mainstream in the radio field is the double superheterodyne system and the direct conversion system. AM and FM receivers still use the superheterodyne system.
- A low-frequency signal is obtained by inputting a received high-frequency signal to a detector after amplification without frequency conversion or without amplification.It is almost never used in practice.It is still seen in AM radios of electronic work kits.
- A high-frequency signal is amplified by a single vacuum tube/transistor, detected, and then returned to the input of the same vacuum tube/transistor to amplify low-frequency signals.A configuration commonly seen in receivers in the days when vacuum tubes and transistors were expensive.It is still seen in AM radios of electronic work kits.
- After the amplified high frequency signal is mixed with the local oscillator to modulate the reception frequency, intermediate frequency amplification or low frequency amplification is performed.Unlike the superheterodyne, which maintains the difference between the reception frequency and the local transmission frequency even if the receiving station is changed, it does not have an automatic interlocking device for the local transmission and the reception frequency.regenerationReception is more difficult than radio.
- This designation is applied to receivers that are made to work with a tuning circuit in part or all to facilitate tuning, and does not refer to a specific circuit system.Auto (AUTO) was given as an acronym to cover autodyne, which refers to regenerative receivers.In Japan, super regeneration (super autodyne) and automatic local transmission mixing (super heterodyne) are famous.
- A method in which part of the high-frequency signal is returned to the input side (positive feedback).Although a simple circuit can provide high amplification, it has the drawback of causing oscillation if the amount of feedback is too strong.There is a method that eliminates the need to adjust the amount of feedback by intentionally interrupting (quenching) oscillation.super regenerationcalled.It is seldom used today.A configuration without a high-frequency amplification stage (parallel XNUMX, XNUMX, etc.) results in unwanted radiation in which signals are emitted as radio waves from the antenna when the amount of feedback is excessive and oscillation occurs.After defeat in World War II1947, the Japanese government Ghq Prohibited the manufacture and sale of regenerative receivers by companies based on the recommendation of.
- high frequency tuning (TRF)
- A method in which tuning circuits are provided before and after the high-frequency amplification stage (multiple stages in some cases), and each is tuned.Also double tuning.
- double superheterodyne
- After the superheterodyne IF amplifier, another mixer and local oscillator are prepared, and the frequency is converted once more.The first IF is called 1stIF, the local oscillator is called 1st local, the second IF is called 2ndIF, and the local oscillator is called 2nd local.Since the frequency is lowered in two steps, the 1stIF frequency can be increased and the image frequency can be separated, so there is the advantage of being strong against image interference with a simple RF filter.This is currently the most widely used method for radio equipment and the like.Theoretically, the more mixers and local oscillators, the more image disturbance can be avoided. Depending on the number of stages, there are triple (3 times) and quadruple (4 times), but in reality, the RF filter is sufficient to reduce the image. It is now very special because it is possible toPentaple (5 times) has not yet appeared.There was a time when it was simply evaluated that a double circuit had better performance than a single circuit, and a triple circuit had better performance than a double circuit. . In the past, 2kHz was often used for the 455ndIF, but recently 2kHz is sometimes used to share the PLL reference oscillator and the 450nd local oscillator.In some cases, the 2ndIF filter is composed of an active filter inside the IC, and in this case, even lower frequencies are used.
- direct conversion
- A method in which the frequency of the local oscillator is made almost the same as the reception frequency, and the audible frequency is obtained directly without using an intermediate frequency.In the past, it was only used for single sideband (SSB) and telegraph (CW) reception by amplitude modulation, but in recent years it has been widely used in mobile phones because it eliminates large and expensive IF filters. be.
Classic receiver example
- Radio receiver (radio) - Radio broadcastreceiver for receivingThe demodulated signal is a voice signal (audio signal),speakerOr convert it into acoustic vibration with earphones and listen to it.
The figure below shows the vacuum tube era (1955Around)5 ball super radio(early transformer-equipped radio using miniature (MT) tubes).
- Vacuum tube example of 5 tube super radio
|Use||ST tube||GT tube (*)||MT tubeTransformerWith||MT tube transformerless||Remarks|
|high frequency amplification||(UZ) 6D6||6SK7||6BA6|
|(**)||High-end machine 6-ball super only|
|Intermediate frequency conversion||6WC5||6SA7||6BE6||12BE6|
|intermediate frequency amplification||(UZ) 6D6||6SK7||6BA6|
|Detection/low frequency amplification||6ZDH3A||6SQ7||6AV6||12AV6|
|power amplification||(UZ) 42|
- (*) GT tubes were not common in Japan.
- (**) Transformer-less MT tubes were manufactured around 1958, the end of the vacuum tube stage, and cost reduction was a priority.
- TV receiver (TV receiverOr just TV) - TV broadcastreceiver for receivingCRT,Liquid crystal display,Plasma displayIt has a display device such as a radio and a voice reception function like a radio.
General coverage receiver (wideband receiver)
the 1930sWhen the use of radio spread to long, medium, and short waves, radios with multiple RF sections appeared to cover all of these bands and were called 'all-wave'.During the war, foreign imports (政府Information that the military wants to hide from its own people) and, in some cases, even military communications could be intercepted.
Advances in technology have led to the use of analogOscillator circuitnotPLL synthesizer, and by skillfully setting the intermediate frequency,Long wavefrom (LW)Hyperwave(UHF) can be received continuously (band switching is automatic depending on the design).thisgeneral coverage(genekaba) receiver, orwideband receiver(Gene cover is used for objects whose reception range is up to short waves, andthe 1940sUntil then, the existence of electromagnetic waves higher than very short waves had not been confirmed, so the same kind was called "all wave").In the early days, it was used as an expensive receiver for business use and as a reception function for multi-band amateur radio equipment, but in recent years, there are also small handy receivers for consumer use.
Kenwoodthe RZ-1,Yaesu RadioFRG-965, standard (Marantz Japan) is the AX700 made by SHARP for overseasCATVI'm diverting the tuner for.SR001 (receiving frequency range: 25 - 1000MHz) has a local oscillation frequency of about 1 - 2GHz and 1stIFPersonal radioand used the receiving circuit of a personal radio.This receiver was capable of receiving long waves due to its circuit configuration, but it was masked because the performance could not be guaranteed.again,AORAR8200MK3, AR8600DESKTOP, etc. are on sale.
New system receiver
In the 2000s, the received signal was directly or after frequency conversionAnalog-digital conversion circuitinput to and perform arithmetic processing to obtain outputDSPThe method has also been put into practical use.a receiver like thissoftware receiver or software radio, AbbreviationSDR (Software Defined Radio).
Software receiver using a personal computer
The received signal captured by the antenna iscomputer OfSound cardAfter down-converting (frequency conversion) to the frequency that can be handled, input it to the sound card of the personal computer,softwareExperiments are being conducted on methods for performing channel selection and demodulation processing.
- ^ Kazumasa Ibata, "Nostalgia Series: The Story of Intermediate Frequency," CQ ham radio, April 2009, CQ Publishing, pp. 4-2009, 144.
- Transmitter / receiver(Transceiver)
- Set top box
- Ore radio
- Digital tuner
- playback receiver
- superheterodyne receiver
- direct conversion receiver