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When we think of "manufacturing," we think of the manufacturing industry that flourished during the high-growth period and highly skilled workers, but I worked for an electronics manufacturer (low-voltage electrical appliance manufacturer) from 1970 to 2008. I was born during the so-called first baby boom, and I'm part of the baby boomer generation. My first experience was designing and developing color TVs, and at the time, the circuit group was divided into the tuner IF block, signal processing (luminance signal chroma) block, deflection (vertical and horizontal) block, and power supply audio block. I remember being in charge of the power supply audio for a new product while being supervised by my senior in the signal processing block. Since then, I have been engaged in "manufacturing" for 38 years, and although I think that the system and approach are quite different between then and now, I will briefly talk about "manufacturing" from my experience. In my case, most of my work is in the video equipment/audio equipment category, so I have no experience with wireless equipment. To create a single product, organizations with various specialized fields are involved, and basically the entire business division is involved. The general flow of creating a product is as follows:
The biggest factor is whether or not the target cost is achieved. ・Parts and materials costs ・Labor costs (direct costs) ・Overhead ・Other patent costs etc. ・Mold cost Mold costs include molds
for general parts (panel/cabinet/electrical/mechanical parts), and
depending on the item, mechanical parts may also be required. If you
develop new semiconductors such as original custom LSi to differentiate
your products, this alone can amount to hundreds of millions of yen,
which is a huge expense. Akizuki LCD ￥800 Amazon-LCD ￥210 Operating Status
【Product Development Process】 During the development process, we first make a prototype by hand and check the functionality and specifications at each step.
I think microcomputers were introduced to audio/visual equipment around 1980, and I remember that home appliances (cooking appliances, etc.) were the first consumer electronics products to be introduced with them. At that time, most products were equipped with microcomputers, but the CPU itself did not have a built-in flash ROM like today's microcomputers, and developed software was mass-produced as a mask ROM, just like making a mold. Therefore, if a software bug was discovered after mass production started, it was somehow dealt with by hardware countermeasure processing. If the hardware was still not able to be dealt with, the mask ROM was remade with the bug-fixed software, and the cost of the mask ROM was spent on W. After that, one-time ROM type CPUs appeared, and I remember that one-time CPUs were used only for the first lot, and the bugs were extracted and then converted to mask ROM. After that, products such as digital home appliances and mobile phones required CPUs with larger systems, and mask CPUs and one-time CPUs could no longer be used, so CPUs with built-in flash ROM appeared to meet these needs. This has made it possible to deal with bugs and upgrades. For products with tuners, such as televisions and digital recorders, or products connected to a network, the manufacturer can automatically upgrade the product without the end user having to do anything. For other products, bugs and upgrades are handled by recalls, and software is rewritten at each base (service station). When a new product is released, online word-of-mouth information appears immediately. If you enter the manufacturer and model number, you will be checked daily to see what is good and bad, what constitutes a bug, etc. Conversely, there are cases where manufacturers use this information to upgrade the product. 【Homemade amateur radio equipment】
Even if you make your own radio, to make equipment that is in line with the times, you need not only analog (AF/RF) technology, but also digital processing, FPGA (Field Programmable Gate Array)/DSP/CPU (software) technology, which is not easy for us baby boomer radio operators. However, if you want to make your own equipment, it is sold by manufacturers, so you can solve the problem by buying it. Moreover, the baby boomer generation has a lot of money, so it is easy to handle. The appeal of making your own equipment is that it is equipment that you cannot buy even if you want to, and there is only one in the world. Amateur radio operators have various aspirations, and now I am not interested in DX or card collecting, and I prefer to ragchew (talk over the radio with radio operators with similar aspirations) with other radio operators in the same situation, and I only operate in SSB mode. Even though the communication signals of today's radios are analog, most of the processing inside the device is digital. In other devices, such as audio/visual devices, the signals themselves have changed from analog to digital, which has revolutionized both manufacturers and users. Nowadays, flat-panel televisions are being introduced with large 50-100 inch screens, and the transition to 4K/8K is on the way. Even with this hardware, television signals will not be able to output beautiful images with 4.5M band analog signals forever. As for computers, smaller and more powerful devices than those installed in the large computer centers of the past have spread to homes for personal use, and there has been a huge change. However, what has changed in the world of amateur radio since 50 years ago? The frequency stability has improved and the stability of the equipment has increased, but for users (ragchewers), there has been no big change. We still communicate with SSB-3KHz analog signals, accompanied by QSB/noise/jamming. From the manufacturer's perspective, digital processing has made it possible to eliminate adjustments and stabilize the equipment, improving productivity. That's why even old people like us can still make our own things; in other words, the input and output signals of wireless devices have not changed since ancient times, so I think that old technology is still applicable today. I once made a TV as an amateur, but even if I had the deep technical knowledge from back then, it would no longer be applicable.
It has long been said that a receiver only needs to cover the three S's (3S). ① Sensitivity - --How weak a signal can be detected ② Selectivity---To what extent can signals from frequency zones other than the receiving band (3KHz for SSB) be rejected? ③ Stability------Frequency stability, especially in the case of SSB If you connect the antenna and the speaker directly, you might get a sound. If the signal is strong, it might sound even if you can't understand it, but it won't satisfy 3S. For the SSB group, fidelity is required in addition to 3S. Recently, there is a group called Hi-Fi-SSB, and some station managers are quite picky, not just saying that it's fine if they can hear it/understand it. Digital equalizer technology allows you to freely set the tone to a considerable extent, but the SSB group is concerned not with zones like this, but with the type and characteristics of the filter. In other words, filters have amplitude and phase characteristics, both of which affect the tone. Manufacturers use digital processing to minimize phase distortion to create filters, and prioritize 3S selectivity, resulting in ideal amplitude characteristics. It is these amplitude characteristics, not the in-band characteristics but the out-of-band characteristics, that affect the tone. As a result, selectivity and fidelity are contradictory items, and manufacturers need to cater to a wide variety of preferences because the end users are numerous and unspecified, but when you build your own equipment, you are the only one target, so you can build equipment that suits your preferences. Here, I will briefly touch on the dynamic range, which you should also take into consideration when building your own equipment. The dynamic range is Whether it is a receiver or a transmitter, the output and input are audio signals, but the definition of dynamic range is the range of sounds that can be reproduced from extremely faint to extremely powerful. The softest to loudest sounds of an orchestra are said to be 120 dB, but to reproduce such a dynamic range sound without disturbing others (neighbors, other family members), a considerable amount of soundproofing is required. The noise level of an ordinary house is said to be 30 to 40 dB, and in a slightly noisy house it is about 50 dB, so to reproduce an orchestra perfectly, a soundproofing device of about 70 dB is required. Compression technology can be used to transmit a large dynamic range signal through a small pipe, but how much dynamic range does an amateur radio device actually need? Apart from a special operating room, if you consider a room given to a father in an ordinary family, if you can secure a range of 60 dB even if you are very concerned about background noise and make it quiet by removing the fan, it will be fully practical. Even if you allow for a margin, 80 dB is over-specified for the device. At the very least, there is no need to set the dynamic range to more than the room you are using it in can reproduce. There are means of headphones that can experience a wide D-range, but there is a risk of hearing loss, so I use them at a low level except in special cases. When considering what parts to use when building your own radio equipment, especially what devices to use, nowadays, even if there is no store nearby that can supply them, you can get a wide range of parts online. However, when it comes to the types of parts, device manufacturers are reluctant to develop devices that are specially designed for amateur radio equipment due to demand. Many new dedicated parts are appearing for consumer devices such as mobile phones and televisions, but the problem is that most of these parts are surface-mounted parts, and are not SOP shaped, but more micro shaped parts, so the options for DIYers are limited. The ICs for rose-shaped devices (MC1496/UPC1037H/AN612), which have long been used as ICs for radio equipment, were developed for color modulation and demodulation in color TVs, and were consumed in huge numbers for consumer devices. Although they are now available for mobile phones, they cannot be used to build HF radios. In this way, you have no choice but to find ICs that were developed for consumer devices in the past and use them for your own construction. On the other hand, in this case, it is convenient to have parts with a SIP/DIP shape. They are not mass-produced, and have no relation to delivery, so they only make one or a few. Of course, devices developed 30 to 40 years ago are not currently produced, but if you search online, you can find them somewhere in the world. In current homemade products, it depends on the expertise of each station manager, but for the baby boomer generation, signals from input to output are handled as 100% analog signals, and the surrounding control processing required to control these (display/SW/DDS, etc.) is controlled digitally if possible, which allows you to make your own products with the operability/ease of viewing, etc. you prefer. 【Receiver】 When building a receiver, first decide on the specifications that match your preferences. In my case, I am a ragchewer and do not use CW or DX communication, so the priority items for the receiver are: ［1］＝、Stability ［2］＝、 Fidelity［3］＝、Selectivity ［4］＝sensitivity The order is as follows. 【1】Maximum Allowable Input Level This is to check the maximum signal input from the antenna in your receiving environment. If you use a high-gain antenna such as a beam antenna, the reception level will be higher, so you need to increase the tolerance. Connect the antenna directly to the spectrum analyzer input and investigate the maximum input signal within the receiving band. Since it varies depending on the time of day/season, obtain the maximum value. It cannot be made too large due to the relationship with sensitivity/dynamic range, so it is desirable to design this item in conjunction with the attenuator function. I use a maximum input of -20 dBm and a 20 dB ATT. Since I set the S meter to S9=-73 dBm, I linearly amplify it up to S9+58 dB, and use the ATT for anything above that, so that it can handle up to -20 dBm+20 dB=0 dBm (S9+78 dB). 【2】Maximum Sensitivity I don't know the exact expression of sensitivity for amateur receivers, but there is a maximum sensitivity and a practical sensitivity, and the antenna input signal value at the point where S/N = 30 dB at the AF output when the signal at the antenna terminal is lowered is called the practical sensitivity, and is expressed in dBu or dBm. The antenna input signal value at the point where S/N = 10 dB at the AF output is called the maximum sensitivity. The target specification is to obtain a practical sensitivity of -110 dBm. 【3】Radio wave type Most of the radios manufactured by manufacturers are all-mode radios, but I prefer only SSB/ISB modes, and nothing else is needed. However, most radios except FM can be detected, and by selecting a filter, you can complete the detection mode. Most radio types are amplitude modulation, so SSTV/data/fax can be used in conjunction with a computer. SSB mode is generally understood, but ISB mode is not often heard of. Independence Side Band: This transmits LSB/USB signals simultaneously. If the content of the modulated signal of each sideband wave is the same signal, it is called the WSB (double-sided band) method, but ISB is a radio type in which the modulation content of LSB and USB is different. The modulated signal can be either audio or data. However, most of the stations we know transmit stereo audio. The LSB side is modulated as L-CH and the USB side is modulated as R-CH. This radio type is called 'B8W'. It is designed to demodulate the above radio wave types. 【4】Transformation Configuration There are various types of direct conversion, single conversion, double conversion, and triple conversion. In the case of receivers, although there is a preference, it is difficult to decide how much consideration to make in the specifications because the radio waves received are from an unspecified number of amateur stations. In the case of transmitters, although they are emitted to an unspecified number of stations, the emitted radio waves are only emitted to one station to communicate with. Basically, it is desirable to make the path through which the signal passes as short as possible (fewer parts), but each configuration has its advantages and disadvantages. A direct conversion path can be constructed with the shortest and fewest parts, but it is difficult to set the sensitivity and maximum allowable input value, and it is not easy to eliminate unnecessary radio waves. In the case of direct, from my experience of building it myself, the antenna circuit (TOP) is not a bandpass filter for each band, but is premised on a method of tracking the receiving frequency using a u-tuning method. To obtain sensitivity, an RF amplifier is inserted, but after that it is detected. If the input is a BPF, strong radio waves from the continent are input to the detection circuit even if the receiving frequency is far away, even at night, and spurious signals are generated due to nonlinear distortion. Therefore, the gain of the RF amplifier cannot be set large. The next idea is to install an AGC circuit on the RF and control the input signal to the detection circuit, but the receiver's AGC circuit should basically be fed back with the reception band (3KHz for SSB), otherwise the AGC will be suppressed by the strong radio waves from the continent. Therefore, it would be ideal to have a narrowband tuning circuit at the input, make it an AGC-RF amplifier, and apply AGC even to the AF after detection, with a total AGC of 20dB for RF and 40dB for AF. It can compensate for the weaknesses of single conversion direct conversion. In other words, by providing one IF stage, it is easier to design the RF amplifier. By ensuring a large gain with the IF amplifier and selecting the desired filter band, narrow-band AGC can be applied, and it is also easier to ensure sensitivity. However, image problems can occur depending on the selection of IF frequency. To eliminate the image, set IF = 9MHz to 10MHz, and this can be done in conjunction with the TOP BPF, but the lower the frequency in the final detection circuit, the easier and more stable the circuit can be. Generally, when considering the availability of filters, etc., one would want to select 455KHz, but at 455KHz, it is difficult to avoid the image due to the TOP BPF characteristics. Therefore, some ingenuity such as adopting a special rejection method is required. Although the double conversion path length is long, it is easy to achieve both sensitivity and selectivity. After all, this is probably the basic configuration of a receiver. 【5】Filter Types
【In the past, most transmitters and receivers were filter type, but
nowadays, SSB signal generation/recovery is digitally processed and can
process low frequencies up to 3KHz. However, when it comes to analog
processing, filters are essential. When transmitting human voice, there
is a 3KHz limit on the higher end, but no particular limit on the lower
end. Generally, the first formant of a man is around 100Hz, and to
transmit this faithfully, 50Hz transmission is required electrically. In
filter type, I have tried to transmit low frequencies by moving the
carrier point inside the filter, but in this case, no matter how good
the shape factor of the filter, the low frequency components on the
opposite side will be sacrificed. Therefore, homemade people use the PSN
(Phase Shift Network) method to modulate and demodulate the voice
signal, and to prioritize fidelity, the carrier point is set far enough
inside the filter so that the opposite side voice is not output.
Manufacturers cannot mass-produce radios with this configuration
(productivity is poor, individual differences are difficult to absorb,
and the unit price cannot be obtained), so it is perfect for DIYers. It
is possible to spend a lot of time on each unit and design it using
expensive parts. 【６】AF Output Power 1W is enough for the speaker output of a radio, and in most cases a device with around 5W output is used. A headphone amplifier is also installed, and this amplifier can be fully utilized with a high-output op-amp. Also, since the playback sound of the receiver is received by an unspecified number of people, it is convenient to add a high-cut tone and a low-cut tone VR. 【7】Various functions It depends on how you use it as a receiver, but items that require special hardware as additional functions will be considered according to priority, but functions that can be processed with software alone, such as the transceive function, RIT function, and IF-Shift function, can be easily processed, but keys (operation buttons) are required. I use a single receiver and process the received signal, waveform monitor, and air monitor audio signal during transmission, all with one receiver, so the minimum required functions are 1）Transceiver Function→Frequency/mode/band can be linked to the transmitter (ON/OFF) 2）Transmission and reception control function →・When transmitting, it is received as an air monitor audio signal, so the input ATT is automatically set to ON. Also, a switch is provided to turn the speaker line ON/OFF, allowing feedback checks to be performed. ・When switching from transmission to reception, if your air monitor signal is received at S9+30-40dB and the other station's signal is weak, you may not be able to see the other station's head due to the AGC recovery time. Therefore, the AGC is immediately discharged at the moment (several tens of ms) when the switch changes from TX to RX, and the gain is switched to maximum. 3）EXTEND function →This is because it is easier to understand your own air monitor audio signal if you check it over as wide a window as possible, so you check it over the widest possible band on the receiver, and set up a switch so that you can also check it over the normal reception band. 4） IF-Shift function →By shifting up and down, you can control the low and high frequency components of the audio signal, and also reject adjacent stations. 5） RIT function →Although this function is becoming unnecessary these days, it is sometimes necessary when communicating on Hi-Band.
【Transmitter】 Unlike a receiver, most communication is one-to-one, so you only need to set it up to your own preferences. This may be the reason why receivers are generally said to be more difficult to set up than transmitters. First, you set the gain distribution for each block. 【1】Balanced Modulator The maximum input amplitude of the balanced modulator is determined by the device used for the balanced modulator that generates the SSB signal from the audio signal. The only analog modulators that can be used here are old I/Q modulation/demodulation ICs, switch-type devices, or devices from decades ago. The maximum allowable input is determined by the level of distortion that can be tolerated. Since exciter-level transmitters are not high-power (linear amplifiers are not included), the target values for all items including distortion (carrier/reverse side, etc.) are Low-Band <-60dB, Hi-Band <-50dB, and the distortion of the balanced modulator output can be secured at about -70dB. For I/Q modulation ICs, even the highest allowable level is around 100mV, and there are some switch-type devices that can tolerate up to 2Vpp input. In any case, the device used here determines the overall gain distribution, and the shape of the carrier wave also changes, affecting the overall result. 【2】Audio Signal Processing Several functional blocks are required for the audio signal up to the balanced modulator that generates the SSB signal. A microphone amplifier, 2TONE signal, external input signal, SW circuit to switch between them, limiting amplifier circuit, and AF filter are required in some cases. The dynamic range of the receiver is covered by AGC, but the dynamic range of the transmitter is processed by the limiting amplifier and ALC. The important thing here is how many Vpp the output of the limiting amplifier is set to. In my homemade work, I set it to 1 Vpp because I installed a 6 dB amplifier in front of the balanced modulator. The (input) circuit up to that point is determined depending on how much the limit width is to be supported. In other words, if you need to apply a 20 dB limit, you need an input = 10 Vpp range, and if you need to apply a 40 dB limit, you need an input = 100 Vpp range. Next, for PSN modulation that does not depend on the IF filter, an HPF/LPF filter is required in the AF. The insertion position of this filter can be either before or after the limiting amplifier, which is the same as the AGC principle of the receiver. In other words, it is ideal to control the gain for signals within the passband. In that case, the correct answer is to place both the HPF and the LPF at the front. If they are placed at the back, when the microphone picks up frequency components that are not emitted from the antenna (high-frequency sounds above 3KHz and low-frequency wind noise), they are input to the limiting amplifier, and the signal is limited by frequency components that are not actually emitted. However, if they are placed at the front, a HPF/LPF with a fairly large dynamic range is required to provide the limiting function. If they are placed at the back, they will not handle signals above 1Vpp, so various types of filters are possible. A filter that is fixed at around 2 positions can be designed with a sufficient dynamic range, but flexible support is difficult unless the configuration is complex.
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