Duplexing wireless series transmission scheme of the one-chip computer

The maximum coverage of the RSR232 serial port transport protocol is 10 meters, which poses significant challenges for remote transmission control. To address this issue, a design has been developed utilizing ultra-high frequency (above 300 MHz) for transmission. This design can effectively meet general transmission and control requirements and is applicable in fields such as computer and microcontroller dispatch control. In scenarios demanding a lower bit error rate, the implementation of CRC codes is recommended. Common modulation techniques include amplitude modulation, frequency modulation, and phase modulation, while digital modulation methods such as frequency shift keying and amplitude shift keying are also prevalent. The On-Off Keying (OOK) modulation mode, despite its limitations, is straightforward to implement and operates reliably, making it widely used in wireless security applications, including car and motorcycle alarms, warehouse gates, and home security systems.

The circuit diagram referenced utilizes an LC resonator; however, this configuration is significantly affected by distribution parameters, leading to stability issues and complexity in debugging, resulting in limited current use. New high-stability devices such as surface acoustic wave (SAW) filters and ceramic resonators have emerged. SAW filters are extensively applied in high-frequency telecommunications due to their compact size, lightweight nature, high center frequency capabilities, and relatively wide bandwidth. These filters exhibit ideal rectangular frequency-selecting characteristics and can be fabricated using methods akin to integrated circuit technology, resulting in lower production costs and greater design flexibility. Compared to traditional circuits, SAW resonators offer a simpler alternative. The typical transmitter circuit, utilizing a SAW device, operates reliably and maintains consistent emission frequencies even with variations in aerial placement, achieving effective transmission distances exceeding 200 meters.

Ceramic filters, formed through the piezoelectric effects of materials such as lead zirconate titanate (PbZrTiO3), are also prevalent. These filters are easier to manufacture compared to other types, allowing for various shapes suitable for miniaturization. They possess superior moisture resistance and heat resistance, making them less susceptible to environmental factors. While the quality factor (QL) of ceramic filters is typically in the hundreds and higher than that of LC filters, their vibrational stability is lower than that of quartz crystal filters. Consequently, the passband is not as narrow as that of quartz crystal filters, resulting in reduced selectivity. Nonetheless, ceramic filters find extensive applications in receivers and other instruments.

In terms of receiver circuits, ultra-audion circuits and superheterodyne circuits are commonly used. The ultra-audion circuit is cost-effective with low power consumption, potentially as low as 100 µA, and offers good sensitivity and stability. However, its anti-jamming capabilities are limited. The superheterodyne receiver, characterized by first-class frequency mixing and two-stage amplification, presents better stability and selectivity compared to the ultra-audion circuit. Overall, the choice of circuit design depends on the specific application requirements, balancing factors such as cost, power consumption, sensitivity, and selectivity.We know, the maximum coverage of RSR232 serial port Transport Protocol is 10M, and the wire transmission, this needs remote transmission control to bring very great inconvenience for some. According to the needs of subject, we have designed one kind because of ultrahigh frequency above 300M Wireless for transmission method, connect result of

uses actual with fine, can general transmission and controllings satisfied, can be used in computer, one-chip computer dispatch control field. Require higher occasion as to the bit error rate, propose adopting CRC code to reduce the bit error rate.

There are amplitude modulation, frequency modulation and phase modulation in the common simulation modulation mode, the common digital modulation method has frequency shift keying, amplitude shift keying, etc. OOK modulation mode although the characteristic is discrepancy, it is easy for the circuit to realize briefly, have steady operation, used in wireless guarding against theft and security personnel field extensively.

Such as the car, motorcycle alarm equipment, the warehouse gate, and in family`s security system, mostly use this type circuit. See Fig. 1 What the Er early projector used is LC resonator, but this circuit is influenced by distribution parameter too big, creep is comparatively serious, stability is not good, and it is complicated to debug, has not basically used now.

Fetch and treat new device of high stability, a common one have saw filters, ceramic resonator, etc. It is very extensive to apply the saw filter in high-frequency telecommunications. This kind of electric-wave filter is small, light, what center frequency can be made is very high, the relative bandwidth is relatively wide, have frequency-selecting characteristic of the rectangular coefficient of ideals. And this kind of electric-wave filter can adopt the one-sided preparation method the same as integrated circuit technology, manufacture simple, low cost, it value plastic property and design flexibilities to be high, quantity production and process, it is the extensive electric-wave filter day by day of a kind of application.

Compared with circuit of Jingzhen, the resonator of the saw is much simpler. The circuit of Fig. 1 is a common transmitter circuit, because of using the saw device, the circuit work is very steady, even hold the other placements of or circuit of the aerial, saw device in hand, emission frequency will not drift about. The effective transmission distance of this circuit is reachable more than 200 meters. The electric-wave filter utilizing some ceramic piezo effects to form, is called the ceramic filter. The commonly used ceramic filter is by the Titanox L [Pb ZrTiO3 ]Make. Compared with other electric-wave filters, whom electric-wave filter this make simple technological process and can be convenient bake over a slow fire and make various shapes, suitable for the miniaturization of the electric-wave filter; And the moisture-resistant characteristic of heat resistance is better, are seldom influenced by external world.

Its QL value is usually several hundred, higher than that of LC filter, but vibratory and lower than the quartz crystal. So the pass-band is not so narrow as the quartz crystal while making electric-wave filter, selectivity is worse than quartz crystal filter.

The ceramic filter is widely used in receiver and other instruments at present. There are ultra-audion circuit and superheterodyne circuit, the low cost of the ultra-audion circuit in the common receiving circuit, the power consumption can be even as small as about 100uA, adjust good superregeneration circuit sensitivity and first grade high and put, first grade is shaken, the superheterodyne receiver put in first class frequency mixing and two-stage is similar. But job stability and person who choose of ultra-audion circuit bad, so antijamming capability too very bad.

Degree of sensitivity and selectivity of the 🔗 External reference