2.4G系统失控了?

endyzhou

前几天搜索了一下关于2.4G系统的信息,说是有人在模型车上用的2.4G模块,因为旁边有2.4G的无线话筒在使用,因此受到干扰而失控了,这是怎么回事呢?
据说2.4G系统发射的信号里都包含了一个特定的编码,以确定发射和接收之间的唯一性,咋还会受干扰呢?

simber

有谁买了FUTABA的2.4G遥控???!!1

hhlwuliao

一般的无线监控信号 传输也是2.4G :em17:

yylch

2.4G的传输更接近值线！！:em17: 我用过的无线AP是5点多G的对偏了信号就不成！！:em17: 也可能是天线的问题！！:loveliness: 根据理论传输上绕过障碍物的能力MHZ>GHZ的！！！

王立刚

:em24:

hzku

那么应该用什么好啊？2。4G都被干掉。还不如AM算了。。

A24

俺怀疑2.4G的可靠性，
无线话筒、无线监控、兰牙、无线网络等到处都有，还有过千瓦发射的微波炉也是2.4G，
兰牙、网络等受干扰一下没事，但模型失控一下就会出事了。

A24

又來一個2.4G的:em17:
http://bbs.5imx.com/bbs/viewthread.php?tid=156107

sagittarius

看看厂家理论:em15:

When talking about breakthroughs in Radio Control technology, quite a few things come immediately to mind. From the first wheel radio, first electronic speed controller, first computerized radio, and first synthesized radio, there have been a number of milestones. Spektrum´s DSM 2.4GHz Spread Spectrum Technology can now be added to this list, as this technology has forever changed the world of Radio Control.
Spektrum´s DSM (Digital Spectrum Modulation) technology is based on an optimized version of Direct Sequence Spread Spectrum. Spektrum´s DSM and DSM2 technologies provide users with pure digital control, providing an impenetrable radio link that´s immune to interference. Providing exceptional resolution and impressive response times, Spektrum Technology offers RC enthusiasts the accuracy, reliability, and locked in feel necessary to provide a totally connected and crystal-free RC experience.

sagittarius

While in development, Spektrum engineers sought to create a radio system that provided the end user with the same locked-in feel as a crystal-based radio while eliminating interference and glitching. Spektrum engineers sought to improve both the modeling experience and safety all at the same time. Just a few years ago, the thought of eliminating crystals and frequency control was not even on the horizon. Now, thanks to Spektrum Technology, this is not only a possibility, it´s a reality.

What makes Spektrum Technology a reality is a combination of two factors: the utilization of a frequency in the higher 2.4GHz frequency band and Direct Sequence DSM (Digital Spectrum Modulation) technology. Moving to a broadcast channel in the 2.4GHz range moves the broadcast signal up beyond the range of model generated noise from motors and vibrations. This is the first step in eliminating glitching and interference. From here, unlike current narrow band 27 and 75MHz systems, Spektrum´s Direct Sequence Spread Spectrum (or DSSS) spreads the data over a wide range of spectrum, which helps to minimize narrow band interference. The encoded information is broadcast to the receiver with its own Globally Unique Identification number (called GUID). The GUID code is what makes it virtually impossible for any other receiver to recognize the transmitted information.

sagittarius

Before you can operate a Spektrum-controlled car or plane, you must first bind the receiver to the transmitter or module. Binding is the process of having the receiver recognize the GUID code of the transmitter or module. Every receiver you plan on using with a particular Spektrum radio or module must go through this binding process to allow a receiver to only recognize one specific module.
Once a receiver is bound, collision avoidance software prevents a Spektrum-equipped radio from transmitting on a frequency that is already in use. All Direct Sequence Spread Spectrum systems are required by the FCC to incorporate active collision avoidance, making it impossible and illegal for more than one transmission on a single frequency.

sagittarius

There are two main broadcast methods that spread spectrum manufacturers can utilize. One format is called Frequency Hopping Spread Spectrum (FHSS). With an FHSS system, the transmitter transmits a narrow band signal and rapidly jumps from one frequency to the next, spending a few milliseconds on each frequency. Originally, Spektrum engineers started their development with FHSS-based systems because they were relatively easy and inexpensive to develop. However, they soon discovered that FHSS had several limitations that would prevent it from being the optimal solution for RC. While more difficult and costly to develop, our engineers began experimenting with Direct Sequence Spread Spectrum (DSSS) and optimized the modulation scheme to overcome critical response and re-link issues. DSSS systems transmit on a single selected frequency but on a very wide band. Only a small portion of that band is used for specially encoded information. In addition, DSSS offers an increase of processing gain for significant improvements in range. With years of development and testing, the DSSS modulation scheme was optimized for RC car and airplane use, and Spektrum´s DSM 2.4GHz Spread Spectrum Technology was born. DSSS provided engineers and hobbyists with the safety, security, and locked-in feeling that is necessary to maintain total and complete control in any vehicle or aircraft.

sagittarius

Above and beyond the basic features of DSM, there has been a technological breakthrough for both air and surface applications thanks to Spektrum. An updated version of DSM technology referred to as DSM2 (second generation protocol) makes it possible to fly any size model with the convenience, safety, and peace of mind of Spektrum. With DSM2, the total latency of your radio system has been greatly reduced, while the bit-rate has been increased. When combined, these improvements provide hobbyists with a faster and more locked-in feeling when compared to traditional 27MHz, 72MHz, or 75MHz radio systems. DSM2 also provided a new opportunity when separating the two receivers. By providing superior path diversity, the DSM2 receiver can now see a broader RF environment.

sagittarius

Spektrum´s AR7000 and AR6000 air receivers feature DuaLink technology. Each receiver features two separate receivers and antennas built into one device. The transmitter transmits on two frequencies simultaneously while the receiver receives and decodes both sets of information. Should one signal be blocked or corrupted or should one receiver malfunction in flight, the other frequency or receiver will take over. DuaLink offers the security of having two radios operating simultaneously on two separate frequencies. This is called dual path redundancy. Regardless of the plane´s orientation, you will still enjoy that same locked-in feeling to your model thanks to DuaLink.
ModelMatch prevents you from flying a model while the transmitter has the wrong model selected. When you bind your receiver to a Spektrum DX7 transmitter, the transmitter remembers the specific memory location that you´ve selected for that aircraft´s profile. In the event that you try to fly a specific model with the wrong model memory selected, the transmitter will not broadcast your transmitter inputs until you change to the proper model memory. Since it is transmitter based, ModelMatch works with all Spektrum air receivers when combined with a DX7 Transmitter.
Finally, there´s ServoSync. With ServoSync, the DX7 transmitter´s signal is re-sequenced to best suit the type of mixing you select. This comes in handy in a number of applications, such as if you have a dual elevator on your big Extra or a 3-servo CCPM setup on your heli, ServoSync will see to it that those servos working together receive their impulses together. The result is more synchronized servo movement that translates into an undeniable, locked-in feel when you fly.

sagittarius

术语表

Collision Avoidance - A protocol which eliminates the possibility of more than one Direct Sequence Spread Spectrum system from transmitting on the same frequency.

DSM - Digital Spectrum Modulation; DSM is the 2.4GHz technology that makes Spektrum possible.

DSM2 - The second generation of Digital Spread Modulation. DSM2 offers significantly reduced latency and a faster response time than any brand of 27, 75, or 72MHz PCM system.

DSSS - Direct Sequence Spread Spectrum. DSSS broadcasts on the 2.4GHz frequency band and generates a wide signal on a single frequency.

Dual Link - Spektrum designed architecture that provides increased RF link diversity. This combined with DSM2 is what makes the full range system possible.

GUID - Globally Unique Identification Code. Each individual module or radio is factory programmed with its own unique serial code. In the binding process, the receiver is programmed to only recognize the GUID code of one specific radio or module.

Servo Sync - A resequencing of the data the DX7 transmits based on the type of mixing you select. This feature helps to sync control services that are connected (such as a swash plate on a helicopter) and is used in radios that have many channels.

sagittarius

官方FAQ

What is DSM?
DSM or Digital Spectrum Modulation is Spektrum's proprietary method of implementing 2.4GHz spread spectrum technology for the R/C industry. DSM divides the 2.4Ghz band into 80 individual channels (frequencies) and incorporates direct sequence spread spectrum with an imbedded GUID (Globally Unique Identifier) code. DSM has been painstakingly optimized by our engineers for R/C surface and aircraft use, offering the most robust RF link in the industry.

sagittarius

What happens if the band is full (80 users for surface or 40 users for aircraft) and I turn on my transmitter?
In the unlikely event that all channels are occupied, the next transmitter will scan the band indefinitely until open channels are available. The transmitter will then acquire the channel(s) and begin transmitting. Only then will the system connect.

sagittarius

What happens if two transmitters are on the same frequency?

To be FCC legal, all 2.4Ghz devices must incorporate a collision avoidance system that prevents the system from transmitting on an already occupied frequency. The chance of two transmitters occupying the same frequency is highly unlikely. If two transmitters should somehow end up on the same frequency, other safeguards, such as the GUID and proprietary time base coding, will prevent interference. Of course, with the aircraft system, the transmitter is transmitting on two frequencies simultaneously. The odds of two transmitters transmitting on the same two frequencies is even, more unlikely but again, should this happen, other safe guards will prevent interference.

sagittarius

这个FAQ完全针对楼主问题

We have several Wi Fi systems and Wireless Routers running at our indoor track. How will this effect the Spektrum system?

These systems typically operate on the 2.4GHz band and, while they do occupy some of the bandwidth (channels), they must abide by FCC rules and incorporate collision avoidance. So while these systems can reduce the number of potential operators (there are 79 possible), the systems will operate harmoniously and not cause each other interference.

endyzhou

:em17: 看不太懂哈...:em20: :em20: