The function of the PPM encoder is to encode the multi-channel PWM signal output by the receiver into a PPM composite signal output (up to 8 channels of PWM input) to connect the supported flight controllers in a single line.
PWM and PPM Introduction
PWM stands for Pulse Width Modulation and PPM stands for Pulse Position Modulation. PWM is a technique used to relay data in the form of a varying pulse width. In PPM (Pulse Position Modulation) the analogue sample values determine the position of a narrow pulse relative to the clocking time.
Advantages
The advantages of pulse position modulation include the following.
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PPM has the most power efficiency as compared to other modulations.
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This modulation has less stable amplitude noise interference.
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This modulation separates the signal easily from a noisy signal.
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It needs less power as compared to PAM.
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Separation of signal & noise is extremely simple
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It has constant transmitted power output.
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It needs extremely less power as compared to PAM & PDM because of amplitude & short duration pulse.
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Easy noise removal in this type of modulation.
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Power utilization is also extremely low as compared to other modulations because of stable pulse amplitude & width.
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PPM communicates only simple commands from a Tx to an Rx, so it is frequently used in lightweight applications because of its low system necessities.
Disadvantages
The disadvantages of pulse position modulation include the following.
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PPM is very complex.
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It needs more bandwidth for transmission as compared to PAM.
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It is extremely sensitive to multi-pathway interference like echoing that can disturb a transmission by changing the difference in arrival times of every signal.
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Synchronization is necessary between transmitter & receiver which is not feasible each time & we require a dedicated channel for it.
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Special devices are required for this kind of modulation.
Applications
The applications of pulse position modulation include the following.
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The PPM is mainly used in telecommunication systems & air traffic control systems.
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This modulation is used in radio control, an optical communication system & military applications.
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This technique is used in planes, remote-controlled cars, trains, etc.
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PPM is used in noncoherent detection wherever a receiver does not require any
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It is used in RF (radio frequency) communication.
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It is also utilized in high-frequency, contactless smart cards, radio frequency ID tags, etc.
關於PPM編碼器
PPM編碼器允許將多達8個PWM(脈衝寬度調製)訊號編碼為一個PPM(脈衝位置調製)訊號。
PPM編碼器的功能是將接收機輸出的多路PWM訊號編碼為PPM複合訊號輸出(最多8路PWM輸入)，以單線連線所支援的飛行控制器。
PWM和PPM簡介
PWM代表脈衝寬度調製，PPM代表脈衝位置調製。PWM是一種用於以變化脈衝寬度的形式傳遞資料的技術。在PPM(脈衝位置調製)中，模擬取樣值確定相對於時鐘時間的窄脈衝的位置。
優勢
脈衝位置調製的優點包括以下方面。
與其他調製相比，PPM具有最高的電源效率。
這種調製具有較小的穩定振幅噪聲干擾。
這種調製方式可以很容易地將訊號從噪聲訊號中分離出來。
與PAM相比，它需要更少的能量。
訊號和噪聲的分離非常簡單
它具有恆定的傳輸功率輸出。
與PAM和PDM相比，它需要的功率非常少，因為它的振幅和脈衝持續時間短。
在這種型別的調製中容易去除噪聲。
與其他調製相比，功率利用率也非常低，因為穩定的脈衝振幅和寬度。
PPM僅從Tx向Rx通訊簡單的命令，因此由於它對系統的需求較低，因此經常用於輕量級應用程式。
缺點
脈衝位置調製的缺點包括以下幾個方面。
PPM非常複雜。
與PAM相比，它需要更多的頻寬來傳輸。
它對回聲等多路徑干擾極其敏感，回聲可以透過改變每個訊號到達時間的差異來干擾傳輸。
發射機和接收機之間的同步是必要的，但不是每次都可行，我們需要一個專用的通道。
這種調製需要特殊的裝置。
應用程式
脈衝位置調製的應用包括以下幾個方面。
PPM主要用於電信系統和空中交通管制系統。
這種調製被用於無線電控制，光通訊系統和軍事應用。
這項技術用於飛機、遙控汽車、火車等。
PPM用於非相干檢測，接收機不需要任何鎖相環或鎖相環來跟蹤載波的相位。
它用於RF(射頻)通訊。
它還用於高頻，非接觸式智慧卡，射頻ID標籤等。