1. 首先是关于MMDVM结构的问题，不知道理解的对不对，我的理解是： > 计算机运行的MMDVM Host负责连接服务器，将数据通过串口发给载有MMDVM固件的MCU→MMDVM固件利用MCU内置的D/A转换器产生基带信号→基带信号通过9600音频接口发送到电台或者ADF7021射频模块→发射到空中，反之亦然 2. 如果是这样的话，ADF7021看数据表好像是只支持2/3/4FSK？这样的话MCU产生的基带信号要为ADF7021单独适配吗，还是说它接收到的信号和通过9600接口连接的车台收到同样的信号？ 3. 如果是同样信号的话，也就是说可以任意替换射频模块？我看到网站说ADF7021不推荐用于新设计了。

您的意思是可以走9600 的fm车台进行通讯？

@"BH6ABO"#p18155 中继板应该就是这么做的，之前发现在早期有用Arduino Due制作中继板的方案，看起来只是加了个放大器，信号应该还是由单片机产生的。而且看起来现在常见的使用STM32的中继板应该也是类似的，没看到上面有其他比较复杂的元件。不过在查看热点常用的ADF7021射频模块的时候发现它是内置FSK调制解调器的，因此感觉“热点板固件”和“原始固件以及中继板固件”可能不一样，并不是由单片机生成信号，而是通过射频模块内置FSK调制解调器来产生信号的。不过问题在于我其实不太会读源码，想着如果能问到的话，要比自己考证快一些。

好吧，最后发现ADF7021热点固件和普通固件确实不同，应该是不能混用。还发现了个有意思的东西，ADF7021虽然不推荐新设计，但是新出的ADRV9002射频模块貌似挺厉害的，双守双发，支持时隙，还带M4核，粗略看来仅这一片芯片就能取代一（甚至二？）整块热点板。

Please provide solutions to the following common problems related to self-made hot spots.

BloodBlade

First, there's the issue of the MMDVM structure. I'm not sure if my understanding is correct, but here's what I understand:

The MMDVM Host, running on the computer, is responsible for connecting to the server and transmitting data via a serial port to the MCU with the MMDVM firmware. The MMDVM firmware uses the D/A converter built into the MCU to generate a baseband signal. This baseband signal is then sent to the radio or ADF7021 RF module via the 9600 audio interface. Finally, it's transmitted wirelessly. The reverse process also occurs when receiving signals.

If that's the case, according to the ADF7021 datasheet, it only supports 2/3/4 FSK? If so, does the MCU-generated baseband signal need to be specifically adapted for the ADF7021, or does it receive the same signal as the vehicle connected via the 9600 interface?
If the signal is the same, meaning that the RF module can be replaced arbitrarily, I saw on the website that ADF7021 is not recommended for new designs.

BH6ABO

So, you mean that I can communicate with a vehicle using a 9600 FM radio?

BloodBlade

BH6ABO The repeater board should be constructed in this way. Previously, I saw a solution using Arduino Due to create a repeater board, which appears to simply add an amplifier, and the signal is still generated by the microcontroller. Furthermore, it seems that the common use of STM32-based repeater boards are also similar, without seeing other more complex components on top.

However, when I was examining the commonly used ADF7021 RF module for "hotspot boards," I discovered that it includes a built-in FSK modulator/demodulator. This led me to believe that the firmware for the "hotspot board" and the "original firmware as well as repeater board firmware" might be different, because they do not generate signals using a microcontroller, but instead use the built-in FSK modulator/demodulator of the RF module to produce the signal.

However, the problem is that I'm not very good at reading source code, and I thought it would be faster to ask if I could get answers.

BloodBlade

Okay, I finally discovered that the ADF7021 firmware for hotspots and the regular firmware are actually different, and they should not be used together.

I also found something interesting: while the ADF7021 is not recommended for new designs, the recently released ADRV9002 RF module seems to be quite powerful. It supports dual-transmit and dual-receive, has a slot clock, and even includes an M4 core. Based on this alone, it appears that just one chip could replace an entire hotspot board (even two?).

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