照理说如果选窄带，能量更集中，能传的更远，但我试了下如果设置窄带的话无法打开中继。并且各大手台的默认模式是宽带，那应该大家都在用宽带吧？为什么手台不默认设置为窄带模式呢？还有几个问题：一般什么时候会用到窄带？如果两个手台一个设置窄带一个设置宽带可以正常直频通联吗？设置窄带对扩大通联范围的作用有多大？音质会有损失吗（我知道用窄带音量会变小，但是不知道会不会降低音质）？

请看A证题库 0225. 对于给定的FM发射设备，决定其射频输出信号实际占用带宽的因素是： [LK0786] 所传输信号的最高频率越高、幅度越大，射频输出占用带宽越宽 0227. 用设置在WFM方式的对讲机接收NFM信号，其效果为： [LK0789] 可以正常听到信号，但声音比较小 0226. 用设置在NFM方式的对讲机接收WFM信号，其效果为： [LK0788] 可以听到信号，但当调制信号幅度较大、音调较高时会发生明显非线性失真按理来说应该能叫开中继啊是不是其他的设置错了 NFM的调频间隔为12.5KHZ，WFM的频率间隔为250khz 手台的25k和12.5k都是NFM吧应该是调步进的对通联的作用就别想了 FM天生不适合打DX 功率全在载波上

按理说，，窄带能量跟集中，通联范围更远，，，你可以试试两个手台在宽带时通联的极限距离，然后两台都调到窄带模式，，通联距离是不是会增加很多?

1. 默认使用25kHz带宽应该是为了兼容市面上的其他设备。 2. 一般是商业用户为了节省频谱才使用窄带。 3. 理想状态模拟信号不会有损失，但实际上人耳分辨率有限，音量也不会完全无损的放大，因此音量降低可以认为就是音质降低。更别说另一方听到的音频幅度会直接被砍断产生失真。 4. 按[这篇文章](https://radiofreeq.wordpress.com/2016/06/21/fm-versus-nfm-for-best-radio-communications/)的说法，窄带模式信噪比更差，距离实际上是降低了的（大约30%）。当然，信噪比差也意味着音质要差，和上一条相同。不过FM模式本来也不是很适合DX。

@"BG2GFC"#p33271 宽窄毕竟是相对的，有些厂家就会将25kHz称为WFM，12.5kHz称为NFM。当然和FM广播比起来他们俩都是窄的。

永远选 25KHz/宽带/WFM 看到哪个选哪个 _注：只有广播那个才是真 WFM_

似乎只有V段的aprs是明确必须要用12.5khz的，其他场合25khz都可以用

我一直不知道，这个带宽是怎么计算的，在中心频率两侧只要有振幅就计算在带宽中，还是要达到最大振幅的百分之多少才计算在带宽中？

发送带宽，，就是发送时所占用的频率大小，，如果你手里邮个sdr就很清楚的看到

How should I choose between wideband and narrowband for my handheld radio?

BH4HOT

Logically, if I choose a narrow bandwidth, the energy will be more concentrated and can transmit further. However, when I tried setting a narrow bandwidth, the repeater would not turn on.
Furthermore, the default mode for most mobile devices is broadband, so shouldn't everyone be using broadband? Why aren't mobile devices set to narrowband by default?
There are a few more questions: When is narrowband typically used? If both handheld radios are set to narrowband and one is set to broadband, will they still be able to communicate directly? What impact does setting narrowband have on expanding the communication range? Will there be any loss of audio quality (I know that using narrowband will reduce the volume, but I'm not sure if it will also affect the audio quality)?

BG2GFC

Please refer to the A-license question bank.

For a given FM transmitter, the factors that determine the actual bandwidth occupied by its RF output signal are: [LK0786]
The higher the maximum frequency and amplitude of the transmitted signal, the wider the bandwidth occupied by the RF output.
Using a walkie-talkie configured for WFM (Wideband FM) reception to receive NFM (Narrowband FM) signals results in the following: [LK0789]
I can hear the signal normally, but the sound is quite faint.
Using a walkie-talkie configured for NFM mode to receive WFM signals results in the following effect: [LK0788]
It's possible to hear the signal, but a significant non-linear distortion occurs when the signal amplitude and frequency are high.
According to my understanding, it should be called a repeater. Is there something else I've set incorrectly?
The frequency spacing for NFM is 12.5 kHz, and the frequency spacing for WFM is 250 kHz.
Both the 25kHz and 12.5kHz settings on the handheld device are likely NFM, which means they should be used for stepped transmission.
Forget about using a Comtac; an FM radio is inherently unsuitable for DX (long-distance) communication. All the power is concentrated on the carrier wave.

BloodBlade

BG2GFC Wide and narrow are relative terms; some manufacturers may refer to 25 kHz as WFM and 12.5 kHz as NFM. Of course, both are considered narrowband compared to FM broadcasting.

BH9FPK

Therefore, using a narrowband signal allows for greater range and concentration, potentially increasing the communication distance between two devices compared to wideband communication. You can try testing the maximum communication distance between two devices in wideband mode, then switch both devices to narrowband mode and see if the communication distance increases significantly.

BloodBlade

Using a default bandwidth of 25 kHz is likely intended to ensure compatibility with other devices commonly available on the market.
Typically, narrowband usage is adopted by commercial users to conserve spectrum.
In an ideal scenario, a simulated signal would not experience any loss. However, the human ear has limited resolution, and volume cannot be perfectly amplified without distortion. Therefore, reducing the volume can be considered as a reduction in audio quality. Furthermore, if one person hears the audio at a lower volume, it will directly be cut off, resulting in distortion.
PressThis articleAccording to the statement, the narrowband mode has a worse signal-to-noise ratio, which actually results in a decrease (approximately 30%). Of course, a lower signal-to-noise ratio also means poorer audio quality, just as mentioned before. However, FM mode is not really suitable for DX.

BG2ELG

Always choose 25kHz / broadband / WFM. Choose whichever one you see.

Note: Only the broadcast version is the true WFM.

BH3PTS

It seems that only V-band APRS requires a specific frequency of 12.5 kHz, while other situations can use 25 kHz.

BG2KUJ

I've always wondered how this bandwidth is calculated. Does it include any amplitude on either side of the center frequency, or only those that reach a certain percentage of the maximum amplitude?

BH9FPK

Send bandwidth refers to the amount of frequency used when transmitting data. If you have an SDR, you can clearly see this.

闽ICP备2021006864号-7

闽公网安备35020602002794号互联网举报中心

用户协议隐私政策社区规范积分规则中继规则转载须知
更新日志联系我们常见问题友情链接运营报告赞助

浩奇科技（厦门）有限公司

是无线电，把我们联系在一起