如果是这样的话，那为什么大家不用ssb呢，难道是因为支持ssb的机器价格贵吗？

1.技术难度高，增加了设计和制造难度 2.机器需要较高的解调能力 3.通信中，接收方需要正确的同步载波和相位信息，但是实际情况是有多干扰，通常无法正确同步 4.UV段故障多，不如短波，ssb是为了减少带宽设计出来的 5.人格启动

@"BH4HOT"#p35297 好像考试题库就有说ssb可以在uv段进行远距离通联）

没必要这么极致的减小带宽吧几百MHz也不缺几M

UV段95%情况下功率并不是限制距离的短板，地平线和建筑物的遮挡才是。

1.技术难度高，增加了设计和制造难度 2.机器需要较高的解调能力 3.通信中，接收方需要正确的同步载波和相位信息，但是实际情况是有多干扰，通常无法正确同步 4.UV段故障多，不如短波，ssb是为了减少带宽设计出来的 5.人格启动

@"YangZifan-BA7KVH"#p35300 减少带宽是其次，重要的是增加信号强度，减少一半的带宽相同发射功率下信号强度就增加一倍

@"[未知用户]"#p35303 诶有道理

@"BH4HOT"#p35303 换句话说，短波经常出现听得见，声音小，喊不到（功率不够） UV大部分是听得到就能喊，喊不到我换个朝向，避开点儿遮挡就能喊

@"[未知用户]"#p35306 我是江苏的，我已经添加10个闹钟了

If the UV band also uses SSB mode for communication, would it be possible to increase the communication distance under the same power?

BH4HOT

If that's the case, then why don't everyone use SSB? Is it because the machines that support SSB are too expensive?

GVZ

BH4HOT It seems that the exam question bank also mentions that SSB can be used for long-range communication in the UV band.

BD4UIN

1. High technical difficulty, increasing design and manufacturing challenges.
2. The machine requires high demodulation capabilities.
3. In communication, the receiver needs accurate carrier and phase information, but in practice, there are multiple interferences, which often makes it impossible to synchronize correctly.
4. UV band has many faults; it's better to use shortwave, as SSB was designed to reduce bandwidth.
5. Personality Activation

YangZifan-BA7KVH

There's no need to reduce the bandwidth so drastically. A few hundred MHz is more than enough for a few megabytes.

BH4HOT

YangZifan-BA7KVH Reducing bandwidth is secondary; the more important thing is to increase signal strength. With the same transmission power and half the bandwidth, the signal strength increases by two times.

BH3PTS

In 95% of cases, the power in the UV segment is not the limiting factor for distance; rather, it's the obstruction from the horizon and buildings.

BH2VZC

BH3PTS
I was also thinking that the power density on SSB at a similar bandwidth should be significantly higher than FM (25 kHz FM / 3 kHz SSB), and this is indeed the case.
For example, the coverage range of the Jinan Yellow River amateur repeater (power unknown), and the international space station amateur repeater operating at 5W, can be directly received by handheld radios using their original antennas in the U-band. Of course, when receiving, it may be necessary to adjust the antenna direction or polarization.

Taking an ISS repeater with a 5W transmitter and 2 dBi antennas for both transmission and reception as an example, the transmitted power is:5W = 37 dBm, with a path loss of 133.3 dB over a distance of 400 km, the final power at the receiver (handheld) is approximately37 - 133 = -96 dBm。The FM mode sensitivity of most handheld radios is significantly higher than this value.

BD4UIN

1. High technical difficulty, increasing design and manufacturing challenges.
2. The machine requires high demodulation capabilities.
3. In communication, the receiver needs accurate carrier and phase information, but in practice, there are multiple interferences, which often makes it impossible to synchronize correctly.
4. UV band has many faults, making it less reliable than shortwave; SSB was designed to reduce bandwidth.
5. Personality Activation

BH2VZC

BD4UIN
Could you please provide a detailed explanation of the synchronization aspects of component 3 and the fault/bandwidth aspects of component 4?
I first encountered this idea; I'll study it further.

BD7PPD-xiaohei-lv

BH4HOT
In other words, shortwave radio signals are often weak and quiet, making it difficult to hear or even speak through them (due to insufficient power).
For UV, I can usually communicate by shouting, but if I can't hear them, I can change my position slightly to avoid any obstructions and then I can still communicate.

YangZifan-BA7KVH

[未知用户] That makes sense.

Ken

For the Suzhou and Wuxi region, we can participate in SSB communication experiments in the U/V frequency band within a few days.
https://mp.weixin.qq.com/s?__biz=MzA5MzI4NjcwMA==&mid = 2687136784&idx = 1&sn = c6dc805e1f4fe51c121e95e51154148f&chksm=b5beec5382c96545aafcfaa50ccce8d8fe15f590997f46a9ba1c0fa9685ea1c789b412a46e2d&scene = 27

There are also introductions about classic full-mode UV machines on this forum:
https://forum.hamcq.cn/d/1419

BD4UIN

[未知用户] I am from Jiangsu, and I have already set up 10 alarms.

BG4IDK

The propagation distance in the UV band is primarily limited by the characteristics of this frequency range. Shortwave communication can travel long distances because the ionosphere acts as a reflector, allowing signals to bounce around the world. In contrast, UV communication relies mainly on line-of-sight propagation. Furthermore, as the frequency of electromagnetic waves increases, their energy attenuation also becomes more significant (5G base stations have more than 4G, which is the principle). Therefore, even the most advanced anti-attenuation modes will not result in a substantial increase in propagation distance.

Bi4KKF

Technical post, fire clamp Liu Ming

BH2VZC The Yellow River repeater, located in Jinan city, has an approximate height of 400 meters and a power output of 25W. When propagation conditions are good, signals can be received from Liaoning province. The primary source of interference is the high density of urban sources.

BD4UIN

BH2VZC Okay, the third point is about "coherent detection." "Coherent detection" (also known as coherent reception) and homodyne detection are applicable to all linear amplitude modulation schemes (including ordinary AM modulation). Demodulation of double-sideband or single-sideband amplitude modulation can only be achieved through "coherent detection."
Synchronous detection involves multiplying a local oscillator signal, which has the same frequency and phase as the carrier, with the received signal to perform demodulation.
The fourth point refers to the specific situation. On a small scale, we encounter common issues with transformer and electrical wire magnetic fields. On a larger scale, this is related to solar activity, which causes abnormal propagation in the UV spectrum.
The above are just personal opinions; please correct me if there are any errors.

BH9FPK

The UV band CW signal has a greater range, but it's limited by line-of-sight propagation and the curvature of the Earth.

BG2KAJ

BD4UIN

In practice, synchronous detection is achieved by regenerating the carrier from the original transmitted signal. The simplest method is to use a PLL (Phase-Locked Loop) to create a carrier with the same frequency and phase, and then inject it. However, for SSB (especially high-performance commercial radios), the carrier suppression is already quite good (e.g., my FT-450D has a carrier suppression of 60dB or more relative to the main signal), so either there is no carrier transmitted or the receiver cannot receive the carrier. In this case, it is impossible to consider the phase of the carrier, and instead, we directly focus on regenerating the frequency of the injected carrier while ignoring the phase effect. Synchronous detection can only be used with AM, SSB-SC, and VSB; pure SSB cannot be used. The most common problem in amateur SSB operation is the frequency difference between the regenerated local carrier and the original carrier, and the phase difference is difficult to determine. Existing analog SSB receivers typically inject the carrier without considering the phase, and it is impossible to achieve synchronous detection.
I don't understand what you mean by "fault," but, based on my own experience, electromagnetic interference generally affects the HF band. On frequencies like 144 and 430, besides other users, there is usually not a significant increase in QRN (radio noise). The highest interference from transformers or other electrical systems typically does not exceed 1 to 3 MHz, and while this can have a noticeable impact, it's generally limited to within the HF band. It's also worth noting that VHF propagation (especially on the 2-meter band) primarily follows line-of-sight characteristics. When Es (skywave ionization) opens up, the signal rapidly degrades, which could be due to changes in duct conditions or rapid changes in propagation polarization. In 2022, when I opened up with JA7KPI on the 2-meter band, he reported that FT8 was working well, and there were periods of good contact with the BY2-JA7 region for almost an hour. However, when attempting USB (upper sideband) communication on 144.200, the signal would rapidly degrade, strengthen, and then degrade again, often with several seconds between each change. This rapid degradation between DX stations is a unique characteristic of the 2-meter band.

Encourage everyone to conduct SSB and DATA mode experiments at distances of 2 meters and 70 cm.~~This level of uncertainty is much more interesting than a repeater station.~~。

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