刚刚看来《再谈铁路通信电磁环境》这篇微信上的文章https://mp.weixin.qq.com/s/vYuET2ItRGd1P3MAW58I4g 其中一段话作者提到“ 早期铁路的下一代无线是450MHz的LTE-R系统。专业研究机构不知如何开始研究，在诚心地恳求下加入了既有的研究团队，开始了下一代的研究。 2016年铁路集团公司在大西线进行了各个专业的试验，其中也有通信的LTE-R的试验。我参加了试验结束后的评审，发现研究院通信部门只进行了450MHz的覆盖测试，对此提出了意见。评审单位不同意把意见写入评审报告，说是参试单位已经知道了就可以了。但是他们真的知道了吗？！那时根据450MHz在铁路电气化区段存在问题做了一些测试，在公众号中已说明了电磁环境情况。由于专家们多是关心系统的功能，对电磁环境情况不是很注意。基本没有做过试验研究。” 业余手台U段430MHz-440MHz距离450MHz很近，为公共安全起见，我觉得还是还是不要在列车上使用业余无线电台为好。这是我个人的第一感觉，不知道是否正确，也希望资深大佬能够给大家分析科普一下铁路通信电磁环境与干扰的内容

> @"arwoon"#p45739 430MHz-440MHz 距离 450MHz 很近多近算近，合法电台都经过杂散谐波测试，指标是合格的。另外U段业余业务也只是次要业务，那是不是也要建议一下使用 430-440作为主要业务的在铁路方圆几百千米的范围内不要使用？

总不能因为水喝多了会水中毒就建议不喝水吧，按这个说法 V 段离航空段也近啊，那是不是只要抬头能看见飞机的都不要用 V 段了

@"BI7LVX"#p45753 我想到的是另外一种情况“超外差”这篇文章中有介绍https://forum.hamcq.cn/d/3258，下面的评论中有提及“刚才又验证了一下，确实如此，我在 U 段设置了好几个频率，接收和发射相差 26 兆，结果都是一样的，互相能够通信。条件受限，没有办法远距离测试，不确定是不是场强太强，抑制起不到作用。”。430-440中，430+26=456，有可能出现问题。以上都可以开放讨论，欢迎大家来讨论。

@"arwoon"#p45771 所以结论是啥，如果要用 430+26=456 来证明手台会影响公共安全，那你猜猜工信部是干嘛的，厂商怎么会拿到核准码。我的观点是，只要是依法设台，在执照允许的范围内发射那都是没问题的，本来现在环境对 UV 段已经不友好了，没必要再拿那么多条条框框来限制自己，还拔高到公共安全的高度。而且我也没听说过有因为业余电台合法发射影响到航空或者铁路安全的。打个不恰当的比方就是，如果我觉得飞机不安全我会选择自己不坐飞机，而不会选择呼吁大家为了自己的人身安全不要乘坐飞机。

我不点名说哪个厂商，毕竟他的机器改装一下还挺好玩的。但是既然说到这个问题了，那不妨思考一下，为什么只有某些特定的手台能打开别人的静噪像八重洲，icom 这些厂商的就不会，但不能深究，毕竟人家有核准码，连工信部都认可的产品，我能说什么，玩就是了，只要是合法发射万一真出了事有工信部给我兜底。

@"BI7LVX"#p45781 在确实出现干扰的时候应当停止发射，否则自身存法律风险，工信部也无法兜底。 **特定的手台**在**该场景下**还是值得注意的。

虽然但是LTE-R专网一般跑在1800MHz左右吧🤔

@"BH6AOV"#p46164 中国铁路不用 LTE-R 吧，GSM-R 直接过渡到 5G-R 了

可能极少部分线路有 LTE-R

@"BG5ELQ"#p46167 目前确实是5G-R了，我摘录的部分只是《再谈铁路通信电磁环境》这篇微信上的文章 https://mp.weixin.qq.com/s/vYuET2ItRGd1P3MAW58I4g中的一部分。在无线电监管方面国家铁路局好像每年都要求铁路集团公司提供高铁沿线的电磁环境报告（普铁也应该需要检测电磁环境吧）。这样的报告要关注什么，对报告提出的问题如何处理好像不太清楚。只是从目前存在的问题看，没看到管理部门给出什么要求。作者根据自己感觉的一些情况发发议论。其中提到了早期的LTE-R。就目前来看，高铁沿线的电磁环境报告（普铁也应该需要检测电磁环境吧）似乎还不够规范。因为很多情况不明，才会引出不要在列车上使用业余无线电台争议性讨论，希望大家发表各自的看法。

Personally, I think it's best not to use amateur radio equipment on trains.

arwoon

I just read the WeChat article titled "Revisiting the Electromagnetic Environment of Railway Communication" at this URL: https://mp.weixin.qq.com/s/vYuET2ItRGd1P3MAW58I4g
In one passage, the author mentions that "the next generation of wireless for early railways is the 450MHz LTE-R system. Professional research institutions were unsure where to begin their research, and after earnestly requesting assistance, they joined an existing research team to start studying the next generation technology.
In 2016, the Railway Group conducted various professional tests on the Daxin Line, including LTE-R communication testing. I participated in the review after the test and found that the research institute's communications department only performed coverage testing at 450MHz. I raised concerns about this. However, the reviewing body disagreed with including my comments in the review report, stating that the participating unit was already aware of the issue. But did they really know?!
At that time, some tests were conducted based on the presence of issues at 450MHz in the electrified railway sections, and the electromagnetic environment situation was already explained in the public account. However, since the experts were primarily focused on the system's functionality, they did not pay much attention to the electromagnetic environment situation. "There were essentially no experimental or research studies conducted."
Amateur handheld radios in the 430-440 MHz range are very close to 450 MHz. For public safety reasons, I believe it's best not to use amateur radio on trains. This is my initial impression, and I don't know if it's correct. I also hope that experienced experts can analyze and explain the electromagnetic environment and interference related to railway communication for everyone.

BI7LVX

arwoon 430 MHz - 440 MHz distance is very close to 450 MHz.

"Anything close enough is considered close, and all legal radio stations undergo spurious harmonic testing. The results must meet the required standards. Furthermore, amateur business on the U band is only a secondary activity. Therefore, it should be recommended that in areas within several hundred kilometers of railway lines, those using the 430-440 MHz frequency as their primary business should not use it."

arwoon

BI7LVX I thought of another scenario, as described in the article "超外差" (https://forum.hamcq.cn/d/3258). The comments below mention: "I just verified it again, and it's true. I set several frequencies in the U band, and the receive-to-transmit difference is 26 MHz, but the results are the same, and we can communicate with each other. However, due to limited conditions, we cannot perform long-distance testing. It's possible that the field strength is too strong, preventing effective suppression." In the 430-440 range, 430 + 26 = 456, which could potentially cause problems. I welcome everyone to discuss these points.

tudoubocai

BI7LVX Actually, I know that three provinces have already banned the use of U-segment: Shanghai, Chongqing, and Zhejiang. They can only use V-segment, and in Shanghai and Zhejiang, it's limited to 144-146.

BI7LVX

It's obviously not advisable to avoid drinking water altogether because of the risk of water intoxication. According to this reasoning, V-segment is also close to the airport segment, so shouldn't we stop using it if pilots can see aircraft with their head-up displays?

BI7LVX

arwoon So, what's the conclusion? If you want to prove that using a 430+26 frequency affects public safety, then you might be wondering what the Ministry of Industry and Information Technology does, and how manufacturers can get approval codes. My view is that as long as the equipment is set up legally and operated within the scope of the license, there's no problem. Moreover, the current environment for UV frequencies is already not very favorable, so there's no need to impose more restrictions or raise the bar to public safety. I haven't heard of any cases where legal amateur radio transmissions have affected aviation or railway safety. For example, if I feel that an airplane is unsafe, I would choose not to fly, rather than urging everyone to avoid flying for their own safety.

BI7LVX

I'm not going to name any specific manufacturer, because modifying their equipment can be quite fun. However, since we're talking about this, perhaps we should consider why only certain specific handheld radios, like Yaesu, and those from manufacturers such as ICOM, can operate on other people's noise-canceling systems, while others cannot. But let's not delve too deeply into it, because they have the necessary approvals, and even products approved by the Ministry of Industry and Information Technology (MIIT) are fine. If something does happen, at least I know that the MIIT will back me up.

BG5EGC

BI7LVX
When interference actually occurs, it should be stopped immediately. Otherwise, there is a legal risk for the operator, and the Ministry of Industry and Information Technology cannot provide any protection.
Specific handheld deviceInIn this scenarioIt's worth noting.

BH6AOV

Although, LTE-R private networks typically operate at around 1800 MHz.🤔

BG5ELQ

BH6AOV China's railway network doesn't need to use LTE-R; it can directly transition to 5G-R.

arwoon

BG5ELQ Currently, we are indeed discussing 5G-R. The excerpt I provided was from an article titled "Revisiting the Electromagnetic Environment of Railway Communication" on WeChat. https://mp.weixin.qq.com/s/vYuET2ItRGd1P3MAW58I4g中的一部分。
Regarding radio frequency regulation, it seems that the National Railway Bureau requires railway groups to provide electromagnetic environment reports along high-speed rail lines every year (and perhaps also requires鐵道 (PTE) to conduct electromagnetic environment testing). The report should focus on [details about what the report should cover], and how to address the issues raised in the report is unclear. However, based on the current situation, I haven't seen any specific requirements from the management department. The author shares their observations based on their understanding of the situation. One example mentioned is early LTE-R. Currently, it seems that the electromagnetic environment reports along high-speed rail lines (and PTE) are not yet sufficiently standardized. This leads to discussions about whether amateur radio should be used on trains, and I hope everyone can share their opinions.

BH6AOV

BG5ELQ As of now, I haven't heard anything specific about LTE-R; 5G-R is still in the whitepaper stage and hasn't been implemented practically.

BG5ELQ

It's possible that a very small number of lines support LTE-R.

yitsunc

BG5ELQ Currently, I only know that the Shanghai City Area Airport Line uses LTE-M (

BD8DLV

Regarding certain technical specifications of handheld devices, it would be virtually impossible to pass a comprehensive testing machine.

BH2VYJ

It's best not to use amateur radio equipment on trains, primarily to avoid causing confusion among staff. Issues like stray signals, radiation, and interference are secondary concerns.

BI2UL

Honestly, it depends on the individual.
If there's a risk, then it should be prohibited, which would prevent many things from happening, including amateur radio.
So, if you're concerned about legal risks, you don't necessarily need the best.
Regarding freedom of use, there's no need to worry excessively, as you can simply turn off the device if it's causing interference without posing a serious threat to safety. For typical, everyday use, devices that pass inspection will generally not cause fatal interference.

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