最近想要尝试使用线性星进行cw通联, 众所周知线性星游戏体验最好的装备是双工电台+卫星模式. 然而囊中羞涩只能考虑用手边的设备打星. 由于uvk5的双边带调制性能相当拉跨, 直接通ssb肯定要被骂, 因此只考虑进行cw通联. 目前设想的是使用uvk5的cec固件cw模式发射, 使用sdr进行接收, 二者使用uv合路器共用一根u7v4的天线, 由于合路器的隔离, k5发射时应该不会烧掉sdr的接收机. 今天使用sdr测试后发现可以输出较为纯净的cw信号(相比fm来说). 测试图如下, 分别是短波台标准的cw信号, cec的cw信号, cec的fm载波信号. 同时这次测试也打消了之前猜测的可以利用fm只掐台不出声的方法发射cw信号, fm载波也有点宽的() [upl-image-preview uuid=6f2646df-54e8-4fb5-8ac6-270f3014c31a url=https://storage.hamcq.cn/2025-10-22/1761156210-19665-b33b5eac6e76ab046690f4f351083ac3.png alt={TEXT?}] [upl-image-preview uuid=a3ac015d-6d33-431e-b5aa-a582f1d6d6db url=https://storage.hamcq.cn/2025-10-22/1761156214-957629-8ccf83685525e58213e0d22bee0f871a.png alt={TEXT?}] [upl-image-preview uuid=115a4fbb-9dca-499d-8d58-ea88bdebde3b url=https://storage.hamcq.cn/2025-10-22/1761156218-516153-8acb1b98bbf6ec093d701a9fd1664c5b.png alt={TEXT?}] 但uvk5不能自动多普勒, 而且不能同步调整sdr的接收频率和手台的发射频率, 因此很难稳定的建立收发回环. 估计通联时只能在固定频率上呼叫cq等待双工大佬过来而不能回应别人的cq. 另外同时调整sdr和手台频率也比较痛苦. 所以想请教各位友台, 这种通联计划是否合理, 同时是否存在同时兼容自动uvk5自动多普勒功能和cw功能的固件. 我发现DTrace和losehu固件提供了自动多普勒功能, 而CEC提供了CW功能, 苦于找不到一种同时兼容二者的固件.

一觉醒来想起来另外一个问题：诺威的n76等手台提供了摩尔斯电码的发送功能和解码功能，这种使用dtfm调制出来的fm模式摩尔斯信号频谱占用是fm载频频率+声调频率两根线还是会占用一大片。换句话说，使用这种原生的fm摩尔斯信号上线性星会不会被打（）

@"BD8DIN"#p83306 ijv固件的话： 1. k5\6接收带宽最低设置到6.5khz？这样的话接收频率要求就没那么高？ [upl-image-preview uuid=996a4df5-7d86-4e56-8425-b9dd7a192cfe url=https://storage.hamcq.cn/2025-10-23/1761184791-947543-image.png alt={TEXT?}] 2.固件有一个Rix/Xit的功能，可以单独微调接收、发射频率 [upl-image-preview uuid=01a5bbe2-88a4-448f-a0e5-b01f9962ce2c url=https://storage.hamcq.cn/2025-10-23/1761184996-430009-image.png alt={TEXT?}]

@"troilus"#p83329 感谢，rit功能用于多普勒可以考虑，这样操作难度会降低一些。我的想法是手台仅用于发射，接收交给sdr了。线性星上占用6khz的带宽感觉还是有点宽了，是ssb的两倍，不过不管怎么说比普通fm好很多，应该也说得过去（？）

@"BD8DIN"#p83306 自动多普勒和固件好处理。SDR和电台同步反向调频也好处理。就是占用频率带宽太大，这个不好处理。

@"BD8DIN"#p83331 发射的话应该还是你sdr看到的频谱水平，没那么宽， 6khz是接收的带宽

@"troilus"#p83329 看了一下, ijv支持自动频率漂移欸, 应该能当自动多普勒的平替了! 顺便它也有cw调制模式, 等我回家刷固件测试一下频谱干不干净. 现在唯一的问题是从说明文档上查到它只支持手键, 需要猛猛练习发报了(

@"BD8DIN"#p83338 按ptt也可以吧

@"troilus"#p83342 不行，你看我上面的图，fm只按ptt不出声发射的载波也会有好几根，不知道是因为我离得太近导致有镜像干扰还是什么，总之测试结果是不太能用的状态

@"troilus"#p83342 哦好像是我理解错了，电键的话发cw按ptt手感和用自动键和手键不一样的，太软了按起来不方便😋

@"BD8DIN"#p83343 是K5本身决定的，之前看过有友台使用SDR接收的RS-44下行有疑似使用K5上行的信号，确实会有不少根。据他描述是“ 七个一模一样的CW信号 ”

Ideas and questions regarding the use of UVK5 and SDR for low-cost linear star CW communication.

BD8DIN

I've been wanting to try using Linear Star for CW communication recently. As everyone knows, the best equipment for a great Linear Star experience is a dual-band radio plus satellite mode. However, with limited resources, I can only use the equipment I have on hand to communicate with stars. Since the UVK5's two-band modulation performance is quite poor, directly transmitting SSB would definitely be met with criticism, so I'm only considering CW communication.

The current plan is to use the UVK5's CEC firmware in CW mode for transmission, and use an SDR for reception. Both will share a single U7V4 antenna via a combiner. Due to the combiner's isolation, the SDR receiver should not be damaged when the K5 is transmitting. After testing with an SDR today, I found that it can output relatively clean CW signals (compared to FM). The test results are shown below: standard shortwave CW signal, CEC CW signal, and CEC FM carrier signal. This test also dispelled the previous assumption that it was possible to transmit CW signals by simply turning off the FM station without making a sound. The FM carrier wave is also quite wide.

However, UVK5 cannot automatically perform multiple Doppler processing, and it also cannot synchronize the receiving frequency of the SDR with the transmitting frequency of the handheld radio. This makes it difficult to establish a stable two-way communication loop. When using Unicom, you can only call CQ on a fixed frequency and wait for someone to respond, but you cannot communicate with other CQ stations. Additionally, synchronizing the frequencies of the SDR and the handheld radio is also quite cumbersome.

Therefore, I would like to ask my fellow colleagues: Is this unified plan reasonable? Also, does a firmware exist that can simultaneously support both the automatic UVK5 and multi-frequency Doppler functions, as well as CW functionality? I have found that DTrace and losehu firmware offer the multi-frequency Doppler function, while CEC offers CW functionality. However, I am struggling to find a single firmware that supports both.

troilus

BD8DIN
Regarding the ijv firmware:

If the minimum receive bandwidth for K5/6 is set to 6.5 kHz, would that mean the required receive frequency is lower?

2. The firmware has a Rix/Xit feature that allows for independent fine-tuning of both receive and transmit frequencies.

BD8DIN

I woke up and thought about another question: The n76 handheld radios from Norway, for example, offer Morse code transmission and decoding capabilities. Given that these use DTFM modulation to create FM-mode Morse signals, what is the bandwidth occupied? Is it the sum of the FM carrier frequency plus the tone frequency, or does it occupy a large band?
In other words, would using this native FM Morse code on a linear star be susceptible to interference?

BD8DIN

troilus Thank you. The use of the RIT function for Doppler processing is worth considering, as this would reduce the complexity of operation. My idea is to use the handheld device only for transmitting and let the SDR handle receiving.

The 6 kHz bandwidth used in linear star mode feels a bit wide, twice the SSB bandwidth, but regardless, it's much better than ordinary FM, and can probably be considered acceptable.

BD8DIN

troilus I checked it out, and the IJV supports automatic frequency drift, which should be a good substitute for an automatic Doppler system! Also, it has CW modulation mode. I'll go home and test the spectrum after updating the firmware. The only problem now is that the documentation says it only supports manual keying, so I need to practice transmitting a lot.

troilus

BD8DIN The transmitted signal should still appear as a spectrum level on your SDR, and it won't be that wide; 6 kHz is the bandwidth for receiving.

troilus

BD8DIN Can I also use PTT?

BD8DIN

troilus No, look at the diagram above. Even when FM is only transmitting on the PTT carrier frequency, you can still see multiple antenna signals. I'm not sure if it's because I'm too close to the source and experiencing interference from reflections, or something else entirely. However, the test results indicate that the signal isn't very reliable.

BD8DIN

troilus Oh, I think I misunderstood. When it comes to using a key for CW transmission with PTT, the feel and operation are different depending on whether you use a mechanical key or an automatic key. The automatic key feels too soft, making it difficult to operate effectively.😋

yitsunc

BD8DIN This is determined by the K5 itself. I previously saw that some other stations were using SDR to receive RS-44 downlink signals, and it appeared that the K5 was also transmitting upward signals. This would definitely result in a significant number of reflections.
According to his description, it was "seven identical CW signals."

BD8DIN

yitsunc Is it actually like this? That is, could I potentially use another radio to reliably transmit CW signals via PTT and reach a satellite?🤔

yitsunc

BD8DIN I don't recommend it; using a proper full-mode UV machine is better than trying to do it manually with linear movement. Otherwise, there won't be much difference between doing it manually and working on the ground.

natsumikka_BA7OPF

It is recommended to first use an SDR to receive your firmware's CW bandwidth locally and check if it meets the requirements. I have tested the CW bandwidth of the K6 CEC firmware, which is approximately 200Hz. Some bloggers have also tested the CW bandwidth of CEC and IJV firmwares, and they indicated that the CW bandwidth indicators for both firmwares are similar.
Regarding reception, I am using the SSB mode of the K6 CEC firmware. Even at high angles, the reception remains clear until the angle drops below around 15 degrees, after which the sound becomes noticeably weaker. This may be due to the wide bandwidth of the SSB mode. As for handling Doppler shift, I have adjusted the frequency step to 0.5 kHz. Based on the CW signal frequencies that I hear from the other station, I decide whether to increase or decrease the frequency.
When dealing with up-and-down signal loops, I use a website that can calculate your up-frequency or down-frequency in real time, depending on whether you're using a fixed up-link or a fixed down-link. The URL is jo3mqy.sakura.ne.jp
After performing the above tests, I successfully established two-way communication with two domestic stations (one JA and one HS) on the RS44 using the CW mode of the K6 CEC firmware.
Initially, transmitting was difficult because I was using the CEC firmware "PTT+M key" automatic key mode. When holding the Yagi antenna with one hand, the probability of sending the wrong message was very high. Later, I bought a CW paddle key ("cw paddle key for quansheng uv-k6") on Taobao, which allowed me to: hold the K6 in my left hand, use my right hand's three fingers to grip the Yagi antenna, and use my two remaining fingers to operate the paddle key. Additionally, CEC could be pre-programmed with some CW sentences, so I didn't need to use my right hand to transmit CQ or my own callsign, or even "5NN TU". The only information that needed to be transmitted with my right hand was the recipient's callsign.

BD8DIN

natsumikka_BA7OPF Thank you very much! I have tested the bandwidth usage, and it was indeed around 200. Your experience is very helpful, thank you!

BD8ARF

Regarding this area, I have conducted some research.
SDR and UVK5 synchronization with Doppler control, as well as linear satellite reverse frequency modulation, can be controlled by computer software. The UVK5 can be connected to a computer using an AIOC connection cable, which includes a serial port and audio interface, allowing for synchronized audio and microphone input to the computer. Once the CW mode on the UVK5 is enabled, it can be operated using keyboard keys on the computer. Additionally, HID cables can be used to map hand controls to the computer keyboard for convenient operation.
Theoretically, this is feasible. However, I don't know how much bandwidth the UVK5 CW modulation uses. If it occupies too much bandwidth, it will likely be criticized for using excessive bandwidth. It is recommended to first test the transmission bandwidth.
The other station reported that K5 had 7 lines during CW transmission, but I don't know what the actual effect is now.

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