navigation message generation code explanation - dwrd[60] instead of dwrd[50]

[virat-fan18]

dwrd[60] - But isn't it enough if the 5th subframe is sent only the first time of the total duration? If we do it everytime while we send the navigation message is sent - aren't we sending the subframes like 5-1-2-3-4-5,5-1-2-3-4-5,5-1-2-3-4-5...etc .Wouldn't this be wrong as It should be 5-1-2-3-4-5-1-2-3-4-5-1-2....etc(as you meantioned in aprevious issue thatwe have to simulate for a time before the transmission time ) ? Great work with the code by the way .

Originally posted by @virat-fan18 in https://github.com/osqzss/gps-sdr-sim/issues/180#issuecomment-2440135438

[cehuidong]

dwrd[60] - But isn't it enough if the 5th subframe is sent only the first time of the total duration? If we do it everytime while we send the navigation message is sent - aren't we sending the subframes like 5-1-2-3-4-5,5-1-2-3-4-5,5-1-2-3-4-5...etc .Wouldn't this be wrong as It should be 5-1-2-3-4-5-1-2-3-4-5-1-2....etc(as you meantioned in aprevious issue thatwe have to simulate for a time before the transmission time ) ? Great work with the code by the way .

Originally posted by @virat-fan18 in #180 (comment)

Because dwrd 9 and 59 are identical. I don't know if I'm right, but I think the principle of the part is as shown in the picture：

[xixi88888888]

dwrd[60] - 但是如果在整个持续时间内只发送第 5 个子帧，这还不够吗？如果我们每次发送导航信息时都这样做，难道我们不是在发送 5-1-2-3-4-5、5-1-2-3-4-5、5-1-2-3-4-5...等子帧吗？这难道不对吗？它应该是 5-1-2-3-4-5-1-2-3-4-5-1-2...等（正如您在上一期中提到的，我们必须在传输时间之前模拟一段时间）？顺便说一句，代码写得很好。

最初发布者@virat-fan18在#180 （评论）

Because this code updates the navigation messages of all satellites in all channels simultaneously, the navigation messages of all satellites are not aligned when received. If all updates are made according to the fastest updating channel, it may cause some slow channels to transmit the next frame's position message. Therefore, using 60 to save an additional subframe (6s) can completely cover the updates of all message frames

[cehuidong]

dwrd[60] - 但是如果在整个持续时间内只发送第 5 个子帧，这还不够吗？如果我们每次发送导航信息时都这样做，难道我们不是在发送 5-1-2-3-4-5、5-1-2-3-4-5、5-1-2-3-4-5...等子帧吗？这难道不对吗？它应该是 5-1-2-3-4-5-1-2-3-4-5-1-2...等（正如您在上一期中提到的，我们必须在传输时间之前模拟一段时间）？顺便说一句，代码写得很好。 最初发布者@virat-fan18在#180 （评论）

Because this code updates the navigation messages of all satellites in all channels simultaneously, the navigation messages of all satellites are not aligned when received. If all updates are made according to the fastest updating channel, it may cause some slow channels to transmit the next frame's position message. Therefore, using 60 to save an additional subframe (6s) can completely cover the updates of all message frames

我看到代码中是将缓冲放在了最前面，并不是让第一子帧的时间为开始时间，这在GPS中没影响吗？还是我理解错误。