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一、引言多机差转是指在一个台址使用两台以上的差转机同时开路收发不同频道的电视信号,使服务区域有多个频道的节目供给用户选择收看。但是,电视是在宽频带的甚高频或特高频频段传送,多台差转机要在自由空间中的同一点进行接收和发射。如果在建台前没有对频道分配和抑制干扰等方面给予足够的重视,建台后有很大的可能性出现自台干扰,这种情况在县或地方厂矿的50W以下小功率差转台是比较多见的。受扰轻的台转发的图像只出现轻微的可见性干扰,但用户尚能收看;干扰严重的差转台根本不能迸行多机同时差转,往往造成不必要的经济损失。为了减小或避免多机差转造成自台干扰,本文以两机同点工作为例,对差转的干扰作些粗浅探讨。
I. INTRODUCTION Multi-machine differential transfer refers to the use of more than two machines at one site to send and receive television signals of different channels at the same time, so as to enable the programs in the service area with multiple channels to be selected for viewing. However, televisions are transmitted in the VHF or UHF bands of broadband and multiple decks are receiving and transmitting at the same point in free space. If we did not pay enough attention to channel allocation and suppression interference before establishing a station, there is a great possibility of self-station interference after the establishment of a station. In this case, the low-power differential platform below 50W at a county or local factory is compared More common. The images forwarded by the lightly lit stations only show slight interference of visibility, but the users can still watch the images. The badly-turned badly-turned-tables can not simultaneously make multiple machines perform differential transfer at the same time, which often results in unnecessary economic losses. In order to reduce or avoid the self-station interference caused by multi-machine differential rotation, this paper takes two machines working at the same point as an example to discuss the interference of differential rotation.