Whitepapers

Wi-Fi HaLow Radio Technology 13 Lower zoom levels require lower throughput so they don't put as much strain on the radio link. Zoom levels 5-8 have the highest data traffic and put the highest strain on the radio link. It is expected and understandable that the user would have to use higher zoom levels to visually find the target and lock to it when they are at a long range from the instrument. However, if the video is laggy and the user suspects that the radio link might be experiencing performance issues, zooming out or turning off the video should improve the situation by reducing the data traffic. Movement within a Video The amount of movement within the video can affect the size of each image frame in the video, and thereby affect performance. The Trimble SX12 firmware includes some clever video compression algorithms; when parts of an image are really uniform, for example a bright blue sky, the instrument is able to compress the image that's being transferred without losing any of the details or quality within the original image. This is also true when using video and pointing at a still scene; because very little is changing within the video from frame-to-frame, the instrument is able to compress the video more. Conversely, when the instrument video is streaming a dynamic scene with lots of movement, for example a forest where every leaf is blowing in the wind, the video frames are larger, and so streaming that type of large video to a controller can have a negative effect on performance: either shorter range, or some lag in the video stream. Effect of High Bandwidth vs Low Bandwidth Channels The terms "bandwidth" and "throughput" are often used interchangeably to mean the amount of data that can be transmitted over a period of time. There is a small difference between the two terms: "bandwidth" refers to the portion of frequency band that is utilized for data transfer and it directly correlates with the theoretical capacity of the radio link for data transfer, whereas "throughput" or "data rate" refers to the empirical amount of data transferred per unit of time. The Trimble SX12 and EM130 have two operating modes to choose from within Trimble Access: High Bandwidth, and Low Bandwidth. In practice, this is synonymous with "High throughput" and "Low throughput." By default, Wi-Fi HaLow radio should be configured to operate on a High Bandwidth channel to provide the best performance. High Bandwidth channels are superior for transferring large amounts of data, which includes transferring scans and panoramas, as well as streaming video. However, it should be noted that Wi-Fi HaLow radio can also be configured to operate on Low Bandwidth channels. These channels have almost half the performance capacity of the High Bandwidth channels, however, they can provide additional range when the radio link is not heavily loaded with video data traffic. If the High Bandwidth channel frequencies are experiencing localized interference, using the Low Bandwidth channels may provide better performance. The following graph is an example of how Wi-Fi HaLow radio could operate in a suburban test environment. In this example, it is expected that the Wi-Fi HaLow radio would provide a fair user experience up to about 400m range when the video is used. If the user does not need the video they can switch to a Low Bandwidth Channel and continue using the radio for approximately another 100 - 150 meter range.

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