In an open environment with no reflection, 30m*30m sounds as fairly accurate actually. The 50m range can be achieve in an environment with reflection which will help to propagate/replicate the signal.
Please note that depending on countries, there currently is a regulation restriction about use of UWB outdoors. (Stationary device cannot transmit).
What is the use case, and why are you looking to cover such a large area ? If you really need to, you may be looking at a custom software/hardware solution becase on DW1000 that will allow you to reach larger distance.
Okay the use case is sport so the 30m is going to be difficult to live with in certain areas (rugby, football etc etc) but maybe not so much smaller playing areas (tennis, badminton, basketball etc) although having said that the maximum of 6m range I’m getting when mounted on my person is seriously limiting - does that 6m sound right?!?
Initially I was looking at the UK but will be looking further afield later, can you point me in the direction of the legislation to which you refer please?
Now that you understand my use case a little better can you give me some pointers about the custom software/hardware solution you mention please?
If you wish to cover larger sport pitch, you can increase the number of anchors. It should allow you to cover fairly large distance, 100m+ with 3 or 4 anchors along each side of the pitch.
The 6m tag range sounds a bit low. The body will attenuate the signal for sure so you may want to be looking at an optimized tag placement, and place anchors in a way the tag is always in LOS with at least 3 anchors.
Whilst I do appreciate that adding more anchors will create a greater coverage area I’m still struggling with the idea that Loss Of Signal (LOS) occurs at maximum 30m - taking the example of a rugby pitch, that’s 70m wide so would in theory need at least three anchors across that width. Mathematically this would be fine but practically it puts one in the middle of the posts! Not only that but there would be at least a 10m swathe of no signal running right down the middle of the pitch some 60m long (120m long rugby pitch length minus two 30m sections covered by the anchors in between the posts at either end of the pitch).
Further to this - although I might be wrong here, so please correct me if I am - but the listener role of the gateway device (passive tag or anchor) can only receive the data from devices within the 30M LOS radius and thus wouldn’t pick up tags on the remaining part of the pitch? In other words the listener can’t get tag data from the combined efforts of all/some of the anchors repeating or otherwise transferring tag positional data?
I did notice that although I was getting LOS at 30m whilst the tag is attached to my back and the anchor behind me and about 6, maybe 10m when my body between the tag from the anchor, I noticed that the tag in free air get LOS at somewhere between 15m to 20m. This leads me to think that the human body (a quite watery based entity) acts as a good attenuator when placed between the tag and anchor but also seemingly acts as a reflector when positioned behind the tag. I’m currently wondering whether I might be able to augment the anchors by a more appropriate antenna thus extending the range. This would bring with it an increase in ERP which may fall foul of the legislation you mentioned earlier though… any thoughts on that matter please?
MDEK and PANS is based on TWR. Anchors and Tags successively need to transmit/receive. So basically you must have similar sensitivity on each device to have a working system.
You could improve the range of anchors using a specific antenna or a LNA (with an impact on power consumption, which should be fine if the anchors are main-powered), but the except if you modify the tags similarly, I think you’re not gonna improve your coverage.
You are right regarding the listener but you could increase the number of listener to cover a larger area.
If you need to cover a very large area I would see the possibilities below :
If keeping a TWR infrastructure, then a custom software/hardware with different channel, data rate will improve the range.
You could look at a TDOA system. In this scheme, the anchors are receiving only, and a LNA will highly increase their range without the need of the same modification on the tag. Is also works complies with the outdoor regulation are the anchors are never transmitting.
[color=#333333]Once again, many thanks for your kind reply.[/color]
Well given that I have the same LOS on both listeners and anchors then however many anchors I need to cover a given area I need as many listeners so that’s instantly doubled my costs not to mention the cost of additional hardware to aggregate that data into one coherent time series.
That said, does the forthcoming PANS v2 not address this issue?
I will have a look at what is involved in TDoA vs TWR and asses the development times and costs of each to see which might be more appropriate for me.
Could you please point me at:
[list]
[]documentation regarding the regulations you make reference to?
[]documentation and/or code that you may know of that exists for the DWM1001?
[/list]
Graham.