So i have setup my base station and surveyed it in and done the post processing, all good. I have my f9p on a building and there is a 60ft tower next to the building, I am using poe to run power and communication up the 60ft tower to my xbee box where I have a xbee pro sx at the full 1 watt ouput setting. I have about a 18inch antenna cable attached from the xbee to a lcom ANTOMNI 900MHZ 8DBI omni antenna. For the rover I have the xbee in a box with a xbee sx and the standard antenna on top of the tractor. I went out to test it and where I am there are some hills but at approx 1.5miles from the tower as I went down a hill I lost correction signal, but I could still clearly see the tower and the antenna so it should not have been the hill causing a problem unless it was fresnel zone issues and 900mhz has a much larger fresnel zone than higher frequencies but still I would think that would not be the issue.
Has anyone else used a similar setup and what kind of distances are you able to see.
Thanks
Make sure you don’t have a mix of to SMA and regular SMA. I know a few guys have had very similar issues to you when they had them mixed and the contacts didn’t touch.
thanks but I am pretty sure not I spent a fair bit of time checking to make sure I had the ends correct not mixing up rpsma and sma.
At which bitrate is the radio transmitting (my memory says it is selectable)?
I only have experience of lower power xbee for a shorter range but I once tested a 1W 400 MHz Satel radio with our Fendt that had the Topcon AGI-4 which again also has a Satel radio inside (but using the cellular antenna at the tractor, not the correct 400 MHz radio antenna). My base radio was inside my garage, upstairs next to a window and only running at 0.1W (I think 1W would have asked for a licence, perhaps on that frequency even at 0.1W but nobody knocked on my door). I could easily reach RTK fix at 2.5 km, not line-of-sight, a small forest blocking the direct view to my base (radio).
In addition to the lower frequency, the thing was 12.5 kHz channel bandwidth with FEC, just enough to transmit the legacy format RTK correction stream at about 3 kbit/s average rate.
Lowering the xbee’s wireless transmit speed should increase your range but in my tests it wasn’t fast enough anymore.
I am transmitting at 250kbps I may try slowing it down and seeing if it works but as m_elias states may not be enough bandwidth.
I wonder if certain areas are worse than others. I cannot get 2 miles line of site with XLR Xbees either. Extremely disappointing…
Isn’t there two slower speeds yet? It’s the very lowest speed that wasn’t fast enough.
yes there is 250kbps 110 and 10
110 is what I’m using
I will try it tomorrow in the daylight, what kind of range/setup are you getting/operating i.e. base antenna height/type?
My GPS+Glonass base transmits at less than 3 kbs average speed, 10 kbs would be sufficient for that. My GPS+Glonass+Galileo+Beidou base transmits at 8200 bps average speed, 10 kbs would not be sufficient.
Going down from 250 to 110 is not any significant change, about a factor of two. If you were able to go down to 10, that would be a factor of 25, a significant change in (line-of-sight) range too.
One could make MSM messages fit into 10 kbs if nothing else works but better to find other solutions if possible.
What update rate do your bases output?
Mine or OP’s? Mine is 1s update rate (except 1005 and similar).
Yeah, yours. I wonder if running 0.5hz would allow 10kps wireless speed? I also don’t know if the Xbee’s serial RX buffer would overflow, might have to set the wired baud lower then the wireless to make sure the rtcm sender buffers the data.
So I tried it at 10kbps with just gps and glonass but it just didnt work, and even using snip there were to many corrupted messages, so went to 110kbps and did not seem to be any different than at 250kbps for distance. I might just try the factory small antenna to eliminate all connections and see what thats like, so far very disappointed in range. When we ran a rural wireless internet service using 2.4 and 5.8 ghz equipment we would get distances of 30-50kms granted that was with point to point equipment but even with a sector antenna and one dish at customer premises we would get 20kms no problems and that was with 25 to 50 meg throughput, so not sure if the xbee stuff is just not very good or I have something else going on
With just a stock antenna on a ten foot pole I got about 3 miles through trees. You should get much more range with line of sight. When you dropped the transmit speed down did you also turn down the F9P to a slower speed? If you overflowed the buffers on the radio it would probably corrupt a lot of data
When I had a SMA polarity mismatch, I only got 1-2.5 miles (at best) with high gain ant and XLR radio on the base. With the proper SMA connectors I got up to 7.5 miles LOS.
Did you still send MSM messages for Glonass and GPS? I guess you still did send 1005 too?
You have to be careful with those slow repeating messages. At least my base is able to schedule those so that only one appears within one second (along with 1004 and 1012 which are legacy messages for GPS and Glonass). A burst of slowly repeating messages may well fill your buffers if the headroom is low.
I was sending 1005 1077 1087 rate time source is set to 1hz baud rate is set to 115200 same as xbees.
I am going to put up a separate test unit hopefully today with just the factory antenna and see if it changes the distance. if Guy1000 is getting 3 miles through trees with factory setup on a 10ft pole I should get at least that line of sight on a 60ft tower. I am pretty sure I did not mess up my connectors but maybe I have a bad connection on one of the cables.