mmelli 0 Report post Posted February 5, 2007 Hi group ! The radio modem manufacturer such as FreeWave or MicroHard said the range is 60 miles ( line of sight ) @ 1 Watt and will be used in my project for a data link between UAV and ground station . The UAV will be equiped with Antenex DTRA 9023 P (low profile). I have a question to do: Can I get this range with this low profile antenna installed on fuselage bottom side and a bi squad antenna on ground station ? Any help will be very welcome. Cheers Quote Share this post Link to post Share on other sites
Terry 5 Report post Posted February 6, 2007 Do you have any links to the aerials ? Can I get this range with this low profile antenna installed on fuselage bottom side and a bi squad antenna on ground station ? The short answer is no unless you can fit a tracking system to you plane that will point the aerial to the groundstation. Terry Quote Share this post Link to post Share on other sites
mmelli 0 Report post Posted February 6, 2007 Do you have any links to the aerials ? The short answer is no unless you can fit a tracking system to you plane that will point the aerial to the groundstation. Terry Hi Terry : In my project I will have a data link such as Horizon from Micropilot ...and I must be reasonable sure about radio modems range in order to communicate the autopilot ( gps position, UAV altitude, UAV attitude, etc... ) Cheers Quote Share this post Link to post Share on other sites
Terry 5 Report post Posted February 6, 2007 Hi mmelli, I dont know much about the Horizon system, I guess Micropilot would be the best people to speak to about it's requirments. 60 miles is a long way with 1W, I think you need to think about if you realy need 60 miles ? 10W would a better option at that sort of range and even then a good tracking system will be required. Terry Quote Share this post Link to post Share on other sites
mmelli 0 Report post Posted February 7, 2007 Hi mmelli, I dont know much about the Horizon system, I guess Micropilot would be the best people to speak to about it's requirments. 60 miles is a long way with 1W, I think you need to think about if you realy need 60 miles ? 10W would a better option at that sort of range and even then a good tracking system will be required. Terry Hi Terry Tanks for your reply. I said 60 miles with 1 Watt range because both manufacturer specified this distance in is own specifications. I do not know how they can " "communicate" at 60 miles . Do you know how they can ? With 45- 50 Km is enough to take information for a 1000 Hectares farm having a ground station antenna on a mobile tower of about 10 meters high (such as telescopic antenna) Here our topography is very plain and this is a good think in a communication matter. My ground antenna will be a bi quad with a moderate directional reception and a low profile antenna as described before. Cheers MMELLI Quote Share this post Link to post Share on other sites
Terry 5 Report post Posted February 7, 2007 (edited) I do not know how they can " "communicate" at 60 miles . Do you know how they can ? Yes they can using high gain aerials at both ends mounted on towers. The accuracy involved is way too high for a hobby UAV though. The UAV will be equiped with Antenex DTRA 9023 P (low profile). I have a question to do: Can I get this range with this low profile antenna installed on fuselage bottom side and a bi squad antenna on ground station ? NO ! The aerial I think you are looking at for your plane is only a standard aerial in a fancy package. With the aerials you describe I would expect the range to be under 5 miles max. If your ground station can stand some dropouts then range will be better, I don't know if it can ? The other way to gain more range is to use a higher gain aerial on your ground station but I would reccomend it be auto tracking for best results. Terry Edited February 7, 2007 by Terry Quote Share this post Link to post Share on other sites
Kilrah 2 Report post Posted February 7, 2007 (edited) A firm that makes RF modules in my region (very good ones, but still in development) managed to get 40km with 500mW power. That was with an omni on the mobile side, but with a high gain one on the fixed side, that was pretty accurately aimed. Actually, the long distance allowed narrowing the beam's angle. I agree with Terry, 60 miles with 1W seems only possible in a fixed application using high gain on both ends. Manufacturers will usually give specs if they can say the highest numbers, so the conditions will very likely be the most ideal ones you'll never have in your own application... Edited February 7, 2007 by Kilrah Quote Share this post Link to post Share on other sites
Mr.RC-Cam 126 Report post Posted February 7, 2007 Manufacturers will usually give specs if they can say the highest numbers, so the conditions will very likely be the most ideal ones you'll never have in your own application... I agree. My personal rule of thumb is to divide the mfg's rated LOS range by {at least} six when their device is used in a airborne mobile application. This will hint at the practical performance. Even then, expect some occasional RF dropouts. Quote Share this post Link to post Share on other sites
elossam 0 Report post Posted February 7, 2007 Mmelli. a modem is for digital transmission and that requires much less output power than analog video requirements for the range. They use sometimes 900 Mhz which gives 3 times more distance than 2.4 Ghz units. and finally the receivers they are using are much more sensitives (about -105 db vs -83 db for video aplications). All that doesn´t mean the manufacturers are telling the true but only a partial true as they don´t tell you how this distance was achieved and sure it would be difficult to replicate the test. In any way I know from guys using Freewave modems at distances over 20 miles (not so far from Mr. Rc-CAM rule) using high gain omni antennas for long range. Maybe they get some drop outs but the modem is set to send many times the same information packet for redundancy. In case you can get the same results your still covering a big surface but... what info are you planning to recover from that area? I doubt you can do the same for video link. Quote Share this post Link to post Share on other sites
Terry 5 Report post Posted February 7, 2007 Maybe they get some drop outs but the modem is set to send many times the same information packet for redundancy As I asked If your ground station can stand some dropouts then range will be better, I don't know if it can ? This will help a lot if it can keep sending the packets until it receives a confirmation. If the data rate is slow then this will help too. Terry Quote Share this post Link to post Share on other sites
Mr.RC-Cam 126 Report post Posted February 7, 2007 If the data rate is slow then this will help too. That is very important. The typical "fine print" long range specs are based on the lowest data rate the radio modem can use. In other words, practical range is reduced as data rate is increased due to the higher required bandwidth. Quote Share this post Link to post Share on other sites
wilson 0 Report post Posted February 8, 2007 (edited) Hello elossam Just a question Are you in Sao Paulo Brazil? Edited February 8, 2007 by wilson Quote Share this post Link to post Share on other sites
elossam 0 Report post Posted February 8, 2007 Nope Willson. I´m from the other side of the Atlantic Ocean. Spain to be more exactly. Quote Share this post Link to post Share on other sites
wilson 0 Report post Posted February 9, 2007 Nope Willson. I´m from the other side of the Atlantic Ocean. Spain to be more exactly. Hola, Elossan, I was just wondering, because I saw SP, which is the Sao Paulo acroname !!! Saludos !!! Quote Share this post Link to post Share on other sites
