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Jan 17, 2010, 06:28 PM
Missileer Extraordinaire
Mel Duval's Avatar
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Comparative Range Test Data on Various Systems (Long Post)


This is old data, but hopefully still useful. A year or so back, a UAV group I sometimes support needed to know what the max range of an off the shelf radio control system was. At the same time, the FAA ARC had some questions about the max range possible for 2.4GHz radios. I mentioned to Fred Marks that I was going to run a test for the UAV guys and was asked to run a test that would compare with testing done in the past for 72MHz. This testing used 72MHz receivers mounted at 50 feet and the transmitter was moved out till the receiver lost the signal. Fred Marks did the bulk of the testing and it directly supported the 1991 narrow band AMA guidelines. This was a major effort and paved the way for the whole narrow band revolution. It produced a significant database relative to range and radio performance that set the standard to be compared to.

It should be clearly noted that this was to be a best case test, with the receiver antennas oriented for the best reception. No attempt was made to block or degrade the signal path from the receiver to the transmitter. The measurement device was an automobile odometer and the distances were rounded to .1 mile. I was not trying to get down to the foot.

A friend has a 50 foot aerial photography mast system that mounts on his Suzuki Tracker. You can see this in the photos. I made a fixture that holds 3 AR 7000 receivers (1 each for the X9303 integrated 2.4, the 9303 module system and the DX-7), 1 AR 6000/DX-6 , 1 AR 6100/DX-7 and one Futaba R607FS. The fixture is made out of a 4” by 48” plank of ¼” balsa. The balsa plank has a 1/16” plywood rib on each side of it making it into a “C” beam along with some 3/32 plywood in the center to make it strong enough to bolt to the mast. The fixture is interfaced to the mast by a couple of metal shelf brackets and a wood dowel that I center drilled and put a piece of ¼”-20 rod in to attach it to the fixture. This is shown in the photos. Each receiver is paired with a full size servo hooked up to the throttle channel that I made a 16” long flag for. I then set up the fail safes for each receiver to actuate the servo to low throttle on loss of signal. The mast was then extended to 50 feet from the ground. I then put the transmitters in the back of my pickup held by a friend and drive them out till we lost link. Some quick testing showed that it takes a LONG way to lose link! After looking a long time for a 3 mile clear stretch of highway, I went out to a stretch of Highway 331 that included a bridge as the last portion shown below. A screen print of a Google Map is shown below. The top of the bridge was at about 2.4 miles from the receiver site. It had a parking area on the other side that had a somewhat obstructed view back to the receiver site at about 2.6 miles.

The procedure was as follows:
-Transmitter held by person in back of open vehicle at approximately normal height
-Cell phones used for communication
-Operation confirmed and odometer zeroed at start of each run
-Transmitter driven out until flag dropped at Loss of Signal (LOS)
-Test run at least two times to verify repeatability
- The Transmitter vehicle slowed down on 2nd run before the initial lost link
position to increase the accuracy of link loss distance measurement

I planned to do all 6 receivers including the parkflyer receivers, but the traffic got too heavy as the afternoon wore on (wonder of wonders, it took considerably longer than I thought to get the test up and running…). For this reason, I focused on the full range systems. The results are actually fairly similar to those seen before with a few interesting differences. The first run was with the Futaba FAAST TM-7 module installed in a 9C transmitter along with a R607FS receiver. At the same time, I also ran a Spektrum DX-7/AR 7000 combination. The Futaba had a pretty consistent range of about 1.8 miles with a definite dropout at about 1.6 miles. On the way back with the truck cab in the way, but the transmitters held as high as possible, I got about 1.5 miles with a solid link all the way once it acquired. Now for the interesting part. The DX-7/AR 7000 repeatedly quit within a few tenths of a second of the Futaba FAAST system. I had them pretty close together and this may have been the issue. Something a little odd was going on as will be seen later. I ran this one about 4 times because I expected a greater range from the JR based some other testing. I ran the 9303/AR 7000 tests next. Both of these had a range in excess of 2.5 miles and both lost and re-reacquired at virtually identical ranges. I lost link on the back side of the bridge but re-acquired in the parking area if I moved to where I had some line of sight back to the receivers. I expect the differences lie in the AR 9000 receivers and the somewhat obstructed view I had back to the receivers from the parking area.
Last edited by Mel Duval; Jan 17, 2010 at 06:59 PM.
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Jan 17, 2010, 06:41 PM
Missileer Extraordinaire
Mel Duval's Avatar
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Second Test at a Better Site


Given that I was running out of road , I started looking for a better place to test. The test was run on the north end of test site B-70. B-70 is the spaceship looking cleared area in the Google Map attached. The exact site was site B-10. I used the same basic setup as last time except that I used my fiberglass mast which attaches to my truck rather than the metal mast we used last time. You can see the 72MHz antenna tubes hanging down from the fixture in the photos. The same flag setup with the 2.4 failsafe lower the flag when it activated on loss of signal. Loss of signal on the 72MHz units was a judgment call relative to picking up a noisy servo as it was being operated slowly from end to end. A photo shot downrange is included along with some shots of the test set-up on the little man-made hill. The hill is about 30 feet or so high. There are no bushes/wires/trees/etc. in the way as you can see. There were, however, some ridges/dips in the road I had not counted upon and had not noticed in my site survey. The first ridge was at about .5 miles, the second at about 1.5 and the big one at about 2.1 miles. The road came back up into line of sight at about 2.5 miles downrange. I also ran into some road maintenance at about 3.9 miles. This limited the 72 MHz testing. I first put the mast up at about 15 feet. The procedure used was the same as before. When we got back from the first test run and had encountered the dips, I put the mast up as far as I was comfortable with in the wind and considering the weight of the fixture. This was in the neighborhood of 30 feet. It did not make much difference, if any.

An thing interesting was that the range I got with the Futaba FAAST system was significantly greater than the previous test. The terrain was quite a bit clearer, the humidity was about 50% or less and the temperature was about 45 degrees. I talked a while to the site manager and he told me the RF environment around his site is pretty clear and had been surveyed previously. The site manager had also worked at other areas and when I told him the data we were getting did not match the data we took down on Highway 331, he mentioned that there is a 2.2 GHz microwave relay link tower/installation on the south side of the bay not too far from the bridge. Just a guess, but it may have been that the relay link was bringing up the noise floor and reducing the range. Maybe not. Another difference was that the data taken on Highway 331 was more absolute. When a system quit, it quit. Out on B-70 there were a number of “blips” before some of the systems lost link, mostly on the Futaba and sometimes on the JRs. It could also be that the considerable delta in humidity (or temp??) made the difference. I do know that the ranges I got were pretty consistent and well within the resolution of my measuring device (the odometer on the test truck and the call from the guy in the back to the front). Another point of interest is that there were some low power 2.4 video transmissions associated with some UAV testing going on at the edge of the compound I was in while I was conducting my test, but I did not see any noteworthy indications of interference at any time.

A summary of the results for this test series is:
1. 72 MHz JR 9303/synthesized RF module/JR 790 PCM synthesized Rx ----- In excess of 3.8 miles
2. 72 MHz JR 9303/synthesized RF module/Hitec-RCD Super Slim FM Rx ----- In excess of 3.8 miles
3. 72 MHz Futaba 7UAF/Castle-Berg 4 ch RX ------------------------------ Became noisy @ 2.1 miles
4. 2.4 GHz JR X 9303 integrated 2.4/AR7000 Rx --------------------------- 3.2 miles
5. 2.4 GHz JR X 9303 integrated 2.4/AR9000 Rx --------------------------- 3.6 miles
6. 2.4 GHz JR 9303 module 2.4/AR 7000 Rx -------------------------------- 3.2 miles
7. 2.4 GHz Futaba 9C/FASST TM-7 module 617FS Rx----------------------- >2.1 but <2.5 miles*
* Because of a dip in the road, the signal dropped out at 2.1 miles. It did not come back by the rise in the road at ~2.5 miles

So my take-aways from this test were:
- The JR 2.4 radios with the diversity receivers had the best range again. They also re-acquired sooner on the way up out of dips in the road than the Futaba did. I guess this is not really surprising. The range difference was not as significant percentage wise this time.
- The JR AR 9000 receiver had almost a half mile greater range than the AR 7000
- The 72 MHz JR radio had more range than I could measure. The Futaba/Berg combo had about as good a range as the Futaba FASST.
- The Futaba FAAST system had a significantly better range this time
Last edited by Mel Duval; Jan 17, 2010 at 06:47 PM.
Jan 17, 2010, 06:51 PM
Missileer Extraordinaire
Mel Duval's Avatar
Thread OP

Last Set of Testing


To get some more data on other radios, I borrowed an XPS and an Airtronics to conduct range testing on. I inquired with the manufacturer about getting a Hitec to use for the test and send back, but was told it was not available. This set of testing just missed the B-70 test series. Another test was planned on B-70, but in between weather and test personnel availability, the test kept getting delayed. Since it was unknown when or if I could get back on B-70, a second Hwy 331 test was conducted. The same basic test set-up was used with a few differences. I used the fiberglass mast mounted on my truck but at full extension, I could not use the big fixture. I built a new smaller and lighter fixture to reduce the load on the mast. The fixture had places for only 3 receivers. The height at the receivers was slightly shorter (~40 ft vs 50ft). The test was re-run along with a JR 9303 2.4 Spektrum module /AR 7000 for comparison purposes. Conditions were about the same as the first Hwy 331 test. The 9303 had results similar to the previous testing, as I was anticipating (and hoping!), since it was my test case. The Airtronics had similar results to the Futaba FASST, maybe because it has what appears to be a very similar antenna system. If I were going to do it again, I would measure the FAAST along with the XPS and Airtronics. In any case, the bottom line was:

JR 9303 module 2.4/AR 7000 Rx > 2.4 miles
JR 9303 XPS module/8 channel Rx ~ 2.4 miles with multiple dropouts at 2.3-2.4 miles
Airtronics RDS8000 ~ 2.3 miles with a deep null at about 2.0 miles

My take on all this testing is simple. Any 2.4GHz radio of those I tested has enough range to fly a model aircraft within visual range, even giant scale or jets. It appears to me that systems with multiple receivers may well have an advantage. Is it enough to matter? I can’t say that. I can say that if I was going to fly a giant scale plane/jet with lots of carbon fiber and/or metal in it, I would use a system with multiple receivers. But that is a PERSONAL choice based on my own internal biases. As was said a long time ago, “You pays your money and makes your choice”.


I have no plans at this time to do any more testing, although I still have the fixtures and mast.
Last edited by Mel Duval; Jan 17, 2010 at 10:15 PM.
Jan 17, 2010, 07:37 PM
Registered User
Nice bit of work there !
Jan 17, 2010, 07:46 PM
mostly gliders
liukku's Avatar

Very good tests!


Hello Mel Duval
Very good tests even though I had completely different values when I tested my Multiplex M-Link 2.4GHz.
The receiver was a 7-channel "light receiver" that comes with the module.
I did the test at 1 meter above the ground, the equipment was installed in the model and it was -10 degrees Celcius cold outside that day. M-link was reliable up to 1000 meters / 0.62 miles
Did you test at ground level as well? If so, what did you get the values then?

/ Ville
Jan 17, 2010, 08:19 PM
Missileer Extraordinaire
Mel Duval's Avatar
Thread OP
Thank you! I did not do any ground level testing since I was trying to generate data equivalent to the previous 72 MHz tests conducted at 50 feet. I did find once you were up about 30 feet or so, farther up did not make any significant difference as long as you have line of sight.
Jan 17, 2010, 08:38 PM
mostly gliders
liukku's Avatar
Quote:
Originally Posted by Mel Duval
Thank you! I did not do any ground level testing since I was trying to generate data equivalent to the previous 72 MHz tests conducted at 50 feet. I did find once you were up about 30 feet or so, farther up did not make any significant difference as long as you have line of sight.
Ok, so there is really such a big difference between 3 feet and 30 feet.
I may try a bit more this summer, at a slightly higher elevation. Hopefully, also the bigger 7 channel receivers with telemetry come onto the market.

Thanks again

/Ville
Jan 17, 2010, 09:40 PM
65 years of RC flying
Daedalus66's Avatar
Many thanks for the fascinating and very useful test work.

My only regret is that you didn't get to test an AR6100, as that might have helped to resolve endless debates.
Jan 17, 2010, 10:21 PM
Registered User
Information much appreciated, a pity only the Hitec Super Slim RX was tested.
Await similar test results on the new Hitec 2.4GHz system which has full telemetry, if at all possible, given:
Aurora 9ch Power Down for Range Check is 1mw - tested to at least 1/4 mile.
2.2KM Rx was inside the car
"Today I did a car ground range test. Full power, not range check dedicated mode. Very impressed ! 2.2km ground level !!!
And must stop the test because of the field iregularities, even if we choosed a very flat area, the car passed behind a small (2-3m) hill that blocked the signal completelly. I guess that this system can do more than 4km in the air ! I wrote system and not Aurora, because was a module mounted on a T9C. Did I mentioned that the Rx was inside the car, placed in the back, having direct vision to the transmitter via the rear window? "
Carbon Fiber Fuse... Report from well known Glider Pilot and Fly RC author Mike Lee

Link to this thread added under "Range check and Range problem solving" on my web page

Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links
Jan 18, 2010, 12:55 AM
Registered User
Thanks for all the time and effort that went into planning and executing these tests.

While many of us would have liked to see more combinations tested (Hitec, Assan, Spektrum ParkFlyer etc) there is a limit to how much equipment any one hobbiest can collect together for these events and what you managed is highly relevant to a huge slice of the user-base today.

The results are certainly interesting and reassuringly align with expectations given the physics that applies.
Jan 18, 2010, 04:34 PM
SlowStick Test Pilot
patrickegan's Avatar
Mel,
Thanks for your efforts!
Jan 18, 2010, 05:19 PM
Registered User
Mel,

Great job!
Jan 18, 2010, 06:10 PM
Registered User
Quote:
Originally Posted by Mel Duval
Given that I was running out of road , I started looking for a better place to test. The test was run on the north end of test site B-70. B-70 is the spaceship looking cleared area in the Google Map attached. The exact site was site B-10. I used the same basic setup as last time except that I used my fiberglass mast which attaches to my truck rather than the metal mast we used last time. You can see the 72MHz antenna tubes hanging down from the fixture in the photos. The same flag setup with the 2.4 failsafe lower the flag when it activated on loss of signal. Loss of signal on the 72MHz units was a judgment call relative to picking up a noisy servo as it was being operated slowly from end to end. A photo shot downrange is included along with some shots of the test set-up on the little man-made hill. The hill is about 30 feet or so high. There are no bushes/wires/trees/etc. in the way as you can see. There were, however, some ridges/dips in the road I had not counted upon and had not noticed in my site survey. The first ridge was at about .5 miles, the second at about 1.5 and the big one at about 2.1 miles. The road came back up into line of sight at about 2.5 miles downrange. I also ran into some road maintenance at about 3.9 miles. This limited the 72 MHz testing. I first put the mast up at about 15 feet. The procedure used was the same as before. When we got back from the first test run and had encountered the dips, I put the mast up as far as I was comfortable with in the wind and considering the weight of the fixture. This was in the neighborhood of 30 feet. It did not make much difference, if any.

An thing interesting was that the range I got with the Futaba FAAST system was significantly greater than the previous test. The terrain was quite a bit clearer, the humidity was about 50% or less and the temperature was about 45 degrees. I talked a while to the site manager and he told me the RF environment around his site is pretty clear and had been surveyed previously. The site manager had also worked at other areas and when I told him the data we were getting did not match the data we took down on Highway 331, he mentioned that there is a 2.2 GHz microwave relay link tower/installation on the south side of the bay not too far from the bridge. Just a guess, but it may have been that the relay link was bringing up the noise floor and reducing the range. Maybe not. Another difference was that the data taken on Highway 331 was more absolute. When a system quit, it quit. Out on B-70 there were a number of “blips” before some of the systems lost link, mostly on the Futaba and sometimes on the JRs. It could also be that the considerable delta in humidity (or temp??) made the difference. I do know that the ranges I got were pretty consistent and well within the resolution of my measuring device (the odometer on the test truck and the call from the guy in the back to the front). Another point of interest is that there were some low power 2.4 video transmissions associated with some UAV testing going on at the edge of the compound I was in while I was conducting my test, but I did not see any noteworthy indications of interference at any time.

A summary of the results for this test series is:
1. 72 MHz JR 9303/synthesized RF module/JR 790 PCM synthesized Rx ----- In excess of 3.8 miles
2. 72 MHz JR 9303/synthesized RF module/Hitec-RCD Super Slim FM Rx ----- In excess of 3.8 miles
3. 72 MHz Futaba 7UAF/Castle-Berg 4 ch RX ------------------------------ Became noisy @ 2.1 miles
4. 2.4 GHz JR X 9303 integrated 2.4/AR7000 Rx --------------------------- 3.2 miles
5. 2.4 GHz JR X 9303 integrated 2.4/AR9000 Rx --------------------------- 3.6 miles
6. 2.4 GHz JR 9303 module 2.4/AR 7000 Rx -------------------------------- 3.2 miles
7. 2.4 GHz Futaba 9C/FASST TM-7 module 617FS Rx----------------------- >2.1 but <2.5 miles*
* Because of a dip in the road, the signal dropped out at 2.1 miles. It did not come back by the rise in the road at ~2.5 miles

So my take-aways from this test were:
- The JR 2.4 radios with the diversity receivers had the best range again. They also re-acquired sooner on the way up out of dips in the road than the Futaba did. I guess this is not really surprising. The range difference was not as significant percentage wise this time.
- The JR AR 9000 receiver had almost a half mile greater range than the AR 7000
- The 72 MHz JR radio had more range than I could measure. The Futaba/Berg combo had about as good a range as the Futaba FASST.
- The Futaba FAAST system had a significantly better range this time

Sure looks like WSMR, (White Sands Muissle Range) New Mexico...
Jan 18, 2010, 07:09 PM
Registered User

Spektrum


Quote:
Originally Posted by kgfly
Thanks for all the time and effort that went into planning and executing these tests.

While many of us would have liked to see more combinations tested (Hitec, Assan, Spektrum ParkFlyer etc) there is a limit to how much equipment any one hobbiest can collect together for these events and what you managed is highly relevant to a huge slice of the user-base today.

The results are certainly interesting and reassuringly align with expectations given the physics that applies.
Yes it is too bd he couldn't have had a Spektrum to use in the tests. But there has been several Spektrum test done and didn't include some of the equipment he used.



>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<
Jan 18, 2010, 08:14 PM
Registered User
JR/Spektrum products were indeed tested (Tx: 9303+AirModule and X9303, Rx: AR7000 and AR9000) just not any of the ParkFlyer Rx (eg AR6100, AR6110 etc).


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