rsilvers

This came out because of talk and promotion about output power and latency.

Here is what I found:

For range I put both units 20 feet in the air on a platform, and then walked away until I found a range for each where they would reliably work. I did not try to find a range where I could get the servo to move barely, but rather, where they worked reliably (likely in contrast to how a manufacturer rates them). Both antennas were vertical.

The Spektrum DSM was 636 feet.
The Nomadio was 531 feet.

I believe both claim about 3000 feet.

How can I explain the Nomadio having less range when Nomadio says it has between 7.5 and 10 times the output power?
(Nomadio claims either 75 or 100mw output while the Spektrum is 10mw).

There is a DSSS concept called processing gain: The processing gain is a measure of immunity to noise. The more the band spread of the signals, the higher the gain. Spektrum set up their data rate to allow for an 18dB processing gain over the FHSS that Nomadio uses. That means a 10mw implementation may have more range than a Nomadio 75mw FHSS system (it could be equal to an 80mw FHSS system). I had posted this weeks ago, and my hypothesis appears to be correct. Nomadio is probably hoping that people will assume that their greater power output equals more range when it fact it mostly likely only results in more power consumption.

No doubt if others test the range they will get different but similar numbers. In any case, do not assume anything about range without doing the test side by side.


I also measured the data rate and latency of a Spektrum DX3 and Pro receiver system using a Tektronix TDS-220 100 Mhz bandwidth digital oscilloscope.

The data rate being sent to the servo from the Spektrum 'receiver' is 20ms per frame, or 50 updates per second.
The data rate being sent to the servo from the Nomadio 'receiver' is 10ms per frame, or 100 updates per second.
(For comparison, JR PCM radios are approx 46 updates per second for Z mode, and 47 for S mode per channel. Standard FM PPM systems are about the same.)
The advanage here goes to the Nomadio -- 100 frames per second is excellent and how it should be done (I feel that anything in the 80 to 120 frames per second range is ideal).


Finally I did latency testing.



Minimum latency of the Spektrum DX3 when using the channel-3 switch is 7-8ms.

Here you can see that the latency is over 6ms:



Here you can see that the latency is less than or equal to 8ms:



Note that this is minimum latency. If the frame is missed, you have to wait until another 20ms passes to pick up the next one. So it is 26ms max, and about 16.5 average.


The Nomadio salesman said that the Spektrum system had about 15ms of latency inherent in the transmission, and another 30ms of latency provided by the transmitter encoding the controls. That would be 45ms. I was not able to duplicate those numbers.

Spektrum's claim of '3ms' is quoted as 'the figure added to your radio's processing time' so I have not confirmed or denied that specific claim because I included the radio processing time in my calculations. If the radio processing time was 4 or 5 ms, then their figures seem accurate.


For the Nomadio I found that latency was always between 13.0 and 16.0ms so that is about 14.5ms average or 2ms (1/500 of a second) less than the Spektrum's average.







Here the Nomadio has a small but measureable advantage for 'average' latency. Also worth noting is that the Spektrum has about 1/2 of the minimum latency of the Nomadio (though also has a greater maximum latency). I don't see an obvious winner on this stat.

agizis

Thanks for your thorough analysis, it was refreshingly scientific.

The problem with your latency analysis is that it went off the grip button. In the Nomadio system steering and throttle get a higher priority than the grip button (mostly because the grip button is a SoftKey in the Sensor so it can be reprogrammed to perform any function in the Sensor).

You need to measure the latency on the steering or throttle analog channels. (Hint for the Sensor, only apply voltages between 0 and 3.5 volts the analog ports on the Sensor). I think you'll be more impressed with our results there.

Also make sure you're running the latest software, it keeps getting faster everytime we release an upgrade.

As far as range numbers go, results will vary. Your range number of the Sensor seems quite short to me. Maybe your unit has an issue. That said, Nomadio has never claimed 3000' range, that's a SpektrumRC (TM) claim.

Best regards,

---Alex from Nomadio

rsilvers

Ok, you spec a 1000 foot range. I don't think there is a problem with my range test, I just tested so that it had to work without stuttering or glitching at all for about 20 seconds. There were further distances where it moved for a second or so with both systems. 500 'reliable' feet is really far -- there is NO chance of seeing a car at that range. I am satisfied with the range.

I accept what you say about the grip button and priority. I sent the system back to the owner so I won't be testing it. It would be nice if you posted what result I would find, if measured the same way as I did with the grip button. I will accept your results if the test is explained in a non-simplified / non market-speak way.

By the way, the React looks nice. I am glad you simplified the enclosure. It looks just perfect now.

agizis

Thanks.

Yes, let me dig up what we did before and see whether it's post-able, or if we need to remeasure again.

Either way, it's likely to take us a couple days.

spawn

So when are we going to see any data?

amatuloo

Post-able?

Nomadio_Sales

I sent him an email and talked to Doug one of the EEs to get the data dug out. Not real high on the priority list with the Bomb Bot and new radios coming out. Send Alex and email perhaps that will help him find the time to get you the test results.

Nomadio_Dave

Sounds like a solid test... and it sounds like you've got some problem with the Sensor, OR you're running 1.x software. There is a very big difference in practical range through the evolution of our software. And in fact, the older software runs in DSSS mode only, nearly identical to Spektrum's "DSM" (I think they use a slower link and longer spreading code, which might, in fact, yield longer range in some cases, as you get a slightly higher protocol gain).

I don't THINK we've ever claimed over 1000ft... but I'm not in marketing. I've never run working Nomadio hardware that benchmarked less than over 1000ft, though your distance is always going to be somewhat location dependent -- I do most of my testing around my farm (26 acres) and the neighbors. I've calibrated the road out back (about 1/2 mile in length), and when I need more distance, I go down US RT 40, which has these handy mile marker posts along the highway (but I do lose line of sight after about 3400ft). I've typically seen about 2100ft with "nomal" Sensor gear along RT40, to the point where the link isn't mostly there, though that's my typical Sensor test with the Sensor up on the mailbox and with me holding the car -- you'd see a bit less with the car on the ground. I usually do drive tests with the military/robotics stuff out to 1000ft or more; it's impossible to actually drive my mini-T even a significant fraction of that 2100ft.

Anyway, that's my test setup; I don't see anything wrong with yours, either. Different results could be explained as more noise in your area, or something different about that Sensor. Read on.

You only get a real 75mW or so when running the frequency hopping software.

Good in theory, no so good in practice. Nomadio systems are always DSSS -- that's actually a hardware protocol in the chip we use (the same chip family, in fact, as the Spektrum does). You can vary the size of the spreading code, either 32-bits or 64-bits, but that's always in the protocol. Our older software, as mentioned, only ran DSSS mode. The 2.x software added frequency hopping on top of DSSS, but the DSSS processing gain is always there.

Yup -- you can't have any real A/B comparison of systems unless you tests, and multiple tests, along the same course under the same conditions.

You may also notice that the Nomadios fire all servos at once; so there's no additional delay between, say, steering and throttle. There is, however, some additional processing delay on the Sensor for buttons vs. pots; the steering and throttle are hard-wired to servo channels but highly optimized. Everything else (at least in the current software) runs via "soft keys", and will have additional latency over the optimized channels. I don't know just how significant it might be. I also don't know if Spektrum is firing all servos at once, as we do, or in series, as most analog receivers will do.

Nope... whoever said that is confused. 45ms is largely undriveable at any normal R/C speeds... believe me, we weren't always fast. Our initial robotics control system was essentially too slow for real R/C driving, and some of our early test people pointed this out in interesting ways.

This will vary by software release (newer releases are faster), and of course, whether you pressed a button or a potentiometer. I think you're pressing a button here, which as mentioned will be slower than steering or throttle.

rsilvers

All makers seem to quote 'max range' and give an asterix. Same with cordless phones. People never take it at face value, or at least should not. I could have done a test in level open field and would not be surprised to get 1000 feet.

The more important number is minimum range (within reason), not max range. I don't mean minimum range if you are in a building, but a reasonable test with some items in the environment. I don't expect industry to quote that because there are no laws and no one else will. I feel that 500 feet will work most of the time and that is way too far to see a car so everything is just fine.

I did the test to prove my theory that the DSM would have a comparable range to the Nomadio even though the Nomadio had between 7.5 and 10 times as much RF power. The Nomadio sales guy stated several times that Nomadio was 75 or 100mw and DSM was just 10mw. Clearly this was designed to influence people that the Nomadio would have more range. I replied that in theory the processing gain of the DSM would make up for that. My hypothesis was backed up by my experiement. While it is factually correct to state that Nomadio has more RF power, it needs to just to keep up -- not to get much further range.

In any case, your system seems very nice and I fully accept that the steering and throttle have priority over the push buttons and that your response time is exceptionally good.

spawn

Nomadio_Sales

Your welcome to test a React

JRexA

Wy don't you arrenge to borrow him one, for testing?

MadDogRC

i got a problem with the method to test the units. they were 20ft in the air which means that a clearer range can be obtained and other factors removed to make range increased.

really, the units should of been tested on the ground, or atleast hovering off the ground. i plan to conduct a few trials of range tests using my spektrum pro tx module and pro receivers in my futaba 3pk. i will do in air tests and on ground tests. i will use a gps system to calculate how far i can go before fail safe kicks in.

tests will be conducted in a pro 4 hara electric vehicle and a tnx 5.2r nitro vehicle.

also, how do u tell if the vehicle is still operable while ur at such a distance that you cannot see it???

SAVAGEJIM

I would love to see your results. BTW, thanks fir bringing forward this thread; I thought it was deleted.

takenotes Bch

Have a friend hold up a pair of binoculars for you, it works pretty well
Can't wait to hear some new results

MadDogRC

ok fellow rc'ers (my new word),
i shall be conducting range testing which will be dead-set accurate and will have only minimal variables.

the new plan:

take my pro4 hara ELECTRIC and my tnx 5.2r NITRO and fit BOTH with a high quality gps system which records just about everything such as speed, but most importantly RANGE/DISTANCE.

i will find a nice stretch of tarmac (road) and drive each vehicle which is fitted with the gps unit and running with a Spektrum Pro receiver and Spektrum Pro module in my 3PK. i will drive each vehicle at 50% throttle in a straight line as far as it goes until failsafe kicks in. when failsafe kicks in the vehicle will stop and the total range from me to the place where the vehicle stopped will have been recorded by the gps. so simply enough. i walk/run to my distant vehicle/s and record down the distances in meters (for the aus boys and ft, for the yanks).

conditions:
fully charged TX battery
fully charged RX battery in TNX and fully charged battery pack in pro4 hara
radio held at chest height and not raised to increase radio range
radio 1ft away from chest (horizontally)
module antenna verticle
receiver antennas full extended and verticle

anything else to add?

i just did a quick range check then and found my spektrum does 669ft approx (+/-10ft

JRexA

Sounds like a good idea.


Ought to get my Garmin Etrex back and try the same with my Sensor, I just have a bit of a problem, finding a straight road, more than 300 feet/100 meters......

MadDogRC

i got the garmin etrex too! mines CAMO though, hehe!

need 100m of road? along my street. i measured it to be around 210m long!

SAVAGEJIM

So, have you done the expiriment? I'm curious of what your results are.

MadDogRC

sorry man, busy with skool studies, etc. havent had time to properly test out anything yet.

MadDogRC

sorry guys, here in Perth its rain rain rain sun rain rain and whenever i get sun i'm either at skool or busy with my gf, lol!

skool holidays in 3 days for me so i should be able to get in some test time shortly.

thanks for your patience!

SAVAGEJIM

No rush, since it is the cooler season for you guys, I totally understand. But as soon as you guys hit your spring and you get more sunny days and therefore more time to test, I really look forward to you results and assesments.

MadDogRC

i'll be able to get my electric testing done very shortly using my pro 4, just need to borrow my mate thats across the road.

nitro testing will be maybe a week or less time? gotta pick up my tnx diffs and shove them in the truck.

cya

MadDogRC

update: bad news.

lhs doesn't have my tnx diffs since the supplier is a jerk. also the weather is crap, raining raining raining. just great!

grrr, this sucks

JCINTEXAS

DYNAMIC TESTING FOR WORRY-FREE FLYING:

Dynamic Testing goes well beyond the standard "range check" which should be regularly performed in accordance with a radio manufacturer's instructions found in the Owners Manual. Dynamic testing is conducted by creating rigorous conditions under which to test your radios.

Here are some examples:
1. Place your 2.4GHz transmitter in a location such that the RF signal must pass through physical barriers to reach the receiver. I have done this by putting the transmitter inside a room and locating the receiver in a distant room. The RF signal then must pass through 3 or 4 walls of my house. My wife moves the control sticks as I observe my receiver and servos for normal operation. I have also placed my receiver behind a 30 gallon aquarium and various other RF barriers including my car. The RF signal lock has remained rock solid. Use your imagination in creating barriers for the RF signal to penetrate.
When satisfied that your radio can do this, make the RF environment more "hostile".

2. Place an "alien" 2.4GHz emitter within 2 feet of your receiver. (2.4GHz cordless phone, cordless earphones, Baby Monitor, WiFi xmitter) With this active alien 2.4 GHz emitter close to your receiver and your transmitter still in the remote location, check to determine if you still have a solid "RF Lock" between your transmitter and receiver.
When satisfied that your radio can do this, make the RF environment more "hostile".

3. Turn off your receiver and transmitter. Leave the alien 2.4GHz emitter(s) active. Turn on your receiver while leaving your transmitter turned off. Check for harmful interference. A properly operating 2.4GHz RC receiver should reject any interference from the alien emitter(s).

4. With the alien emitter(s) still active, turn on your RC transmitter. Your receiver should quickly reacquire the signal from your transmitter and operate normally.

5. This test requires one or more additional 2.4GHz RC transmitters. Turn on the transmitter to which your receiver has been "bound". Place it in a remote location as per described above. Place a seperate 2.4GHz RC transmitter within 3 feet of your receiver and turn it on. Now turn-on the receiver. Check to determine if their is any harmful interference. Your receiver should acquire the RF signal from the transmitter to which it has been bound and should operate normally.

I have two Futaba FASST radios (6 and 7 channel). Both radios have passed all of these tests with flying colors. I have not detected a single glitch.

I hope others in this Forum will run tests such as I have described here and will keep us all informed of their results.

Regards
J.C.