RF power measurements

[Stealthmatt]

My testing is only measuring transmitting power.

For the craft, I measured video transmit power. Each craft was sending video to the RC's with iPad Air2 running Go app 2.8.3.

For the RC, transmitting measurements were taken with RTH enabled on each RC to make sure it's sending a control command. I tried stick input but the RTH seem to work more consistently, so that's what I used as a baseline for comparison purposes.

FYI, the Go app isn't going to change transmit power from the craft or RC. The RF output is fixed in the RC and craft so it complies with the FCC filings that DJI committed to. DJI cannot adjust the power outputs after filing with the FCC a fixed output number. However the new Go App may streamline the processing (H.264 decompression) of the video to be more reliable, but it doesn't change the power outputs.

They just made tweaks to 2.8.3 because of the video issue in 2.8.2 and lots of people have reported further distance, yes they may have streamlined the compression of video. However, I wouldn't put it past them if they did a quick and dirty and just increased power output till they can sneak a proper fix back in later.

But if you tested with 2.8.3 then thats all good.

That that little dongle picks up transmit power and you dont need to have it inline with the aerial? thats pretty dope, I think I might need to pick one of them up.

 

[Sinisalo]

I have DJI Go version 2.8.0 and the newest Phantom 4 firmware ( Version 1.01.0410) and my RC firmware is Version 1.6.0. I have noticed a 100% improvement on signal quality and range with the new firmware. I can sit down in my backyard and fly to places that I previously had to stand up and point the controller towards with a parabolic antenna booster. I will do a better test of range tomorrow but so far I am impressed.

I did the update and wasn't expecting anything but the altitude feature listed in the release notes, I have also experienced bettery battery life. I am doing a timelapse of my yard since I have a large garden growing and I re-seeded my whole lawn. I set up a mission in Autopilot to do a panorama shot of my front and my back yard. I have been running the mission every day I have the chance. My mission used to end with my battery life around 55-60% but now I am ending with around 69%.

 

[John Locke]

They just made tweaks to 2.8.3 because of the video issue in 2.8.2 and lots of people have reported further distance, yes they may have streamlined the compression of video. However, I wouldn't put it past them if they did a quick and dirty and just increased power output till they can sneak a proper fix back in later.

But if you tested with 2.8.3 then thats all good.

That that little dongle picks up transmit power and you dont need to have it inline with the aerial? thats pretty dope, I think I might need to pick one of them up.

I really doubt DJI would change the power output of their product after filing with the FCC, committing to a design at a specified output. But we can always hope .

As for the Immersion RF power meter, there are two different ways to measure. You can use an antenna like I did to measure RF power, or you can us the included Attenuator that allows you to connect directly to an SMA connector to get a more accurate reading. Since DJI doesn't have SMA connectors I had to use an antenna for this comparison test. These meters aren't cheap, $150, and you'll have to buy a $10 antenna for it to compare it's without SMA connectors. I'll be done with mine in a couple weeks if you'd like to buy it. $100 with antenna, less than a month old.

 

[IBV]

I measured peak power output on the RC port (P4 RC) of 10-11dBm, or 10-12mw with a RigExpert IT-24.

you mean minus 10dbm I guess.. 10dbm would be 15.8mw...

 

[jstjohnz]

you mean minus 10dbm I guess.. 10dbm would be 15.8mw...

Between +10 and +11dBm. 10dBm = 10mw. This is measuring the actual transmit power level at the RC's antenna port.

 

[phantom3menace]

So where's the best deal on an Inspire controller?

 

[John Locke]

So where's the best deal on an Inspire controller?

If you can find an early Phantom 3P controller (GL300A) on Ebay, that might work good with a P4 like the Inspire RC. Those are going for less than $200 in ebay. However the Inspire does transmit a little more power, based on my measurements. 33 vs 27, when the P4 RC was at 22. Here's an Inspire RC for sale.

FYI, if you ever want to install an Itelite antenna on the Inspire RC you will have a third antenna you have to bring out and install a small 5.8Ghz antenna on, otherwise you'll blow the RF transmitter in the RC for the 5.8Ghz link for a second RC. This assumes that you might want to preserve this second controller link channel in case you buy an Inspire someday, or you might want to sell the RC as an Inspire RC someday.

 

[phantom3menace]

I wonder if A, B or C revisions differ in output power?

 

[With The Birds]

I wonder if A, B or C revisions differ in output power?

They do.

 

[phantom3menace]

They do.

Okay, so can I assume an A is better than a B?

 

[With The Birds]

Okay, so can I assume an A is better than a B?

I don't think that is a safe assumption. From the FCC certification doco I recall A & B being the same with C less. If you search it has been covered in detail in earlier posts.

 

[IBV]

So where's the best deal on an Inspire controller?

Right
I use RF-explorer and it displays the various frequencies. I don't get more than -12dbm at a specific frequence. However, it seems the controller is using a certain bandwidth.
How much dbm did you measure at the bird?

 

[ddh1313]

Will jump in here a bit.
My first drone was a P3P with B type RC. Reading all the threads about RC Tx and which type has what, I decided to buy off the net an Inspire RC type C since it has the most Tx power.
If you can find, the first P3P RC was type A that also has good Tx power, almost as much as the Inspire type C RC.
I am not a fan of RC mods, sails maybe but nothing else. The only reason I can see to get the new Tx cables and amps is if you want to fly from inside the house or car. Remember, even if you have unlimited Tx power, you can only fly about 8 miles round trip being limited by the battery capacity.

Just curious if you obtained the type C and if so, have you done any range comparison testing?

 

[John Locke]

Can you look at your RCs and drone FCC IDs and compare the published Tx versus the reading you got? Curious if they are close. I only have the Inspire C RC and the original P4 RC that I never use.
FCC database shows Inspire C RC at almost 0.8W, the most powerful RC so far.
FCC ID Database Search

Hey Dacon, how did you find the various Inspire and Phantom RC listings? I tried your link but no joy finding what I'm looking for.

 

[WetDog]

Hey Dacon, how did you find the various Inspire and Phantom RC listings? I tried your link but no joy finding what I'm looking for.

You have to have the FCC ID number. Which means you probably have to look it up or get your magnifiers on. For the B version the link is:

FCC ID SS3-GL3001501 C1 by SZ DJI TECHNOLOGY CO., LTD

This brings up a list of likely candidates for the other controllers

FCC ID SS3-GL3001500

 

[John Locke]

If you go to:
FCC ID Database Search
you can type in the FCC number that's printed on your controller near the model number, such as:

SS3-GL3001510 (P4 GL300C)
SS3-GL3001501 (P3P GL300A)
SS3-GL6581410 (Inspire GL658A)

This will take you to the FCC filing by DJI that is stating the power of the transmitter (control signal) they have tested and validated. This shows the pattern of detuning that DJI is doing.

When you click search, go to the bottom of the page and you'll see the RF power output numbers for your controller. Here's the controllers I own and the power output listings:

BTW, my GL300B controller has the same SS3-GL3001501 listed below, so there is not difference in output claimed between GL300A and GL300B.

These listings agree somewhat with my crude measurement comparison using the Immersion meter, however not entirely. My test results show the Inspire GL658A having considerable more output versus GL300A, but the FCC listings have them at almost identical (assuming the typo I show above is correct).

However, notice the significant output reduction in the GL300C. This is apparently why the Phantom 4 struggles to have the 2+mi range as P3P (comparing stock controllers)

 

[Dacon Productions]

Check for Inspire C type RC.

 

[John Locke]

Check for Inspire C type RC.

I don't have the FCC # for that. Do you?

 

[Dacon Productions]

My radio.

 

[Dacon Productions]