Range tests

[Engine Doctor]

22 hours ago, gangster said:

For years I have always range tested models at the start of every session. I lost my thoroughness on this one when after range testing with an FRSKY module in a TX. I inadvertently left it on low power, no warning on the mode I was using. I consequently went out of range and it cost me a new Hanger Monkey on its maiden flight. A lovely flyer it was too. But in reality I am a big advocate of regular range checks. I have little time for all the excuses, interference etc from people who never range check

A good routine when performing a range check with FrSky is to get into habbit of performing a fail safe test at the end by turning off you tx. That way the range test/reduced range setting will be switched off and full range / power restored ? 

I have also flown with the reduced range setting enabled  😳 but luckily i had no problems and never noiticed until after I landed. That was with an Arrows T33 so although its readonably quick its size means its not flown too far out. 

[gangster]

8 minutes ago, GrumpyGnome said:

Unless I've misinterpreted things, a number do include them - my Radiomaster and Taranis have all sorts of signal strength gubbins..... don't Spektrum, for example, gather telemetry about fades, frame losses etc.....?

Yet none of these new fangled systems can beat what most transmitters had back in the day. A meter on the front that you could glance at as part of your pre take off check. Telemetry etc is no use if you have to go look in menus to find it. Yes it will give details if received signal strength but I guess 90% of the time it will not be read until after the bin liner has been deployed 

[Dickw]

2 minutes ago, gangster said:

Yet none of these new fangled systems can beat what most transmitters had back in the day. A meter on the front that you could glance at as part of your pre take off check. Telemetry etc is no use if you have to go look in menus to find it. Yes it will give details if received signal strength but I guess 90% of the time it will not be read until after the bin liner has been deployed 

The strength of the signal received 'at the receiver' is displayed on the main screen of my (11 year old) transmitter via telemetry, so a quick glance at the screen before take off confirms that the signal is OK. I think most telemetry transmitters probably operate like this.

 

Dick

[gangster]

10 minutes ago, Dickw said:

The strength of the signal received 'at the receiver' is displayed on the main screen of my (11 year old) transmitter via telemetry, so a quick glance at the screen before take off confirms that the signal is OK. I think most telemetry transmitters probably operate like this.

 

Dick

Sounds a good facility and indeed had got to be an aid to ground range checking. Well worth a glance before take off although may not show up at close quarters

[GBG]

On the latest Ethos Frsky transmitters the tx repeatedly calls out "Range Check" whenever you are in that mode. Also the tx gives out spoken warnings when the RSSI or VFR hit low or critical levels. You don't need to look at the tx screen.

[Nigel R]

1 hour ago, gangster said:

A meter on the front that you could glance at as part of your pre take off check

 

What does that meter tell you though?

 

[Nigel R]

2 hours ago, Cuban8 said:

I wish manufacturers would include a proper diagnostic tool that will give the operator confidence in the strength of signal radiated. How difficult or expensive would that be to include on a mass produced product?

 

I'm almost 100% sure that even the most basic telemetry (e.g. Spekky AR620 or similar) is that tool.

 

 

[GrumpyGnome]

Yep, on my TX16 screen, I show signal strength. I also have warnings for low and critical levels.

 

And I have it 'called out' when I flick a switch - along with things like flight mode, flap position, undercarriage position, flight/motor time....

 

No need to hunt in menus, except when setting up the plane in the first place.

Edited September 18, 2023 by GrumpyGnome

[gangster]

39 minutes ago, Nigel R said:

 

What does that meter tell you though?

 

RF voltage at the aerial, the most likely reason for that to drop would be flat/ failed battery cell. A very useful facility back in the day

[MattyB]

3 hours ago, gangster said:

Yet none of these new fangled systems can beat what most transmitters had back in the day. A meter on the front that you could glance at as part of your pre take off check. Telemetry etc is no use if you have to go look in menus to find it. Yes it will give details if received signal strength but I guess 90% of the time it will not be read until after the bin liner has been deployed 

 

It's one of the great mysteries of aeromodelling... Why do those don't use or fully understand telemetry seek to "educate" those who do use it every single flight on why it's "worthless"?  A short summary for those who aren't aware of how a modern voice enabled TX and RX that features RSSI telemetry works (e.g. Frsky, Jeti, Radiomaster, etc)...

 

The RX is transmitting it's received signal strength (and often the power supply voltage too) back to the TX in real time from the moment it is switched on. The TX is (by default) monitoring that in real time, and providing audio warnings (again by default - no mandatory configuration required) based on multiple RSSI thresholds that are fully tuneable pre-flight should the pilot choose to do so. This means you will be alerted via a voice call out to any signal strength issue well before the model goes out of range, enabling it to be turned back and landed. In addition the pilot can configure TX telemetry info on the home screen by default if he wishes to, and have RSSI and RX pack voltage called out periodically on an ongoing basis or on demand at the flick of any switch. In combination this functionality is akin to flying around at full transmission power whilst simultaneously carrying out an automated real time range test, every second of every flight. Finally the TX voltage itself is also actively monitored and subject to voice callouts if it dips below pre-set thresholds, so again you'll be notified well before a transmission failure occurs that you should land and charge the transmitter.

 

So yes, it really is far, far superior to an analogue signal strength meter on a TX from the 80s... 😉

 

Edited September 18, 2023 by MattyB

[Ron Gray]

Don't forget VFR as well!

[Jon H]

Bit late to the party but i always range check any new model or model that has been apart, rebuilt etc. After that as a track record of perfect operation develops i tend to not worry about it too much. Clearly any twitching or other issues are cause for immediate landing and investigation, but if its all working fine i tend to leave it alone. 

 

Modern radio is so much better than it ever used to be in terms of reliability. In the old days when you assembled and tuned your own radio gear i can understand the need to check it every time, but with modern gear i really do not see a need for it. Especially as 2.4ghz gear cannot be accurately tested by powering it down. Its the equivalent of power testing your engine by running it at half throttle and its just not telling the full story. I will do it on a new model/rx etc as its the only option but beyond that it is of very questionable utility. 

 

I pay more attention to getting the installation right in the first place so equipment is isolated from vibration etc, cables are in good condition, batteries checked and all that sort of stuff as its usually a connected piece of equipment (battery, switch etc) that fails before the tx or rx. 

 

 

 

 

[toto]

Good call on setting up this thread Rich. 

 

I think as it rolls on some very useful information will be able to be gained from it. My range test will be this weekend coming at the earliest and I'll post up what I done and how it was done.

 

I'm hoping that there will be somebody available that will be interested enough in conducting a thorough range test with me rather than the rush to the sky version. 

 

I'll report back.

 

Toto

[Ron Gray]

2 hours ago, Jon - Laser Engines said:

but beyond that it is of very questionable utility

Not really as it gives feedback on signal strength, if that is lower than your normal feedback then something has changed (maybe a damaged aerial). As I have said several times before, for the sake of an additional few minutes at the start of the session it's a worthwhile exercise and imo good practice.

[Jon H]

1 hour ago, Ron Gray said:

Not really as it gives feedback on signal strength, if that is lower than your normal feedback then something has changed (maybe a damaged aerial). As I have said several times before, for the sake of an additional few minutes at the start of the session it's a worthwhile exercise and imo good practice.

 

If your rf module or antenna is not running at its full load/stress then you arent testing it under real conditions. like an engine set too lean it may be fine running at lower power, but will fail when asked to carry its full load. In the case of a radio this would manifest as shortened range obviously, but it would not be apparent on the ground in this low power mode. 

 

Range testing it with a power down mode is all we have mind you, and if you want to do it then by all means do. But its not the be all and end all of tests when it comes to 2.4 and it is far less useful than a range test with a 35 meg set

 

 

[Ron Gray]

3 minutes ago, Jon - Laser Engines said:

and if you want to do it then by all means do

On more check before flying cannot be a bad thing and it will pick up a dodgy aerial, I know that from my own experience! The thing to do is to always compare the readings coming back, if they are much different from the last time then something must have changed!

[Jon H]

12 hours ago, Ron Gray said:

On more check before flying cannot be a bad thing and it will pick up a dodgy aerial, I know that from my own experience! The thing to do is to always compare the readings coming back, if they are much different from the last time then something must have changed!

 

With a telemetry system it is more useful for sure. For a system like my Futaba its not going to help much

[Ron Gray]

Ah yes Jon, I forgot you were still running on steam!

[Jon H]

1 hour ago, Ron Gray said:

Ah yes Jon, I forgot you were still running on steam!

 

So far i have never lost a model to a radio problem and a massive chunk of my flying has been on 35 meg. So perhaps steam is the answer? I would gladly take it over a system that poop's itself in the presence of a cdi unit. 

 

 

[leccyflyer]

15 hours ago, Ron Gray said:

On more check before flying cannot be a bad thing and it will pick up a dodgy aerial, I know that from my own experience! The thing to do is to always compare the readings coming back, if they are much different from the last time then something must have changed!

Agreed.  Up to now I haven't felt the need, or made use of the telemetry provided by many of my receivers, but I'm thinking that I'll incorporate that into my post flight checks alongside my religiously checking the per cell battery voltage.

[Ron Gray]

1 hour ago, Jon - Laser Engines said:

that poop's itself in the presence of a cdi unit.

Too true, but a) the steam driven system drops its pants when another one comes along unless it’s been made crystal clear b) faulty CDI units no longer an issue for me as manufacturer has rectified the problem!

[Jon H]

37 minutes ago, Ron Gray said:

Too true, but a) the steam driven system drops its pants when another one comes along unless it’s been made crystal clear b) faulty CDI units no longer an issue for me as manufacturer has rectified the problem!

 

35meg shoot downs are not failures of the radio so a range check wont fix those. But my comment earlier was regarding 2.4ghz. My 8j has no telemetry feedback giving signal monitoring so its not going to help me there either. 

 

As for the CDI issue. yea i know its fixed, but closing the stable door after the horse has bolted is sub optimal. 

 

In any event the point i am trying to raise is that the range test procedure used for 27/35/40meg is not applicable to 2.4ghz so powering down is the best equivalent. While it is the best equivalent it is not as accurate as the old 35meg procedure due to the way it works. 

 

 

 

 

[Cuban8]

On 18/09/2023 at 09:57, GrumpyGnome said:

Unless I've misinterpreted things, a number do include them - my Radiomaster and Taranis have all sorts of signal strength gubbins..... don't Spektrum, for example, gather telemetry about fades, frame losses etc.....?

Yes, I get loads of telemetry info with the DX8G2, but that's only with respect to how the rx is seeing and interpreting what the tx is transmitting. Interestingly, Spektrum give no guidance in the DX8 manual as to what % figure the rssi alarm should be set to.

When I had the radio brand new I guessed a setting of 30% below which the alarm would go off. The system passed all the usual range check and orientation tests with no problem but the rssi alarm was constantly going off during a flight. I had to set the figure to 5% to shut it up. Again, range checks, fades and holds were within limits. How useful is that rssi figure I wonder? I've operated the system for six years now without an issue. 

Still no idea as to how good the tx output power is at the tx aerial other than from a range check. Not ideal IMHO. 

I know of a flyer who lost two very expensive models due to a tx that was not transmitting to 100% of its capability. This was not picked up by the usual operator checks and the system clearly  worked OK  most of the time other than during a certain set of unusual  and unique circumstances.  these were only  discovered after the tx was returned for inspection by the distributor. BTW, it was an advanced model of radio so not a cheapy, and also not a Spektrum product.

A clear an unambiguous diagnostics warning that things were not right with the rf output during boot up would almost certainly have prevented a lot of hassle. I think it's fair to say that range tests will tend to highlight poor rx installations rather than compromised RF output of a transmitter. A lot to be said for a proper full distance and full power check as has been mentioned.

Edited September 19, 2023 by Cuban8

[leccyflyer]

Surely the important part is what the receiver is receiving from the transmitter? A  meter on the transmittter itself would only be half the story and wouldn't tell you whether the receiver had a good enough signal to adequately control the model. The range check doesn;t just check the power being radiated, it checks the integrity and strength of the signal at the receiver is adequate to control the model, which is the important thing.

[Phil Green]

19 hours ago, Jon - Laser Engines said:

If your rf module or antenna is not running at its full load/stress then you arent testing it under real conditions. like an engine set too lean it may be fine running at lower power, but will fail when asked to carry its full load. In the case of a radio this would manifest as shortened range obviously, but it would not be apparent on the ground in this low power mode. 

 

In a nutshell 🙂