Primarily for general aviation discussion, but other aviation topics are also welcome.
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#1848825
24 January 2021, SpaceX released a new group of 10 Starlink satellites, the first Starlink satellites in polar orbits. The launch surpassed ISRO's record of launching the most of satellites in one mission (143), taking to 1,025 the cumulative number of satellites deployed for Starlink to date.

23 May 2021, UKGA continues to discuss the development of Cheap and Cheerful (less that 50 quid!) solutions to allow aircraft to detect one another.

Struggling to assess which fact is the more extraordinary.
kanga liked this
#1848827
Gustosomerset wrote:24 January 2021, SpaceX released a new group of 10 Starlink satellites, the first Starlink satellites in polar orbits. The launch surpassed ISRO's record of launching the most of satellites in one mission (143), taking to 1,025 the cumulative number of satellites deployed for Starlink to date.

23 May 2021, UKGA continues to discuss the development of Cheap and Cheerful (less that 50 quid!) solutions to allow aircraft to detect one another.

Struggling to assess which fact is the more extraordinary.


What is extra-extraordinary is the Cheap and Cheerful less that 50 quid solution does pretty much the same thing as a £700 Flarm thing.
gaznav liked this
#1848854
It cheap, as it's as there is absolutely no assurance that it is actually legal to operate it, nor of its actual physical performance*.

Using a solution that has passed no testing to ensure its performance is within legal limits, does not generate other unwanted spurious RF emissions, and is not adversely impacted by other RF emissions from other intentional radiators.

What gain of the antenna will still permit it to stay within the legal EIRP?
What is the TX power level across the available frequency band?
What is the accuracy of the transmitted frequency over time, and does it transit unwanted harmonics?
When it transmits does it adversely impact other EC whilst airborne?
Is it impacted by any other RF transmission (immunity tested)?

If you are happy to carry an intentional radiator onto an aircraft and use it for EC purposes, with absolutely no assurance of its performance or impacts on other instruments, that is your decision. If this also adversely impacts other pilots EC solutions, you'd need to be happy about that too.

* Naturally, if they come with certification to the required standards and a set of documents that list the performance of the software-based radio side over a frequency range then the above is moot. Does anyone have a sample set of the documentation available?
By riverrock
FLYER Club Member  FLYER Club Member
#1848897
@rjc101 If someone sells an RF transmitter into the EU / UK to an end user then it has to be certified to conform. It doesn't need to supply a sample set of documentation. Depending on which set of regs its conforming to, it may display the CE symbol or other mark.

For SoftRF, there is a list of hardware that has been tested to work listed here: https://github.com/lyusupov/SoftRF and for some of the tested items, they've documented certificates held.

On performance - none of the portable items - DIY or on the market - will be able to assure you of performance, as it depends how they are mounted.
#1848899
Straight Level wrote:....

What is extra-extraordinary is the Cheap and Cheerful less that 50 quid solution does pretty much the same thing as a £700 Flarm thing.


While I agree Flarm is over priced, there is a big difference - this device simply tells you a contact is there and roughly how close horizontally it is .... Flarm actually works out whether it is collision risk - in a crowded environment the simple devices will just show loads of contacts, you need something that highlights the ones to worry about.... such as Flarm or SD .
#1848901
riverrock wrote:@rjc101 If someone sells an RF transmitter into the EU / UK to an end user then it has to be certified to conform. It doesn't need to supply a sample set of documentation. Depending on which set of regs its conforming to, it may display the CE symbol or other mark.

For SoftRF, there is a list of hardware that has been tested to work listed here: https://github.com/lyusupov/SoftRF and for some of the tested items, they've documented certificates held.

On performance - none of the portable items - DIY or on the market - will be able to assure you of performance, as it depends how they are mounted.


Agreed, anything sold should be tested to confirm. Sadly, many, many products on eBay and AliExpress are sold without any formal testing completed. Many items sold as bare circuit boards will have a disclaimer somewhere that exempts them from performing any testing and so issuing suitable conformity certificates, as they are 'development boards' and not sold as complete products. As such it is the buyers' responsibility to ensure they operate within legal limits.

Hardware tested to work with software does not give any assurance that the transmitter is performing within the permitted limits.

I've no issue if people want to do this stuff, just so long as they are aware that they are responsible for their actions in taking such devices onto their aircraft and the impact it may have on those in the air around them.
#1849070
@rjc101

The TTGO T-Beam used in SoftRF has a uBlox GNSS/GPS, an ESP32 microprocessor and a 868MHz SX1276 Long Range (LoRa) low power transceiver on it. Here is the book of words on the transceiver: https://semtech.my.salesforce.com/sfc/p ... qcpqh9qSjE

More detail here: https://www.semtech.com/products/wirele ... ore/sx1276

It’s a ubiquitous device used on a range of LoRa uses for the ‘Internet of Things’. The 868MHz one used in SoftRF is also used in Stratux EU too, so there are very many of these being used. Outside of these uses you’ll find it on automated gas/electricity meter readers, wireless alarm and security systems, long range irrigation systems and other industrial monitoring equipment uses. I very much doubt it is going to cause ‘Armageddon’ on the 868 MHz bands because it probably would have done by now.

Now it could go out of spec, like any device, but on 868 there are so many devices blasting out up to 500mW that I think it would be really hard to spot. Also, under Ofcom’s Interface Requirements 2030 document then ‘airborne use’ is authorised too.

Now, I’m still with you that using amateur built kit for airborne collision awareness is not the best idea. But seeing as there is a lot of this kit still still out there, then I came to conclusion that I should make myself visible with a cheap SoftRF to those that can’t see my ADS-B Out. Which is why I will probably push out Legacy FLARM Air V6 as there are an awful lot of classic FLARMs out there that don’t see my ADS-B. I thought that was a good thing to do, to make myself visible to FLARM, PAW or FANET (I choose the former), but reading your post, I’m not so sure now? Do you think that Ofcom should ban the carriage of devices that use such devices on a board like T-Beam in aircraft for airborne use? If so, please say why.
Dusty_B liked this
#1849153
@gaznav

A datasheet doesn't give any assurance the device you are using is compliant. It is how you implement the module, with its supporting electronics and software take to make up these boards. There are numerous app notes relating to that module over how not to do things that could cause problems with the design. Were these followed in this specific hardware design?

For all your example uses, every one of those will have been through compliance testing to ensure they work as expected for both emission and immunity.

A simple example, GNSS. Signals for GNSS to operate run down at ~ -160dBm with receivers needing a signal of more than ~ -150dBm to initially pick up the constellations. A *tiny* harmonic in the GPS bands can reduce the sensitivity of a GNSS receiver to the point it won't work, or won't work reliably. This could come from the RF transmitter, the power supply, a combination of multiple devices on the PCB. I recently diagnosed a problem with a GNSS receiver back to battery lead (3.7v only supplying ~30ma), which was radiating a clock harmonic from a crystal oscillator in a totally different part of a PCB. This harmonic was conducted through the DC-DC converter and out onto the battery lead. It was a 24MHz oscillator that seemed to resonate with the PLL inside a processor to generate the harmonics up at 1.5GHz.

gaznav wrote:I very much doubt it is going to cause ‘Armageddon’ on the 868 MHz bands because it probably would have done by now.


Who mentioned 'Armageddon'?

You free to do as you wish. You are using a software-based radio system, that has had no formal testing to ensure it is operating within the legal limits for your intended purpose or is immune from doing something odd when exposed to inbound RF for the purpose you are using it for. It could be it stops working after a transponder pulse at 25W upsets its clock signal enough to cause a reset, or go into an unknown state. No one knows, they have not been tested for the task they are being put to. Not many meter reading applications have to function close to a high power pulse transmitter.

The RF emissions and immunity for systems in aircraft have orders of magnitude lower limits at certain parts of the spectrum. Whilst this isn't a formally tested device, I would consider it best practice to honour the standards even if not looking to achieve formal compliance.

What capacity is your 18650 battery? Be interesting to know how much power the module chews if it only lasts 6 hours on a charge. If it doesn't get that hot, where does that power go? I also presume the 18650 cell you are using has an integrated protection circuit, so if there is a problem with the board the battery won't have a thermal runaway event?

The bottom line, anyone using such things has to accept that what they are carrying onto their aircraft will have no detrimental impact on them nor be detrimental to others. This could be as simple as transmitting FLARM unintentionally at too higher a power, so impacting the ability of others to receive the already low power FLARM signals.

Only you, or anyone else following your example, can make the decision that everything is within the limits and there is no negative impact to you or the others around you.
#1849199
Sooty25 wrote:@rjc101 is this a swipe at just @gaznav s' device, or at all non type approved, carry on, 868MHz systems in general?


No this is nothing to do with @gaznav, I'd have posted the same regardless. It is any device that hasn't been through testing to check it complies with the relevant legal limits for emissions and immunity for the intended purpose. So FLARM will have spent time in an EMC lab to ensure legal compliance, as has PilotAware. SkyEcho is different, it's not a consumer product but is self-certified against the CAP designed to promote EC. But it will still have been through some testing.

For the avoidance of doubt, my concern (for want of a better word) is these cheap modules are unknown quantities. They are basically development kits, anyone wanting to integrate one into a device is free to do so, but that device would need to be tested for the use case of that product to be legally sold and operated. To operate one in an aircraft where potential side effects are unknown is the sole responsibility of the person doing it. They have to accept that, and that it may also adversely affect others.

If such a module were used in an aircraft, personally I would also ensure any emissions were below the limits in the aviation standards, where they are tighter than the consumer electronics limits. Plus I would check that there are no ill effects from the other high power transmitters often found nearby in an aircraft. Not technically or legally required for portable carry-on electronics, but for me, that feels appropriate.

Type approval for fitting into an aircraft is something totally different, that has its own limits. Anything with a formal type of approval (e.g. a TSO) does not need to carry "consumer" marks such as an FCC, CE or the UKCA. In fact, it should not, unless it has also been specifically tested within the parameters for those tests. They are totally different.

Broadly speaking, it doesn't have to be an actual transmitter. There are lots of posts all over the place saying how item X only cost £5 is amazing, I've used it and it works great for doing Y. I've saved £200 by using it and here are the plans for how I made it. It may well work fine for that person, you build one and connect it up. The cable you used was slightly shorter than the one in the blog post and from a different site, but it was £1 cheaper so that's good. You may then have unwittingly created a perfectly tuned radio transmitter from the frequency of a component and the length of the wire. You may not notice your GNSS takes longer to get a fix or briefly drops out from time to time, or that you need to be closer to someone else to pick up a FLARM signal. But you have degraded the sensitivity of things you rely on, without knowing it. If lots of people do the same, everyone suffers.
Tim Dawson, kanga liked this
#1849329
@rjc101

Thanks again for your thoughts, opinion and fact. I’ve thought a lot about what you have written today. But I couldn’t help thinking that when it comes to stray “wigglies” what about the many USB chargers that are used with the very many different USB cables (of different lengths) connected to the many different mobile phones and tablets used in GA aircraft? Many of these phones and tablets are transmitting on the 4G 800 MHz band and the chargers may be the ones that your own company produce to a suitable test schedule. But from what you’re saying I take it that you can’t use any USB cable connected to one of these certified chargers unless it’s been through the same testing regime for EMC? Also, how could every possible combination have been tested too in order to ensure carry-on device don’t cause the interference you state?

Also, you don’t seem to take issue with these ‘development boards’ being used on the ground? But that doesn’t really make sense from my perspective, as the radio waves care not if they are being emitted from the ground or the air if this is something that affects many aircraft at range. If you are worried about emissions interfering with the electronics and nav aids within or in the close vicinity of aircraft - then many have none in aircraft that they fly (I can’t imagine any effect it could have on a 1952 Chipmunk and a 1967 Condor that I fly)? If these development boards are such an issue then surely they would be outlawed, but they aren’t, and there are literally hundreds of thousands of them out there in use for the various things I have already stated. As you appear to be in the AV/IT consultancy game then the ubiquity of these boards should be well known to you, too, as they are used for various IOT purposes. I also understand that the Open Glider Network is using these boards too in various devices of their own design. So I suspect they are everywhere now, and being used in various GA types across Europe in various devices - and in the air and on the ground. SoftRF and Stratux EU with these development boards are being used by more than just a few folks - indeed SoftRF was used to track the FAI Grand Prix World Final in 2019.

If this is the significant problem that you suggest, wouldn’t it be the right thing to do to raise the dangers that these devices supposedly pose to GA to Ofcom or the CAA or EASA?

I know that you manufacture USB chargers for GA aircraft, but have you declared any commercial interest in EC devices that you have as I see that your website advertises the Pilot Aware? I’m sorry if that comment is ‘below the belt’ but there is so much commercial interest at stake here, I’m finding it hard to work out who to trust and what their motives are. Other EC manufacturers have been keen to raise the fact that Stratus EU and SoftRF emit and receive their protocol, so I hope you understand how conflicted that message is to those that are just trying to understand the best and most cost effective options?
Last edited by gaznav on Tue May 25, 2021 11:35 pm, edited 1 time in total.
#1849334
skydriller wrote:@HansGruber This device is NOT using the mobile phone network. You are confusing it with the "Safesky app" as on the flyer live broadcast the other night.
Oh, and wrt you comment directed @gaznav , for once he is actually reviewing something without banging on about SE2, so credit where its due eh?
Regards, SD..
Yes, credit where it's due, still waiting for an honest assessment from him on whats best for GA EC. Unless you're hoping that SE2 will be granted access to TMAs, and you don't care that 70% of GA is Mode S/C, 'cos, you haven't got an electrical system.
I get it, that's a thing. But not the case for most GA. So, selfish?
#1849335
gaznav wrote:@rjc101

Thanks again for your thoughts, opinion and fact. I’ve thought a lot about what you have written today. But I couldn’t help thinking that when it comes to stray “wigglies” what about the many USB chargers that are used with the very many different USB cables (of different lengths) connected to the many different mobile phones and tablets used in GA aircraft? Many of these phones and tablets are transmitting on the 4G 800 MHz band and the chargers may be the ones that your own company produce to a suitable test schedule. But from what you’re saying I take it that you can’t use any USB cable connected to one of these certified chargers unless it’s been through the same testing regime for EMC? Also, how could every possible combination have been tested too in order to ensure carry-on device don’t cause the interference you state?


In my post, I said product X, specifically not to mention chargers. The X could be a softRF transmitting device using a different type of badly suited coax cable to a mismatched antenna. I was trying to keep everything generic. I have also suppressed my normal signature on this type of post too, as it links to my charger website. It didn’t seem appropriate for this subject. You have created a link where there isn't one.

As you have brought the charger subject up...

In your example, both the USB charger and the phone will have passed regulatory testing. The aim of this, and the reason why there are such tests, is to prevent the scenario you created. You are free to use any cable, that meets the USB specification, and all should be well *.

The problem is many USB chargers from online stores have never been tested and some are frankly dangerous, regardless of what the adverts say. Hence you can have issues where item X works fine for me but is terrible for you.

* However, note that the EMC limits for consumer devices are much higher at some frequencies than those for aviation, especially around the VHF radio comm / NAV and GNSS frequencies, hence why many people have issues with generic plug-in chargers in aircraft. People use them because they are deemed affordable and they have an old cigarette lighter socket to plug them into, even though they are not ideally suited for use in the GA environment. {edit to add numbers} For standard consumer CISPR between 108MHz to 152MHz the limit is 65dBuV/m, for Class M aviation it is 35dBuV/m to 37dBuV/m. For Class H (potentially more appropriate to GA as it is for emissions nearer to antenna, but the standards are geared toward CAT) it is 25dBuV/m to 27dBuV/m.

gaznav wrote:Also, you don’t seem to take issue with these ‘development boards’ being used on the ground? But that doesn’t really make sense from my perspective, as the radio waves care not if they are being emitted from the ground or the air if this is something that affects many aircraft at range. If you are worried about emissions interfering with the electronics and nav aids within or in the close vicinity of aircraft - then many have none in aircraft that they fly (I can’t imagine any effect it could have on a 1952 Chipmunk and a 1967 Condor that I fly)? If these development boards are such an issue then surely they would be outlawed, but they aren’t, and there are literally hundreds of thousands of them out there in use for the various things I have already stated.


I have an issue with any development board, or untested system, being used on the ground or in the Air in a device being sold. It is more concerning when the devices actively transmit. When people DIY solutions they are not products, so legally require no testing. However, the operator is still legally responsible for anything the device may do outside the legal limits. So you are free to do as you wish, providing you accept it’s your responsibility, even if you have no idea there even is an issue.

In your aircraft scenario, it may well not affect you. However, if you are transmitting FLARM at too much power, or the transmitter design is poor so it has way too much power at the start (TX power overshoot), or it takes too long to stop transmitting, that signal could cause issues for other nearby FLARM installations. We shall ignore the potential situation when FLARM issue an update that tweaks the protocol, and the official installations are updated but the OpenSource project lags behind or the DIY'ers never update them. Now you may be actively causing problems for others, because you may not have checked the module was updated and applied it.

gaznav wrote:As you appear to be in the AV/IT consultancy game then the ubiquity of these boards should be well known to you, too, as they are used for various IOT purposes. I also understand that the Open Glider Network is using these boards too in various devices of their own design. So I suspect they are everywhere now, and being used in various GA types across Europe in various devices - and in the air and on the ground. SoftRF and Stratux EU with these development boards are being used by more than just a few folks - indeed SoftRF was used to track the FAI Grand Prix World Final in 2019.

If this is the significant problem that you suggest, wouldn’t it be the right thing to do to raise the dangers that these devices supposedly pose to GA to Ofcom or the CAA or EASA?


I am indeed an independent IT/AV consultant, but I also do custom electronics design and embedded firmware. Mostly bespoke for specific requirements. I have some of my work on the website, some I cannot post details nor discuss owing to NDA's or other legislation.

I am aware of lots of these type of boards. Generally, it is those used to transmit where issues have come up. As the whole design is more critical to correct performance. More often it is a problem with the supporting electronics than the RF modules themselves. A poorly executed design, often combined with sub-optimal component choices to keep the cost down. I suspect most of the deployment scenarios you describe are used as receivers rather than transceivers. For me, it is the transmitting side where you can create problems for others. If you do something that only causes you grief, it's not good but I don't mind that so much (nothing personal). When there is the potential to impact others, it is a concern.

I recall a discussion where a different, but similar, board being DIY’d as a drive gate opener and gate bell/intercom extender. It worked fine, only when they used the intercom it caused jamming errors on the wireless alarm system. This was “resolved” by buying a different style of the board from AliExpress. It may still cause problems elsewhere, but as the alarm fault went away the owner didn’t worry about it. They were not concerned that it might impact anyone else, it was cheap and that trumped everything else.

When lots of people do the same because it’s "Cheap and Cheerful", you can end up with lots of small problems waiting to catch someone out. There is no source to register a complaint against, the boards are not sold with testing done for any particular purpose. For me, the consequence of something bad happening could be worse in the air than on the ground. Especially if it causes something to happen that increases the workload of the pilot. I have previously made comments via CHIRP in response to reported events.

gaznav wrote:I know that you manufacture USB chargers for GA aircraft, but have you declared any commercial interest in EC devices that you have as I see that your website advertises the Pilot Aware? I’m sorry if that comment is ‘below the belt’ but there is so much commercial interest at stake here, I’m finding it hard to work out who to trust and what their motives are. Other EC manufacturers have been keen to raise the fact that Stratus EU and SoftRF emit and receive their protocol, so I hope you understand how conflicted that message is to those that are just trying to understand the best and most cost-effective options?


I have no link or commercial arrangement with PilotAware, nor any EC device. As one use for my chargers is to power the devices I have a page on the site for that from the early days of PilotAware. The PAW team tested and mention my chargers the same as they do for the Anker range of plug-in chargers. The page does also help with SEO. I added it years ago, and do need to update or edit that page to be more generic, cover different EC devices or remove it.

I have a policy that I neither solicit nor accept referral fees or kickbacks. This is stated on the front page of my main website. I have walked away from projects where I was offered referral fees to steer things in a specific direction. It’s not how I believe things should be done. Hence why I have specifically kept what my company does out of the conversation until you raised the subject.

{edited to put replies and comments in context, fix typos etc.}
Last edited by rjc101 on Wed May 26, 2021 11:18 am, edited 1 time in total.
gaznav liked this
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