5G

[Brandt]

FYI - Potential 5G interference issues for aviation 

https://www.wsj.com/articles/faa-plans-warnings-to-pilots-airlines-over-new-5g-rollout-11635524648?st=mdfurj009paqd0i&reflink=desktopwebshare_permalink

[EricJ]

It's probably a non-issue, and certainly not an issue for our general aviation airplanes.

[Brandt]

It's probably a non-issue, and certainly not an issue for our general aviation airplanes.

What leads you to that conclusion? I agree about radar altimeters but appears to have other impacts.


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[EricJ]

6 hours ago, Brandt said:

What leads you to that conclusion? I agree about radar altimeters but appears to have other impacts.

The affected band is 3.7 to 4.2 GHz that some G5 signals will occupy.   Radar altimeters are 4.2 to 4.4 GHz.   There is no overlap, so only altimeters with poor filtering will be susceptible, and since the radar transmit they may be creating inteference to G5 receivers in the adjacent band as well.   If either meet normal and long standard FCC band isolation requirements and normal engineering standards they won't interfere with each other.

I don't know of any other GA equipment that have operating frequencies even close to that band, so nothing else should be affected.

 

 

[Brandt]

The affected band is 3.7 to 4.2 GHz that some G5 signals will occupy.   Radar altimeters are 4.2 to 4.4 GHz.   There is no overlap, so only altimeters with poor filtering will be susceptible, and since the radar transmit they may be creating inteference to G5 receivers in the adjacent band as well.   If either meet normal and long standard FCC band isolation requirements and normal engineering standards they won't interfere with each other.

I don't know of any other GA equipment that have operating frequencies even close to that band, so nothing else should be affected.
 
 

I was curious as to the inference that it might affect glideslopes.


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[EricJ]

On 10/30/2021 at 9:29 AM, Brandt said:

I was curious as to the inference that it might affect glideslopes.

The high end of the glide slope band is 335 MHz, more than a thousand ten times lower frequency than the 3.7 GHz G5 equipment in question.   The closest GA equipment off the top of my head would likely be GPS, which is in L-band around 1.5 GHz.   Still a non-issue.

Edited November 1, 2021 by EricJ

[Brandt]

8 minutes ago, EricJ said:

The high end of the glide slope band is 335 MHz, more than a thousand times lower frequency than the 3.7 GHz G5 equipment in question.   The closest GA equipment off the top of my head would likely be GPS, which is in L-band around 1.5 GHz.   Still a non-issue.

Not disputing you.  Just wondering then why the FAA concerned

[EricJ]

29 minutes ago, Brandt said:

Not disputing you.  Just wondering then why the FAA concerned

The only potential issue is with radar altimeters, which are pretty rare on GA airplanes.  I think it's a low probability of there being actual problems unless the radar altimeter is defective and has insufficient band filtering, or a 5G transmitter in that band was defective and bleeding energy up into the radar altimeter spectrum.   C-band used to be populated long ago with analog satellite television, and I don't know what other users there have been since then.   Since the 5G sources will be terrestrial the FAA is probably just concerned about potential intereference with terrestrial transmitters that are defective.   I think the FAA is just being diligent, but just about all radio applications have to live with other applications in either adjacent or the same bandwidth.   It isn't anything particularly new or unmanageable.

Somebody has a whole website about it from the 5G side:   https://www.5gandaviation.com/

[PeteMc]

My guess is that the "problem" was recognized because a lot of the older/older design Radar Altimeters probably don't do a good job of of filtering out adjacent bands.  And it was probably discovered on the bench vs. in real flight (since there have been no 5G related crashes I'm aware of).

Best bet would be for everyone to keep screaming about it and the FAA (hopefully paid by the 5G people) will offer highly discounted replacement Radar Alt. that are not affected by adjacent bands. 

 

[EricJ]

If anybody wants to worry about actual more serious affects to navigation systems caused by interference, Ligado (formery Lightsquared) is still in the process of deploying a system that many expect will interfere with GPS.   After many, many years of many diverse industries successfully campaigning to get the FCC to prevent it in order to preserve the integrity of gps, it is now moving forward toward deployment.

The radar altimeter thing is remotely similar, but kinda pales in comparison imho.

 

[N201MKTurbo]

[carusoam]

Or somebody trying to sell WAAS GPS devices to the last hold-outs still using the radar altimeter to be alerted to the DH, or is it DA….?

Anyone still using their radar altimeter in their Mooney?

Best regards,

-a-

[A64Pilot]

On 10/31/2021 at 10:47 PM, carusoam said:

Or somebody trying to sell WAAS GPS devices to the last hold-outs still using the radar altimeter to be alerted to the DH, or is it DA….?

Anyone still using their radar altimeter in their Mooney?

Best regards,

-a-

I have one and find it useful as a back up, I’d never use it to determine MDA, but I would abandon an approach if it said I had less clearance than I was expecting to see.
Its not as good as the ones we had in the Military, over foliage it isn’t as reliable,maybe it’s just old?

[Jerry 5TJ]

Category II and III ILS approaches often require a radar altimeter to determine the minimum descent height.  

The FAA is saying that these approaches may be NOTAMed out of service due to the adjacent band RF interference from the 5G sites.  

It is technically true that a radar altimeter with sufficient filtering can operate near a C band 5G site.  But many legacy radar altimeters were designed when 3.7-4.2 GHz was a satellite downlink band with only weak signals near the ground (the satellite transmitters were 22,000 miles overhead). 

Few if any Mooney aircraft or pilots have the special crew and airframe approval needed to use those Cat II and III approaches so it’s not a problem for our flying.  

[GeeBee]

Yeah, it is a non-issue for radar altimeters that are new. What about the ones whose antennas have suffered thousands of insults, such as coffee and soapy water out the drains that smears across the belly and antennas. For instance in the A330 we had to stop the Flight attendants from pouring coffee down galley drains because it was affecting our RAs. Add in asphalt and chemical soaked water spray. Now where are you? The lab is an entirely different place from the real world.

[tls pilot]

AIR-21-18.pdfHere is the latest FAA Issuance on this subject

 

 

[EricJ]

2 hours ago, Jerry 5TJ said:

Category II and III ILS approaches often require a radar altimeter to determine the minimum descent height.  

The FAA is saying that these approaches may be NOTAMed out of service due to the adjacent band RF interference from the 5G sites.  

It is technically true that a radar altimeter with sufficient filtering can operate near a C band 5G site.  But many legacy radar altimeters were designed when 3.7-4.2 GHz was a satellite downlink band with only weak signals near the ground (the satellite transmitters were 22,000 miles overhead). 

Few if any Mooney aircraft or pilots have the special crew and airframe approval needed to use those Cat II and III approaches so it’s not a problem for our flying.  

^This.    It is not practical to expect the FCC to abandon a large chunk of desirable spectrum for terrestrial use because there are some legacy applications in different spectrum with old equipment that performs poorly due to long-ago legacy conditions.   Spectrum is a limited resource with increasing demands for it, and I don't expect the FAA to win this one.   There might be some delays beyond the initial voluntary one, but ultimately some old radar altimeters are going to have be retired or replaced.

[Jerry 5TJ]

2 hours ago, GeeBee said:

Yeah, it is a non-issue for radar altimeters that are new. What about the ones whose antennas have suffered thousands of insults, such as coffee and soapy water out the drains that smears across the belly and antennas. For instance in the A330 we had to stop the Flight attendants from pouring coffee down galley drains because it was affecting our RAs. Add in asphalt and chemical soaked water spray. Now where are you? The lab is an entirely different place from the real world.

In theory, theory and practice are the same....

[ilovecornfields]

I did notice after getting my booster shot that I don’t get any radar altimeter readout on my G500 display. Not sure if it’s related.

[N201MKTurbo]

37 minutes ago, ilovecornfields said:

I did notice after getting my booster shot that I don’t get any radar altimeter readout on my G500 display. Not sure if it’s related.

Oh, crap, I bet you weren't wearing your tin foil hat when you got your booster. The foil keeps the 5G rays from activating the nano-particles in the vaccine.

[Will.iam]

One more reason to go LHS and ditch the old RA. 

[GeeBee]

Lldar is not 100% either. A bicyclist in Phoenix can attest to that. Equally so, I have it on my car and I had a sensor failure after driving in heavy rain on a freshly paved road. Had to stop and clean the sensor.

 

[N201MKTurbo]

2 minutes ago, GeeBee said:

Lldar is not 100% either. A bicyclist in Phoenix can attest to that. Equally so, I have it on my car and I had a sensor failure after driving in heavy rain on a freshly paved road. Had to stop and clean the sensor.

 

I know exactly where that bicyclist got hit. If there were human eyeballs in that car, the bicyclist probably still would have gotten hit. The only people around there that time of night are the homeless. It is at a trail crossing where a dirt path crosses the road. It is a very infrequently used path. There is no crosswalk or signs where that path crosses the road. Nobody rides or hikes there in the middle of the night. The road is cut through a mountain in the middle of town. People usually speed on that road. It is posted 45, but it is not uncommon for cars to go 60+ through there. The road is also very dark. That trail crossing is just past the crest of the road so cars have no visibility of someone crossing and the crosser cannot see oncoming traffic from one direction. You have to be very careful crossing there. I blame the crosser not the driver. The police didn’t even cite the driver (monitor) of the car because they understand the situation. Uber got screwed in that deal.

[GeeBee]

So given all that, why did the Lidar not detect the object?

[A64Pilot]

24 minutes ago, GeeBee said:

Lldar is not 100% either. A bicyclist in Phoenix can attest to that. Equally so, I have it on my car and I had a sensor failure after driving in heavy rain on a freshly paved road. Had to stop and clean the sensor.

 

What kind of car has LIDAR? What’s it’s used for?