Comparison of ADS-B and XM weather

narchee

narchee

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I found this picture on another site. The left is XM, the middle is regional ADS-B and the right is national ADS-B.

The ADS-B images don't look as good. What about the rest of the weather offering from ADS-B? Is it as good as XM? Is it as reliable? XM is very reliable seeing you're getting it from the satellite.

Any opinions from those familiar with both?
 

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One is free and the other costs 30 bucks a month from a company with the worst customer service since Ghengis Khan?
 
Try canceling your XM service. Plan on being on hold 30+ minutes
 
All three look reliable to me. It shows an area to avoid.
 
Having been on the other side of efforts like this, I wonder if it's intentionally degraded so as not to compete with private sector. Part of me hopes there's room in the ADS-B standards to upgraded the resolution of the weather products as time goes by...
 
Actually, the regional doesn't look half bad. National can be blocky, 'cause I'm not there yet. :)
 
What bothers me is if there is a spatial degradation, what about temporal? With that level of coarseness they must have a bandwidth issue with ADS-B. :dunno:
 
We have in-panel XM and ADSB via stratus.

The ADSB radar is very poor compared to XM. The other ADS-B products are nice, however (ie NOTAMs, etc. )

Having both, I would not give up XM.


Sent from my iPhone using Tapatalk
 
It's been well documented that the different products will have a different resolution. ADS-B will be more blocky.

As others have said, we can put up with the blockiness because the price point can't be beat.
 
narchee said:
I found this picture on another site. The left is XM, the middle is regional ADS-B and the right is national ADS-B.

The ADS-B images don't look as good. What about the rest of the weather offering from ADS-B? Is it as good as XM? Is it as reliable? XM is very reliable seeing you're getting it from the satellite.

Any opinions from those familiar with both?
Click to expand...

I have XM data and audio in the cockpit and wouldn't want to give up either. The audio is great for long flights and the weather works on ground, which is an issue with ADS-B. Compared to the cost of operating the airplane, the XM subscription is minimal. I recently bought a Stratus 2S, but have no plans to cancel the XM.
 
"Blockiness" is not that bad, esp. considering that it's an area you (generally) want to avoid, not finely thread your way through.
And comparing ADSB weather, with its slight (and known) delay, to live Stormscope data, I have never had a big issue merging the two sources. The ADSB lag has never been excessive, and its larger coverage and greater details are a welcome addition, complementing the limited Stormscope picture.
Never used XM, so can't compare.
 
n12365 said:
I have XM data and audio in the cockpit and wouldn't want to give up either. The audio is great for long flights and the weather works on ground, which is an issue with ADS-B. Compared to the cost of operating the airplane, the XM subscription is minimal. I recently bought a Stratus 2S, but have no plans to cancel the XM.
Click to expand...

My thoughts as well.
 
Why is it I cannot find good music to listen to on XM Radio when I'm in the plane, but all my favorites come on Spectrum as soon as I jump in the car? First world problems and all...;)
 
I get my ADSB weather from a Dual XGPS170 receiver with the display handled through an Android tablet running Droid EFB and it is less blocky than the images shown by the OP. I guess the software and hardware you are using makes a difference. The ADSB WX in the attached picture shows the image is 1 minute old and it was certainly good enough for me to avoid the thunderstorms in the actual picture. I was also able to tell there was clear sky behind the storm so I wasn't trying to get around a line of storms that extended indefinitely along my intended route of flight. Both were very good bits of information to have. I also like having my WX imagery on the larger display of my tablet as opposed to the typically smaller XM radio screens. And yes, the headwinds had my ground speed down to 86 knots with an airspeed of 105 knots. It was a miserable ride across the desert of central New Mexico en route to the Seattle area.

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Flyhound said:
The ADSB WX in the attached picture shows the image is 1 minute old and it was certainly good enough for me to avoid the thunderstorms in the actual picture. I was also able to tell there was clear sky behind the storm so I wasn't trying to get around a line of storms that extended indefinitely along my intended route of flight.
Click to expand...
It wasn't 1 minute old. It may have been received 1 minute ago, but it is well documented that the NEXRAD radar images transmitted by both XM and ADS-B take 5-10 minutes to produce (because they're made up of multiple scans at different angles into the atmosphere) and then have to be processed and transmitted to you, which takes another few minutes.

So most likely the radar image you're looking at is 10-15 minutes old (or possibly even older!)

Please, for your own safety, do not use XM or ADS-B radar for tactical thunderstorm avoidance.

-Josh
 
Thanks for the post. Very informative. :yes:

Even more reason why I still like and have XM weather.
 
ADS-B isn't bad enough to warrant paying for XM is my thought. Especially since the mandate is by 2019. I've had both, and I don't miss XM enough to start it back up.
 
It depends what kind of flying you do and what you want. I have both - XM pro in G1000 panel and ADSB on foreflight and intend to keep both. But I get a LOT more with XM than just ADSB- current icing product, cloud tops, reflectivity tops, satellite imagery, winds aloft, etc... Many things are available on XM that you can't get on ADSB so for my type of flying (lots of 1000nm+ trips) it is worth it. If I flew a trainer type plane for shorter stuff, I'd be ok with foreflight and the stratus.
 
iflyvfr said:
Why is it I cannot find good music to listen to on XM Radio when I'm in the plane, but all my favorites come on Spectrum as soon as I jump in the car? First world problems and all...;)
Click to expand...

What audio panel do you have? I tried listening to it once in mine (g1000 + gdl69a) and gave up as it sounded like the audio was going through a tin potato.

Sounded similar when I flew a 172 with a g530 and some other random garmin audio panel.

The bluetooth audio over the zulu.2 was /much/ better...
 
ADS-B wx via Stratus and Foreflight has limitations, but it suits my VFR purposes, and the price is right. I don't think the difference in resolution of the radar depiction makes a bit of difference, especially with the time lag involved -- I'd keep my distance either way.

I had XM on a Garmin 496 in my Sport Cub and it worked well. One distinct advantage over ADS-B was the ability to receive wx while on the ground, even if no Wi-Fi or cell service is available. I used to take that airplane camping in the Idaho backcountry in group flights to airstrips in deep canyons with no phone, cell, Wi-Fi, or even a way to see weather beyond the first ridge. But I could still receive the XM satellite on the ground, and for days at a time my airplane would be the only source of weather information for the entire group.

But I'm mad at XM now anyway -- they just dropped my favorite elevator music channel. :mad:
 
narchee said:
I found this picture on another site. The left is XM, the middle is regional ADS-B and the right is national ADS-B.

The ADS-B images don't look as good. What about the rest of the weather offering from ADS-B? Is it as good as XM? Is it as reliable? XM is very reliable seeing you're getting it from the satellite.

Any opinions from those familiar with both?
Click to expand...

different strokes....for different folks. What you are seeing with XM is highly massaged data and more like a composite image (the worst activity with in an altitude band...and could be quite high or low) where the ADS-B is more like a base reflectivity. If you don't know the difference....it prolly doesn't matter much to you then. :goofy:

Both XM and ADS-B are not good for tactical operations....cause the lag time "can" be as much as 10-20 minutes. That clearly is not acceptable with convective activity.

but, I'm quite happy with free.....so ADS-B is fine for me.:yes:
 
happypilot876 said:
It wasn't 1 minute old. It may have been received 1 minute ago, but it is well documented that the NEXRAD radar images transmitted by both XM and ADS-B take 5-10 minutes to produce (because they're made up of multiple scans at different angles into the atmosphere) and then have to be processed and transmitted to you, which takes another few minutes.

So most likely the radar image you're looking at is 10-15 minutes old (or possibly even older!)

Please, for your own safety, do not use XM or ADS-B radar for tactical thunderstorm avoidance.

-Josh
Click to expand...

While I agree with the fact that XM is for strategic vs. tactical use, you're wrong about the update rate. XM rarely is more than 5 minutes old and I can't vouch for whatever you're using as a display, but mine tells you the date on the image data NOT the reception time (which isn't even available to me).

It's clear when the data is old, the MX20 changes the color of the update time in the corner of the FIS screen when you've got old data displayed.
 
The perceived "better resolution" of XM radar is a ridiculous argument. Anyone who's using XM or ADSB as if it were the same as an onboard radar transceiver giving a real-time picture of what's ahead is completely misusing XM and ADSB radar. If you're using it for strategic planning then the "blockiness" of ADSB matters not one iota.

It is true that XM weather includes a few extra weather products. Satellite imagery, icing info, etc. are pluses compared to ADSB (ADSB has winds aloft, which someone incorrectly mentioned earlier as an XM-only benefit)...though YMMV about how important those extra products are while flying.
 
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I didn't run out to get a widget to get ADS-B while I had the XM. I agree, its cost was minimal in the grand scheme of things, and its usefulness was utterly amazing. Now that I don't' have that GPS anymore, however, I'm not running out to replace it. There will be an ADS-B solution in the airplane within a couple years, and I'll get it then. In the meantime there are radio sources of weather information, though they're not nearly as intuitive.
 
I like the lightning info on XM which ADSB does not have...


Sent from my iPhone using Tapatalk
 
Jim_R said:
The perceived "better resolution" of XM radar is a ridiculous argument. Anyone who's using XM or ADSB as if it were the same as an onboard radar transceiver giving a real-time picture of what's ahead is completely misusing XM and ADSB radar. If you're using it for strategic planning then the "blockiness" of ADSB matters not one iota.
Click to expand...

Simply not true. I use XM weather today in combination with onboard weather radar. The weather radar gives me a real time view but when you get close to precipitation you can miss what is lurking behind the cell in front of you. I use the XM to make strategic decisions and the resolution is just right for that. As others have said you can see how old it is and you can also keep note of how it is changing. This combined with also noting the wind and cross referencing with the onboard radar (which remains the ultimate authority close up) makes it very useful. I don't want to give up this resolution. Most of the other posts on this thread have shown me I won't like ADS-B weather. Sure it is free. Sometimes free stuff is, well, not so amazing. When I upgrade my equipment to ADS-B I'll make sure I keep the XM weather.
 
I only fly our plane with xm VFR and activate xm weather April-September, mostly for radar. XM can take 5-10 minutes to load all of the weather on startup but it is accurate and you don't need to worry about going out of an ads-b area. I've been using a friends dual 170 GPS/ADSB unit and it has worked less than 1/2 the time and we are sending it in for another replacement. Traffic turns on and off, and weather comes and goes.
 
narchee said:
Simply not true. I use XM weather today in combination with onboard weather radar. The weather radar gives me a real time view but when you get close to precipitation you can miss what is lurking behind the cell in front of you. I use the XM to make strategic decisions and the resolution is just right for that. As others have said you can see how old it is and you can also keep note of how it is changing. This combined with also noting the wind and cross referencing with the onboard radar (which remains the ultimate authority close up) makes it very useful. I don't want to give up this resolution. Most of the other posts on this thread have shown me I won't like ADS-B weather. Sure it is free. Sometimes free stuff is, well, not so amazing. When I upgrade my equipment to ADS-B I'll make sure I keep the XM weather.
Click to expand...

Really? You need to see 5 or 6 little red pixels showing a rounded edge on a cell instead of 1 red block? That's going to make a difference in your decision making?

If you've got onboard radar, you do a different type of flying than me, so maybe it really does make a difference to you. Me, I care if it's a big yellow blob with some red in it, or a big green blob with no yellow in it. I don't need ultra-tiny pixels for me to try to steer some tens of miles away from something that looks bad. Blocks are information enough.
 
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Jim_R said:
Really? You need to see 5 or 6 little red pixels showing a rounded edge on a cell instead of 1 red block? That's going to make a difference in your decision making?

If you've got onboard radar, you do a different type of flying than me, so maybe it really does make a difference to you. Me, I care if it's a big yellow blob with some red in it, or a big green blob with no yellow in it. I don't need ultra-tiny pixels for me to try to steer some tens of miles away from something that looks bad. Blocks are information enough.
Click to expand...

For me yes. I get your point if your plan is to stay well clear like a 100 nm clear. Then you don't need it. But if you're reasonably close like 20 nm or so then even with XM that could use higher resolution. The higher resolution also helps you see how things are changing. To me that is almost as important as the current image. I always watch to see when it changes then I immediately know by comparing where it was, how things are moving or intensifying or dying out at least at that point in time. You can't really do that with giant red pixels. If the XM is showing very intense stuff then of course I also stay well clear.
 
Jim_R said:
Really? You need to see 5 or 6 little red pixels showing a rounded edge on a cell instead of 1 red block? That's going to make a difference in your decision making?

If you've got onboard radar, you do a different type of flying than me, so maybe it really does make a difference to you. Me, I care if it's a big yellow blob with some red in it, or a big green blob with no yellow in it. I don't need ultra-tiny pixels for me to try to steer some tens of miles away from something that looks bad. Blocks are information enough.
Click to expand...

This is how I use it also. And in any case, the regional detail is plenty good for how I use it. I don't need rounded edges or the ability to see that it is raining at the corner of 13th and Ave K. I would, however, love to see tops info - not sure if XM has that or not.

Patchy Light green with a little dark green or a small bit of yellow = possible depending on the trends.

If I see a lot of yellow or a building trend or anything more reflective than yellow = avoid

I can look at the radar on the ground, then monitor the national radar in flight and plan diversions early when needed. As I get closer I can use the regional radar for a more tactical display. I've found the radar received via ADS-B to be pretty accurate and very much current enough for the kind of weather I'm willing to fly through (read: not thunderstorms).
 
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The 496 with XM was truly a handy little box I do miss from time to time because you could take it with you in a rental car or anywhere, and have weather and street guidance.

But now 3G and 4G are everywhere and we get weather and guidance off a smartphone, so that killed the 496.
 
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