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XM Satellite Weather Woes

garrys

Active Member
Several of my pilot friends have been noticing degraded performance from their XM Satellite Weather systems, like very slow to receive the first data packet, and subsequent updates spaced out up to an hour apart (they are supposed to update every 5 minutes, max). Has anyone else been experiencing problems? Rumor has it that XM is experiencing bandwidth limitations and have selectively degraded those users they consider "infrequent" users. I don't even know if this makes sense, but I'm throwing it out anyway for those who are much more technical than I am.
Garry Stout, Tampa FL RV7A
 
Several of my pilot friends have been noticing degraded performance from their XM Satellite Weather systems, like very slow to receive the first data packet, and subsequent updates spaced out up to an hour apart (they are supposed to update every 5 minutes, max). Has anyone else been experiencing problems? Rumor has it that XM is experiencing bandwidth limitations and have selectively degraded those users they consider "infrequent" users. I don't even know if this makes sense, but I'm throwing it out anyway for those who are much more technical than I am.
Garry Stout, Tampa FL RV7A

Doesn't make much sense to me...

XM's signal is one way. Our radio/GPS does not report back. It would take bandwidth to selectively degrade a users radio, just as it does when subscribing or unsubscribing. XM only sends the subscribe/unsubscribe signals for a limited amount of time........due to bandwidth.

L.Adamson ---- RV6A
 
We havn't had any issues like that with our XM weather.

We have radar within 5 mins, airport details with 10 mins, and TAF with 10 mins.

At worst looped radar within 18 mins.


Maybe your xm antenna doesn't have a clear view of the sky? or is failing?
 
WX slow

Hi Garry,
Our ID is verified before the SAT sends us info. Opportunity there to discriminate in various ways without affecting bandwith. My service has been turned off by XM more than once due to not using it for over 30 days despite paying every month by auto credit card system that they control with my permission! I try to use it every 2 weeks to stay active. I also have a switched electric circuit, that does not require the master, to make it easy to turn the WX system on when I get to the hanger so it can collect info while I preflight and load plane. I get very good reception in the all metal hanger.
Anywhere Map XW in RV6a
 
XM doesn't 'disable' your service. They have no idea if you are using the service or not. Your unit may 'forget' that it is authorized to receive the data (or maybe you have a dying battery), but again XM doesn't know that you haven't flown for 30 days.

It seems like every summer the discussion about XM service being slow comes up. Of course it's slower...there are far more storm systems in the summer. The more storms there are, the more nexrad/lightening strike/cloud cover data there is to pipe across the satellites.
 
It seems like every summer the discussion about XM service being slow comes up. Of course it's slower...there are far more storm systems in the summer. The more storms there are, the more nexrad/lightening strike/cloud cover data there is to pipe across the satellites.

Logical, I agree with Jamie
 
Seeing this subject come up on a fairly regular basis makes me happy I have WSI weather. It just never seems to stumble.
Now that I've said that, it will probably not work on my next flight!:rolleyes:
 
XM

XM doesn't 'disable' your service. They have no idea if you are using the service or not. Your unit may 'forget' that it is authorized to receive the data (or maybe you have a dying battery), but again XM doesn't know that you haven't flown for 30 days.

Let me tell what I recall: Unit could not get the weather, my computer shows that I need to contact them, ID not accepted. I called them, gave them on the phone my ID. They said a "refresh" signal would be sent out for a certain time (don't recall the exact term for this). My unit picked up this in the next few minutes and worked fine after that. No batteries were replaced in any of my equipment, this is for certain. On the call to customer service I asked them to explain why this happened. They said that from time to time they purge IDs that have been inactive. I have been around, seen **** like this before. I believe customer service on this one. I don't know everything, but I don't pretend to either.
 
You may want to keep in mind that "space weather" like solar activity can affect reception too.
 
Like Jamie sez, it is impossible for them to know if you have been active or not.... It is a one way system!

But!!!! They may have a feature built into the receiver that requires a certain "heartbeat" or similar from their system ever so often to stay enabled. If it does not get the heartbeat within the window, it dies...

Those people who answer the phone there most likely have no idea how the system works. All they are doing is reading the flow charts...
 
Had the same issue

in our Lance --- monthly updates paid, but airplane not flown regularly --- called XM, and they sent the refresh signal, but it took nearly two hours to get it. I was told that lack of use (unkown time frame) and the unit gets dropped.
 
Someone who works for or worked for XM posted a description of the process awhile back but I cannot find it.

Apparently every so often every XM sends a coded signal to every reciever ID if yours is not on and doesn't receive it then you no longer will receive weather info at least until you refresh.

Or something along those lines.
 
The "Heartbeat" I mentioned above....

Apparently every so often every XM sends a coded signal to every reciever ID if yours is not on and doesn't receive it then you no longer will receive weather info at least until you refresh.

Or something along those lines.
 
Similar situation

Just two weeks ago today I was flying to South Dakota from Chandler, AZ. During my first leg, I noticed my XM weather wasn't working. At my fuel stop at Dalhart, TX I called XM. They said my weather subscription had been suspended due to lack of use. I use it almost everyday!!!!

The part that aggravated me was that they wouldn't give me the same rate I had signed up for last Oshkosh. I signed for a year with quarterly billing. I signed up for two months and will renegotiate at Oshkosh this year. I'll get my pound of flesh there!!!!

On the return trip a week later, the XM weather was invaluable.
 
XM doesn't 'disable' your service. They have no idea if you are using the service or not. Your unit may 'forget' that it is authorized to receive the data (or maybe you have a dying battery), but again XM doesn't know that you haven't flown for 30 days.

Let me tell what I recall: Unit could not get the weather, my computer shows that I need to contact them, ID not accepted. I called them, gave them on the phone my ID. They said a "refresh" signal would be sent out for a certain time (don't recall the exact term for this). My unit picked up this in the next few minutes and worked fine after that. No batteries were replaced in any of my equipment, this is for certain. On the call to customer service I asked them to explain why this happened. They said that from time to time they purge IDs that have been inactive. I have been around, seen **** like this before. I believe customer service on this one. I don't know everything, but I don't pretend to either.

My plane with XM/radio & weather didn't fly for 2 1/2 months. And when it briefly flew, someone else was flying. My truck with XM radio wasn't driven for close to four months. I had an on the job injury & called XM for a temporary cancellation. Without either radio being on, for such a length of time to recieve the deactivation signal......neither was was turned off. That's the way it is. XM does not get individual ID's uplinked from our radios to the satellite. They run the activation & turnoff signals for a limited amount of time, due to bandwidth. They also run specials for a limited time, in which your un-used radio is activated for two weeks. Then a signal is sent out to de-activate it. I suppose that helps clear up a few "feebies" that can occur from time to time.

L.Adamson
 
Why is it that different pilots report such widely varying experiences with XM? That absolutely shouldn't be the case. Something screwy is going on, and I don't think ANY of us know the whole story.
As far at the XM communication being "one way", I don't think so. If I haven't paid my monthly subscription, they turn me off, which means they send out a discreet signal to each and every unique subscribere ID. Same thing when they "refresh" the service......they send out a refresh signal to my Unique ID.
 
Why is it that different pilots report such widely varying experiences with XM? That absolutely shouldn't be the case. Something screwy is going on, and I don't think ANY of us know the whole story.
As far at the XM communication being "one way", I don't think so. If I haven't paid my monthly subscription, they turn me off, which means they send out a discreet signal to each and every unique subscribere ID. Same thing when they "refresh" the service......they send out a refresh signal to my Unique ID.

Well.....this IS the internet, and the fact is, on the 'net, you primarily hear about the problems that people have - you don't get the 95% of the people that have never had a problem logging on to say "I didn't have a problem today!" So you have to keep that in perspective. If it makes you feel better, I have only had my XM drop out once or twice in over four years of CONSTANT flying and use.

As for the one-way, this was described a few posts back. It takes just a slight amount of cleverness to design a radio that needs to get "pinged" every once in awhile in order to work. I don't believe it has any kind of transmitter - it's just a receiver that needs to get a code to get activated, and can also receiver a code to be de-activated (it's still receiving all the time, it just refuses to give you any data. It can be built with a "watchdog timer" that forces it to deactivate itself if it doesn't hear an appropriate code every so often. I'm not saying that I know specifically how it works, I am just saying that the logic to design it this way is not that hard to engineer.

Paul
 
It is still "one way"... From them to your receiver...



As far at the XM communication being "one way", I don't think so. If I haven't paid my monthly subscription, they turn me off, which means they send out a discreet signal to each and every unique subscribere ID. Same thing when they "refresh" the service......they send out a refresh signal to my Unique ID.
 
I had an intermitten problem with my 396 Garmin receiver. I moingved the antenna, thought I had a conflict with my other GPS, finally I turned off my I Phone. It seems to be the solution to the problem. My IPhone has a gps receiver and so it makes sense that the two my conflict. I will continue to monitor the situation but I would try it.

STeve Anderson
RV 7A Flying
Lafayette, La.
130 hoiurs
 
I've heard the same...but

I had an intermitten problem with my 396 Garmin receiver. I moingved the antenna, thought I had a conflict with my other GPS, finally I turned off my I Phone. It seems to be the solution to the problem. My IPhone has a gps receiver and so it makes sense that the two my conflict. I will continue to monitor the situation but I would try it.

STeve Anderson
RV 7A Flying
Lafayette, La.
130 hoiurs

I asked XM tech support if a GPS receiver would interfere with the XM and I was told that I could put the antennas and receivers as close to one another as I wanted to. There is a lot of talk about XM/GPS interference on the net but XM tech support doesn't seem to agree. BTW, my GPS reciever/antenna and xm antenna are side by side (almost touching) and seem to work fine. I just do the refresh thing as a precaution. If I flew everyday I don't think it would be required.
 
Several of my pilot friends have been noticing degraded performance from their XM Satellite Weather systems...
Garry Stout, Tampa FL RV7A

What I've noticed is how the yearly fee keeps degrading too :(. I got my renewal notice a few weeks ago and the Aviator Lite subscription has gone from $360/yr to $420. :eek: Considering how seldom I use it, I've got to believe I can get the info cheaper off a cell phone. This is likely to be my last year using XM weather.

Despite my infrequent use, I have never noticed any interruption in service. For $420/yr why would they risk cutting someone off from a prepaid subscription? That's marketing suicide.

Correction 6/26/10: With taxes it came to $454.56 for the Aviator Lite annual subscription.

Chris
 
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I don't believe it has any kind of transmitter - it's just a receiver that needs to get a code to get activated, and can also receiver a code to be de-activated (it's still receiving all the time, it just refuses to give you any data.

There's an analogy here with satellite based subscription television. The dish receives every channel, the receiver can decode every channel, but I can't watch every channel. But I can call up the provider and subscribe to a new channel, even with the landline modem built into the receiver unplugged - in other words, the "activation" is delivered via satellite. There is a portion of bandwidth explicitly set aside for this purpose.

A while back, we investigated the possibility of using XM to multicast tracking data *back* to aircraft in a secure and selective manner based on the same principles. As I recall from those discussions, Paul, you are exactly correct.
 
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