Comments:

1. It was my understanding that the XM Radios only understand AACplus (at least any selling today). XM also has a channel limit of 255 (8 bits of info).
   
   I think the dual receivers have 2 sets of chips unless it can be handled by a new set of firmware. by IdRatherBeSkiing
   
2. DaJoker, you make some excellent points, and stress the conjecture part of it very well. by HomieG
   
3. Quote:

   Originally Posted by IdRatherBeSkiing It was my understanding that the XM Radios only understand AACplus (at least any selling today). XM also has a channel limit of 255 (8 bits of info). I think the dual receivers have 2 sets of chips unless it can be handled by a new set of firmware.

   I am hoping very much that my two XM MyFi's (Purchased in 2005) will get all the signals.
   
   Here's hoping that everyone can use their existing receivers. by goreds2
   
4. That would definitely be a pleasant surprise. But here's my question...if they are able to pick up both signals, why develop so-called "interoperable" radios. They'd already have them. by RoadRunner
   
5. Quote:

   Originally Posted by RoadRunner That would definitely be a pleasant surprise. But here's my question...if they are able to pick up both signals, why develop so-called "interoperable" radios. They'd already have them.

   maybe they're compatible but not fully somehow? is that even possible?
   
   - Jon by jon01
   
6. Quite possible. Currently it comes down to codec transmission. Take away that limitation though, and transmit in a single codec, and we have the possibilities. by DaJoker
   
7. If this is true, that is one more piece of ammo in the merger's favor with the FCC. I would love to keep my JVC SR2000 as long as possible.
   
   Till its tits up! by tgajr
   
8. I have five Sirius radios on my account. Two can pick up all of the Canadian channels. The other three cannot. If many Sirius radios can't even pick up all of the Sirius channels, how can we expect them to also pick up the XM stations? by Beaver_Creek
   
9. Quote:

   Originally Posted by Beaver_Creek I have five Sirius radios on my account. Two can pick up all of the Canadian channels. The other three cannot. If many Sirius radios can't even pick up all of the Sirius channels, how can we expect them to also pick up the XM stations?

   What channels do you get which others may be missing? I get a couple of canadian rock channels, a French canadian channel and some CBC.
   
   I am interested in how my reception is. Any feedback is appreciated. by tgajr
   
10. I hope this is true, because I really don't fill like buy a new radio! I paid for a $350 unit and I own two $150 Soloist units! by WolfViper
    
11. Quote:

    Originally Posted by DaJoker Quite possible. Currently it comes down to codec transmission. Take away that limitation though, and transmit in a single codec, and we have the possibilities.

    That makes sense...thank you! by RoadRunner
    
12. On two of my radios I get Info Plus (channel 187), RCI Plus (188), Rock Velours (192) and Energie 2 (193). I do not receive these channels on the other three receivers. by Beaver_Creek
    
13. Speculation has been that this is due to channel addressing and that older radios simply can not tune to these higher channel numbers and not a limitation of being able to broadcast them. by DaJoker
    
14. If that is the case, why don't the just give them lower channel numbers? (There are many available.) by Beaver_Creek
    
15. Currently, they try to group channels together in genre form. But, you are now thinking in the right direction on how all this is possible. by DaJoker
    
16. Quote:

    Originally Posted by DaJoker Speculation has been that this is due to channel addressing and that older radios simply can not tune to these higher channel numbers and not a limitation of being able to broadcast them.

    But the older radios do get Playboy which is 198, and they used to get Hardcore Sports, but no longer do since February 14. I believe the limitation is the total number of channels these older radios can receive. I believe the limit is 128 channels (2 to the seventh), which is exactly how many channels the radio that powers DogstarRadio receives. by myquealer
    
17. This is a possibility as well. Good catch. by DaJoker
    
18. I'm an engineer, so I know a bit about how the radios work. Without getting too technical, the best likely case is that an existing Sirius or XM radio might be capable of receiving both sets of signals, but they'd always be handled as two different sets of channels with a "hard" mode switch between them (kind of like "AM" vs "FM"). In other words, you could switch your radio from "Sirius" mode to "XM" mode, but it would take a few seconds (maybe 20-50 seconds or more) before it locked on to the new mode's signal and authenticated itself.
    
    That's the best case. I'm not saying it's definitely possible, just that even under the most ideal circumstances, the best anyone with an existing radio can hope for is to be able to reflash their radio and switch it back and forth between "Sirius" and "XM" modes.
    
    OK, I lied. I'm going to get techincal anyway. Here's the hardcore explanation:
    
    Sirius radios don't tune channels. They tune 3 bitstreams -- two from the satellites above, one from the nearest terrestrial repeater. The signals are combined together to produce a single encrypted bitstream that carries all of the audio channels and meta information about them. This encrypted bitstream gets passed along to the baseband chip.
    
    The baseband chip checks its records to see whether it's been authorized to decrypt the bitstream. If it hasn't, or it's about to need a refresh, it decrypts and examines the first chunk of the encrypted bitstream's datagram for the subscriber ID burned into the chip at the factory. If it sees its number, it notes the authorization. Otherwise, it waits for the next datagram and does nothing further with the current one.
    
    Once authorized, the baseband chip deserializes the bitstream into the various channel streams. The desired stream then gets buffered and fed to the codec, which transforms it into an uncompressed PCM datastream. That datastream passes through a low-end DSP, and finally gets fed to a digital amp, which is basically a high-power DAC whose output needs no further amplification. Alternatively, it outputs it to the FM transmitter for PnP use.
    
    Anyway, the point I'm trying to make is that the chips involved are fast enough to process Sirius' bitstream in one gulp, but NOT fast enough or equipped with sufficiently-large buffers to take in a bitstream twice as large (encompassing Sirius and XM's content) in a single operation. They're pretty fast chips to begin with, and value-engineering will ultimately result in chips that are just barely fast enough to do the task they're designed for, but nothing more.
    
    Ironically, that's also why the most likely radios to be reflashable to support both Sirius and XM are the old ones. In electronics, the first generation of a product tends to be a lot like the original prototype, including the chips. Prototypes are built with logic chips that can be reprogrammed (called FPGAs), and often use the fastest DSPs, memory, and microcontrollers available at the time, because at the initial design time there's a lot of uncertainty about how much raw power will ultimately be needed. Making matters worse, in some cases the initial production run begins before the firmware has even been finalized. Thus, the first-gen hardware tends to be over-engineered and exceed the likely baseline specs by a big margin. It's also why first-gen hardware has so many problems... lots of things that work flawlessly with 10 or 20 handmade prototypes given hours of individual love and attention by people who make $100k+ a year don't start to become evident as problems until you've made the first thousand with semi-skilled laborers at a factory in China, or the first 100,000 on a high-speed robotic assembly line.
    
    This brings us to the second-gen, which fixes almost all of the problems that were discovered during the first production run, but still tends to be a little over-engineered unless few problems were discovered during the first round. As a practical matter, second-gen products are usually the best ones you'll ever be able to buy, because the third-generation is almost always focused on cost-cutting and finding ways to use cheaper components without breaking your now-flawless design too badly. Think back to DVD players. The first DVD players were expensive, big, and had some quirks... but many could actually be reflashed by burning new firmware onto a CD-R and cycling the power with a burned firmware disc in the tray. The second-gen players were still built like tanks, were reflashable, and expensive... but they worked well. Most of these players are still in service, and will continue to work for years. Fast forward to the present generation of DVD players, which literally break if you give them a dirty look, skip on discs a 2G player can handle without breaking a sweat, and have the approximate build quality of a 1970s Soviet vacuum cleaner (but cost $29.99 at WalMart instead of $699 at SoundAdvice).
    
    Wrapping up the whole thing as it relates to Sirius radios, the first-gen radios were big, hot, and packed lots of raw computing power that was never needed. The second-gen radios were just as big, hot, and over-engineered... but actually worked as expected. Since that point, new radios have gotten smaller, cooler, and draw less power... but that's because the capabilities of the chips used to build them have been downscaled to *exactly* what they need to be to achieve their intended purpose. First-gen FPGAs became third-gen ASICs that get die-reduced with each new generation. by miamicanes
    
19. Quote:

    Originally Posted by myquealer But the older radios do get Playboy which is 198, and they used to get Hardcore Sports, but no longer do since February 14. I believe the limitation is the total number of channels these older radios can receive. I believe the limit is 128 channels (2 to the seventh), which is exactly how many channels the radio that powers DogstarRadio receives.

    Honestly, I don't think the channel number has anything to do with the stations position in Sirius' broadcast spectrum. When Sirius does their 'channel updates', they are essentially telling our radios to 'map' the channels. For example, map station WFXT534T98 to channel 29. Channel 29 doesn't actually exist. It's only a placeholder.
    
    Just like channel 6 (TV) is not really channel 6. It's actually 83.25MHZ (Video) and 87.75MHZ (Audio). Technically the frequency of what we know as channel 6 could have been 'mapped' to any channel number.
    
    
    EDIT: Ah Miamicanes beat me too it! I'm a reaaallly slow typer! by NHTracker
    
20. OK, so maybe Sirius tuners can pick up XM's signal. The frequencies are close enough so I wouldn't doubt it. But 2 completely codecs, it seems like the Sirius tuner could get the XM signal but wouldn't know what to do with it, and vice versa.
    
    Unless at the start, the 2 companies thought a merger might happen and all radios can decode both and are just keeping that a secret from us? Doubt it though by yg17
    
21. could a unit like the stiletto or the inno be able to decode the signal through a firmware update? by soxnationonline
    
22. Quote:

    Originally Posted by NHTracker Honestly, I don't think the channel number has anything to do with the stations position in Sirius' broadcast spectrum. When Sirius does their 'channel updates', they are essentially telling our radios to 'map' the channels. For example, map station WFXT534T98 to channel 29. Channel 29 doesn't actually exist. It's only a placeholder. Just like channel 6 (TV) is not really channel 6. It's actually 83.25MHZ (Video) and 87.75MHZ (Audio). Technically the frequency of what we know as channel 6 could have been 'mapped' to any channel number.

    But doesn't channel 5 have a slightly lower frequency than channel 6 and channel 7 a slightly higher frequency (and so on from 2 to 69 or 84 or whatever (with a gap for FM))? So the units are different, but the numbers do have meaning. In the case of Sirius where it is just data being decoded the channel numberss are potentially completely irrelevant to the data. by myquealer
    
23. Quote:

    Originally Posted by yg17 OK, so maybe Sirius tuners can pick up XM's signal. The frequencies are close enough so I wouldn't doubt it. But 2 completely codecs, it seems like the Sirius tuner could get the XM signal but wouldn't know what to do with it, and vice versa. Unless at the start, the 2 companies thought a merger might happen and all radios can decode both and are just keeping that a secret from us? Doubt it though

    I suspect the encryption and method of sending the bitstream is a bigger hurdle than the encoding. There is all sorts of technical mumbo jumbo (left hand, right hand, is just the beginning of stuff I don't understand) about how the data is sent from the satellites to our radios, and I have read that it is sent in a somewhat different way from the repeaters. The HM technology that would supposedly add 25% to the Sirius bandwidth is yet another means, one which current radios presumably do not support.
    
    I don't know, but I suspect XM uses a different means of sending that bitstream to the radios with different decryption needed. I hoped miamicanes was going to get into that in his detailed post, but he only got into how Sirius works. by myquealer
    
24. Not sure how true this is, or exactly what it means in the long run but:
    
    
    
    
    Quote:

    Will current XM subscribers need to buy new radios? No.

    http://www.xmradio.com/merger/index.xmc by timewaster
    
25. Quote:

    Your current radio will allow you to enjoy all SIRIUS programming. And in the future you will be able to receive enhanced programming.

    This can easily be read to mean that your Sirius radio will only receive from the Sirius satellites, and that after the merger the Sirius satellites will include some channels that used to be exclusive to XM. by pto
    
26. Quote:

    Originally Posted by pto This can easily be read to mean that your Sirius radio will only receive from the Sirius satellites, and that after the merger the Sirius satellites will include some channels that used to be exclusive to XM.

    I agree that this can be interpreted in several ways. I was thinking along the lines of some of the XM programming may be sent over the Sirius satellites and replace some of the Sirius programming, and vice versa. by Celt1997
    
27. Quote:

    Originally Posted by myquealer But doesn't channel 5 have a slightly lower frequency than channel 6 and channel 7 a slightly higher frequency (and so on from 2 to 69 or 84 or whatever (with a gap for FM))? So the units are different, but the numbers do have meaning. In the case of Sirius where it is just data being decoded the channel numberss are potentially completely irrelevant to the data.

    Absolutely irrelevant. Take the case of say, DirecTV. I subscribe to their HD package, and also I receive HBO. I receive two versions of HBO-HD. One in the 70's, one in the 500's. Same channel, two different numbers, but only one copy of the signal. Channel mappings are more than likely meaningless like this for Sirius as well. by DaJoker
    
28. My take from listening to the conference call with Mel and Richard was that both Sirius and XM will be using their existing satellites for a long time after the merger and that they will be broadcasting the same content on each service. Mel mentioned that there was research into an interoperable receiver going on.
    
    I just cant' see the current receivers being compatible.
    
    As miamicanes points out, both XM and Sirius units have three receivers working at the same time.
    
    - One receiver picks up satellite A
    - Another receiver picks up satellite B
    - The third receiver picks up any repeater that might be nearby.
    
    The repeater and satellite signals have to be separated so they don't interfere with each other and so that no unwanted non-Sirius frequencies that are nearby can cause interference.
    
    To do this they use filters. These filters ensure that ONLY the desired frequency is received and all other frequencies are rejected.
    
    Below is a bock diagram of a Gen 2 Sirius chipset. I realize many won't understand exactly what they're looking at, but note where the antenna goes in on the left and follow the path to the right...
    
    Note the things that say FILTER. There is a LOT of filtering going on in a Sirius receiver. This ensures that ONLY the desired frequencies are picked up.
    
    
    
    Now.. The sirius signals are between 2320.000 Mhz and 2332.500 Mhz. XM signals are between 2332.5 and 2345
    
    Since a Sirius receiver is carefully designed NOT to receive anything outside of where its satellites and repeaters work, I can't see any way for it to pick up XM signals. Conversely, XM radios will not be able to pick up Sirius signals.......
    
    Another way of looking at it is to consider your FM radio. It goes from 88 Mhz to 108 Mhz. Try to tune past 108 Mhz up to 128 Mhz.... You can't.... The radio wasn't designed to receive that frequency. The same applies to XM vs Sirius.
    
    I can't see the receivers being interoperable. You'd need two completely separate tuner 'front ends'. by jwt873
    
29. Quote:

    Originally Posted by myquealer But doesn't channel 5 have a slightly lower frequency than channel 6 and channel 7 a slightly higher frequency (and so on from 2 to 69 or 84 or whatever (with a gap for FM))? So the units are different, but the numbers do have meaning. In the case of Sirius where it is just data being decoded the channel numberss are potentially completely irrelevant to the data.

    The channel numbers do refer to specific frequencies as assigned by the FCC in the NTSC world. But, when we finally convert to DTV, a good number of stations will keep their digital channel rather than their analog channel. In this case, they'll keep using their analog channel as a virtual digital channel so that they can keep their brand image. For example, virtual channel 2-2 in Boston is really broadcast on the frequencies alloted to channel 19.
    
    BTW --- there is also a huge gap between channel 6 and 7. Channel is is just below the FM band, and channel 7 is somewhere in the 180 MHz range IIRC. by robertq
    
30. Quote:

    Originally Posted by DaJoker Speculation has been that this is due to channel addressing and that older radios simply can not tune to these higher channel numbers and not a limitation of being able to broadcast them.

    First of all, good summary on the codecs.
    
    I'm a bit confused about the higher channel numbers. When Hardcore Sports (ch.186) first came on, my two receivers were not picking it up. After I did a refresh signal from the SIRIUS website, I got the channel on both receivers. Since the 2/14 channel update, I lost Hardcore on both receivers. by PhillyPhan
    
31. PhillyPhan - Hardcore sports was removed from SIRIUS' lineup. by syphix924
    
32. Quote:

    Originally Posted by soxnationonline could a unit like the stiletto or the inno be able to decode the signal through a firmware update?

    It depends on how much of this stuff is done through software (firmware) vs the hardware (chips) themselves. It the codec is chip based, I would not want the firmware required to bypass it. by IdRatherBeSkiing
    
33. Quote:

    Originally Posted by syphix924 PhillyPhan - Hardcore sports was removed from SIRIUS' lineup.

    Apparently American subs with newer radios still have it.
    
    http://www.siriusbackstage.com/forum...light=hardcore by redflag
    
34. Quote:

    Originally Posted by redflag Apparently American subs with newer radios still have it. http://www.siriusbackstage.com/forum...light=hardcore

    I'm calling "shenanigans" (or a failed channel update for those folks who still get 186). Even SIRIUS said the channel was off the lineup on Feb. 14:
    http://www.sirius.com/servlet/Conten...=1158082411510 by syphix924
    
35. Quote:

    I'm calling "shenanigans" (or a failed channel update for those folks who still get 186). Even SIRIUS said the channel was off the lineup on Feb. 14: http://www.sirius.com/servlet/Conten...=1158082411510

    Canadians still have it.
    
    http://www.siriuscanada.ca/Channels-e.htm
    
    Before Hardcore Sports was formally added for American subs, owners of newer SIRIUS units claimed they could get it, along with other then Canada-only channels. I'd be curious to hear more from those people. by redflag
    
36. Quote:

    Originally Posted by redflag Fine. So I guess you want to call Chad, Michigan Made (an admin) and Sirius Rich (among others) liars.

    Calm down. Re-read my post. I never called anyone a "liar", and never even called those who receive 186 as causing "shenanigans". Only that it's peculiar that SIRIUS said the channel's gone, and MOST listeners don't have it post-Feb. 14th.
    
    Perhaps the use of "shenanigans" was improper. I apologize. I won't use the word "shenanigans" ever again.
    
    Captain O'Hagan: I swear to God I'm going to pistol whip the next guy who says, " Shenanigans."
    Mac: Hey Farva what's the name of that restaurant you like with all the goofy shit on the walls and the mozzarella sticks?
    Farva: You mean Shenanigans?
    Mac & Thorny (together): OOOOOOOOOOOOOO.
    
    Are you calling SIRIUS a "liar"? I'm not...I'm calling them "inept at channel updates".
    
    EDIT: damnit!! you updated your post!! I was off searching for the quote from "Super Troopers"...aww....now I look like an ass.... by syphix924
    
37. Quote:

    Originally Posted by syphix924 I'm calling "shenanigans" (or a failed channel update for those folks who still get 186). Even SIRIUS said the channel was off the lineup on Feb. 14: http://www.sirius.com/servlet/Conten...=1158082411510

    The channel update worked fine and as planned. Hardcore Sports acknowledged that it would still be available on newer receivers. I am pretty sure that older receivers are limited to receiving 128 channels, and Sirius chooses which channels the older receivers get. Before February 14 Hardcore Sports was among the 128, but several other Canadian channels were not. After February 14 with the addition of new channels they had to take one channel we currently receive out of the 128 and Hardcore Sports is the channel they chose. by myquealer
    
38. Hm...I formally apologize for my use of "shenanigans" (*WHAP!!*).
    
    So, what channels are in the 129+ category?? by syphix924
    
39. Quote:

    Originally Posted by syphix924 Calm down. Re-read my post. I never called anyone a "liar", and never even called those who receive 186 as causing "shenanigans". Only that it's peculiar that SIRIUS said the channel's gone, and MOST listeners don't have it post-Feb. 14th. Perhaps the use of "shenanigans" was improper. I apologize. I won't use the word "shenanigans" ever again. Captain O'Hagan: I swear to God I'm going to pistol whip the next guy who says, " Shenanigans." Mac: Hey Farva what's the name of that restaurant you like with all the goofy shit on the walls and the mozzarella sticks? Farva: You mean Shenanigans? Mac & Thorny (together): OOOOOOOOOOOOOO. Are you calling SIRIUS a "liar"? I'm not...I'm calling them "inept at channel updates". EDIT: damnit!! you updated your post!! I was off searching for the quote from "Super Troopers"...aww....now I look like an ass....

    
    
    Sorry for the edit. I toned my response down for just the reason you stated. by redflag
    
40. Quote:

    Originally Posted by syphix924 Hm...I formally apologize for my use of "shenanigans" (*WHAP!!*). So, what channels are in the 129+ category??

    I believe they are all Canadian channels for US subscribers. I don't know channels what Canadian subscribers with old radios are missing. Anyone? by myquealer
    
41. Ok...just checked...I could have SWORN that I wasn't getting Hardcore Sports anymore (on my Xact XTR8CK), but I am....
    
    weird.
    
    okay...back to the subject of the thread...sorry for the distraction... by syphix924
    
42. Quote:

    Originally Posted by Celt1997 I agree that this can be interpreted in several ways. I was thinking along the lines of some of the XM programming may be sent over the Sirius satellites and replace some of the Sirius programming, and vice versa.

    Thats what I figure they will ultimately do. if there are two channels that are essentially clones of themselves simulcast them on both services and then only worry about the exclusive content. That way bandwidth is freed for more content. (im not going to say better quality, maybe initially but I can see them adding more as the years go on) by Ryokurin
    
43. Quote:

    Originally Posted by syphix924 Ok...just checked...I could have SWORN that I wasn't getting Hardcore Sports anymore (on my Xact XTR8CK), but I am.... weird. okay...back to the subject of the thread...sorry for the distraction...

    Actually, this does kind of go back to the subject of the thread. If there's a limit on the amount of channels a current SIRIUS radio can receive, assuming they could pick up both sets of signals, would the al la carte selection be to pick which 128 from both services you want? by redflag
    
44. Quote:

    Originally Posted by redflag Actually, this does kind of go back to the subject of the thread. If there's a limit on the amount of channels a current SIRIUS radio can receive, assuming they could pick up both sets of signals, would the al la carte selection be to pick which 128 from both services you want?

    When you are used to 130 channels, picking 128 should be easy. For an XMer who is used to 170, it can be more difficult.
    
    To get content (other than channels simulcast on both systems) from the other provider, I don't see how you would not need new hardware. by IdRatherBeSkiing
    
45. Quote:

    Originally Posted by IdRatherBeSkiing To get content (other than channels simulcast on both systems) from the other provider, I don't see how you would not need new hardware.

    That's what I'm thinking. That's the reason for the upcoming dual reception units. by redflag
    
46. The biggest hurdles in receiving both subs on one receiver are:
    1) different transmission modes
    2) managing 2 different authentication identities
    3) decoding both codecs.
    
    Existing radios can almost certainly receive the full 25 MHz of bandwidth.
    
    The satellites are not doing any of the encoding and merely re-broadcast what they get from the uplink. They can be repurposed at anytime to service either system.
    
    My guess is we will see a phased transition that will likely go something like this:
    
    A new tiered content system will be introduced almost immediately, probably only available on XM radios since they already have a tiered, paid subscription infrastructure. Sirius and XM will both lose about 25% of their content at this time to give bandwidth to the new tiered system. The signals will probably then be re-distributed among the satellites to improve reception for both service subscribers.
    
    Then a big push will go into creating radios that can receive all of the programming. My guess is that this will be based on the XM hardware so that the XM receivers out there will be able to receive all of the basic content and only those wanting the premium programming will have to upgrade hardware. The Sirius hardware would at this point be deprecated.
    
    I really think this is a bad move for consumers and I hope it doesn't happen but if it does go through this is the most likely transition scenario. IMO
    Then, when the life-cycle of our existing receivers is over by dantodd
    
47. Quote:

    Originally Posted by dantodd A new tiered content system will be introduced almost immediately, probably only available on XM radios since they already have a tiered, paid subscription infrastructure. Sirius and XM will both lose about 25% of their content at this time to give bandwidth to the new tiered system. The signals will probably then be re-distributed among the satellites to improve reception for both service subscribers. Then a big push will go into creating radios that can receive all of the programming. My guess is that this will be based on the XM hardware so that the XM receivers out there will be able to receive all of the basic content and only those wanting the premium programming will have to upgrade hardware. The Sirius hardware would at this point be deprecated. I really think this is a bad move for consumers and I hope it doesn't happen but if it does go through this is the most likely transition scenario. IMO Then, when the life-cycle of our existing receivers is over

    XM does not currently used a tiered approach. At some point in the past, they did. But the XM model does allow channel manipulation via radio id. I am sure the Sirius models do the same thing since XM Canada and Sirius Canada use this method to filter out some of the channels to make the CRTC happy.
    
    My best guess is that they will split the programming over the 2 sats. If you have a current XM, you will get 1/2 the content. If you have a Sirius, you would get the other 1/2. If you have both, they will allow you to link the 2 together for a discount. Going forward, new radios will have both chipsets included and the transition will be the same as a channel change.
    
    I don't think any of this is official as they can't work together on it until the merger is final. However, if I was doing it, it would be the only way to insure I didn't either piss off 8 million or 6 million subs enough for them to cancel. by IdRatherBeSkiing
    
48. Quote:

    Originally Posted by dantodd Existing radios can almost certainly receive the full 25 MHz of bandwidth.

    Do you have anything to support this? by jwt873
    
49. Don't forget that Sirius also has tiering ability, ala Playboy radio. Sure you don't currently pay for the tier, but it is a tier none the less. by DaJoker
    
50. XM has 170 channels?
    
    How many of those are sports game channels or all of them complete channels? by TacoKid
    
51. I would pay $7 a month more for Air America Radio and a handful of XM Music stations today. Today XM/Sirius. Today. Today. Today. by onehandle
    
52. Quote:

    Originally Posted by TacoKid XM has 170 channels? How many of those are sports game channels or all of them complete channels?

    69 commercial free music
    5 CC commericalized music
    46 talk + complete sports stations
    21 Traffic / Weather stations
    29 Play by Play channels of various sports
    1 emergency channel
    1 preview channel
    
    = 172 channels (170 without the last 2).
    
    141 usefull stations + play by play + preview + emergency by IdRatherBeSkiing
    
53. I'm not an engineer, so I can't make much claim to understanding the tech talk up there (though my engineer girlfriend is fascinated by it).
    
    However, it seems there's an easier way to get compatibility in the radios and that's at the studio level. Since the satellites are bent pipes, basically, and already fixed as costs (since they're already launched), the solution might lean more along the lines of combining studio operations.
    
    The merger is going to save most of its money on content costs, since that's where the majority of duplication occurs. So why wouldn't they consolidate the programming into one single broadcast, and then separately encode it into each services respective broadcast signal?
    
    That way, you're just producing one channel of 80's music, but sending it to two different types of receivers. Or am I missing something? by timmy765
    
54. Lets see if I can ask this without sounding stupid...Is there a "Middle" frequency that BOTH Sirius and XM radios can understand and can be used as a "Carrier" to "FOOL" the current chipsets and allow reception of all content? by v1ru5
    
55. Quote:

    Originally Posted by v1ru5 Lets see if I can ask this without sounding stupid...Is there a "Middle" frequency that BOTH Sirius and XM radios can understand and can be used as a "Carrier" to "FOOL" the current chipsets and allow reception of all content?

    The problem is the data compression scheme's are different. Has much more to do with that, than it does with the frequencies that transport those incompatible data streams. by HomieG
    
56. Quote:

    Originally Posted by jwt873 Do you have anything to support this?

    just a lot of experience with microwave radios. I don't have enough interest in looking into the exact schematic but at that frequency the filters and PLL controllers are almost certainly able to tune at least 25 MHz. by dantodd
    
57. Quote:

    Originally Posted by DaJoker Don't forget that Sirius also has tiering ability, ala Playboy radio. Sure you don't currently pay for the tier, but it is a tier none the less.

    That's why I mentioned that XM has the tiered, paid infrastructure. Since it will almost certainly take some time to combine operations the billing and authentication system on XM will probably be the one used for tiered content since it has the ability to track multiple tiers already. The XM billing system will probably not be hooked directly into the authentication system on Sirius because it isn't really that easy at the enterprise level and would be relatively expensive. Additionally there are more XM receivers out there so it represents a larger customer base for upselling to the premium content. by dantodd
    
58. Quote:

    Originally Posted by HomieG The problem is the data compression scheme's are different. Has much more to do with that, than it does with the frequencies that transport those incompatible data streams.

    Plus the satellites, are really just rebroadcasting whatever gets sent up so they can send either signal to any of the satellites. The early XM birds only have enough power to broadcast 1/2 the signal but they can work around that. I suspect that if they merger goes through one of the XM birds will begin broadcasting Sirius and one of the active Sirius birds will always be broadcasting XM. This will give Sirius the ability they were looking for in launching Sirius-5. It will improve the reception of both services. Naturally sending both signals over the terrestrial network will greatly improve the reception of Sirius. by dantodd
    
59. Quote:

    The merger is going to save most of its money on content costs, since that's where the majority of duplication occurs.

    Compared to the care and feeding of their respective satellite constellations and paying down their purchase price, filling Howard & Oprah's bank accounts, and keeping the NFL, NBA, and MLB happy, the cost of content production for the music channels is practically zero. Eliminating music channels to cut costs would be like building a new PC that's crippled with a single stick of ram instead of a matched pair just to save $10 on something that costs more than $800 anyway.
    
    Sirius doesn't want to axe music channels to cut costs... it wants to axe music channels to free up bandwidth for video, which it thinks it can make more money selling than music (despite the fact that there are at least two mobile video companies about to launch this summer who'll collectively spank anything video-related Sirius can even fantasize about doing with their limited bandwidth.
    
    
    Quote:

    So why wouldn't they consolidate the programming into one single broadcast, and then separately encode it into each services respective broadcast signal?

    Because they'd lose half of their customers outright if they did. Musically, Sirius and XM are polar opposites. Over the span of 24 hours, there might be one, maybe two, songs that get played on a pair of XM and Sirius channels that people who don't ever listen to music would wrongly describe as "overlapping" based solely on their names or channel descriptions. Sirius and XM appeal to completely different audiences who can't even stand to be in the same room if there's music playing, because they'll be fighting over it within 30 minutes. by miamicanes
    
60. Quote:

    Originally Posted by myquealer But the older radios do get Playboy which is 198, and they used to get Hardcore Sports, but no longer do since February 14. I believe the limitation is the total number of channels these older radios can receive. I believe the limit is 128 channels (2 to the seventh), which is exactly how many channels the radio that powers DogstarRadio receives.

    That's almost certainly it.
    
    It's apparent that when you receive a channel lineup (through activating a radio, adding playboy, or when Sirius sends out a lineup change), a table is kept locally with the channel information (including displayed number, name, and category; these can be deduced because you can turn off the radio, unplug the antenna, turn it on, and this information is still displayed!). I would suggest that due to either soft/firmware (for those who speak C... struct chan_ent chan_table[128];...) or hardware limitations (if a channel entry is, say 64 bytes, the NV memory chip that stores this information might only be 8 kbytes), this table in older receivers is limited to 128 (2^7) entries. At some unknown point, soft/firmware or hardware was upgraded when Sirius decided they wanted to offer more than 128 channels across the service (with the Canadian offering on the horizon). by leviramsey
    
61. Quote:

    Originally Posted by IdRatherBeSkiing 69 commercial free music 5 CC commericalized music 46 talk + complete sports stations 21 Traffic / Weather stations 29 Play by Play channels of various sports 1 emergency channel 1 preview channel = 172 channels (170 without the last 2). 141 usefull stations + play by play + preview + emergency

    And the traffic channels are one per city, while Sirius pairs up cities on traffic channels. Take out those 10 extra traffic channels and you've got 131 channels.
    
    It would be interesting to chart the average number of XM channels active at any given time (i.e. averaging out sporting events). I doubt it's higher than 140 channels. by leviramsey
    
62. Quote:

    Originally Posted by leviramsey And the traffic channels are one per city, while Sirius pairs up cities on traffic channels. Take out those 10 extra traffic channels and you've got 131 channels. It would be interesting to chart the average number of XM channels active at any given time (i.e. averaging out sporting events). I doubt it's higher than 140 channels.

    15 of those are for MLB. XM does not pre-empt talk channels for MLB games. You get the home broadcast of every MLB game. During baseball season almost all of those are active. Of course, now, they are not in use although still there (simulcasting MLB Home Plate).
    
    I'd say your average is about right considering all the time where broadcasting is not happening on these channels. by IdRatherBeSkiing
    
63. Add 2 to my XM counts... I forgot that Sirius has LA and NYC on dedicated traffic channels. by leviramsey
    
64. First, both Sirius and XM receivers do an excellent job of mirroring capabilities. So far as I can tell, channels can be individually blocked or enabled on specific receivers on both systems, allowing tiering.
    
    So far as interoperability, maybe the receiver's front ends could be made compatible. Sirius receivers must receive up to three carriers simultaneously, one from each bird and a ground repeater. XM receivers must do this also, but their transmissions are further divided into two "ensembles" per satellite or repeater. Each ensemble transmits only half the channels. So with XM, there are 6 carriers instead of Sirius' 3, however XM receivers only receive one "ensemble" at a time.
    
    Potentially the biggest compatibility problem is the channel service decoder. This takes the 3 streams from the front end, combines them into one stream, decypts and pulls out the data for the channel of interest. Understandably, Sirius and XM keep this part of the algorithm fairly secert, because this part contains the most sensitive algorithms that might allow thieves to make radios that would steal the service.
    
    Then there's the codec. While each has their own tweaks, most of the information about the codecs is more well known. Although Sirius and XM use different codecs, as far as I know they are just tweaked versions of standard codecs.
    
    So far as I know, current interoperable prototypes just have both chipsets in one box. Seems to me that it took a couple years to get current ASICs designed and into production, so I wouldn't be surprised if it takes a while to get interoperable ASICs to production. In the meanwhile, maybe we'll see both-chipsets-in-one-box interoperable receivers. by tps
    
65. Mel has finally cleared this up. Of course you'll need a second receiver to get all the other service's content. Duh. They're not going to waste half their capacity simulcasting, nor will your existing receivers magically pick up the other band. The idea is to make the other service a fairly inexpensive add-on, whether you get it via a new interoperable receiver or an additional single-band unit. They can simply mate the account, just like on Family Plan. Here's Mel:
    
    
    Quote:

    Q: Once the dual-chip device hits the market, what will happen to the satellite radios that consumers currently have? A: The radios won't be obsolete. … Let's assume that you are a subscriber and you like Sirius. If you want to get something additional, then that's your choice and you can always decide to buy a new radio. But we're not migrating you or forcing you to pick up some XM content (on a dual device). So I think the opportunity of having one radio is again giving consumers more choice. Shortly after the merger, we will have a radio that will be able to get both services, so you'll have a choice if you want to buy that radio or not.

    http://www.usatoday.com/money/media/...ius-usat_x.htm by JJS