TiVo SDV Oddity

A reader contacted me today to ask me about something odd he’s been experiencing with his TiVo Series3. He’s a Time Warner Cable user in Raleigh, NC, and lately they’ve been adding new HD channels using SDV in his area. The oddity is that he’s been able to tune in three of these channels – A&EHD, TBSHD, and GOLF/VSHD – on his Series3. This is odd because the S3 is physically incapable of tuning SDV channels, that’s what the Tuning Resolver that’s coming out in 2008 is for. He said that early on he got error messages that the channels were unavailable, as I’d expect, but that he’s been able to regularly tune them lately. This is very odd indeed, and I had three theories:

1. The channels aren’t actually SDV, but are standard linear channels and TWC just gave out bad info about them being SDV. The S3 would be able to tune these channels like any other cable channel. The earlier error messages could’ve been a coincidence – some unrelated problem. Or perhaps the guide was updated before the channels were live.

2. The channels did start out as SDV, but demand was high enough that they were always in use, so TWC just converted them to linear channels. That would explain the error and then the channels working regularly.

3. The channels are SDV, and someone else on his cable network segment has tuned the channels. When an SDV STB tunes an SDV channel the head end dynamically assigns the channel to a frequency and then tells the STB which frequency to tune for the channel. I suppose it is possible that this updated channel map is also being picked up by the CableCARDs in his S3, allowing him to tune in the SDV channel so long as someone else on his segment has previously requested it. He would lose access to the channel whenever no one else on his segment was viewing it. And it is just coincidence that his tests have fallen during times when the channels are in use.

Now, I did some poking around online, and from what I can tell those three channels are SDV in Raleigh, NC, and have been since they were added in October. That seems to indicate hypothesis number 3.

Has anyone else who lives in an area using SDV been able to tune SDV channels on their CableCARD TiVo? Can anyone else who lives in Raleigh confirm that these are SDV channels? Can you tune them, or any other SDV channels, with your TiVo?

I suppose the ultimate test would be someone who has SDV channels, a CableCARD TiVo, and a regular cable STB. Find an SDV channel that the TiVo cannot tune. Then tune that channel with your STB. That would cause the head-end to issue a frequency for the channel. Then try to tune it on your TiVo again. If it works on the TiVo, then we know the TiVo can tune SDV channels if they’re in use. Unfortunately, if it doesn’t work all it means is that it doesn’t work there. Different cable systems could handle the channel mapping data differently. So it not working in one location doesn’t mean the TiVo is incapable of doing it everywhere. (And it working in one location doesn’t mean it will work everywhere, but it does mean it could work.)

About MegaZone

MegaZone is the Editor of Gizmo Lovers and the chief contributor. He's been online since 1989 and active in several generations of 'social media' - mailing lists, USENet groups, web forums, and since 2003, blogging.    MegaZone has a presence on several social platforms: Google+ / Facebook / Twitter / LinkedIn / LiveJournal / Web.    You can also follow Gizmo Lovers on other sites: Blog / Google+ / Facebook / Twitter.
This entry was posted in TiVo and tagged , , , . Bookmark the permalink.
  • http://bjdraw.com Ben Drawbaugh

    I’d say it was #1
    My understanding is that they can change a channel to or from SDV in a matter of minutes and actually on the fly to optimize the network. Mari has done a post on a demo she received where she was able to see how they monitor the network and make changes based on viewers usage in real time.

  • http://www.gizmolovers.com/ MegaZone

    It is probably one or two, the channels are linear for some reason. It is curious, I’d love to get some more data points.

  • David

    I suspect theory #2. I’m on TWC in San Antonio and I’ve seen the same behavior with my S3. Several times I’ve seen channels that are initially advertised as not available to CableCard customers will later become tunable. Sometimes (but not always) these channels are dropped from the “Not Available” page on the twc-sa.com web site. Unfortunately their site is generally out of date so I don’t really trust it.

  • Cathy

    I believe TW has to update the cablecard with the mapping info that makes the channel tuneable. This is the explanation I received for not getting newly added HD channels from my TWC affiliate. They don’t want to give Cablecard users access to anything that will become SDV later, because then they would have to take away something we had and we might ask for lower rates or rebates at that time. In the meantime, they feel o.k. about charging us the full fee even though we aren’t getting the full service because they didn’t raise the rates when they added the new channels and therefore we aren’t paying more for less than we had before; we’re just paying the same as our neighbors pay and getting less. (Yes, this is really what they said!!!)

    Anyway, these are linear channels and TWC must have updated his cablecards with the mapping info. Maybe some knowledgeable tech “fixed” a problem for another customer without realizing that his bosses had decided not to make these channels available to Cablecard users.

  • Glenn

    Ditto Ben’s comment. I would assume that SDV means “switched”, meaning the binding between the channel name (Bravo HD say) and the actual frequency and program number used (FREQ=6MHz band, PN=number from one to N within the MPTS their QAMs put the channels within that band) for that channel is DYNAMIC. There would seem to be no guarantee that the same frequency and PN would be assigned to Bravo HD each time your neighbour tuned it in. Unless there is something DHCP like about the assignments, i.e. they tend to use the same one over and over again as long as its available… and he’s just lucky the frequency/PN assigned early on is near the end of their search list…

  • MichaelM

    For what it’s worth, I have a STB and a Tivo3 with Multistream Card connected to the same cable outlet. I use TWC in Austin, and I tried an experiment: tune in a channel I know is SDV on the cable box, and then, after a few minutes, try to tune that channel on the TiVo3.

    It didn’t work for me.