99 not 125, why?

Ch 99 is below ch 8 on the frequency spectrum, its from the original way cable worked from the start because some of those frequencies were used by aircraft and at the start of cable the FCC was afraid that a cable leak might interfere with airplane communications. Ch 100 to 125 was almost never (if ever ) used by any cable co as they went to digital, so tuners above 99 make no sense. Its like UHF, the older tuners went to ch89 or something like that but no OTA station went that high so new tuners go only to a lower number, and the higher numbers went to other people for their non TV use. (I think Cell phones use some part of the old UHF band)

 

Lessd covered most things well. Cable companies have started to use above 99 more now, mostly for digital channels. The TiVo S3 goes to 125: it can handle the HD digital channels while the S2s can't.

 

I would hope TiVo S3 can go to ch135 vs ch125, otherwise it won't be able to handle all the channels on 860MHz head-ends.

 

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UHF used to go up to 83. Now it goes somewhere in the high 60's. The frequencies from that uppper 60's cutoof point to channel 83 have been reassigned for mobile (cell phones and such) use, IIRC.

 

I'm not positive. I only saw it go up to 125 during the scan and afterwards, but I can't swear that it didn't quickly flash through 126-135 while I wasn't looking (assuming my local franchise doesn't do anything with 126-135). I certainly had no channels above 125.

 

Channel layout for cable

Ch 2-6 is from 60Mhz to 88Mhz (all Freq are the Max for the channel)
Cable 5A, ICC5, ICC6 is from 78Mhz to 90Mhz not used much, also known as A8-A6
Cable 95-99 is from 96Mhz to 120Mhz Also known as Cable A-5 to A-1
Cable 14-22 126Mhz to 174Mhz
Cable 8-13 186Mhz to 216Mhz
Cable 23-94 is from 222Mhz to 648Mhz
Cable 100-125 is from 654Mhz to 804Mhz
Cable 126- 135 is from 810Mhz to 864Mhz
Cable 136 if there is any would start at 864Mhz and go up 6Mhz per channel

All digital both HD and Non HD are in that frequency range, all digital channels have a dash or dot in them like 3-1 or 77-12. Ch 77 would be analog if it existed. With Cable cards the lineup gets re-mapped from ch 1 to 999 (all will not be used but could be) so in my Comcast cable co in CT 3-1 is CBS HD and the cable card re-mapped it to 233 and the frequency is 615Mhz or channel 89-x

If the above is clear your better then most that why the cable co give out cable boxes or Cable Cards to make the numbers more understandable to people.
I do not know if the Series 3 goes above 121 as that the highest Cable channel I have but I think it should cover the full range up to 900Mhz

 

I was just stating that there was no reason for an S1 or S2 to tune beyond 99, so they didn't, but there is a reason for the S3 to tune digital stations over 99 (though as I said in my area there was nothing beyond 125 that was detected.)

 

This came up with the MyHD ATSC/QAM tuner card for PCs. That card has(had?) the limitation of 125. At the time most understood that 860MHz systems could go above 125, but until they started doing so, it wasn't that big a deal. A few weeks later, someone posted their cable system moved some digital channel above 125 and they weren't able to receive it. I think as cable companies look for more bandwidth for their HD channels to compete with DBS and FIOS, they will start using the higher channels and over time this could be an issue if TiVo can only go to 125.

 

My educated guess is the TiVo software as just written to 99, to make it easier to discern between no-box and box channels.