MacLeech
The one and only
Premium
join:2001-07-14
SoCal
| reply to spfaff
Re: Wasteful Channel Lineup means fewer HD Channels?
said by spfaff :
750/6 = 125 and 860/6 = ~143,... what happened to the remaining 8 slots each ? Check the included list for a standard "slot" layout with frequencies.
There are gaps in the slot arrangement to make room for certain other users.
--
Don't mind me, I'm just trying to help...
|
|
cypherstream
Looking forward to the future of things.
Premium,MVM
join:2004-12-02
Reading, PA
clubs: | reply to spfaff
Subtract 54 first. The first 54 MHz is the return path.
750-54 = 696.
696 / 6 = 116. There's no issues putting at least one or two channels over, so add one for 117. (Don't add 2 because ch 1 doesn't count). |
|
spfaff
@comcast.net
| reply to cypherstream
said by cypherstream  :I'm going to try to use the term Slots instead of channels to try not to get confused. A slot is this description is a 6 MHz wide "RF Channel". In a 750 MHz system there are 117 "Slots". In an 860 MHz system there are 135 "Slots". 750/6 = 125 and 860/6 = ~143,... what happened to the
remaining 8 slots each ? |
|
bicker
join:2007-05-10
Burlington, MA
| reply to cypherstream
"What he said." 
said by keithbart :You said "they can fit 10 or more ADS channels on one channel". If a system like mine uses ADS does that mean we should have room for more HD channels. Only after they get rid of analog service entirely. You might have digital service, but your neighbor may be relying on analog service, so those analog "slots" won't be freed up until your neighbor gets shafted. :-\ |
|
cypherstream
Looking forward to the future of things.
Premium,MVM
join:2004-12-02
Reading, PA
clubs:
4 edits | reply to keithbart
I'm going to try to use the term Slots instead of channels to try not to get confused. A slot is this description is a 6 MHz wide "RF Channel".
In a 750 MHz system there are 117 "Slots".
In an 860 MHz system there are 135 "Slots".
Each "Slot" a can contain any of the following:
-1 Analog Video Channel
-12 Digital Video Channels (sometimes more with higher compression)
-Up to 3 High Definition Digital Video Channels.
-38.8 mbps data channel.
-Any mixture of Standard digital video channels and 1 or 2 HD digital video channels.
So say you have 70 analog channels in a 750 MHz system, you have exactly 47 free slots to use for digital purposes.
In an ADS system they will duplicate those 70 analog channels in the digital format. For simplicity say they use 10:1 compression for ADS. To carry 70 channels in the digital format you would use 7 Slots used to recreate the analog lineup in the digital domain. Now your down to 40 free slots.
Say your system has 42 HD Channels all on 3:1 compression. That's an additional 14 "slots" used, so now were down to 26 free slots.
Now say your system has 6 Channel slots dedicated to video on demand, and 2 slots dedicated to high speed internet / digital voice. Now your down to 6 available slots. (Some systems get away with 4 VOD channel slots and 1 data channel slot).
At 12:1 compression you now have room for 72 additional digital channels (Premiums, Digital plus, etc..) because 12 * 6 = 72.
750 MHz systems don't give you much room as you can see. Mainly because those 70 Analog channels are taking up a whole lot of space, plus the system amplifiers are poorly designed and can not pass 135 or more channel slots.
So ADS actually takes up room on the system, but it's done for a number of purposes.
-Better picture quality to people using digital boxes.
-Less expensive boxes can be deployed that do not contain any analog tuner.
-DVR's handle all digital signals better. You can store more programming. Some Motorola DVRs were also buggy when recording analog channels.
-Stepping stone to going to an all digital service. People with boxes won't notice a difference because they are already tuned to the digital version.
-Easier to place channels in tier, move them around, authorize and deauthorize.
Keep in mind some of those "slots" are unusable. Those who use 104.2 MHz for their OOB "Box communication" channel will not be able to use slot # 97. Some area's might have noise issues on certain frequencies close to radio stations and broadcast towers. Some trouble channels are 95,96,97,17,18,19,20. A GOOD system however will be tight against "ingress" and not run into that problem. On the contrary some 750 MHz systems will not have an issue broadcasting up to 121 "slots" instead of the normal 117. |
|
keithbart
join:2007-01-01
South Bend, IN
| reply to bicker
said by bicker :It allows them to graphically present related channels together in the channel line-up. Again, no waste of resources. All that is "used up" is a number, and they have a minimum of 999 numbers to work with, so until they fill up all 999 slots, putting the same stream on two "channels" costs nothing. It should be noted that often you will find some channels broadcast as analog (for customers with analog service) and ADS (analog digital simulcast, for customers with digital service). That's another matter, and the incremental "waste" of bandwidth is only 1/10th of what it seems, if even that, since they can fit 10 or more ADS "channels" on one channel. However, it isn't even "waste" since the two different customer-bases have specific needs, and or gain specific benefits, that call for the channels to be presented in the specific format intended for them. bicker, I'm confused. You said "they can fit 10 or more ADS channels on one channel". If a system like mine uses
ADS does that mean we should have room for more HD channels.
Is this the same as analog migration? |
|
bicker
join:2007-05-10
Burlington, MA
| reply to IPPlanMan
It allows them to graphically present related channels together in the channel line-up. Again, no waste of resources. All that is "used up" is a number, and they have a minimum of 999 numbers to work with, so until they fill up all 999 slots, putting the same stream on two "channels" costs nothing.
It should be noted that often you will find some channels broadcast as analog (for customers with analog service) and ADS (analog digital simulcast, for customers with digital service). That's another matter, and the incremental "waste" of bandwidth is only 1/10th of what it seems, if even that, since they can fit 10 or more ADS "channels" on one channel. However, it isn't even "waste" since the two different customer-bases have specific needs, and or gain specific benefits, that call for the channels to be presented in the specific format intended for them. |
|
IPPlanMan
Holy Cable Modem Batman
join:2000-09-20
Washington, DC
1 edit | reply to sansri88
Thanks for the info.... How can you tell that they're "alias" links and not separate streams though?
Re AMC:
AMC is non-HD on 53 and 138
AMC HD is on 218
It's been that way for quite sometime... Why would they have multiple links to the same thing?
--
"We're going to start at one end of (Fallujah), and we're not going to stop until we get to the other. If there's anybody left when that happens, we're going to turn around and we're going to go back and finish it."
Lt. Col. Pete Newell: 1st Inf. US Army |
|
