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SWM 16 in the works...


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144 replies to this topic

#41 OFFLINE   evan_s

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Posted 02 September 2009 - 05:36 PM

What does each of the current 102 Mhz wide SWM channels contain? Multiple transponders? Do you know how many?


The pdf I linked to earlier says 1 32mhz channel based on operator modulation scheme which would imply a standard single ku transponder. Keep in mind that a single Ka transponder from the spaceway sats is 65mhz and it still has to work with a SWM.

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#42 OFFLINE   Tom Robertson

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Posted 02 September 2009 - 06:01 PM

What does each of the current 102 Mhz wide SWM channels contain? Multiple transponders? Do you know how many?

1 channel per transponder. Allows DIRECTV lots of flexibility and future, albeit limits the number of channels a SWiM can carry today.

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Tom

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#43 OFFLINE   Tom Robertson

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Posted 02 September 2009 - 06:11 PM

I'm by no means "on the inside" for this, other than working with things like this.
Two SWM(8s) could be mated with a DECA crossover filter, and have a "single line" become a dual line. This isn't a stretch, but seems a bit of a kludge. Single Wire Multi-switch becomes "dual line multi-switch".
Each tuner needs only one transponder, but if they keep the current 100 MHz "spacing", then they not only will be below the guide channel, but have to also go below the DECA "block" too. This would mean only the new wideband receivers [H/HR23 and up] would work on this system, since the earlier receivers "stop at" 950 MHz.
Since it's been a couple of years with the current SWM system, "there may be" improvements in the chips to narrower the bandwidth to maybe something as low as 50 MHz, which would give each tuner one transponder. Firmware changes in the SWM "I would think" would be all that is needed, since the receiver should simply "ask" for channel/transponder "x" and the SWM sends it on "the tuner's channel".
"If this" is true, then it would be backwards compatible, which is a much better solution.
It seems as if they double up on the cables, or cut the channel bandwidth in half.
In this case "their mileage may vary", but I wait to see what they end up doing. :)

What if they put 8 channels on the center conductor and 8 on the braid? :)

(Just being goofy, wasn't being serious...) :D

Am I right thinking a "two wire system" would require filters at the low end for the communication channels as well as the high end for the transponder channels?

Thanks,
Tom

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#44 OFFLINE   dsw2112

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Posted 02 September 2009 - 06:25 PM

What if they put 8 channels on the center conductor and 8 on the braid? :)

(Just being goofy, wasn't being serious...) :D


And with Quad shield we can get 32 channels on the braid :D

#45 OFFLINE   k2tech

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Posted 02 September 2009 - 06:26 PM

Speculation threads are certainly "fun".....of course 90% of the information is typically wrong.....but they are fun. :D


Doubtful it is speculation....came down from Val Allen who runs the D* Installer Forums and he pre-tests all the equipment for D*. I don't believe he would post this without being sure....

I guess you may mean "speculation" is about how it would work :lol:

#46 OFFLINE   bobnielsen

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Posted 02 September 2009 - 06:33 PM

And with Quad shield we can get 32 channels on the braid :D


And if you separate the strands, you can get many more :D

#47 OFFLINE   rudeney

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Posted 02 September 2009 - 07:00 PM

When I first read/heard about this, I was thinking of the dual output. Then after a bit more thinking, narrowing the channel bandwidth, seems more like the way they'll do it.
I don't follow your first "problem". "the chips" are in the SWM, not the receiver. The receiver [tuner] tunes to only one channel [of the many on a transponder], so none of this is on the receiver side. A receiver can tune to both SWM & non SWM channels. The SWM simply acts as a "pre-tuner" narrowing down the signals coming from the dish [and converting them]. A tuner in "non-SWM" mode is being fed 500 MHz of channels. In current SWM mode is fed 100 MHz. "A channel" is somewhere around 5-6 MHz, so "really" the transponder bandwidth, would be the minimum bandwidth [needed] for "a SWM channel" [which I think is about 36 MHz].


The SWM places 8 (plus one for guide data) streams that take up 102mhz of bandwidth each onto the coax. The specific 8 streams that are carried are requested by the connected tuners using a separate control frequency. Now, it may be possible to build a SWM that can cram the same data stream into 51mhz of bandwidth and thus be able to pack 16 streams into the space where we have 8 today. However, the tuners in the receivers would still need to be changed so they can decode a stream from those 51mhz bands instead of the 102mhz they have today (and yes, I know it's 100mhz + 2mhz for buffer, but I think you know what I'm saying). Maybe the tuners are capable of being programmed to do this, maybe not.

#48 OFFLINE   evan_s

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Posted 02 September 2009 - 07:12 PM

The SWM places 8 (plus one for guide data) streams that take up 102mhz of bandwidth each onto the coax. The specific 8 streams that are carried are requested by the connected tuners using a separate control frequency. Now, it may be possible to build a SWM that can cram the same data stream into 51mhz of bandwidth and thus be able to pack 16 streams into the space where we have 8 today. However, the tuners in the receivers would still need to be changed so they can decode a stream from those 51mhz bands instead of the 102mhz they have today (and yes, I know it's 100mhz + 2mhz for buffer, but I think you know what I'm saying). Maybe the tuners are capable of being programmed to do this, maybe not.


51mhz is narrower than the bandwidth of a single TP from spaceway 1 or 2 so I don't think there is any way they could do that.

#49 OFFLINE   cartrivision

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Posted 02 September 2009 - 07:31 PM

The SWM places 8 (plus one for guide data) streams that take up 102mhz of bandwidth each onto the coax. The specific 8 streams that are carried are requested by the connected tuners using a separate control frequency. Now, it may be possible to build a SWM that can cram the same data stream into 51mhz of bandwidth and thus be able to pack 16 streams into the space where we have 8 today. However, the tuners in the receivers would still need to be changed so they can decode a stream from those 51mhz bands instead of the 102mhz they have today (and yes, I know it's 100mhz + 2mhz for buffer, but I think you know what I'm saying). Maybe the tuners are capable of being programmed to do this, maybe not.


I don't think the tuners would have to change. Right now, to tune a single video channel the tuners are looking at a subset of the whole SWM channel that contains a full transponder's worth of data that is on the channel. If the SWM instead sent only half of the transponder's bandwidth down each SWM channel the tuner would simply do what it normally does when the video channel of interest is on the lower half of a 102 Mhz wide SWM channel today. As VOS pointed out in an earlier post, the SWM is simply translating a wide range of RF signals into a fixed range of RF that the existing tuners are already capable of being tuned to. As long as SWM technology does not require the full transponder's worth of data to be available at the tuner input for single channel tuning to work right, putting more channels on the SWM line (with less data on each channel) would only require a software update to the current SWM capable receivers.

This assumes that the transmission/receiving method that is being used could still work even if a tuner can't "see" a whole transponder's worth of data at one time... and maybe that's a bad assumption.

Edited by cartrivision, 02 September 2009 - 07:38 PM.


#50 OFFLINE   netraa

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Posted 02 September 2009 - 07:40 PM

One more thing to consider, a dual lead SWiM lnb departs (in a small, but significant way) from the single point of entry for a current SWiM LNB.

#51 OFFLINE   JosephB

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Posted 02 September 2009 - 08:01 PM

One more thing to consider, a dual lead SWiM lnb departs (in a small, but significant way) from the single point of entry for a current SWiM LNB.

But it's at least as good as the current alternative (two SWM-8 switches) and much better than the current approved residential solution (WB68s, with dual runs to DVRs)

I think the fact that it's 16, double the normal 8, shows that they're just adding an additional SWM output on the dish. If they were cramming more onto the coax, it'd probably be less than 16..something like 10 or 12 as has been mentioned before.

#52 OFFLINE   veryoldschool

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Posted 02 September 2009 - 08:05 PM

I don't think the tuners would have to change. Right now, to tune a single video channel the tuners are looking at a subset of the whole SWM channel that contains a full transponder's worth of data that is on the channel. If the SWM instead sent only half of the transponder's bandwidth down each SWM channel the tuner would simply do what it normally does when the video channel of interest is on the lower half of a 102 Mhz wide SWM channel today. As VOS pointed out in an earlier post, the SWM is simply translating a wide range of RF signals into a fixed range of RF that the existing tuners are already capable of being tuned to. As long as SWM technology does not require the full transponder's worth of data to be available at the tuner input for single channel tuning to work right, putting more channels on the SWM line (with less data on each channel) would only require a software update to the current SWM capable receivers.

This assumes that the transmission/receiving method that is being used could still work even if a tuner can't "see" a whole transponder's worth of data at one time... and maybe that's a bad assumption.

Using 70 MHz bandwidth "and" the non existant SWM 11 range, gives 16 + guide, and handles the 65 MHz Spaceway Transponder.
"The key" is if the SWM chip maker has a "new and improved" chip they're working on.
The receiver "SWM screen" already has "n/a" slots, and the same [receiver] software works with the old SWM5 and SWM8, which would [again] seem to point to the SWM being the one telling the receiver "what it has and where to tune".
2.3 MHz "comm"
974 MHz guide data.
1076 MHz "and up" for 16 SWM channels [with the receiver topping out at 2156 MHz] following the 70 MHz, 2 MHz, 70 MHz spacing.
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#53 OFFLINE   HRJustin

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Posted 02 September 2009 - 08:05 PM

I dont see why the DECA filter couldnt be built into this new SWM system. If it was an LNB with two outputs(8 tuners each) it could have a DECA crossover filter internally. The frequency range that DECA uses has nothing to do with the SWM frequencies. The way that SWM works has already been proven theres no need to change around frequency blocks per channel. This way there would still only be one cable ran to each receiver location. The only thing that would be different is running two cables from the dish. Then because the filter is internal in the LNB the DECA cloud would pass through both coaxes.

It would be easier to make a standalone multiswitch like the SWM8 it would just be the SWM16. But then four cables would need to be ran from the dish no matter what. So I think the LNB version would be alot better for residential use.
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#54 OFFLINE   HoTat2

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Posted 02 September 2009 - 08:08 PM

I don't think the tuners would have to change. Right now, to tune a single video channel the tuners are looking at a subset of the whole SWM channel that contains a full transponder's worth of data that is on the channel. If the SWM instead sent only half of the transponder's bandwidth down each SWM channel the tuner would simply do what it normally does when the video channel of interest is on the lower half of a 102 Mhz wide SWM channel today. As VOS pointed out in an earlier post, the SWM is simply translating a wide range of RF signals into a fixed range of RF that the existing tuners are already capable of being tuned to. As long as SWM technology does not require the full transponder's worth of data to be available at the tuner input for single channel tuning to work right, putting more channels on the SWM line (with less data on each channel) would only require a software update to the current SWM capable receivers.

This assumes that the transmission/receiving method that is being used could still work even if a tuner can't "see" a whole transponder's worth of data at one time... and maybe that's a bad assumption.


Hummm...

You lost me on that. How can the SWM allow less than the full transponder bandwidth on it's RF channels? If the transport stream on the transponder consists of statistically multiplexed TDM data restricting it's bandwidth beyond the minimum required for the entire stream will distort the signal resulting in reduced amplitude and even worse intersymbol interference.

#55 OFFLINE   veryoldschool

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Posted 02 September 2009 - 08:12 PM

Hummm...

You lost me on that. How can the SWM allow less than the full transponder bandwidth on it's RF channels? If the transport stream on the transponder consists of statistically multiplexed TDM data restricting it's bandwidth beyond the minimum required for the entire stream will distort the signal resulting in reduced amplitude and even worse intersymbol interference.

read my post [three mins earlier :lol:]
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#56 OFFLINE   veryoldschool

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Posted 02 September 2009 - 08:15 PM

I dont see why the DECA filter couldnt be built into this new SWM system.

There is every expectation that the DECA "bandstop" filter will be added to the SWMLNB/SWM8 new production runs.
"If the dual output" is what happens, the it's simple to have bandstops on each for the SWM(s) and bandpass between the dual cables, all incorporated.
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#57 OFFLINE   veryoldschool

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Posted 02 September 2009 - 08:24 PM

If they were cramming more onto the coax, it'd probably be less than 16..something like 10 or 12 as has been mentioned before.

I don't see this as "cramming more" but merely having the same size pie and cutting it into smaller slices, to feed more people. each piece is 30% less.
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#58 OFFLINE   HRJustin

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Posted 02 September 2009 - 09:09 PM

It just seems like its more trouble then its worth to try to divide the channels up onto smaller channels. SWM must have been tested to find the best number of channels to fit on a single coax. Its already currently working just fine with 8 channels per coax. It just seems like a waste to try change it around just to fit more tuners on one coax. I really dont think that there is a strong demand for installs with more then 8 tuners. Running two coax from the dish is still much better then running 4 in then using two SWM8s, or two wb68, wb616 with two coax ran to each DVR.
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#59 OFFLINE   veryoldschool

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Posted 02 September 2009 - 09:49 PM

It just seems like its more trouble then its worth to try to divide the channels up onto smaller channels. SWM must have been tested to find the best number of channels to fit on a single coax. Its already currently working just fine with 8 channels per coax. It just seems like a waste to try change it around just to fit more tuners on one coax. I really dont think that there is a strong demand for installs with more then 8 tuners. Running two coax from the dish is still much better then running 4 in then using two SWM8s, or two wb68, wb616 with two coax ran to each DVR.

:lol: I'm not using all of my eight channels now.
DirecTV seems to "have a plan", or the SWM16 wouldn't have been mentioned.
"If" the SWM chip maker has improved their chip, there is no "technical reason" a 70 MHz channel wouldn't work [and would be backwards compatible]. The current 100 MHz is simply wasting bandwidth, but at the time, I'm sure was an economical means.
Also remember that DECAs need SWM systems, so this would also increase [the need] for the users that do have more than eight tuners.
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#60 OFFLINE   JoeTheDragon

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Posted 02 September 2009 - 10:24 PM

A Whole house DVR! Can you Imagine?
1 or 2 cables running from the ODU to a centralized IRD up on a shelf in the basement. The only trick would be getting HD from the box to the TV locations.


cat5, rg6, will work and you can have a mini box at the tv.




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