Jump to content


Welcome to DBSTalk


Sign In 

Create Account
Welcome to DBSTalk. Our community covers all aspects of video delivery solutions including: Direct Broadcast Satellite (DBS), Cable Television, and Internet Protocol Television (IPTV). We also have forums to discuss popular television programs, home theater equipment, and internet streaming service providers. Members of our community include experts who can help you solve technical problems, industry professionals, company representatives, and novices who are here to learn.

Like most online communities you must register to view or post in our community. Sign-up is a free and simple process that requires minimal information. Be a part of our community by signing in or creating an account. The Digital Bit Stream starts here!
  • Reply to existing topics or start a discussion of your own
  • Subscribe to topics and forums and get email updates
  • Send private personal messages (PM) to other forum members
  • Customize your profile page and make new friends
 
Guest Message by DevFuse

Photo
- - - - -

Digital SWM theory and speculation


  • Please log in to reply
236 replies to this topic

#26 OFFLINE   HoTat2

HoTat2

    Hall Of Fame

  • Registered
  • 5,720 posts
  • LocationLos Angeles, CA.
Joined: Nov 16, 2005

Posted 25 December 2013 - 02:57 PM

Based on that 98% figure, it would have to come down to DSWM being cheaper than analog SWM and entirely replacing it, because the volumes for SWM16 replacement would be too small. That's clearly a higher bar, but I don't believe it is as hopeless you feel it is. It will all come down to the cost per unit to make the DSWM ASIC, the NRE costs will become insignificant if it replaces the ASWM entirely. The ASWM contains a number of discrete components, including 9 SAWs and 3 RF5200 (or similar) chips, along with a 6x9 multiswitch at the input, all of which would be replaced by the DSWM ASIC.

 

The big unknown is the size of that ASIC. I understand the scale of it, but i don't really know what the computational requirements for each transponder are to implement the filtering, and the wiring for a mux able to handle up to 264 inputs (one per transponder) won't be pretty and could require a couple additional metal layers on its own. ...

 

 

Just a couple of questions here;

 

1) Where does an internal 6x9 multiswitch fit into the picture of the ASWM?

 

From the ASWM schematic in the patent in Fig. 2 its looks as there are just 4 inputs issuing from the LNB module illustrated in Fig. 3A.

 

The two Sat A inputs are fed to one RF5200 chip as well as branched off to feed the two other RF5200 chips effectively in parallel with the first. And likewise the two inputs from 119 and 110/119 (i.e. Sat B and B+C) are fed to one RF5200 chip as well as branching off to feed the two others in parallel. Thus each RF chip has 4 inputs for a total of 12 combined.

 

2) I've counted and recounted, and I can't see why 264 inputs (at 1 per transponder) to the DSWM internal mux. are necessary.  

 

For an SL-5 for instance, with the current transponder assignments and channelization schema, the 99 slot = 48 tps. max, 101 = 32, 103 = 48 max. 110 = 3, and 119 = 11, totals only 142. Even adding prospective RDBS band only adds 36 more transponders for a total of only 178.  :confused:   


DIRECTV sub. since Sep. of '95


...Ads Help To Support This Site...

#27 OFFLINE   P Smith

P Smith

    Mr. FixAnything

  • Registered
  • 20,289 posts
  • LocationMediterranean Sea
Joined: Jul 25, 2002

Posted 25 December 2013 - 04:28 PM

[chip's layers]

Umm, OK, if it metal layer, then it would more interconnection planes then a "layer"

I'm aware of MDP stage of wafer's processing and many more ...

[/chip's layers]



#28 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 25 December 2013 - 08:28 PM

Just a couple of questions here;

 

1) Where does an internal 6x9 multiswitch fit into the picture of the ASWM?

 

From the ASWM schematic in the patent in Fig. 2 its looks as there are just 4 inputs issuing from the LNB module illustrated in Fig. 3A.

 

The two Sat A inputs are fed to one RF5200 chip as well as branched off to feed the two other RF5200 chips effectively in parallel with the first. And likewise the two inputs from 119 and 110/119 (i.e. Sat B and B+C) are fed to one RF5200 chip as well as branching off to feed the two others in parallel. Thus each RF chip has 4 inputs for a total of 12 combined.

 

2) I've counted and recounted, and I can't see why 264 inputs (at 1 per transponder) to the DSWM internal mux. are necessary.  

 

For an SL-5 for instance, with the current transponder assignments and channelization schema, the 99 slot = 48 tps. max, 101 = 32, 103 = 48 max. 110 = 3, and 119 = 11, totals only 142. Even adding prospective RDBS band only adds 36 more transponders for a total of only 178.  :confused:   

 

 

There is no multiswitch shown in the drawing, I'm assuming it is covered under the "routing of LNA signals to all three chips" label on Figure 2. If there's no multiswitch, each SWM chip would require six inputs to be able to select any possible channel on its three outputs. The only FDM chips on Entropic's site that aren't designed for the FTA market, the RF5200/RF5201, have two or three inputs, as opposed to the four inputs shown in the drawing. As with the flex ports, some detail has been omitted. We're left to fill in the blanks with what we know (ASWM supports flex ports) and with guesses for what we don't (there must be some sort of multiswitch, or there are six inputs to each chip)

 

The analog SWM patents, which quite accurately describes today's SWM (along with other embodiments & details that were not implemented) also show and mention a multiswitch at the front end. Of course, the drawing in those patents shows an 8x8 multiswitch, but with nine outputs coming from the FTM! There's always some things that make you scratch your head and leave it up to the reader to fill in the gaps...

 

I said up to 264 transponders, but there aren't that many today. The four outputs of a SL3/SL5 each stack 2 Ka bands (24 tpns) and one Ku band (16 tpns) for a total of 40. I guess I did the math backwards and got 16+16+12 for 44, oops :) Not all the transponders on 110/119 are active, but you have to do the design to support them all unless you assume that slot will always be used for 110/119 and there will never be more tpns added there.

 

So far, 4*40 = 160, then there are the two flex ports. If they're truly flexible, they'll support 40 more themselves based on a similar stack plan. 6*40 = 240. Who knows, if they anticipate ever possibly having a Ku band arrive in 250-750 or 1650-2150, they might support the possibility of as many as 48 transponders per LNB, or 288 total.

 

They could make the mux simpler if it only supports what they have today and what they know they'll have in the immediate future, but the flexibility of the DSWM is wasted if they limit it to save pennies by cutting it down to the minimum needed. They can still limit it via software, so it won't attempt to digitize the unused bands/transponders and the mux can ignore those inputs. That'll save a bit of power.


Edited by slice1900, 26 December 2013 - 04:01 AM.

SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21


#29 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 25 December 2013 - 09:13 PM

[chip's layers]

Umm, OK, if it metal layer, then it would more interconnection planes then a "layer"

I'm aware of MDP stage of wafer's processing and many more ...

[/chip's layers]

 

 

OK, keep in mind I'm not an EE, the closest I've come to actually doing this is playing around with Mentor Graphics and Cadence tools when I worked an electronics company. That said, I don't see why you'd need more than a single plane for this. There is no "order" to which tpn has to go to which input of the mux, they're all equivalent. Just because the mux is shown in the drawing with the inputs on the left doesn't mean it wouldn't be entirely ringed with inputs. You'd almost have to do that, since its size would be dominated by the number of vias it has to support.

 

On the "mux metal layer", you only need to find an unbroken point to point route between each output (labeled 506 in Figure 5) to the input of the mux. You have the entire chip area in which to do so, so you could make some pretty circuitous paths if necessary. If you had to pop down to a lower layer in a few places where paths just had to cross that shouldn't be too much of a problem. The place and route software was already pretty good at this sort of thing when I was toying around, and it has undoubtedly advanced a hell of a lot since. I doubt the guys doing this ASIC would be doing much hand routing, that's typically reserved for speed critical stuff.


SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21


#30 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 28 December 2013 - 04:11 PM

I managed to obtain some additional information about the DSWM ASIC. Unfortunately I cannot reproduce it, but I learned some interesting things.

 

The DSWM ASIC implemented in 45nm CMOS uses 7 metal layers and I'd estimate the die size at a bit over 30 sq mm (based on holding a ruler up to a die photo that identified a few functional blocks and the sizes of those functional blocks identified elsewhere) If produced in sufficient quantity, I'd guess it should cost under $10/ea. This is more metal layers than I expected, but this is a mixed signal ASIC and I suppose I should have realized this will add additional layers. It uses RDL packaging, which is a cost saving measure made possible by the small number of I/Os.

 

The ASIC has only 14 input bands (same as SL5 + 72.5/95) not the 18 I was guessing to allow for truly flexible flex ports. All are input to the ASIC on B band (250 to 760 MHz) Only 14 bands is rather surprising given that one of the stated goals of the DSWM in both the patent and the paper was flexibility to increase the number of inputs/satellites. Assuming 14 inputs is accurate (i.e. not a "fib" to avoid tipping their hand for future plans) it puts some limits on what Directv's future plans are, if any, for customer content delivered from RDBS/BSS. That is, if they add it from 99 and/or 103, they would have to replicate channels from and drop 119 and/or 95.

 

Based on the block diagrams and additional description, the DSWM ASIC implements the second embodiment from the patent, not the first. There are 24 output channels, making a DSWM23 module possible. The channel width isn't provided but VOS already said they were "half the size", and it looks to be just under that (<=50 MHz rather than 51 MHz) I have output from a spectrum analyzer showing the 24 channels, but unfortunately it is a poor reproduction and it isn't possible to read the scales on either axis.

 

The ASIC monitors temperature, so it can presumably shut down or put up alerts on the receivers or something if it gets too hot. The power consumption for the entire ASIC, with all 14 DSP "slices" active is 9.4 watts, but if certain input bands are not used (i.e. have no channel from them selected) the DSP slices dedicated to them are deactivated to reduce power consumption. The 9.4 watts does not include whatever else a DSWM module may need, though external components shown are mostly passive devices.

 

The figure of 9.4 watts doesn't seem to match what Stuart was suggesting about the DSWM13's power consumption, though we should find out actual numbers fairly soon for a better comparison. If accurate, it is only a couple watts more than a SWM8, which seems to be fine for inclusion in a LNB.


Edited by slice1900, 28 December 2013 - 04:13 PM.

SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21


#31 OFFLINE   P Smith

P Smith

    Mr. FixAnything

  • Registered
  • 20,289 posts
  • LocationMediterranean Sea
Joined: Jul 25, 2002

Posted 28 December 2013 - 05:57 PM

Unfortunately I cannot reproduce it

perhaps we could follow you if there is an URL ?



#32 OFFLINE   HoTat2

HoTat2

    Hall Of Fame

  • Registered
  • 5,720 posts
  • LocationLos Angeles, CA.
Joined: Nov 16, 2005

Posted 29 December 2013 - 11:47 AM

So to summarize your latest findings on the DSWM ASIC;

 

1) Only 14 band inputs, where 12 alone of those would be needed for a SL-5?

 

2) All bands are converted to the Ka-lo range of 250-750 MHz to feed the ADCs instead of a starting frequency in 10-100 MHz range as suggested in the patent?

 

3) Up to 24 possible outputs, but only 13 activated in the present implementation?

 

I must say I'm underwhelmed and sort of confused by the specification choices from the manufacturer if accurate.    


DIRECTV sub. since Sep. of '95


#33 OFFLINE   P Smith

P Smith

    Mr. FixAnything

  • Registered
  • 20,289 posts
  • LocationMediterranean Sea
Joined: Jul 25, 2002

Posted 29 December 2013 - 12:46 PM

that's why I'd like to explore original documents...



#34 OFFLINE   inkahauts

inkahauts

    Hall Of Fame

  • DBSTalk Club
  • 17,669 posts
Joined: Nov 13, 2006

Posted 29 December 2013 - 01:32 PM

Don't forget everything does need to come back to working with decas limit or 13 nodes for this particular need and distance requirements. Also If they used lower channels would it not interfere with deca? And the way vos has talked about it, I don't even think using moca2 with twice the bandwidth would allow more nodes because the issue is distance and signal amplification more than number of nodes that can be active at one time for this implementation.

#35 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 29 December 2013 - 02:57 PM

I had a friend who works for a company with a corporate IEEE membership obtain the ISSCC paper and some slides and Q&As from the presentation, but I can't reproduce them here or make them available on the web. Apparently they encode something on all downloads that links back to the downloader to prevent redistribution. He was pretty adamant that he would only give them to me if I promised I wouldn't share them with anyone, because he could get in a lot of trouble at work even for sharing this material with me, I'm sorry. I can answer questions however.

 

Most of the detail was about circuit level specifics, like using the time delay inside the ADC circuit to generate an extra bit of resolution, the noise factors through different parts of the circuit, etc.

 

 

1) Only 14 band inputs, where 12 alone of those would be needed for a SL-5?

 

Yes, I found that rather surprising as well. Unless Directv's engineers told NXP to claim there were only 14 bands / DSP slices to hide their future intentions/capabilities, it puts some boundaries on what they can do with RDBS without duplicating and dumping other stuff. Also limits speculation about Directv someday changing how to they uplink locals to allow Ka from 101 to be converted to customer broadcast, or applying for Ku from 99 and 103 if/when the FCC approves 2* Ku spacing.

 

 

2) All bands are converted to the Ka-lo range of 250-750 MHz to feed the ADCs instead of a starting frequency in 10-100 MHz range as suggested in the patent?

 

Yes, the bands are input to the ASIC at a slightly higher range than in the patent. The high end 760 MHz was specifically provided in several places, so I don't believe that was an error. I have seen mention of converting Ku to 250 - 750 MHz and both Ka bands to 260 - 760 MHz in several LNB related patents, if they're doing it elsewhere (such as in a SWM LNB) they may have wanted to re-use the same front end.

 

 

3) Up to 24 possible outputs, but only 13 activated in the present implementation?

 

The DSWM13 could never have supported more than 15 channels due to DECA limitations, but per VOS the DECA losses were a problem so they had to design it for only 13. In the DSWM13, the ASIC would presumably be programmed to limit itself to 13 channels - there's a flash interface on the DSWM ASIC designed to use an external flash module. There is no mention of exactly what is stored there, or how programmable it is.

 

 

Don't forget everything does need to come back to working with decas limit or 13 nodes for this particular need and distance requirements. Also If they used lower channels would it not interfere with deca? And the way vos has talked about it, I don't even think using moca2 with twice the bandwidth would allow more nodes because the issue is distance and signal amplification more than number of nodes that can be active at one time for this implementation.

 

FWIW, MoCA 2.0 retains the same 16 node limit, so even if Directv upgraded for more speed it won't change that limit. Presumably a DSWM23 wouldn't be a problem, since MoCA is primarily intended for MRV, and you'd have to be very receiver/client heavy to run into problems.

 

If I upgraded all my H20s to H24s and wanted to network them all I'd be restricted to putting 15 on a DSWM23, though I could always feed the output into a two way splitter and put a diplexer/DECA on each leg if I wanted to use the full 23 channels. I'd probably need multiple layers of splitters anyway as I don't foresee a SWS-24 offered anytime soon :)


SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21


#36 OFFLINE   inkahauts

inkahauts

    Hall Of Fame

  • DBSTalk Club
  • 17,669 posts
Joined: Nov 13, 2006

Posted 29 December 2013 - 04:41 PM

Sounds like the 24 Dswim would be pointed at mdu since you can and have to put a bsf for each unit in place to keep everyone's system self contained and create a deca cloud for every unit. So the next question will be how much will a Dswim 24 be over a swim32?

#37 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 30 December 2013 - 03:07 AM

Sounds like the 24 Dswim would be pointed at mdu since you can and have to put a bsf for each unit in place to keep everyone's system self contained and create a deca cloud for every unit. So the next question will be how much will a Dswim 24 be over a swim32?

 

So long as they make a DSWM LNB, a DSWM23 module would be almost exclusively a commercial/MDU product. As such, it probably would have more than two outputs. That would allow them to maintain the output at the current ~ -30 dbm AGC level, along with the same splitter/distance guidelines, and avoid the need for a BSF :) This would be very nice for the MDU market, since say four units sharing 23 channels is a more flexible solution that I'd guess probably works out more often than four units each getting exactly 8 channels as with a SWM32 or SWM8 based solution.

 

Based on the ASIC's die size, and that it doesn't appear there's anything that costs much in a DSWM module beyond the ASIC, I think the cost of production for a DSWM23 and a SWM8 would be very much in the same ballpark, if produced in similar quantities. While I believe this bodes well for a DSWM LNB, the existence of a DSWM LNB would mean quite a bit fewer DSWM23s would be produced compared to SWM8s/SWM16s. Worse yet for the DSWM23 price, Directv would almost have to keep selling SWM8s for some time, since there is MDU gear designed for them. While I don't think the price for a DSWM23 would be as bad as the red headed stepchild that is the SWM32, they definitely won't be on Ebay for $50 like SWM8/SWM16s, either!

 

I will say, given how small the die already is, and the rather modest power consumption indicated, there doesn't seem to be any real need to shrink it further. Mass production in 45nm would be a reasonable decision, unless there was something beyond rather minor fixes/enhancements they needed/wanted to do. In that case, shrinking to 32nm/28nm as part of the redesign probably makes sense.


SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21


#38 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 31 December 2013 - 12:59 AM

I made a few updates to my post #2, to include details learned from the paper other materials I received and where it differs from or clarifies the patent description. I added a link to an Entropic patent application filed August 2012 for a Directv LNB that uses a single LO with frequency divisors to receive Ku from 101, Ka lo/hi from 99/103, and RDBS/BSS from 103. The main reason I added it was because it describes and implements a requirement for output of individual bands in the 250 - 760 MHz range. Not saying that is what a DSWM LNB would look like, but I felt it was "interesting" enough to include in light of the match with the input range expected by the DSWM ASIC. However, the prior art indicates a similar input frequency range is used in the analog SWM LNB, so a DSWM LNB could presumably use the same front end as a SWM LNB (likewise a new model of analog SWM LNB could use the front end from this patent)

 

One detail I missed on initial reading of the paper relevant to the last few posts. The patent states the DSWM would shift the frequency to "near baseband" before digitization (the exact wording was "tunable starting frequency from 10 to 100 MHZ, or beyond these limits if desired.") The paper states the ASIC expects an input in the B band (250 - 760 MHz) but that after digitization it is shifted to a frequency "centered around 0", i.e. -250 to +250 MHz. The 24 output channels are similarly generated at -600 to +600 MHz, before being shifted to L band (950 - 2150 MHz) prior to passing through the DAC at the output.


Edited by slice1900, 31 December 2013 - 01:00 AM.

SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21


#39 OFFLINE   inkahauts

inkahauts

    Hall Of Fame

  • DBSTalk Club
  • 17,669 posts
Joined: Nov 13, 2006

Posted 31 December 2013 - 04:34 PM

So long as they make a DSWM LNB, a DSWM23 module would be almost exclusively a commercial/MDU product. As such, it probably would have more than two outputs. That would allow them to maintain the output at the current ~ -30 dbm AGC level, along with the same splitter/distance guidelines, and avoid the need for a BSF :) This would be very nice for the MDU market, since say four units sharing 23 channels is a more flexible solution that I'd guess probably works out more often than four units each getting exactly 8 channels as with a SWM32 or SWM8 based solution.

Based on the ASIC's die size, and that it doesn't appear there's anything that costs much in a DSWM module beyond the ASIC, I think the cost of production for a DSWM23 and a SWM8 would be very much in the same ballpark, if produced in similar quantities. While I believe this bodes well for a DSWM LNB, the existence of a DSWM LNB would mean quite a bit fewer DSWM23s would be produced compared to SWM8s/SWM16s. Worse yet for the DSWM23 price, Directv would almost have to keep selling SWM8s for some time, since there is MDU gear designed for them. While I don't think the price for a DSWM23 would be as bad as the red headed stepchild that is the SWM32, they definitely won't be on Ebay for $50 like SWM8/SWM16s, either!

I will say, given how small the die already is, and the rather modest power consumption indicated, there doesn't seem to be any real need to shrink it further. Mass production in 45nm would be a reasonable decision, unless there was something beyond rather minor fixes/enhancements they needed/wanted to do. In that case, shrinking to 32nm/28nm as part of the redesign probably makes sense.


Wait, why are you saying they won't need a bsf in easy terms? I don't see how they couldn't. And I also don't see why they'd need more than one output unless they where just going to create a unit that was built like two dswim13 which would be far less versitale for MUDs than one dswim24 would be. I'd also expect them to make these units have a regular power output like today's sims units not the higher voltage that the dswim appears to have. You wouldn't use a tap system in an mdu.

#40 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 01 January 2014 - 03:18 AM

Wait, why are you saying they won't need a bsf in easy terms? I don't see how they couldn't. And I also don't see why they'd need more than one output unless they where just going to create a unit that was built like two dswim13 which would be far less versitale for MUDs than one dswim24 would be. I'd also expect them to make these units have a regular power output like today's sims units not the higher voltage that the dswim appears to have. You wouldn't use a tap system in an mdu.

 

 

The DSWM13 was designed for a specialized market, and as such is about as applicable to the direction of future DSWM products as the H20i was to the direction of future receivers. We know how many channels the ASIC is capable of, and why the DSWM13 was limited to only 13. We know the reason why it has a high power output and uses taps rather than splitters. Neither choice would be made with a DSWM LNB targeted at the residential/light commercial market or a DSWM23 module targeted at replacing the SWM8/SWM16/SWM32 in commercial/MDU markets.

 

There is nothing in the DSWM ASIC's design that biases it towards the DSWM13's high output level. According to the paper, the DSWM ASIC includes 14 multistage AGC amps (30 db dynamic range, 20 db max gain, very similar specs to the ASWM) to level adjust each band before it's digitized, along with a digital AGC stage after the mux that individually levels the 24 channels to the desired output strength. I have no idea what limits there may be on the range of that "digital AGC amplifier". Like digital filtering, I'm sure some of the limitations of the analog RF world affect the digital equivalent, but if we assume it is merely able to manage the same specs as its 14 analog brothers, it should be capable of the DSWM13's required output level as well as the level desired from a traditional SWM output. That is, if you assume a traditional SWM outputs at -30 dbm, and a DSWM13 outputs at -10 dbm (based on clues provided by VOS) that's covered by a 20 db max gain. The extra 10 db of dynamic range covers the 10 db difference in the strongest and weakest transponders in a single band (this was mentioned in the patent)

 

You suggest a DSWM23 wouldn't "need" more than one SWM output sharing its 23 channels. So why does the SWM8 have two outputs sharing only 8 channels? Wouldn't similar reasons for that decision apply to a DSWM23, only moreso considering it would have nearly 3x the channels? Having an internal splitter can't cost much, or the SWM8 would have just one output. Multiple outputs would allow each to have the same ~ -30 dbm output as today's SWM ports do, therefore having the same splitter/length recommendations. That makes training/support easier, as there wouldn't be a separate set of guidelines for the DSWM module.

 

I believe it also makes sense for a DSWM23 module to block DECA from passing between those multiple outputs. First, because without BSFs it would exceed the 16 node limit in some commercial use cases. Second, the DECA loss budget would be significantly impacted if there were 8 way splitters used on the outputs (i.e. > 4 receivers/DVRs on at least two of those outputs) in addition to the 4 way internal splitter. Third, it avoids the need for a BSF pigtail on each output in MDU environments. Fourth, I just can't think of any use cases where you must use multiple outputs and must pass DECA between them. On the other hand, Directv would have to add something to filter DECA, so maybe they leave it out to save a few pennies and figure BSFs will be used where needed, since that's already the case with SWM8s (which I assume require a BSF on each output in a MDU where two units share one SWM8)

 

I do not expect to see another SWM16 or SWM32 like product that combines multiple DSWM23s into a single unit. The only advantage they offer is density, and perhaps in the case of the SWM32, cascade support. A DSWM23 would already offer the density advantages of the SWM16/SWM32, so there's no need for a lower volume product that's even more dense.


SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21


#41 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 01 January 2014 - 04:13 AM

The mention of cascading made me recall something I was intending to post but forgot. I stated in a recent post here that I assumed the ASWM used a 6x9 multiswitch in the front end. The "prior art" in the DSWM patent shows RF5201 chips being used, and I couldn't quite figure out how that worked since Entropic's site showed they had only two inputs, but they'd need three to work with a multiswitch at the front end. The problem of course was that the prior art showed four inputs, and that wasn't even including the flex ports it left out! It just didn't make sense. It turns out the "routing of LNA signals to all 3 chips" shown in the prior art (figure 2) don't count as inputs - the chips use side channels to share inputs with each other. So 3 chips x 2 inputs each = 6 inputs, now it makes sense!

 

Following this design, the SWM16's rather large legacy loss makes perfect sense, since each LNB input must be split six ways to go to the six RF5201 chips (three on each "SWM8 half") The loss from a two way split between "halves" followed by a balanced three way split inside the RF5201s exactly matches the "slightly over 10db" legacy loss reported for the SWM16. While this isn't much of an issue for the SWM output since it is gets the benefit of the AGC boost, based on this I'd expect the SWM8 may have a few db greater margin for loss at the input since it is only split three ways. If someone had a splitter and a SWM8 and SWM16, and a method for attenuating the input in stages (maybe by just adding splitters to one polarity while trying to tune a channel on that polarity via the SWM output on each of them using identical receivers) I'd expect the SWM16 to lose the signal "one splitter's worth" earlier. The SWM32 is reported to have an output that is about level with its input, so it must have a ~16 db AGC amp at the front end - to make up for the twelve way loss it suffers - and thus should be much more tolerant of weak input than the SWM8 or SWM16.

 

It also makes sense why Entropic's site shows the apparently unnecessary RF5200 - which is a 3 input / 3 output version of the 2 input / 3 output RF5201. That has to be what the SWM5 used, since if it used RF5201s it would lack sufficient inputs with which to support flex ports. I googled it and though I could only find a couple rather crappy stock photos, it looks like the SWM5 had only two legacy ports, which fits my hypothesis perfectly. The one thing I'm not clear on is why the SWM8 doesn't support the HD satellites on its legacy outputs, since there is no reason why it shouldn't be able to access any satellite via the RF5201. It would appear Directv must have put bandpass filters on these outputs that only allow the 950 - 1450 MHz range to pass, for some reason.

 

I figured all this out when I was looking at the RF5201 on Entropic's site. When I looked for similar products, I saw the RF5218 (used in European CSS systems) After a bit of googling I found some very detailed information on the very similar RF5210, which is sold under the RF Magic brand, which Entropic owns. It was easy to see how the RF5210 works, and the prior art in the DSWM patent with the very similar RF5201 suddenly made perfect sense. It turns out there is actually a 6x4 multiswitch in each of the three RF5201 chips in the ASWM (3 outputs for SWM, 1 for legacy) rather than external 6x9 multiswitch at the front end I was assuming (which would have been wrong anyway, I forgot about the legacy ports - it would have required a 6x12 multswitch)

 

Here are the links to a couple sources with functional diagrams of the RF5210:

 

http://52ebad10ee97e...T_RF5210_DS.pdf

http://rfdesign.com/...cs/703RFDF4.pdf

 

This brings up another point. The DSWM ASIC includes no legacy multiswitch, so there's an implementation choice for a DSWM module. Either integrate a legacy multiswitch in the module to allow it to support the 4 legacy + 2 flex ports as the SWM16 and SWM32 do, or use splitters at the front end to provide cascade outputs. Those "cascade ports" would not act as legacy ports, because they'd be polarity locked (i.e. the 99/101 even port would always output only that polarity and an attached receiver could not change it) You'd lose ~5db on each cascade from that splitter loss, so you couldn't cascade very far unless it included an amplifier.

 

The pictures of the DSWM13 shows the traditional six outputs, but Stuart stated "the DSWM13 doesn't have any legacy ports, despite what you see" so perhaps they're cascade only ports. There's also the possibility they do absolutely nothing in the DSWM13. That might be the case if, for example, they built it using the chassis they plan to share with a future DSWM23, which will have some sort of legacy/cascade output. Maybe I'm wrong, but I kind of get the impression that Directv is progressively discouraging cascading more and more, so I guess I wouldn't have been shocked if the DSWM13 didn't have those six outputs at all. Of course, the reverse could be true, and they will support cascading with the DSWM13, but the DSWM23 will leave those ports out. Oh well, once Stuart is allowed to give us more details we can learn what those ports on the DSWM13 are/do, and it will provide some direction for future speculation :)


SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21


#42 OFFLINE   veryoldschool

veryoldschool

    Lifetime Achiever

  • Moderators
  • 42,165 posts
Joined: Dec 09, 2006

Posted 01 January 2014 - 02:32 PM

[Moderator hat on]

 

Is there any interest in this?

 

[/Moderator hat off]


A.K.A VOS

#43 OFFLINE   P Smith

P Smith

    Mr. FixAnything

  • Registered
  • 20,289 posts
  • LocationMediterranean Sea
Joined: Jul 25, 2002

Posted 01 January 2014 - 03:04 PM

practically for himself only



#44 OFFLINE   HoTat2

HoTat2

    Hall Of Fame

  • Registered
  • 5,720 posts
  • LocationLos Angeles, CA.
Joined: Nov 16, 2005

Posted 02 January 2014 - 01:04 PM

practically for himself only

Lots of interest here ... :)

 

Though it did take me a while to quite understand it. 

 

Hope I got it right as described in my next post.


DIRECTV sub. since Sep. of '95


#45 OFFLINE   Stuart Sweet

Stuart Sweet

    The Shadow Knows!

  • Topic Starter
  • Super Moderators
  • 37,032 posts
Joined: Jun 18, 2006

Posted 02 January 2014 - 01:25 PM

The purpose of a discussion thread, though, is to discuss... not to work on the rough draft of your own personal white paper. Is there any more to be said? More importantly, is there anyone else besides one person saying it? 


Opinions expressed by me are my own and do not necessarily reflect
those of DBSTalk.com, DIRECTV, DISH, The Signal Group, or any other company.

#46 OFFLINE   HoTat2

HoTat2

    Hall Of Fame

  • Registered
  • 5,720 posts
  • LocationLos Angeles, CA.
Joined: Nov 16, 2005

Posted 02 January 2014 - 02:15 PM

So slice to summarize your latest findings here.

 

If I'm understanding this correctly, each RF5201 chip used in the present ASWM has an integrated 6 x 4 multiswitch of which 2 (3 in a 7 x 4 MS for the RF5200 and 5210) of the 6 inputs of the MS are "officially" labeled as "LNB inputs" The other 4 are only used for cross-connects when paralleling the chips?

 

So for the DIRECTV ASWM starting at the top of the diagram of fig. 2, one chip will receive the two LNB inputs from the Sat B and B+C lines, plus feed those sames lines to the other two parallel chips on two of their cross-connect inputs.

 

Though not illustrated the chip in the middle of the patent diagram will have the two LNB inputs from the flexports as well as feed the same to the two other chips in parallel above and below it in the diagram via two of their cross-connect inputs.

 

And the third chip will receive the two Sat A LNB inputs as well as feed it to the two other chips in parallel on two of their cross-connect inputs.

 

So again to reference the ASWM diagram illustrated the patent (i.e. Fig. 2).

 

Chip "C0" has 6 inputs which are Sat B and B+C from the LNBs, Sat A (2 lines) LNBs via cross-connects, and two flexport lines via cross-connects.

 

Chip "C2" 6 inputs are the two flexports on the LNB inputs though not illustrated in the diagram, the two Sat B and B+C lines via cross-connects, and two Sat A LNB lines via cross-connects, 

 

Chip "C6" 6 inputs are the two Sat A lines from the LNBs, the two Sat B and B+C lines via cross-connects, and the two flexport lines via cross-connects.

 

Hope all this is correct ... :)

 

... The one thing I'm not clear on is why the SWM8 doesn't support the HD satellites on its legacy outputs, since there is no reason why it shouldn't be able to access any satellite via the RF5201. It would appear Directv must have put bandpass filters on these outputs that only allow the 950 - 1450 MHz range to pass, for some reason. 

 

Actually, it's my understanding that the SWiM-8 passes both the Ku and Ka-hi bands, but not the Ka-lo.

 

This was corrected in the later SWiM-16 of course.

 

It's just a guess and maybe a bit of a reach as well, but I wonder if there was some sort of design error in the original SWiM-8 external multiswitch where the European 950-2150 MHz frequency range for legacy ports of the SWiM switch for that market was also put into DIRECTV's version here in the U.S.?    


Edited by HoTat2, 02 January 2014 - 02:21 PM.

DIRECTV sub. since Sep. of '95


#47 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 02 January 2014 - 03:54 PM

I think we're on the same page with the ASWM.

 

I wasn't aware that the SWM8 passed Ka hi via the legacy ports, that makes it even more strange. Your theory might be right, or it might have something to do with the off air port (though I think I read somewhere that the SWM8 doesn't pass OTA via the legacy ports) I guess the reason for the SWM8 not passing B band will remain a mystery.

 

Since the DSWM ASIC has no provision for output of legacy bands, a DSWM module would have to provide any legacy/cascade ports by splitting the 6 LNB inputs or adding a multiswitch within the module. Either solution would result in notably less thru loss than the SWM16 exhibits through its legacy ports. But even with near zero loss, IIRC Directv only supports two levels of cascade with the SWM32. I have no idea whether they'd consider cascade or legacy support important in future products, given that they've abandoned legacy support on receivers/DVRs introduced the past few years.


SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21


#48 OFFLINE   HoTat2

HoTat2

    Hall Of Fame

  • Registered
  • 5,720 posts
  • LocationLos Angeles, CA.
Joined: Nov 16, 2005

Posted 02 January 2014 - 07:34 PM

I think we're on the same page with the ASWM. ...

 

 

Glad to hear that ... :)

 

But if this is definitely how the ASWM is wired, be it the external multiswitch or integrated SWiM LNB, then it must use the standard Sat A, B, B+C (250-750 MHz, 950-1450 MHz, 1650-2150 MHz) frequency stack on its 4 inputs plus 2 additional inputs for the flexports.

 

So that leaves me wondering then, in what way is converting all the satellite bands to the ~250-760 MHz range illustrated in the other patent about using a single LO and freq. divider chips considered "the prior art?" :confused:    


DIRECTV sub. since Sep. of '95


#49 OFFLINE   inkahauts

inkahauts

    Hall Of Fame

  • DBSTalk Club
  • 17,669 posts
Joined: Nov 13, 2006

Posted 02 January 2014 - 08:35 PM

A theory in the swim8 legacy outputs. A swim8 is a swim5 with more channels I believe is all. That product never saw real production. But since there's only three legacy outs IMHO it was strictly meant for sd boxes so they probably didn't care about passing all signals anyway. And three legacy out plus 5 swim channels were a total of 8 so I have a feeling the first interation was all about a couple Hi Definition receivers and a couple sd for people. They realized their mistake and pumped it up to 8 possible Hi Definition tuners on swim. And they just left the legacy outputs alone at the time.

#50 OFFLINE   slice1900

slice1900

    Hall Of Fame

  • Registered
  • 4,063 posts
  • LocationIowa
Joined: Feb 14, 2013

Posted 02 January 2014 - 10:26 PM

Glad to hear that ... :)

 

But if this is definitely how the ASWM is wired, be it the external multiswitch or integrated SWiM LNB, then it must use the standard Sat A, B, B+C (250-750 MHz, 950-1450 MHz, 1650-2150 MHz) frequency stack on its 4 inputs plus 2 additional inputs for the flexports.

 

So that leaves me wondering then, in what way is converting all the satellite bands to the ~250-760 MHz range illustrated in the other patent about using a single LO and freq. divider chips considered "the prior art?" :confused:    

 

 

Well, recall that the 'single LO' patent is for a LNB, so the prior art within would likely be for a SWM LNB, not a SWM module. If you look at the RF5210 block diagram in the datasheet I linked to previously, the four (or six in the case of Directv's ASWM) LNBs are passed through the internal multiswitch intact, and not split/converted to individual bands in the 250 - 760 MHz range. The three multiswitch outputs pass through a mixer, a SAW filter etc. which isolates the 'transponder of interest' and places it at the proper frequency for the intended SWM channel.

 

There's no way to know for sure where the prior art from the single LO patent may fit in. Maybe it is used in the SWM LNB - but if so it uses something other than the RF5201 FTM. Maybe this prior art was designed for a first embodiment version of the DSWM but they decided not to go further with it (too expensive, too power hungry, whatever) Without more information, we can only guess. If we could open a SWM LNB and Entropic is kind enough to mark their ICs, we could see what's in there. That might point us in the right direction.


SL5, PI-6S, SA-6AL, 3xSWM16; 21 H20-100, 1 H20-600, 7 H24-700/AM21





Protected By... spam firewall...And...