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Directv splitter specs


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#1 OFFLINE   slice1900

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Posted 10 March 2014 - 01:55 PM

Does anyone know if Directv or their suppliers ever published specs for the SWM splitters? I saw something on Sonora's site which appears to be for the older SWM splitters (non green label) which looked a bit odd to me.

 

According to Sonora, the SWM splitters have higher losses at lower frequencies and lower losses at higher frequencies. As far as I knew, splitters always had higher losses at higher frequencies. Is this correct - can splitters be designed to have less loss at higher frequencies? If so, I guess this would be done to compensate for the slope of RG6, which attenuates higher frequencies more than lower frequencies? Then I wonder why more splitters aren't designed in this way, or designed to have a flat loss across their frequency range?

 

http://www.sonorades..._sws_splits.pdf

 


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#2 OFFLINE   veryoldschool

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Posted 10 March 2014 - 02:33 PM

When you sell to only one customer, there isn't a need to publish the specs.

"According to Sonora" should raise a red flag.

 

The pdf is for splitters that are pre DECA.

 

Aside from the change for DECA, splitters are mostly all the same.

Skywalker does publish specs for theirs.

 

2-way:
   
Insertion Loss (dBMax):
 5-40MHz: 4.3
 40-1000MHz: 4.4
 1000-1750MHz: 4.8
 1750-2050MHz: 6.2
 2050-2300MHz: 7.3
 
Isolation (dB Min):
 5-40MHz: 16
 40-2300MHz: 22

 

The only thing that can be "played with" are the stripline lengths inside, but even these can't vary that much.

 

Slope compensation is fairly lossy, by attenuating the lower end more than the upper end..


A.K.A VOS

#3 OFFLINE   slice1900

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Posted 10 March 2014 - 04:18 PM

When you sell to only one customer, there isn't a need to publish the specs.

"According to Sonora" should raise a red flag.

 
Thanks, I figured the specs probably hadn't been released but I was curious. I assume Sonora either got their figures from Directv or measured them....why are you suspicious about their data?
 
The only thing that can be "played with" are the stripline lengths inside, but even these can't vary that much.
 
Slope compensation is fairly lossy, by attenuating the lower end more than the upper end..

 

So in the absence of other requirements, if you wanted to design a splitter that compensated for slope, you'd take a regular splitter and add additional attenuation to the lower frequencies?

 

I believe you've mentioned in the past that the green label / MRV approved splitters are specifically designed to have reduced port to port isolation in the DECA frequency range. If that's the case, would such a design have any effect on the insertion loss in lower frequency ranges?

 

Holland has some splitters designed for SWM/MRV in commercial/MDU environments they say they worked closely with Directv to design, which also have slightly higher losses at lower frequencies. In this case the specs also state the port to port isolation, shown as 19 db from 4-475 MHz in their 8 way splitter, 20 db from 950-1820 MHz, 15db from 1820-2150 MHz, but only 10db from 475-625 MHz. Exactly what you'd want in a splitter designed for MRV. They state 12db of loss in the SWM range of 950-1820 MHz, but 16db in the unimportant 4-475 MHz range.

 

I'm just trying to understand how SWM splitters and in particular those designed for MRV may differ from a "typical" splitter in their design to accomplish Directv's specific goals for reduced port to port losses in the DECA frequency range.

 

http://www.hollandel...T-Splitters.pdf


Edited by slice1900, 10 March 2014 - 04:18 PM.

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#4 OFFLINE   AntAltMike

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Posted 10 March 2014 - 04:33 PM

I thought that back when the green label splitters were first released, someone here popped the back off one and found no technical wizardry in them, and the conjecture was that a splitter earned a green label by passing a port-to-port max isolation standard, whereas most splitter specs guaranteed a minimum port-to-port isolation.    Prior to this novel use of the robust quality of digital signals, port-to-port was considered an invalid signal path for analog signals, not just because of high and less predictable loss, but also because the loss was not sufficiently "flat across the channel", and so analog signals sent "laterally", output port to output port, often produced visibly ugly pictures even when the visual carrier strength and C/N ratios were acceptable.

 

Sonora's pdf linked above claims that those splitters use stripline technology to minimize the losses at 950-1850 MHz.

 

I've always considered Sonora's specs to be very reliable, except for a few typos on some of their literature.


Edited by AntAltMike, 10 March 2014 - 05:11 PM.


#5 OFFLINE   AntAltMike

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Posted 10 March 2014 - 04:38 PM

So in the absence of other requirements, if you wanted to design a splitter that compensated for slope, you'd take a regular splitter and add additional attenuation to the lower frequencies?

I don't know of anyone deliberately incorporating slope compensation into a splitter.  As VOS pointed out, slope compensation tends to be lossy, so the passives industry has preferred to inject or develop reverse slope externally, where it can be independently managed.  Passive distribution systems do not ordinarily need slope compensation, as tuners can deal with a severely sloped input spectrum as long as the signal strengths fall within the receivers input window, whereas distribution systems with downstream amplification often perform better when the signal going into an extender amp is "flat".


Edited by AntAltMike, 10 March 2014 - 05:30 PM.


#6 OFFLINE   AntAltMike

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Posted 10 March 2014 - 05:10 PM

When you sell to only one customer, there isn't a need to publish the specs.

Specs are useful to verify the efficacy (loss budget) of a distribution plan, and to test individual components for proper functionality. 



#7 OFFLINE   veryoldschool

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Posted 10 March 2014 - 05:48 PM

Specs are useful to verify the efficacy (loss budget) of a distribution plan, and to test individual components for proper functionality. 

Yes they are and it's best to use the "worst case" values.

 

I have yet to see the inside of a green labeled splitter, while I have seen the non green labeled.

 

"I believe" the 475-625 MHz is filtered and bridged with a resistor network, leaving the out of band to have the normal isolation [given as min]

Isolation is a wanted quantity and spec'd as min.

Loss is undesirable and spec'd as max. 


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#8 OFFLINE   veryoldschool

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Posted 10 March 2014 - 05:51 PM

I assume Sonora either got their figures from Directv or measured them....why are you suspicious about their data?

A NDA limits me, so I will only say I don't agree all the time. 


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#9 OFFLINE   samrs

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Posted 10 March 2014 - 07:24 PM

A NDA limits me, so I will only say I don't agree all the time. 

You signed an NDA!

 

photo-thumb-445551.gif?_r=1366000409

 

Kick that in the dirt.


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#10 OFFLINE   slice1900

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Posted 10 March 2014 - 08:55 PM

Yes they are and it's best to use the "worst case" values.

 

I have yet to see the inside of a green labeled splitter, while I have seen the non green labeled.

 

"I believe" the 475-625 MHz is filtered and bridged with a resistor network, leaving the out of band to have the normal isolation [given as min]

Isolation is a wanted quantity and spec'd as min.

Loss is undesirable and spec'd as max. 

 

 

I was kind of thinking along the same lines, that perhaps the DECA frequencies are separated out and separately handled. Effectively including a diplexer inline with the splitter that follows. If that was the case, is it possible that depending on how that diplexer is implemented you might see more insertion loss on the lower frequency side? I assume when you say filtered/bridged by a resistor network, you're speaking of a diplexer - forgive my utter ignorance of such basic EE, I took the CS path as an undergrad! :computer:

 

What you say about specs and min/max makes perfect sense, and I do see insertion loss and isolation specified in splitters and other devices in exactly the way you suggest. Holland's specs for isolation on this splitter family are really interesting in light of your comment. The frequencies below DECA range are specified as a maximum, the DECA range is specified as +/- 2db from the provided figure, and the L band/SWM range is specified as a minimum.

 

The range between DECA and L band, 625-950 MHz, is the most interesting though, showing the min/max isolation as 18/45 db on the 8 way, 10/45 db on the 4 way, and 8/40 db on the 2 way! Such a wide range can't be the QC range at any one frequency, but rather that some frequencies in the range are "as low as" the lower figure and other frequencies are "as high as" the higher figure. Such a wide range looks like the roll off of a filter - perhaps that of the diplexer that I/we believe may precede the splitter?


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#11 OFFLINE   slice1900

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Posted 10 March 2014 - 09:11 PM

You signed an NDA!

 

photo-thumb-445551.gif?_r=1366000409

 

Kick that in the dirt.

 

I agree it tends to put a damper on discussion when someone has information that is restricted by a NDA, but having signed more than a few over the years, and having even more often given "my word" that I wouldn't say something, I absolutely cannot fault him or anyone else for keeping to such agreements. If you fail to do so, you would no longer be trusted with it in the first place.

 

The information that Sonora provides that I've had the opportunity to independently verify has turned out to be right on the mark, but that doesn't mean there aren't some inaccuracies somewhere. I've had experience with companies that are "selling something" that stretch/bend/conceal/subvert/etc. the truth to help their sales, and I don't know enough about Sonora to have any idea whether or not they may do that in some cases.

 

I point to them often on dbstalk.com for facts/figures simply because they are one of the few sources of such information that is publicly available when it comes to equipment designed for Directv. Unfortunately Directv seems to limit the distribution of specs about their equipment, so one has to look for potentially less reliable sources (i.e. this whole thread would be unnecessary if Directv published the QC specs they held their splitters to...)


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#12 OFFLINE   veryoldschool

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Posted 10 March 2014 - 09:13 PM

RF specs have "standard" notation. ie min and max.

The marketing tends to bend these "just a bit" :lol:

 

I haven't opened up a DECA splitter to see what they did.

"You know" whatever they did was "on the cheap".

Power dividing with resistors is cheap.

A band stop/band pass diplexer is one way to "filter" the DECA, but I'm not sure it's the cheapest.


A.K.A VOS

#13 OFFLINE   veryoldschool

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Posted 10 March 2014 - 09:19 PM

Unfortunately Directv seems to limit the distribution of specs about their equipment, so one has to look for potentially less reliable sources (i.e. this whole thread would be unnecessary if Directv published the QC specs they held their splitters to...)

"I think" this is a bit backwards from how it's done.

A supplier will propose their specs and unit price.

DirecTV will accept/approve them or not, and price is the significant factor.


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#14 OFFLINE   slice1900

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Posted 10 March 2014 - 09:31 PM

"I think" this is a bit backwards from how it's done.

A supplier will propose their specs and unit price.

DirecTV will accept/approve them or not, and price is the significant factor.

 

That may be. It seems as though it could lead to more confusion, if someone had a working install, something breaks, and an "identical" part made by a different manufacturer is swapped in and their install no longer works due to a difference in specs. But I guess that's what Directv's overly pessimistic guidelines are for.

 

But you may be right, perhaps I shouldn't blame Directv for the lack of published specs, but instead blame Zinwell, WNC and PBI :)


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#15 OFFLINE   AntAltMike

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Posted 10 March 2014 - 11:29 PM

As I recall, we had to rely on numbers furnished by MicroRoyal when trying to engineer DISH DPP distribution that pushed the limits of those components.  I think MicroRoyal was also the company that came up with the SW21x that had a different command set than did the DISH approved SW21, which made it economical to add one more satellite into DISH systems.

 

I haven't had any intimate contact with Sonora for about a decade, but as I recall, once DirecTV had committed to the stacking technology that NAS was using, Sonora seemed to be on the outs with DirecTV.  That was around the time that DirecTV was consolidating the manufacture or branding of its receivers, and Sonora seemed to basically be reacting to whatever it could learn of DirecTV's distribution systems.  In those days, DirecTV had allowed some real underfunded and irresponsible compaines to operate systems in MDUs, and they became more of a headache for DirecTV than they were worth.  Is Sonora now, or has it ever been, a DirecTV approved supplier of parts?


Edited by AntAltMike, 11 March 2014 - 03:27 PM.


#16 OFFLINE   veryoldschool

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Posted 11 March 2014 - 03:22 AM

Is Sonora now, or has it ever been, a DirecTV approved supplier of parts?

I think it's taken some effort:

TAMP6-T12_medlrg.jpg

Sonora Design TAMP6-T12
A.K.A VOS

#17 OFFLINE   slice1900

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Posted 11 March 2014 - 03:34 AM

I remember seeing Directv's approved products spreadsheet once, and it included a bunch of Sonora gear for commercial/MDU. It isn't just that TAMP6 amp they designed in conjunction with Directv, but several of their other amps, splitters, taps, etc. were listed too.

 

When I looked at NAS's web site once to see if they had any interesting info like Sonora provides, it appeared not to have been updated for at least five years. I suppose they now provide information directly to MDU installers, but if I didn't know better seeing such an out of date web site would make me think they were out of business.


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#18 OFFLINE   veryoldschool

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Posted 11 March 2014 - 05:56 AM

I remember seeing Directv's approved products spreadsheet once, and it included a bunch of Sonora gear for commercial/MDU.

Not sure of the date, or what you saw, but getting the TAMP6 on the list was a big deal for Sonora, and fairly recent.

Sonora hasn't been known for having the DirecTV logo associated with their products.


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#19 OFFLINE   AntAltMike

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Posted 11 March 2014 - 06:26 AM

(Waxing nostalgic)

 

Back around 2001 or 20002, DirecTV was sending out really weak signals on transponders 30 and 32, which carry HBO and Showtime.  The speculation was that DirecTV had inherited some contractual terms when it took over USSB that were less favorable than the terms it had or was about to impose on its other program providers, and that those USSB contract terms were set to expire when DirecTV satellite S2 (D2?) expired, but since that satellite had already been demoted to back-up status, the end of life clause was inconveniently delayed and so they temporarily switched it back on to deplete it.  The problem this created with Sonora equipment was that Sonora's most powerful distribution amplifiers had automatic gain control, pushing their outputs up to a level where intermodulation with a balanced load (meaning flat input spectrum) was normally pretty close to the point of becoming unacceptable, but now, when you introduce some strong spotbeams, which didn't exist when those amplifiers were designed, and weaken two CONUS beams, the intermodulation was beating up the weak transponders 30 and 32.  Since there was no way to turn off the AGC in those amplifiers, we had to incrementally pad down the input until the outputs finally started to drop, and from there, we further padded it until signal quality on transponders 30 and 32 was restored to an acceptable level, which meant of course that we no longer had AGC and so for maybe a year we would have serious rain fade problems.  Ah, the good old days, the good old days...


Edited by AntAltMike, 11 March 2014 - 03:31 PM.


#20 OFFLINE   slice1900

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Posted 11 March 2014 - 12:20 PM

Not sure of the date, or what you saw, but getting the TAMP6 on the list was a big deal for Sonora, and fairly recent.

Sonora hasn't been known for having the DirecTV logo associated with their products.

 

The Directv logo doesn't appear to be necessary for something to be on the approved list. I poked around a little bit and found this:

 

https://sites.google...ourse-materials

 

If you download (view doesn't work) the Approved Materials List for Dec 2011, there are a couple dozen Sonora products listed. I think the difference with the TAMP6 was that Sonora worked with Directv in its design. Maybe that's why it has the Directv logo instead of the Sonora logo / polarity color scheme.

 

There are some products listed for NAS like the PI-6S and SWM-E2 where Sonora sells the same product under the same name, but it isn't listed. Not sure if that means Sonora's PI-6S and SWM-E2 aren't approved for some reason, or if they would be found on a more recent version of this list.


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