232 replies to this topic

[olo131]

Welcome cypherstream

or hello seeing you have been around here longer the me thank you for joining this topic. I started this to help everyone to get a better understanding of how others view the upcoming DOCSIS.

Your input will become helpful to others.

olo131

[Forbins]

looking at ccors data sheet for 26/4 and 23/4. The throughput loss is almost identical, so i still don't see why we're using them. For ***** and giggles, i tested it myself and have found no difference in all the ones i tried. about 1db on on gig on both taps.

[RF Dr...]

Remember everytime you change QAM to a larger QAM you loose attenuation by 3db in the return

I forgot about that. We still have 26 value taps everywhere, which is nuts in my opinion. I used to hate those back in the day when i was a field service tech going into homes. Nothing like running multiple drops to one customer just to desperately try to shave down that TX levels.

Do you guys use those taps where you work?

gotta love our interdiction units...their all the same.
except the internal dc and eq.

[Dak]

gotta love our interdiction units...their all the same.
except the internal dc and eq.

We built Winona MN with SA (BT) interdiction taps. Whooboy what a pain in the butt. Nothing like hanging shoe boxes on the strand. We had a design that specified one port per customer. A 10 count pole could have 3 taps on it. Add an LE and the LE would be 5' from the pole. I convinced the management to split the taps up on both sides of the pole. Sometimes you just gotta do it!
Yeah, every tap is just like an amp, with a separate pad and EQ and provisions for conditioning the reverse path. You have to have 18 dB exactly (if memory serves me correctly) into the tap so that the AGC portion of the tap works. Probably not a problem down there in Alabamy, but in the frozen north it has to suck. Too low of signal and the jammers are visible. Too high of signal and little Jimmy gets to see the tata's on Showtime and CinaSmut.

Still, it sure beats a truck roll for a disconnect!

Dak

[RF Dr...]

gotta love our interdiction units...their all the same.
except the internal dc and eq.

We built Winona MN with SA (BT) interdiction taps. Whooboy what a pain in the butt. Nothing like hanging shoe boxes on the strand. We had a design that specified one port per customer. A 10 count pole could have 3 taps on it. Add an LE and the LE would be 5' from the pole. I convinced the management to split the taps up on both sides of the pole. Sometimes you just gotta do it!
Yeah, every tap is just like an amp, with a separate pad and EQ and provisions for conditioning the reverse path. You have to have 18 dB exactly (if memory serves me correctly) into the tap so that the AGC portion of the tap works. Probably not a problem down there in Alabamy, but in the frozen north it has to suck. Too low of signal and the jammers are visible. Too high of signal and little Jimmy gets to see the tata's on Showtime and CinaSmut.

Still, it sure beats a truck roll for a disconnect!

Dak

on our system we need a minimum of 26 db @ 55 MHz and 24 db @ 750 MHz. just eq's and dc's in ours, no pads. we use 4 and 8 port units. only a couple locations have 2 units housing to housing.
you are exactly right though...its alot on the strand and a pain to set up sometimes. also no jammers here, (no movie channels on expanded basic, gotta get a set top) output is supposed to be 16/10 @ the port. and the dc voltage needs to be between 7 and 8.4 VDC. if the voltage isnt right then it starts messing with the MER. and FEC will suck especially the freq. that is the same as a over the air digital signal. it will dam sure let you know that you have ingress issues.

[cypherstream]

gotta love our interdiction units...their all the same.
except the internal dc and eq.

We built Winona MN with SA (BT) interdiction taps. Whooboy what a pain in the butt. Nothing like hanging shoe boxes on the strand. We had a design that specified one port per customer. A 10 count pole could have 3 taps on it. Add an LE and the LE would be 5' from the pole. I convinced the management to split the taps up on both sides of the pole. Sometimes you just gotta do it!
Yeah, every tap is just like an amp, with a separate pad and EQ and provisions for conditioning the reverse path. You have to have 18 dB exactly (if memory serves me correctly) into the tap so that the AGC portion of the tap works. Probably not a problem down there in Alabamy, but in the frozen north it has to suck. Too low of signal and the jammers are visible. Too high of signal and little Jimmy gets to see the tata's on Showtime and CinaSmut.

Still, it sure beats a truck roll for a disconnect!

Dak

on our system we need a minimum of 26 db @ 55 MHz and 24 db @ 750 MHz. just eq's and dc's in ours, no pads. we use 4 and 8 port units. only a couple locations have 2 units housing to housing.
you are exactly right though...its alot on the strand and a pain to set up sometimes. also no jammers here, (no movie channels on expanded basic, gotta get a set top) output is supposed to be 16/10 @ the port. and the dc voltage needs to be between 7 and 8.4 VDC. if the voltage isnt right then it starts messing with the MER. and FEC will suck especially the freq. that is the same as a over the air digital signal. it will dam sure let you know that you have ingress issues.

Oh man Christopher... I've seen those in an Adelphia system in Scranton, PA. Shortly after Comcast took over, they removed them all! It was required to certify area's for digital voice service. I haven't worked with them but I've heard horror stories. Concept is real nice though. Scientific Atlanta makes an addressable tap that supposedly fits in a 9" housing (like the multimedia stretch tap housings).... but I haven't seen that in person.

Were going all digital in 3 or 4 months. Customers will complain when their digital TV QAM tuners won't work because we will encrypt all the QAM channels. This way we don't have to ever to roll trucks to change traps. Everythings addressable through a Motorola DCT/DCH/DCX or DTA. They are thinking of leaving all the drops connected and eliminating most basic truck rolls. I don't know how I feel about this.

Edited by cypherstream, 30 November 2009 - 09:18 PM.

[RF Dr...]

gotta love our interdiction units...their all the same.
except the internal dc and eq.

We built Winona MN with SA (BT) interdiction taps. Whooboy what a pain in the butt. Nothing like hanging shoe boxes on the strand. We had a design that specified one port per customer. A 10 count pole could have 3 taps on it. Add an LE and the LE would be 5' from the pole. I convinced the management to split the taps up on both sides of the pole. Sometimes you just gotta do it!
Yeah, every tap is just like an amp, with a separate pad and EQ and provisions for conditioning the reverse path. You have to have 18 dB exactly (if memory serves me correctly) into the tap so that the AGC portion of the tap works. Probably not a problem down there in Alabamy, but in the frozen north it has to suck. Too low of signal and the jammers are visible. Too high of signal and little Jimmy gets to see the tata's on Showtime and CinaSmut.

Still, it sure beats a truck roll for a disconnect!

Dak

on our system we need a minimum of 26 db @ 55 MHz and 24 db @ 750 MHz. just eq's and dc's in ours, no pads. we use 4 and 8 port units. only a couple locations have 2 units housing to housing.
you are exactly right though...its alot on the strand and a pain to set up sometimes. also no jammers here, (no movie channels on expanded basic, gotta get a set top) output is supposed to be 16/10 @ the port. and the dc voltage needs to be between 7 and 8.4 VDC. if the voltage isnt right then it starts messing with the MER. and FEC will suck especially the freq. that is the same as a over the air digital signal. it will dam sure let you know that you have ingress issues.

Oh man Christopher... I've seen those in an Adelphia system in Scranton, PA. Shortly after Comcast took over, they removed them all! It was required to certify area's for digital voice service. I haven't worked with them but I've heard horror stories. Concept is real nice though. Scientific Atlanta makes an addressable tap that supposedly fits in a 9" housing (like the multimedia stretch tap housings).... but I haven't seen that in person.

Were going all digital in 3 or 4 months. Customers will complain when their digital TV QAM tuners won't work because we will encrypt all the QAM channels. This way we don't have to ever to roll trucks to change traps. Everythings addressable through a Motorola DCT/DCH/DCX or DTA. They are thinking of leaving all the drops connected and eliminating most basic truck rolls. I don't know how I feel about this.

wonder why they were required to remove them for digital voice? we have voip here, with no issues, except ocasional ingress.

[cypherstream]

gotta love our interdiction units...their all the same.
except the internal dc and eq.

We built Winona MN with SA (BT) interdiction taps. Whooboy what a pain in the butt. Nothing like hanging shoe boxes on the strand. We had a design that specified one port per customer. A 10 count pole could have 3 taps on it. Add an LE and the LE would be 5' from the pole. I convinced the management to split the taps up on both sides of the pole. Sometimes you just gotta do it!
Yeah, every tap is just like an amp, with a separate pad and EQ and provisions for conditioning the reverse path. You have to have 18 dB exactly (if memory serves me correctly) into the tap so that the AGC portion of the tap works. Probably not a problem down there in Alabamy, but in the frozen north it has to suck. Too low of signal and the jammers are visible. Too high of signal and little Jimmy gets to see the tata's on Showtime and CinaSmut.

Still, it sure beats a truck roll for a disconnect!

Dak

on our system we need a minimum of 26 db @ 55 MHz and 24 db @ 750 MHz. just eq's and dc's in ours, no pads. we use 4 and 8 port units. only a couple locations have 2 units housing to housing.
you are exactly right though...its alot on the strand and a pain to set up sometimes. also no jammers here, (no movie channels on expanded basic, gotta get a set top) output is supposed to be 16/10 @ the port. and the dc voltage needs to be between 7 and 8.4 VDC. if the voltage isnt right then it starts messing with the MER. and FEC will suck especially the freq. that is the same as a over the air digital signal. it will dam sure let you know that you have ingress issues.

Oh man Christopher... I've seen those in an Adelphia system in Scranton, PA. Shortly after Comcast took over, they removed them all! It was required to certify area's for digital voice service. I haven't worked with them but I've heard horror stories. Concept is real nice though. Scientific Atlanta makes an addressable tap that supposedly fits in a 9" housing (like the multimedia stretch tap housings).... but I haven't seen that in person.

Were going all digital in 3 or 4 months. Customers will complain when their digital TV QAM tuners won't work because we will encrypt all the QAM channels. This way we don't have to ever to roll trucks to change traps. Everythings addressable through a Motorola DCT/DCH/DCX or DTA. They are thinking of leaving all the drops connected and eliminating most basic truck rolls. I don't know how I feel about this.

wonder why they were required to remove them for digital voice? we have voip here, with no issues, except ocasional ingress.

When Comcast swallowed up that Adelphia area in NE PA, the Central PA division took over. Central PA division also handles my area in east central PA (Reading, PA). I heard from a guy that works up there that they WOULD NOT roll out Comcast Digital Voice in a node until all of those taps were replaced. That was a Comcast business decision. Technically, like in your system, they WOULD WORK, but Comcast had a different agenda.

[Dak]

on our system we need a minimum of 26 db @ 55 MHz and 24 db @ 750 MHz. just eq's and dc's in ours, no pads. we use 4 and 8 port units. only a couple locations have 2 units housing to housing.
you are exactly right though...its alot on the strand and a pain to set up sometimes. also no jammers here, (no movie channels on expanded basic, gotta get a set top) output is supposed to be 16/10 @ the port. and the dc voltage needs to be between 7 and 8.4 VDC. if the voltage isnt right then it starts messing with the MER. and FEC will suck especially the freq. that is the same as a over the air digital signal. it will dam sure let you know that you have ingress issues.

Yeah, since you said that I went back and looked in my files. I think we used like 23.5 dB on 750 MHz and 15.5 at 55 MHz. This was into the AGC amp. 8 port taps were 3.5 dB higher.

I am attaching a couple of pics of the schematics we used as our guide for these.



Dak

Attached Files

•  4_port_BT_Interdiction_Tap.pdf   56.9K   32 downloads
•  8_port_BT_interdiction_Tap.pdf   66.47K   24 downloads

[LinetechAA]

How many upstream and downstream channels are you guys running with D3? We have 3 down and 3 up in my areas. It is hard to see anything except modems firing in our return.

Edited by LinetechAA, 14 December 2009 - 05:24 AM.

[olo131]

How many upstream and downstream channels are you guys running with D3? We have 3 down and 3 up in my areas. It is hard to see anything except modems firing in our return.

We plan to do 2 for phones and 2 for modems on DS plus all th old stuff until D3 phases out legacy modems (DOCSIS 1.1 and 2.0)

olo131

[the computer genius]

Question. I'm not in the cable modem business but I am a computer technician. but this has to do with the docsis3 and 2 standard

I brought (returned by now) a docsis 3 modem to replace my docsis 2. it was a motorola 6120. I am on the comcast network and I am on the lower teir. which is 16mps sustainable and 20 with powerboost. Due to the price of the service I was going to stick with the lower tier then switch to the higher tier later on.

What I had found was when I went on speedtest.net (with my new modem) my download speeds were about 10 points lower than my docsis2 modem. For example from Florida to NYC with my new modem was 10mbps while with old modem it was 21mps. From Florida to Californa it was 5 mbps for docsis 3 and 18 with docsis2. However from Florida to Atlantia with my new modem docsis3 it was 25mbps while with the old one it was about 24500 mbps, to try to download on a local server miami or naples it was about the same 24,000 to 25,000 on old and the same on new.

After troubleing shooting this from disconnecting router, and even going over other clients homes after I put back the old modem that is when I got the faster speeds accross the board. however with everyday surfing you couldn't tell the difference. the same 450MB download from HP was the same with the old modem and the new modem.

is there something I'm missing here. other than being a defect why would a docsis 2 modem be faster when it comes to distance (as from what i can see) than a docsis3 my old modem is an aris eta modem from comcast.

[olo131]

Welcome to the site TCG

The way I see it your trying to compare apples and oranges, while you think there both fruit they are just not the some. Your new D3 Modem has a different standard and sits in a different area of the spectrum. The fact is the D3 modems do allow faster speeds because of channel bonding but you may not always see that. but there are a lot of factors to consider that your old D2, D1.1 or D1.0 doesn't have.

Lets take 2 super cars one a front engine and one a rear engine both capable of going fast and you know the rear engine car is the better design but for some reason you don't get the same results every time. I personally never liked the speed boost technology it is a give and take tech to get the speed you have to give up quality.

I know I didn't give you the answer you wanted, as why there is a difference, but this is my theory to your question. Stick around there are lot of of guys here who either work for said company or running D3 in their systems and can better answer the question


Good luck
olo131

[cypherstream]

Oh yeah, this topic. That reminds me... We have a boatload of Motorola SB6120's and Arris 702g emta's, all DOCSIS 3.0. I just upgraded my emta to a Arris 702g. It rocks. Locked onto 3 downstreams on 112,113,114. Upstream is still 16QAM ATDMA 5120msym @ 29 MHz.

Hopefully in a month we'll roll out 64QAM upstream, but there's a bit of noise. Some of the cable plant is 45 years old (sans actives of course). Don't get me wrong, over 60+ miles of cable have been replaced. Were a great little 750 MHz system considering the age of some of the stuff. Also in a month the first group of analog channels will be cut. So we will have room to bond a 4th channel for the downstream. Theres about 130,000 subscribers on our plant.

Edited by cypherstream, 23 February 2010 - 07:18 AM.

[System Tech Senior]

Sounds good.. 130,000 is a pretty good chunk of customers.

[daveyboy]

Remember everytime you change QAM to a larger QAM you loose attenuation by 3db in the return

I forgot about that. We still have 26 value taps everywhere, which is nuts in my opinion. I used to hate those back in the day when i was a field service tech going into homes. Nothing like running multiple drops to one customer just to desperately try to shave down that TX levels.

Do you guys use those taps where you work?

[daveyboy]

Remember everytime you change QAM to a larger QAM you loose attenuation by 3db in the return

I forgot about that. We still have 26 value taps everywhere, which is nuts in my opinion. I used to hate those back in the day when i was a field service tech going into homes. Nothing like running multiple drops to one customer just to desperately try to shave down that TX levels.

Do you guys use those taps where you work?

where i work our system is set up for 1 gig so we have 32/23 taps on the outputs of our amp's and le's

[System Tech Senior]

32/23 taps????

[Kimbo]

32/23 taps????

[Kimbo]

Remember everytime you change QAM to a larger QAM you loose attenuation by 3db in the return

I forgot about that. We still have 26 value taps everywhere, which is nuts in my opinion. I used to hate those back in the day when i was a field service tech going into homes. Nothing like running multiple drops to one customer just to desperately try to shave down that TX levels.

Do you guys use those taps where you work?

where i work our system is set up for 1 gig so we have 32/23 taps on the outputs of our amp's and le's

Did you mean that your amp outputs are 32/23?