New Member: an uplinker
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SCPC audio. see Pacifica Network Uplink Page
There are also a variety of other data transmissions on the other horizontal transponders.
Truck dishes are at least 1.8m; usually the receive site dishes are also fixed uplinks which are in the 6m range.
Thanks NewsTruck, my 1.2 Meter dish looks small now 
One other question how are transponders labeled for digital broadcasts, how do you specify example: transponder 17 and then the letters.
One other question how are transponders labeled for digital broadcasts, how do you specify example: transponder 17 and then the letters.
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Thanks NewsTruck, my 1.2 Meter dish looks small now
One other question how are transponders labeled for digital broadcasts, how do you specify example: transponder 17 and then the letters.
Not sure I understand the question... The transponders are all wide enough to handle six individual 4.232 streams (actually nearly 6Mb/sec mpeg video per each). So we just subdivide them just like a real estate developer would, into 17A, 17B, 17C, 17D, 17E, and 17F. Hard to believe, but they were actually designed to hold one (1) analog video channel, which is the way we used to do it. Some small TV stations still have analog-only uplinks, which means that they take up the space of 6 digital channels of similar quality.
Thanks for your reply, that was very informative, what I mean is how do you connect a transponder to a frequency, example:
TP 1a = 10 MHz
TP 1b = 15 MHz
TP 2a = 20 MHZ
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TP 1a = 10 MHz
TP 1b = 15 MHz
TP 2a = 20 MHZ
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Many of us use an old analog receiver slaved to the DVB receiver to pick up the analog that is still up there
This time of year, college football games are usually the culprit First, don't confuse transponder with channel. A transponder is a physical device with a specific width. Think of how wide a big highway is. You can see the actual TRANSPONDER frequencies at (click) Ku-band. How they get subdivided is up to the customer, just like painting lanes on a highway that someone else has physically built.
A channel is a part of that highway; think of it as a lane.
You can make up wide lanes or narrow lanes; it's all up to how you paint the stripes. How SAFE the highway is, is helped by being able to not put too many lanes on that space, so that each car has some breathing room to its left and right.
Each transponder when it's built has a physical maximum width with a specific center frequency; it's manufactured that way.
Think of a big 6-lane highway before the stripes are put down.
All you do is divide the width needed for each channel with a bit of room for safety in between each channel.
For example, the center frequency of AMC1's transponder 17 is exactly 12040, and you have about 36MHz of clear real estate, stretching from (12040-18=) 12022 to (12040+18=) 12058.
You know how wide each car is, so you know that you can fit approximately 6 lanes in that 36MHz width, so you find the middle of the road, and just start drawing lines based on centering 6 lanes on the middle. So the easiest math is just to divide the 36 by 6, giving you 6 lanes (channels).
Since the lower end is 12022, you place the "A" channel in the center of the 6, making it 12025. Then just add 6 for each additional channel.
Thanks for that explanation, do all transponders (or most) have 36 MHz of bandwidth? or do other run at different bandwidths?
Thanks.
Thanks.
36 is by far the most common; DISH (Echostar) uses 30; some are wider (SBS-6 was 43 MHz).
Most were originally designed to carry 1 analog FM video channel at contribution quality, which takes 36 MHz. The fact that we now subdivide them into channels is a relatively recent practice.
A good overview of the US satellites is at Spacecraft: Communication - USA
Transponder freq and scanning?
Hello and welcome. I read through all the posts and hope I came up with a smart question.
So a Sat has say 17 transponders. Is there a way or a chart somewere to show on that certain satellite what the total bottom and total top frequency is? I assume since each satellite or some have difference widths on them. This need to be a wider scan or do you just keep it to a certain number / freqencies? I know you covered both sats and what sides you use.
So when we blind scan. We are not scanning more than what we need to.
Also what cool equiptment do you use to receive in the truck? Rack mount industry stuff?
Thanks,
Josh
Hello and welcome. I read through all the posts and hope I came up with a smart question.
So a Sat has say 17 transponders. Is there a way or a chart somewere to show on that certain satellite what the total bottom and total top frequency is? I assume since each satellite or some have difference widths on them. This need to be a wider scan or do you just keep it to a certain number / freqencies? I know you covered both sats and what sides you use.
So when we blind scan. We are not scanning more than what we need to.
Also what cool equiptment do you use to receive in the truck? Rack mount industry stuff?
Thanks,
Josh
There is a guide for satellite transponders, printed monthly, called the "Keystone Communications North American Satellite Guide", but it goes for $235.00/year. It really has much less information than Lyngsat, but it does do what you asked for -- deal with the satellites at the transponder level.
My primary receiver is the original Nokia D-Box using DVB-2000. It's been in there for 7 years. I use it primarily for monitoring.
I also have a Standard International universal analog receiver, which can do any bandwidth / deviation level / subcarrier audio scheme. Almost never used or even looked at. My analog uplink hasn't been used in 6 years.
For critical downlinking, I have 2 Tandberg Alteia receivers, which can do 4:2:0 and 4:2:2, which output digitally to Sony Betacam SX decks. You might think that's great, but know that they take nearly 30 seconds to change channels. But the output is very stable.
As far as pure picture quality, there's not much difference between the Tandbergs and the Nokia or any other receiver - mostly it has to do with sync stability and available options, something the home viewer doesn't really need, so don't feel like you're missing out on something...
And no, they can't blind scan, no remote control, no Diseqc, no polarity changing (except via 2 separate inputs) and they have a whopping 10 memory locations.
-John
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If they are like the Digitrans 7150T, the user must enter all relevant transponder data manually to simply switch channels. Do the Tandbergs have an SDTI option, or uncompressed SDI? (I ask because you mentioned Beta SX )
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Talking about transponder sharing among different uplinkers, it goes to an extreme level with satellite internet (VSAT) terminals.
Imagine this scenario except with hundreds of channels per transponder, and with collision avoidance and TDMA algorithms involved. It's amazing that VSAT works so well for all its challenges.
Imagine this scenario except with hundreds of channels per transponder, and with collision avoidance and TDMA algorithms involved. It's amazing that VSAT works so well for all its challenges.
If they are like the Digitrans 7150T, the user must enter all relevant transponder data manually to simply switch channels. Do the Tandbergs have an SDTI option, or uncompressed SDI? (I ask because you mentioned Beta SX
1) Like I said, it has 10 memory locations, so for my 10 most-used channels, I don't have to enter those manually.
The unit is mostly designed to be controlled by a computer; it generates it's own web pages, and a full IP interface, so it can connect to a web browser. The encoders do, too.
2) Yeah -- it's all SDI, both from the downlink to tape (coming down) and from tape to the encoder (going up). From the camera in the field to your home, it's all digital. Unfortunately, it does get MPEG-re-encoded once, going from SX's IBIBIBIBIB (editable) to a standard IBBPBBPBBPBBPBBI when uplinked. Live shots are actually just IBBI to minimize the delay.
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Yeah, but if you look at it on a spectrum monitor, it's not that bad. Unless you were to have some uplink run amok and either drift in frequency or suddenly start shooting out hundreds of watts, overpowering everyone else... I'm sure there are horror stories, just like in every other operation...
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