How to determine if a sat tuner is good or bad

[T_G]

Wasn't sure where to park this thread, so I am starting here. Maybe we can move it to a better place once we get started.

Quite often people ask: Does this or that receiver have a good tuner, sensitive, blablabla. The problem is, how do you determine if the tuner is sensitive or not? If he is good for fringe signals?

Is there some sort of reference signal on one of the sats one could use to compare between receivers without actually having both of them in your living room?

Maybe we could work out a forum standard to test a receiver so we could compare them.

Let's hear some ideas

TG

 

[Low Profile]

The main problem is creating a 'standard' signal. Because free space loss (and transmitted power) will vary - you can't use a transmitted satellite signal for anything absolute, but only as a real time comparison between two receivers.
To test a receiver I would suggest that a calibrated signal source is used. Most receivers quote a signal level in the order of -65 dBm, which according to my calculation equates to 154uV. This would have to be an IF signal (950MHz to 2150MHz), and would have to be modulated with a test pattern. Then reduce the signal until you 'lose' the signal beyond an acceptable level.

Alternatively you could simply set up a received signal chart that users can input details of signals received - and with what set-up. If you are going to do this then I would suggest that you start with one satellite to get any vaguely meaningful data.

 

[HB13DISH]

I think that there should be a tuner sensitivity detailed specification, specified by the receivers manufacturers.
Unfortunately over the past years there hasn't been enough pressure on the manufacturers to show the parameters in their specifications and therefore they "got away with it".
It is not in their interest to do this as it means more work load at the testing stages and better quality control which means more money spent until the product is out of the factory.
There are two type of tuners:
1 - The conventional canned tuner module which is manufactured by companies like Alps, Telefunkin, Samsung, etc.
The module is then soldered to the receiver motherboard by the receiver manufacturers.
2 - The new integrated type of tuners which is part of integrated circuits made by the receiver chipset manufacturers like Broadcom.
The receiver manufacturer need to install only the "F" connector in order to interface with the receiver circuitry.
For example the Dreambox 8000 and I believe that the Technisat PCI DVB-S2 card SkyStar HD 2 has this kind of tuner, as I can't see any can after the "F" connector. But the older SkyStar HD has a can.
It would be interesting to check this point on the Qbox and I would be surprised if they use the old canned type.
Edit: Just remembered your pictures in the Qbox thread. They do use canned tuner
See attached photos for Technisat.
I believe that the new type of tuners (integrated in chipsets) would have better controlled specifications repeatability than the older type which used crystals, inductors, capacitors in their design which can deteriorate in performance over the years under constant operation.

Going back to this thread objectives:
1 - Obviously we can't get any detailed data from the manufacturers and we have to build some sort of a database based on input from members.

2 - Most members have only dealt with few receivers in their whole life and if they where lucky or unlucky to have bought a receiver which was good for their strong signals needs under Hot Bird or Astra but they discover the tuner is not so good when trying to catch channels from other satellites like Nilesat in the UK.

3 - Installers are the best people to know which receivers have a good tuner sensetivity, as they deal with the same receiver over a long period.
But would Sky installers be willing to share such information?
Their input is probably not that important because ANY receiver can receive Astra 28.2E. Therefore we need the input from other installers who specialize in installing multi satellite systems and from different countries in Europe and the Middle East.

4 - The database should specify the channel names and on which satellite.

5 - The database should have the exact receiver model number and the tuner part number and by which manufacturer. A photo is always a good thing to have.

Hope that this helps a little.

 

[dig deep]

I think we shoulöd do this in a more easier way if we want it to be done while we live.

Let us decide what transponder on what satellite (a weak signal) and ask all members what they say. Can they see it, what signal strenght do they have and does it pixel a lot. Then they state what reciever they use.

From that You can decide if some recievers looks better (or worse)

 

[gasth404]

What You think about SIGMA Prozessor SMP 8634 LF, what is inside new AzBox HD. In shops can read that new integrated type but speed is 300 MHz what less then DB 8000 400 MHz MIPS Processor.

 

[Channel Hopper]

Problem is, the tuner has to cope with frequencies from the downconverted signal to a connector at the end of the connector, and the IF window is now determined to be in excess of 900 - 2150 MHz (some 70% of the spectrum available through the incoming port) and filtering out as much as possible from signals outside the range.

Add to that the need to
1) demodulate all digital signals just after the tuner and process those that matter,
2)the bugs that always appear in any chipset produced, plus the patches to aleviate the known issues (of course before the specifications are released by the STB manufacturer and then 'massaged' down to a cost - before further mucked about by the brand name technician - to give the user a user friendly firmware for their WhatSatellite Award winning model receiver)
3) the parameters of any transmmission that plays outside the MPEG rules (in itself open to question when uplinked and stuck on a satellite a few miles above you)
4) the internal receiver interference provided by other processes - CAMs/CI circuitry, embedded decryption solutions, and the SMPS power supply, and
5) Localised crap that comes in from outside the usually non-shielded receiver - Dect phones in particular, other domestic entertainment kit stuffed into the same cabinet, plasma screens, mobile phones, even laptop screens (ever seen the radiation curves from inverter circuits ?), the local chav that paid 300 quid for his bigbore exhaust, clear indicators and ICE, forgetting the troublesome ignition suppressor, plus the good old immersion heater owned by the pensioner next door.


Screening is paramount in any test, wideband reception and zero IF solutions have never been accepted by parties dealing with true DX reception characteristics, because on paper and in practice, sensitivity of the 950-2150 spectrum can never be achieved.

 

[Mostie]

Well there's absolutely no difference between a Technomate TM9100s and a Vantage X211 CI. I've been checking the 2 of them over the last few days.