Dish Size

redcap007

Living in Malta I use a 1.1m dish, no way I can increase the size, neighbours. I want to get a Sky HD Box, have been told I need a 1.5 dish at least. Is there a way, maybe the L&B that I can increase the receiving power of my present 1.1m dish.

Thanks Guys

Topper

Welcome to the forum redcap007

No there is no substitute for dish size as it is the dish that collects the signal and gives it to the lnb. If your installation was done professionally then you probably already are extracting all you can from such a small dish. Otherwise some fine tuning may gain a small amount of signal. Do not forget you need good signal quality to receive HD as the amount of information required for such HD detail is greater than with SD.

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redcap007

Sad!! for me I am not allowed to increase dish size.

redcap007

Robbo

Hi, Taking a quick look at the footprints on Lyngsat, you may be able to receive quite a few of the Sky transponders, with your 1.1 dish. The problem area will be Astra 2D.

stvy

Hi,

I am in a fringe reception area for 28.2E. I have a 1.2m channel master dish with feedhorn and 0.3dB LNB. AFAIK its about as optimised in terms of positioning alignment as I can get it.

You might consider a matched feedhorn for your dish and a 0.2dB LNB to optimise it. Perhaps you cant do this but a 1.2m dish will make a big difference and might not be noticed by the neighbours....

I previously used an old pace S*y SD box and a Dreambox DM7020-s. I noticed that the dreambox had much lower sensitivity as the Bit Error Rate would start to increase in bad weather and I would get picture breakup and eventually the loss of the Astra 2D channels. In contrast on the pace Sky SD box it pretty much had no problems even in the worst weather...

Now, what is exactly the sensitivity of a particular receiver is something that I have found hard to find. For example for most receiver sensitivity is listed in dBm. In addition there will be a SNR, in dB, required to get reception of a DVB-S or DVB-S2 transponder with zero bit error rate. Typically for higher bit rate modulation rates you need more SNR to succesfully receive the signal. Now DVB-S2 transmissions use higher modulation rate, and therefore need more signal to succesfully receive the transmission.

By knowing the estimated signal strength of the satellite footprint at your location, the gain of your dish, LNB specification, a ball park figure for rain fade, and the sensitivity of the receiver you can calculate if you can succesfully receive the transponder. This would ensure you didn't purchase any equipment only to find out it will not do the job....

Using the example of a home wifi (802.11#) system the sensitivity might be listed as -98dBm. It is the receiver chipset that is the important part, since many companies produce wireless routers with intel chipset they all in fact have the same sensitivity, the output power is the same because of regulatory limits, and the only difference in range etc is from the vendors choice of antennas.

It would be safe to assume that all the different satellite receivers have the same sensitivity if they have the same chipset. So there is not much to gain there which could help you out.

However I have noticed that since I bought a DM800 (again I don't know what the receivers sensitivity in dBm is and the required SNR to successfully receiver DVB-S and DVB-S2 transponders), I am not suffering from as large a rain fade problem as I had with the DM7020-s on DVB-S trandponders. In fact so far (touch wood) I have had no problem with the DVB-S2 transponders either. I would therefore assume that the sensitivity of the chipset is better than the DM7020-s chipset for DVB-S transponder. The DVB-S2 transponders have a little lower SNR as would be expected than the DVB-S for my location.

So what am I getting at here? Since s*y were transmitting at a certain power level for DVB-S then they would have to either transmit at a higher power level for DVB-S2 or the consumers would need to switch to higher gain (larger) dishes, and/or the receivers would have to have improved sensitivity. Since Sky has not required everyone to increase their dish sizes, I am guessing the DVB-S2 receiver have a higher sensitivity, and perhaps SKY has a slightly increased output power on DVB-S2 transponders.

But here is my point, why not do some investigation and find out what is the optimal receiver for you? One particular chipset might be more sensitive than the other. A couple of dB increase in signal will give a massive improvement in bit error rate. Perhaps you can find something that will work with your 1.1m dish?


Good luck,

Stvy

redcap007

Thanks for the replies. Not being technical I do not really understand fully so I am asking a Pro Satellite installer to look into it for me.

Again many thanks