MMDS Set-up Complete Beginner

Mpeg2 means 4 to 6 SD channels per mux, mpeg4 give 8 to 12.

 

Have a question about using the Yagi aerial from satandcable.

Have got one of these and a chorus mmds box (to try out, waiting to get a box-T).
I notice on the back of the yagi V and H (which I persume are polarisation) , does it make a difference which one is pointing up ?

I've read previously on this thread that you take the chorus Freq. (in my case this was 282000) and add 440000 which gave me 722000 and I get good signal strenght upto 70 but no signal quality. Is there anything else I can change on the chorus box, or do I just need to continue adjusting the aerial ?

thanks...

 

need help trying to get what sounds like a yagi aerial and dreambox 5oot working together.Have got channels from irish dtt trial working but suffering from picture freezing and break up but cannot get ch***s to lock on.I used a neighbours Ch***s set up to do the scan and all channels were received but reconnected back to my own aerial and no joy.Aerial alignement may not be good i can get dtt trial even if i move my aerial within a 70 degree arc.How important is line of sight?Ihave also tried manually stepping up my frequencies but still no joy.Sat and cable say my signature file or services file needs updating.Can anyone help?

 

Line of sight is important as is the polarity of the aerial.
The Yagis have a working beamwidth of ~30 degrees I'd say.
The Yagis sold by Sat and Cable operate at a Higher IF than Chorus.
The frequencies are shifted by 440Mhz,a standard Chorus scan will not work as has been repeatedly stated on this forum.
Try a manual scan at 674Mhz and see if you get a lock.
Alternatively you can align the aerial simply using the analogue signal .
Its probably the easiest way to align an aerial.
Run the cable into the back of your tv and do a scan.
It should pick up a few free analogue channels.
Move the aerial until you get the reception on these as good as possible.That is the optimum spot then.

 

The terrestrial.xml file needs to be changed,add 440Mhz to each frequency.

 

thanks for the replies, I dont think that chorus box can do a manual scan so might just wait for a box-t. Any ideas on the polarization H or V pointing up ?

thanks...

 

[/quote]

thanks for the replies, I dont think that chorus box can do a manual scan so might just wait for a box-t. Any ideas on the polarization H or V pointing up ?

thanks...[/quote]
You dont need a receiver to tune the analogue channels.
Just put the cable into the tv rf in.
Look at your neighbours aerials to assertain the polarity.

 

thanks for the replies, I dont think that chorus box can do a manual scan so might just wait for a box-t. Any ideas on the polarization H or V pointing up ?

thanks...[/quote]
You dont need a receiver to tune the analogue channels.
Just put the cable into the tv rf in.
Look at your neighbours aerials to assertain the polarity.[/quote]

thanks, just tried the analogue stuff and I get a good reception (though I think the aerial has nothing to do with it!, I plug out the cable from aerial and still have the same quality analogue stuff!!)

Dumb q, but looking at the neighbours chorus mesh dish, how you do figure out the polarity ?

thanks again

 

thanks for the reply have tried 440mhz added to each freq but no joy do i need to change any other settings/

 

Just need to confirm a few things before purchasing the MMDS Integrated downconverter + aerial (including power supply) from sat and cable:

1. I live exactly 15 miles from the transmitter, perfect line of sight, but across a bay. Will the aerial be able to cope with this?
2. I have a wireless broadband antenna on the roof also. Its uses the same transmitter. I have a feeling they may be using the same frequency. How far apart will the antenna need to be in order that this problem be negated?
3. On the website they list 2 products: MMDS Integrated Aerial + downconverter (without power supply) and MMDS Integrated downconverter + aerial (including power supply). Obviously there is a typo in one of these. But which one? This, combined with the picture, which shows an item without the large mesh i normally associate with MMDS aerials, has me really confused!

 

15 miles should be fine.
I have used a Yagi over longer range and as long as you have direct line of sight there will be no problem.
There are 2 types of aerial yes.
One is the mesh type the other is the Yagi type which looks like a rod with washers on it.
They both do the same thing .
The Yagi works better if there are obstructions like trees or buildings in the way .
I have a Yagi on my own house as I couldnt get a decent signal even with a 24db grib.
I noticed one thing about the Sat and Cable Yagis though.
They are designed for a working frequency of 3Ghz instead of 2.5Ghz.
The spacing between the washers is 2.5cm .
For 2.5Hz the quarter length wavelength spacing should be 3cm.
I use a 3cm spacing rod and it means a better signal in poorer weather conditions.
Heavy rain seems to affect the Yagis more than a grid type aerial .
Overall though the Yagis are a good piece of kit.

 

This is exactly the type of information I was looking for. Thanks!
Is it possible to adjust the washers so that they are 3cm apart? Or is there a shop online that sells Yagis with 3cm spacing? Just to give me 1 last option, is there somewhere I can buy a mesh antenna, as my next-door neighbour, who is a c****us subscriber uses one of these and it works well.

 

hesby try here http://www.satandcable.co.uk/s/index.php?cPath=44
make sure you get one with the power supply m8

 

My sat and cable Yagi kit arrived. I mounted in in place of my FTA Satellite dish. I fitted the power supply, and connected it to the Eurovox TX. I got the first signal at 722Mhz, and at various steps up to the mid 800s. The first bar read 83%, but the quality was 40-50%. Moving the antenna slightly had little affect on this. No matter what kind of scan i did, I could not find any channels
I then plugged the aerial directly into the back of the TV. I found a few channels - including Eurosport, UTV and Sky News, However I could just barely make out what these channels were. The only channel I could pick up that was watchable was Sky One, and this was still a little snowy.
My next door neighbour is a chorus digital subscriber, with a mesh antenna. My eurovox tx worked perfectly on his system.
As i mentioned before, I live 15 miles exactly from the transmitter, which is on a mountain across a bay. The only thing i can conclude is that i am just out of range for this aerial.

 

All Satandcable YAGIS are now 3cm spaced

 

Mine, which arrived on friday, has 2.5 cm spacing. So unless they have changed them in the last few days...

 

Did you try varying the polarity of the aerial ?
H or V on backplate.
The aerial should point parallel to the ground directly at the transmitter.
15 miles across a bay should be ok as its direct line of sight .
Is it a main transmitter you are pointing at or a beam bender ?
A beam bender has a much shorter range .
BTW the 2.5cm spacing isnt a big issue unless you have a weak signal ,in most situations it wont matter.

 

I didn't realise the Yagi antenna were 'affected' by polarity. I saw the H and V, and assumed that the V should point up and the H parallel to the ground. I've taken down the aerial and put back the satellite dish, but if you think this is worth a try, should I try again with the Yagi turned 90degrees.

 

If you have the incorrect polarity it attenuates the signal hugely.
Try it with H pointing up I bet it will make a big difference.
You could just hold it out a window to do a quick check if you dont want to remove the satellite dish.

 

those markings on the back seem confusing. for a horizontal polarity you'd think you go with parrell to the ground not pointing up.