Reception Problems

[snapperoonie]

Today I loaded the latest VIX image onto my VU+Duo and set about scanning in the satellites, the problem i have it dosn't matter which satellite i go to i can't scan in frequencies around 12480Mhz or 11642Mhz everything else comes in fine.
For instance when at 19e tuning to 12480 satfinder shows SNR is hovering around 67% but flickering around alot, AGC shows a steady 69% and the lock tick is flashing on and off.
If i move the dish around to 28e i get exactly the same readings.
Similarly the same thing hapens when i try 11642H on 13e and 11642V on 28e.
I think the other frequencies are ok, 80-90% signal.
I'm using an 80cm dish with a less than 6 month old Inverto black Ultra LNB,
though i never changed the co-ax when i fitted it.
Any light you guys can shed on this??
Regards,
snapperoonie:confused:

[Detlef]

This looks like the old DECT phone problem. If you have such a phone (or other equipment that uses 1800MHz) try turning it off or moving it to another location.

[snapperoonie]

Thanks for that, there is a cordless phone within 3 feet of the Duo i'll try turning it off tommorow, cant do it tonight as my son has just settled down to watch TV.
Regards,
snapperoonie:respect-055:

[satwyn]

if the problem was not there with the last image then probably not the phone

[snapperoonie]

The problem was there all along but it wasn't untill today that i realised it was the same frequencies on all sats.
Because i was bored, i was watching the frequencies on the scan with one eye and checking them against Lyngsat and the satbeams site, sad i know, but there you go

[snapperoonie]

Just managed to check and it's definitely the phone.
Thanks again lads.

[Detlef]

It is probably somewhere on Satpimps but, if not, here is the explanation.

The Sats we watch have freqencies of between 10700 and 12750MHz. This wouldn't survive a trip down the coax cable to the receiver so it is reduced (by a process called heterodyne, or to put it simpler, subtraction) in the LNB. Even then the frequency spread from the Sats (2000MHz) is too great for a receiver so a (uni)LNB has two modes a 9.75 GHz and a 10.6 GHz local oscillator which gets subtracted from the Sat frequency such that the signal sent to the receiver lies between ~1000 to 2000 MHz (a spread of 1000MHz).

Most DECT phones operate at a frequency of 1880 to 1900MHz which lies in the upper range used by Sat receivers.

This means that Sat transponder frequencies of around 11640 and 12490 produce an LNB signal to the receiver in the same part of the band as a DECT phones and whilst the phone signal is very small the LNB output is even smaller so can suffer unless the phone and base station are kept well separate.

[dog-man]

Glad I found this thread.

I have had this problem since my DB 7020 days and could never see a pattern that would help me find what was causing the problem.

After reading this, I tuned to one of the problem channels and switched off my cordless phone base and the problem was gone.

Now I will have to find another location for the base and do some rewiring for the phone line.



dog-man

[snapperoonie]

Just an update.
Problem solved, last weekend i moved my dish from a tripod mount in the garden and mounted it on a wall, this necessitated running the coax via a different route so i took the opportunity to replace my old CT100 (at the time considered the best available) with some new Webro WF100, don't know if it was th re-routing of the cable or that the new cable is better shielded, i suspect the latter as the phone and base station is less than 3 feet from the receiver, but the end result is no more problems.
Regards,
snapperoonie.

[echelon]

Glad I found this thread.

I have had this problem since my DB 7020 days and could never see a pattern that would help me find what was causing the problem.

After reading this, I tuned to one of the problem channels and switched off my cordless phone base and the problem was gone.

Now I will have to find another location for the base and do some rewiring for the phone line.



dog-man

been known about for years , I remember it causing problems on some tps channels on hotbird a few years ago