Channels on 99mhz not working (interference).

[DaMacFunkin]

Hello I have a duo2 with internal dvb-c/t2 tuner and a solo2 with usb cable tuner, I get 99%snr on all my channels, until I just discovered I get 0% and tune failed on Alibi Hd, comedy Centeral hd, SyFy HD and TCM hd, I certainly had no problems with them in the past, a quick investigation shows that ABM is scanning them all in on 99mhz 256qam, if I go into manual scan 99mhz isn't listed as a pre-transponder?
Is it ABM not scanning correctly or do we need a lamedb update?
My area is 40967(preston1).
Anybody else have this problem with 99mhz?

[abu baniaz]

Pre-defined transponders will be shown based on your tuner config and location/provider in corresponding cable/terrestrial/satellite xml file.

Having said that, those xmls are used for conventional scanning. ABM does not use them. It updates lamedb with transponder details.

In the manual scan option, you can enter whatever details you wish to be scanned.

Lamedb is used for tuning, those three xmls are used for scanning.

[DaMacFunkin]

So do you get channels on 99mhz? Is it possible that 99 MHz has been added in my area and isn't in the cable.xml? Also you say you can add what info you want in a manual scan, yes I know I can add the MHz value as 99 but how could I possibly know what symbol rate to enter?

[abu baniaz]

Maybe I am not explaining properly. It does not matter what is in cables.xml if you are using ABM.

For UK, SR is 6887 and 6952. A conventional frequency step scan is similar to blind scan on satellite.

[DaMacFunkin]

Thanks Abu I will try the 'blind' scan later, don't know why just that mux has dissapeared

[lincsat]

It does seem a low frequency, lowest in my "Pure" area is 123MHz. I thought cable had to keep clear of band II (88-108 MHz) but maybe that has changed with Digital.

[Joe_90]

As an aside, 99MHz is right in the middle of the FM transmitter band. Unlikely any cable company would / could use that frequency to carry signals either analogue or digital. I would suspect that whatever log you're looking at is reporting the frequency incorrectly. As abu says, ABM would not be using cables.xml - it has its own list of "home" frequencies for cable systems.

[DaMacFunkin]

@lincsat That's exactly what I was thinking, I've never seen channels on frequencys as low as that, can I ask if you are able to recieve a signal on those channels in your area?
I won't get a chance to do any more tests till I get home from work,

[DaMacFunkin]

As an aside, 99MHz is right in the middle of the FM transmitter band. Unlikely any cable company would / could use that frequency to carry signals either analogue or digital. I would suspect that whatever log you're looking at is reporting the frequency incorrectly. As abu says, ABM would not be using cables.xml - it has its own list of "home" frequencies for cable systems.

So why do you think it would suddenly have changed Tony, I know for a fact I was watching Comedy Central hd last week and the only thing I have changed is a software upgrade to hades11 on both boxes.

[Joe_90]

Sorry - no digital cable system. My local cable company haven't upgraded from analogue, yet! Houses are 1970's vintage. I use sat and terrestrial only.

abu may be able to shed light on whether any changes have been made to ABM cable transponder lists. A debug log of you running ABM might help?

[lincsat]

@DaMacFunkin Do you get any channels on 107 and 115 MHz? Try manually scanning them in case your missing channels are on there. 107 is within Band II, so may not be in use but 115 I have heard of being used in non-pure areas.

[DaMacFunkin]

Maybe I am not explaining properly. It does not matter what is in cables.xml if you are using ABM.

For UK, SR is 6887 and 6952. A conventional frequency step scan is similar to blind scan on satellite.

I've changed my tuner settings to exactly how it looks in those pics now when I press to scan it says searching for transponders and fails on every single MHz and then says nothing to scan, I've tried again with my service id instead of 00000 and it does the same, I can get it to do a service scan if I change my tuner setting from frequency steps to provider then use Virgin media 6952 it scans in 550 channels, but those 4 are missing?
As said before every channel tunes fine from an ABM scan except them...

[DaMacFunkin]

Ok I got to the bottom of my problem, thank you for any ideas or assistance sent my way, and I'm sorry for insinuating that ABM was the problem, it just seemed strange that the same 4 channels had disappeared on 2 different boxes. After researching about 99mhz I found some information on another site that stated a lot of ex Telewest areas run muxes on 99mhz and that it is extremely susceptible to noise or interference, can you believe that a loose connection on one of my 2 duo2 cable connections was knocking 99mhz of on duo2 and solo2 which is on another feed... (Obviously noise was feeding back) As it is I knew which tuner it was because that tuner was also struggling to display 107mhz as well whilst all channels on 121mhz and above where still reporting almost perfect signal. Problem sorted and I know what to look for or give advise on in the future.

[Joe_90]

I'm glad you found the source of your issue. I'm really surprised that a cable supplier is allowed to use frequencies in VHF Band II. Although technically a closed system, cable systems are capable of leaking RF or can be subject to interference from other RF sources. 121MHz is slap bang in the middle of the aeronautical band also.

[DaMacFunkin]

Yeah it amazes me too considering how paranoid they have become about noise leaking into the system, if you send a box back now they give you a screw on cap to put on the tap.