I can imagine a situation where the pol was never correct yet no carrier of sufficient strength and/or bandwidth was present on the other side so you had no troubles. A new carrier is put up on the opposite pol that now is bleeding over on you. Just idle speculation but I have seen this exact situation many times before.
Allen Porter
Network Systems Engineering
Office: 770.369.9663
Cell: 678.984.3577
One Convergent Center
190 Bluegrass Valley Pkwy
Alpharetta, GA 30005
770.369.9000
www.convergent.com
-----Original Message-----
From: BILL TIDWELL [mailto:bill@waft.org]
Sent: Sunday, July 16, 2006 12:08 AM
To: CRTech
Subject: Re: [CRTech] satellite ebno woes
By adjusting the polarization I was able to go from 5.1 to 9.8 on the
EBNo's. I just can't imagine why it would start acting up after this
many years of running fine.
Thanks for everyone's help.
Bill Tidwell
Jerry Mathis wrote:
> On 7/13/06, Steve Runck <steverunck@kfnw.org> wrote:
>>
>> So things were humming along fine, and then all of a sudden you started
>> losing signal? If so, I wouldn't throw the TI angle out too quickly
>> but,
>> of
>> course, a spectrum analyzer would remove a lot of the guesswork. I will
>> say
>> that in this day of multiple potential sources of interference, I
>> consider
>> a
>> TI filter to be standard equipment on my satellite dishes.
>>
>> Steve Runck
>> Staff Engineer
>> KFNW AM-FM, Fargo, ND
>> 701-282-5910, Ext. 235
>> steverunck@kfnw.org
>> Audio Streams at <http://www.kfnw.org>
>>
>>
>>
>> > -----Original Message-----
>> > From: BILL TIDWELL [mailto:bill@waft.org]
>> > Sent: Wednesday, July 12, 2006 11:01 PM
>> > To: CRTech
>> > Subject: [CRTech] satellite ebno woes
>> >
>> >
>> > I'm currently pulling my hair out over a satellite problem.
>> > I have an
>> > ABR202 receiver on Galaxy 4 (I think) and the EBNo is down to
>> > 6 and the
>> > sync light is flashing and getting dropouts about 4/minute.
>> > I checked
>> > alignment, replaced the receiver, changed the LNB, and made sure the
>> > cable was OK. No bugs or water and it has a pretty clear shot with a
>> > 3.7 meter dish. The last thing I'm going to try is an
>> > attenuator, but I
>> > kinda doubt it will work. Symptoms haven't changed with any of the
>> > above. The new LNB is a 20 degree, 60 db gain, 5 khz stable
>> > osc. I set
>> > the M0 setting down to 2.0 so the unit is more tolerant of
>> > low EbNo's
>> > before dropout, but I need to find the real problem. Someone
>> > I talked
>> > to didn't think much of my TI hypothesis. Is it spectrum
>> > analyzer time?
>> >
>> > Bill Tidwell
>> > WAFT
>> >
>> > playing engineer for WAYR in Brunswick Ga. at this time.
>> >
>> > ---------------------------------------------------------------------
>> > For CRTech resources visit http://CRTech.org/
>> > To unsubscribe, e-mail: crtech-unsubscribe@crtech.org
>> > List problems? E-mail: TechStaff@CRTech.org
>> >
>> >
>>
>>
>> ---------------------------------------------------------------------
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>> List problems? E-mail: TechStaff@CRTech.org
>>
>>
>
> Two things I have found will make a radical difference in your Eb Nos:
>
> 1. Are you using an old Chapparel motorized feedhorn? Dump that sucker
> and
> get a single port single polarity (assuming you're not using the dish for
> multiple feeds) feedhorn and put that on the dish. You might have to get
> creative with the mechanical mounting, and you might need the adapter
> plate
> they sell separately to mount the feedhorn.
>
> 2. When you install the new feedhorn (and if you don't, then check
> this with
> the existing feedhorn), check the focal point adjustment. This is a
> commonly
> overlooked adjustment. I don't have the formula in front of me to
> calculate
> it, but I or someone can post it if you need it. If you have the dish
> maker's specs, they should list it. When you have the distance,
> measure from
> the bottom of the dish (the bottom of the "bowl", that is) to about 1/4"
> INSIDE the feedhorn. Again, you may have to get creative with the
> mechanical
> mounting of the feedhorn to get this properly set.
>
> I suspect this may be your problem. With the focal point improperly
> set, you
> are picking up both adjacent satellite signals, and you're probably
> getting
> interference from an adjacent satellite.
>
> By following the steps above, I increased the Eb on a signal we use
> from 10
> to 14. YMMV.
>
> ------------------------------------------------------------------------
>
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