cannot lock on low symbol rates

[Mateosat]

Hi there,

I have several FTA boxes, nothing special. A Topfield 5050i and a Showbox 500. They're set up for Galaxy 19, 97W. Vertically polarized transponders are noticeably weaker on my set than the horizontal ones.

Low symbol rates (i.e. xxxx four digit) are impossible for me to receive. What's the deal with those low S/R? Are they weaker signals or do I need a different receiver?

Any help is greatly appreciated.

 

[brentb636]

Actual 4 digit frequencies are C-band, and you need at least a 6 foot dish and c-band lnbf to tune them ( like LATV , 3744 V 3250 ) .
5 digit frequencies are generally Ku band ( mostly 11700-12200 ) over North America . Sounds like you're trying to tune C-band with a Ku band lnbf .

 

[Mateosat]

Dear brentb636,

My mistake. I meant low symbol rates, not frequencies. I tried to edit the name of the thread, but apparently to no avail.

Thanks for your help

 

[AntAltMike]

Hi there,

I have several FTA boxes, nothing special. A Topfield 5050i and a Showbox 500. They're set up for Galaxy 19, 97W. Vertically polarized transponders are noticeably weaker on my set than the horizontal ones.

Low frequencies (i.e. xxxx four digit freqs.) are impossible for me to receive. What's the deal with those low freqs? Are they weaker signals or do I need a different receiver?

Any help is greatly appreciated.

I once installed a warped, 30" dish for someoone (we didn't realize at first that it was warped), and the high frequencies peaked at a slightly different angle than did the low frequencies. Try manually peaking the dish at the low frequencies using the receiver as a signal strength meter. If the lows get stronger but the highs get weaker, you have a warped dish.

I was able to salvage this dish because I had a spectrum analyzer that let me see all the transponder strengths at once, but if you don't have one, it might be impossible for you to do so.

 

[B.J.]

Different receivers are different in this respect. There are two issues, first some receivers just don't work well on VERY low SRs, but the other, more common issue, is that low SR signals are very narrow, and if the LO freq of your LNBF has drifted a bit, the receiver may not be able to find the signal. If this is the cause, you can sometimes change the frequency of the signal by a MHz or two up or down, and see if that helps. Some receivers will search on their own until they find the nearest signal, but if the LO freq is off enough, it may find the wrong signal, particularly if there is another signal nearby. Also, it seems like some receivers have freq steps that are so large, that they might just jump over some narrow signals.

These low cost consumer LNBFs will typically drift +/- 2 MHz with temperature changes. I have one KUL1 LNBF that has drifted as much as 5 MHz at times. This makes locking on narrow, low SR signals difficult.

HOWEVER, I would not expect such behavior unless the SR was down in the range of 2000-4000. Above that, I would assume that most receivers shouldn't have a problem. Actually, of the receivers that I have used, all but one would lock transponders with SRs down as low as around 2000, provided that I altered the freq to account for LO drift. The only receiver that has given me a problem with the low SR signals (below 3000) is my Genpix Skywalker-1. It often has a hard time locking on low SR signals, and I THINK that it's because of the freq steps it uses due to some anomolies I've noticed when using it with TSREADER.

Anyway, you really shouldn't have a problem unless the SR is below 4000.

 

[Mateosat]

Thanks Mike,

Again, my problem is with the symbol rates, not the frequencies. Possibly your theory holds with the S/R as well. The dish did get some knocks in the past so it could be off just a tad. It's a possibility.

 

[updatelee]

A freq with a SR of 1000Ks/s (1Ms/s) is just over 1Mhz wide, so if your lnb is drifting +/-5mhz then your going to have a hell of a time locking that signal. freq stability becomes more and more important with narrower bandwidths, ie low SR

 

[Mr Tony]

I fixed the title to show symbol rates not frequencies

 

[Mateosat]

To B.J., Updatelee and Iceberg,

Thanks. I never new that low S/R are narrow. Since my LNB's are all cheap I figure the frequency must be off. Now about that LNB. Is it so that the frequency is just off by a certain percentage or does it drift? If it's just off I guess fiddling with the freq settings should do the trick. If it drifts however, I guess I should be looking for a new LNB. Can you guys recommend me some good ones?

I should mention that I am looking at Galaxy 19 and my low S/R settings are all from feeds on the lyngsat map. Can you guys confirm one strong low S/R transponder?

Thanks a million. I really appreciate your input.

 

[Mateosat]

I also receive Satmex 6. I see some low S/R on lyngsat like 12126 V 3255. Is this a working xponder?

 

[Mr Tony]

I should mention that I am looking at Galaxy 19 and my low S/R settings are all from feeds on the lyngsat map. Can you guys confirm one strong low S/R transponder?

Thanks a million. I really appreciate your input.

on AMC5 (79W) is KTEL
11900
H
2170

 

[turbosat]

Mateo I couldn't get anything on the Satmex6 frequency, just for grins I scanned the V=side of that sat, but I don't really get that much of a signal off that one here in the southeastern US. Maybe I'm not really in their footprint that much, don't know about your location either.

 

[updatelee]

cheap lnb's tend to drift, usually related to temperature, even good lnb's will have a certain amount of variation in frequency due to stability.

the invacom qph-031 has a rated stability rating of 1mhz, norsat makes some excellent lnb's that have way better stability then that. Ebay sells some lnb's which you'll be lucky to get 5mhz stability + drift ! lol

 

[Mateosat]

To torbosat and Updatelee,

My locations is just off the coast of Venezuela. I'm located in Curacao, Netherlands Antilles.
I'll do some frq tweaking tomorrow to see if I can get a lock on a low S/R transponder. If I'll be able to just catch it I'll know it's the LNB right?

Is this the reason most feeds are low S/R? To make it harder to lock on?

 

[Tron]

Is this the reason most feeds are low S/R? To make it harder to lock on?

I think its more of an economic issue. The more bandwidth they use, the more they have to pay. Since the commercial facilities that feeds are meant for have equipment that is far superior to ours, they don't have a problem with these issues ...

 

[Mateosat]

Thanks to y'all for your advice. I'll be looking out for a decent LNB or two.

 

[updatelee]

The Invacom QPH-031 is an excellent consumer grade lnb, Sadoun sells them for $69usd

QPH-031 Invacom 0.3dB DBS and VSAT LNBs plus VSAT Ku Band Transmitters - BUCs, Receive Satellite TV, Quad CP LP 2-way Satellite communications

Norsat makes some excellent commercial grade lnb's, you'll need a feedhorn as well for them, and they are designed primarily for prime focus insted of offset dish's. a good norsat lnb will run around $300 plus another $100 for a feedhorn.

Ive had two invacom qph-031's over the years and still have one now. for the money you wont get anything better for under $100, the noise floor is ALOT lower then any cheap ebay lnb (even though the ebay specs claim better)

 

[updatelee]

offtopic but relates back in a way, check out

UHF-Satcom.com - Kepler Mission

home made 32Ghz Ka band lnb with aprox 1khz freq stability by taking a 137mhz gps signal, using the 10.7mhz ref outout and multiplying it 3420x to get the LO for the first IF mixer

pretty cool stuff imo.

 

[WTguy]

I am not savy with your particular receivers but if you can find the menu to do a manual search, then play with the sr numbers a little,,,add/subtract 1,2, 3 or whatever points. I usually have luck this way if I cannot scan a signal. Good luck.

 

[Mikhel]

I also receive Satmex 6. I see some low S/R on lyngsat like 12126 V 3255. Is this a working xponder?

I'm located right on both SatMex strongest footprint and that transponder it's not active, it seems, however, that there could be a spotbeam directed towards southamerica altough in their website they state only at C band they do have a spotbeam comprised of a few transponders, beamed towards southamerica only.

Cheers

Mike