Merc II blindscan Symbol rate errors

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brentb636

brentb636

Thread Starter
SatelliteGuys Pro
Jun 24, 2006
4,278
6
5 miles N of Saugatuck, Mi
Here's something that niggles at me, and maybe someone can help me out with their experiences. My main system is a Fortec 90/Merc II/Invacom QPH031 lnbf. Typically I blindscan several birds in the evening looking for new HD or 4:2:2 feeds ( maybe the find of my life, for example ). If I find a likely feed, chosen by a reasonably high symbol rate, I put that channel ( TP freq/polarity/SR into TSreader and try to acquire the video with tsreader and VLC.
It doesn't work that easily because my Merc II reported Symbol rates are always about 1% high. SR of 30000, for example , is reported as 30031. Tsreader doesn't lock on that 30031 signal. I've learned to live with this and automatically try a SR about 1% less than reported by the Merc II, and now I get a lock on the first or second try ( since 1% still leaves room for a little error ).
Question : Is it the Merc II, or is it the QPH-031 ? Does anyone with this combination have the same problem? Does anyone running the Merc II with this combination get the Symbol rates more exactly? Does anyone running the Merc II with a standard linear see this problem ? If I weren't retired and on a limited budget ( that's kind of a joke, you know), I suppose I'd just buy a decent standard linear and try it out.

Hope you can help.

:)

Brent
 
updatelee

updatelee

SatelliteGuys Pro
Jul 22, 2006
1,604
111
CFB Edmonton
we have identical setups, damn near, lol.

fortec mercury II, sg2100, 1m winegard, invacom qph-031
skywalker-1 with access to the same dish/lnb

and guess what ? I have the same issue. lol.

fortec usually seems to scan the symbol rates in a little high. the skywalker is incredibly fussy, on high symbol rates like 30000 you usually need to be within 10 to get a lock, with low symbolrates like anything under 3000 you need to be withing 2 to get a lock, sometimes tighter if the fec isnt hot.

my dreambox's are fussier then the fortec for symbol rates, but no where near as fussy as the skywalker.

your probably not going to like my solution, but it works 100%, its acurate to within 1Ks/s its amazing.

and it didnt cost me a dime, because I had all the hardware allready, now I dont imagine most people would have it all, but you might get lucky like me.

I had read about this technique before on satforums but there wasnt alot of details, goign from post to post to post I finnaly figured it all out, so Im not taking credit for this, some other smart dude figured it out before me.

basically someone figured out that if you take an analog ird (like my toshiba trx-2220) and attach the baseband output to the ant input on a shortwave radio (I use my icom pcr-2500) and start scanning, for some reason behond my knowlage, you;ll get a lock on a freq that just happens to be the symbol rate of the dvb signal your tuned to on the analog ird.

I know it sounds rediculous, your tuning a freq with an analog ird, to determine the symbol rate of a digital signal. but it works. with amazing acuracy.

there are two things you need in the analog ird, baseband output, not all do. and the ability to manually tune a freq. My toshiba trx-2220 has a baseband output and is really easy to tune any freq I want, some irds you have to go into a diagnostic mode and enter the freq in hex, not fun.

and you need a shortwave receiver, obv its gota have a digital display and be acurate on its tuning, if it tunes a few khz high then its not going to help you is it. hehe.

if you want more info just ask, Id be more then willing to give you a hand, this symbol rate issue was a real pia untill I got this setup running.
 
turbosat

turbosat

SatelliteGuys Master
Dec 26, 2006
9,003
80
Oneonta,AL
I bet it is, when I saw the word ICOM, I saw it as $COM lol. I know they make great equip.
And I'm sure you have other uses for it besides a freq counter!
 
brentb636

brentb636

Thread Starter
SatelliteGuys Pro
Jun 24, 2006
4,278
6
5 miles N of Saugatuck, Mi
Thanks for the great idea , Updatelee !
I don't have the hardware, but sometimes that sort of thing shows up. :)
In my former life, I spent 8 years as a Motorola radio tech ( for GM ) and have run into
ICOM equipment. I've clipped this thread into my clipboard substitute ( Clipmate by Thornsoft), where I can find it readily. Just a couple more things to look for in my daily adventures on Craigslist.

Thanks,
Brent
 
cracklincrotch

cracklincrotch

SatelliteGuys Pro
Sep 28, 2007
1,026
0
Halifax, Nova Scotia
and you need a shortwave receiver, obv its gota have a digital display and be acurate on its tuning, if it tunes a few khz high then its not going to help you is it. hehe.

So my RCA Victor A23 that was my grandparents wedding present won't work? :D
 
cracklincrotch

cracklincrotch

SatelliteGuys Pro
Sep 28, 2007
1,026
0
Halifax, Nova Scotia
I couldn't part with it. It does work. Put all new caps in it as the old paper ones were just that, old. Only two AM stations locally and although there's four SW bands on it I've never picked anything up on it.
 
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