How sensitive?

Discussion about the MiniTiouner board and the MiniTiouner Digital ATV Receive Software. See also http://www.vivadatv.org/index.php
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biker_bob
Posts: 36
Joined: Sun Oct 23, 2016 8:02 am

How sensitive?

Post by biker_bob » Tue May 23, 2017 7:13 am

Having just got a serif MiniTiouner running I find it seems to be a bit deaf. Is this to be expected?

My free to air satellite receiver gets pictures from GB3HV around 90% of the time, eg I lose about a minute of reception every 10 minutes due to it being a weak signal.

With the MiniTione I'm lucky to get reception 10% of the time. EG. I get a new frame every so often and very occasionally see movement (a few frames in a row).

This is with the same LNB used on each receiver pointing in the same direction etc.

The MiniTioune reports a signal strength of around -60db and an MER of around 7. Sadly I don't get this sort of information on the satellite receiver, just a signal strength bar which nominally hovers around 75% full.

If this is normal that's fine. The MiniTiouner at lease can do 2m / 70cm which the satellite receiver can't.
If it's not normal then any suggestions as to what might be the issue?
Bob G1XIE / M0AJZ

g8gtz
Posts: 1732
Joined: Wed Apr 07, 2010 6:26 pm

Re: How sensitive?

Post by g8gtz » Tue May 23, 2017 7:39 am

Hi Bob,

The original Serit 4335 tuner does need some gain in front of it - https://wiki.batc.tv/Serit_tuner For 146, 437 and 23cms the ideal system is a low noise pre-amp at masthead followed by a band pass filter and then a satellite line amp just before the tuner.

On 3.4 GHz, you shouldn't see any difference as you have the gain of the LNB in front of it - happy to have a look sometime.

BTW - I've seen that selecting DVB-S rather than auto mode helps a lot in gaining a lock on weak signals - you can make it default to DVB-S mode by editing the .ini file.

73 Noel

G8XZD-TV
Posts: 109
Joined: Fri Feb 22, 2013 6:41 pm

Re: How sensitive?

Post by G8XZD-TV » Tue May 23, 2017 6:21 pm

My tests on the serit 1, 2 and the sharp+sup2400 tally exactly with jean Pierre's findings in his post on vivadatv.

I can also confirm using dvbs rather than auto gives a mer "gain" of about 3 in minitioune.

I have not done any tests involving filters/preamps, would be good to hear any other peoples test results.

73. Ian.

F6DZP
Posts: 217
Joined: Fri May 27, 2011 9:59 am

Re: How sensitive?

Post by F6DZP » Tue May 23, 2017 8:20 pm

Hi Bob,

which NIM do you use? 1st version (FTS-4335) or 2nd version - (FTS-4334L)
FTS-4335 is very less sensitive (no booster) and Noise figure is about 11/12 dB
The NIM that is inside your free to air satellite receiver has probably booster (preamp)
FTS-4334L has a booster that gives about 15dB of gain ( depending the frequency) and Noise figure is about 5/6dB

As the noise figure of all NIMs are relatively great, we should always use a preamp with a low noise figure and 10dB gain more than what we loose in the coaxial.

As you are receiving 3.4Ghz with a LNB that gives gain and lower the noise figure, if you compare the FTS-4334L and the free to air receiver you should not have a big difference.

Yes, always prefer the use of DVB-S or DVB-S2 mode, not auto.

last observation,
very occasionally see movement (a few frames in a row).
perhaps your observation is also disturbed by the Windows decoder that takes time to resynchronize after the loose of signal.
Could you observe instead the time when you get TS packets without error or not?

Jean-Pierre F6DZP

biker_bob
Posts: 36
Joined: Sun Oct 23, 2016 8:02 am

Re: How sensitive?

Post by biker_bob » Wed May 31, 2017 6:58 am

Thanks for all the replies.

Finally solved the issue. Someone suggested I check that 'Low SR' is un-ticked. Having done that the whole thing sprung into life.
Is there a list some place that describes what all the buttons, switches and dials do?
Bob G1XIE / M0AJZ

g8gtz
Posts: 1732
Joined: Wed Apr 07, 2010 6:26 pm

Re: How sensitive?

Post by g8gtz » Wed May 31, 2017 7:23 am

There is documentation on the vivadatv site but we are also trying to build up the wiki page https://wiki.batc.tv/MiniTioune_software but need others to add their knowledge / experiences.

I've added the comment about low SR tick box to the page.

biker_bob
Posts: 36
Joined: Sun Oct 23, 2016 8:02 am

Re: How sensitive?

Post by biker_bob » Wed May 31, 2017 12:07 pm

Cheers G8GTZ.
I have tried logging into the wiki page but not yet worked out quite how to. When I work it out I might add a few notes here and there if I can.
Bob
Bob G1XIE / M0AJZ

G8GKQ
Site Admin
Posts: 2794
Joined: Sun Mar 22, 2009 1:21 pm

Re: How sensitive?

Post by G8GKQ » Wed May 31, 2017 5:21 pm

Hi Bob

To log in to the Wiki, you first need to request an account here: https://wiki.batc.tv/Special:RequestAccount.

Please use your callsign as your requested username. I'll then approve the account and you'll be all set to add things to the Wiki.

Dave
G8GKQ

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