MUX Overflow

Help and support for the BATC DTX1 ATV digital encoder and modulator system
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g8vpg
Posts: 311
Joined: Fri Oct 11, 2013 9:35 am

MUX Overflow

Post by g8vpg » Thu Feb 13, 2014 9:50 am

I have just received a DTX1, which we intend to use for trials at GB3ZZ. I have changed the preset 3 frequency to 1316MHz. When I tried to change the FEC from 3/4 to 1/2 (or 2/3), it reports MUX Overflow. It works fine on 1316MHz at FEC3/4, and on 1249MHz at FEC1/2. Can someone please explain?
73 Shaun G8VPG.

g4wvu
Posts: 51
Joined: Sat Jun 22, 2013 10:42 am

Re: MUX Overflow

Post by g4wvu » Thu Feb 13, 2014 11:19 am

Hi Shaun - you will need to reduce the video encoder data rate (effectively TS gross rate) . 3/4 FEC & 4 MS/s will support gross data of 6Mb /s minus overheads ~ probably around 5Mb/s video. 1/2 FEC & 4 MS/s will support 4 Mb/s (gross) etc. Go into encoder settings & reduce the encoder rate (CBR if using constant bitrate) to about 3mb/s for 1/2 FEC . (2/3 FEC will support a bit more.) The status readings "page" will tell you how much you have left at any given FEC/SR. combination. E.G. stuffing 2%, TS 93%, overhead % etc. I don't have it in front of me but you get the idea. The status page is useful as it saves you doing maths - just set a rough rate (below overflow) & up it untill there is minimal stuffing packets (< 1- 2% will max the video quality V FEC/SR). It's a good well configurable piece of kit IMHO.. have fun ;)

73s Mark

g8vpg
Posts: 311
Joined: Fri Oct 11, 2013 9:35 am

Re: MUX Overflow

Post by g8vpg » Thu Feb 13, 2014 11:52 am

Thanks Mark!
I understand what you mean and will have a play with the settings. I am new to DATV and hence am on a steep learning curve!
73 Shaun.

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