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Preparing for Freeview DVB-T with H.264/AVC

The main focus of my planning is:

  1. Upgrade the fixed wiring and antenna
  2. Get DVB-T hardware for MythTV backend
  3. Collection electronic program guide (EPG) data from MHEG
  4. Display content using MythTV frontend

 

Upgrade wiring

 

Although strictly not necessary, I have gone through and removed components from the wiring that are dubious.  I have focused on using:

  • RG-6 cable
  • F connectors
  • 2G Hz splitters with F connectors
  • Microstrip style baluns
  • A medium gain antenna

 
What I did was to use the analog Prime signal as a reference benchmark. Prime is on a similar (but higher) frequency to the DVB-T channels. Although we are in a high signal area, the quality of the picture has always been marginal to watch. The aim was to get a reasonable picture so that the DVB-T QAM64 carrier could be decoded with good SNR.
 
Sugarloaf on the Port Hills of Christchurch is transmitting Freeview on three DVB-T transponders. They are:

  • Channel 47, 682MHz
  • Channel 49, 698MHz
  • Channel 50, 706MHz
Given that the frequencies are higher than VHF channels, using better cable is probably a good idea. The cable loss

at 700MHz of RG-6 is approximately 25.1dB/100m, whereas RG-59 is 30.7dB/100m.  So even on a long 33m cable run, the 1.9dB performance improvement is unlikely to make a significant impact. However, as part of a general cleanup, I only installed RG-6.

 

I got ride of old ferrite style splitters, and wall plates with Belling-Lee connectors. Getting rid a single wall plate with a build in ferrite splitter significantly improved the performance of the analog Prime service (Channel 63, 799.25MHz). It was one of the last things I removed from the fixed wiring, and it should have been the first (but I didn't know it was there, and had assumed the wall plate was just a wall plate).

 I changed the antenna from an medium gain multi-purpose antenna to a Gizmo. This provided both legacy VHF, and UHF support. This antenna has a microstrip balun, and a 'F' connector. The outside connections are all crimped, and sealed with 3M Scotch 23 and then UV protected with PVC tape.

DVB-T tuner hardware

Given that DVB-T is here to stay, I wanted to get a tuner solution that would last a while. I looked for a pure DVB-T solution, that didn't need to have analog tuning and MPEG2 encoding. With an initial configuration of three transponders on Sugarloaf, it was important to support at least two transponders at a time, and more would be desirable. Supporting four transponders offers a 'Tim the tool man Taylor' style solution. Using the multi-rec support in MythTV, having 4 virtual tuners per transponder is reasonable.

My current MythTV backend server is limited in the space available (it already has two DVB-S tuners, a telephony card, and a SATA adapter). Using four PCI slots for four tuners is not viable, and will require future motherboards to support at least four PCI slots. Going for dual tuners would still require two PCI slots, and dual tuners are less common and come at a price premium.

I tool a look at USB based tuners. Support and availability is variable.

So I decided to build a PCI quad tuner, using 4 mini-PCI modules.

Collection of EPG

The Freeview platform will only provide full EPG information via MHEG5. The current and next program is provided via EIT.

TODO. How to get the EPG data into MythTV?

Display content

 
The Freeview platform has content in various H.264/AVC. MythTV NZ has a useful status page with codec support.

The frontend is an AMD x2 3800+, with 'nVidia GeForce 8400 GS' graphics. Will this have sufficient grunt to decode and display the content stream?

 TODO: Get MythTV v0.21 (or later) frontend working

 

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