Tuner issues on startup

[Andy H]

Previously the only way to start the box decoding again was to do an auto scan, where it would find the same channels that it already had known about and then start working again.

 

[/df]

Do you have reception problems on any other TV decoders? I understand that recent weather patterns have caused interference in various areas, and perhaps depending on your aerial.

If the problem is down to recurring corruption in the tuning database, It's possible that the System Flush update will help, as it leaves you (AIUI) with clean reformatted RW flash file systems (where the relevant database lives). OTOH the flash storage itself might be on the way out, though I'm not sure anyone has actually found a case of this.

 

[Andy H]

It's almost 100% not an RF issue, I am in the primary service area of Crystal Palace, and have two aerials at home, both of which feed other devices, none of which have had any issues at all.
The faulty Humax has been tried on both of them.
The signal indications on everything, including the faulty Humax when it wasn't working, were all as expected.
(I work as an RF engineer in the broadcasting industry, so am familiar with disappointing signals and mis behaving decoders!)

Thanks for the suggestions of the system flush and should the fault re-appear, I will give that a go next, and obviously report back here.

 

[Andy H]

Since installing the custom firmware, the box has not lost the tuning information.
Early days, but certainly looks promising, as I would have expected the usual problems by now.

 

[Black Hole]

If you can be bothered, it might be instructive to re-install standard firmware and see if the problem returns.

 

[Andy H]

I did try downgrading the original standard firmware back to the previous version and then back to the most up to date one before I added the custom firmware, and the problem was still there.

 

[Black Hole]

I can't think of any effect the custom firmware could have had on this.

 

[Trev]

Is it me being wrong yet again?
Tunefix? Isn't restoring channels just about what it's for?

 

[prpr]

Is it me being wrong yet again?

Yes.

Tunefix?

Unlikely to be installed.

Isn't restoring channels just about what it's for?

No. It deletes or moves things.

 

[Trev]

Thanks for that. It won't be tunefix even if he has installed it then.
I was obviously thinking of the schedule restorer thingy.

 

[RobH1]

I was obviously thinking of the schedule restorer thingy.

Too many nights poring over technical jargon, Trev?

 

[/df]

I suppose, from the specs of the components involved and the APIs used by the Humax settop binary, that tuning works like this:

• the Humax settop program presents the GUI for tuning and the user selects and initiates a tuning operation;
• the settop program issues a matching tuning command, or series of them, to the tuner/demodulator module (CXD2820R), perhaps using the NEXUS_I2c_* APIs;
• the tuner/demodulator module executes the command(s) and sends the results back to the settop program;
• the settop program offers the results to the user with a Save option;
• if Save is chosen, the results are written to the /var/lib/humaxtv/channel.db SQLite3 database;
• subsequently, to tune to a particular service (ie, "TV channel"), the settop program obtains the tuning parameters from the database (in fact, it probably loads it into internal data structures at Save or startup) and issues the necessary tuning command(s) to activate the associated multiplex and possibly also extract the requested service from that multiplex;
• the selected service is then available in the MPEG-TS stream output of the tuner/demodulator module;
• the settop program issues commands to the on-chip coprocessing modules of the BCM7405 settop IC to route the selected service into the Data Transport module and then to AV decoding, processing and display output, or to a recording file; this data flows using DMA between the coprocessor modules and doesn't involve the settop program itself, which is just a controller.

Although the HDR has two modules, they are effectively twins and the same tuning data would apply to both.

Based on this, corruption of the tuning database is the likely cause of missing channels that can easily be recovered, as other failure modes would be likely to break some part of the chain above.

The hidden service menu provides a way for non-CF users to save and restore configurations, including tuning and network settings. Once the system lets you reach Menu>Settings>System>System Information after it loses channel or decides to have a factory reset, you can restore your settings in that way.