Decided to spend some time studying behavioural pattern of cluster/receiver :)

I measured voltage on receiver inputs and was surprised there is nothing there -- cluster doesn't keep receiver under power all the time. So I connected a LED (basically a bulb) to receiver power inputs and waited a bit. Nothing happened :)

Then I drove car and when I switched off ignition and removed key after the trip the LED immediately came ON (but only for about 5-10 minutes, I didn't measure exact length).

http://forum.a8parts.co.uk/attachmen...1&d=1379849617

Interestingly, if you just switch engine on/off when car is stationary and remove key, this will never happen. Cluster should receive a bit of speed signal when ignition was ON. Only in this case the receiver gets power from cluster for 5-10 minutes when ignition goes OFF.

Taking into account signal structure (it takes one full minute to receive time and date signal) there are only 5-10 attempts to read time from air until cluster shuts down the receiver.

http://www.giangrandi.ch/electronics...dcf77-circ.gif

Perhaps receiver is switched ON at random time periods when car is parked. I will learn about it soon. +++

UPDATE: Receiver is always OFF while driving. If receiver was ON after accomplished trip and then I decide to continue journey, the receiver will go OFF immediately when I switch on ignition.

Sunday update.
Antenna symbol was there toady too, did not dissapear as far as I can tell.

Many thanks Goran. We need to understand if antenna symbol sometimes disappears in your car. That will indicate a need for more powerful receiver antenna.

Where is your receiver at present?

On my table

You can take a horse to water......:-(

OK, where is it installed in the car when you're testing it?

OEM place for receiver is difficult to reach. I tried via passenger footwell and there is no access. There is no other convenient place to position sensor in high enough location at passenger area, so I put glove box back and forgot about passenger side option.

I tried to install receiver inside visor, which is above instrument cluster. Visor is hollow inside. Slot inside visor is great in geometry terms and is conveniently placed above everything. But car lost signal after 3 days. Interestingly, receiver works tip top on top of visor.

There is plenty of space right behind instrument cluster and there's a lot of space behind knee panel. I just don't want to randomly test different locations, as testing location is cluster in/out job with risks to scratch trim, etc. And it takes 3 days to understand if reception is good. And I don't want to mount the thing permanently, drive for a couple of months, and then understand that location is suboptimal. I'm now doing research to understand long wave receivers, understand antenna theory, etc.

Also, in newer models Audi moved receiver behind rear bumper cover, so it stays outside chassis of the car and there's only a layer of bumper plastic separating it from street -- maybe there is a reason for that. Audi now use newer receivers. Electrically they are compatible with old ones. This is all very interesting.

I opened receiver case and I studied circuit board that demodulates signal and sends pulses to cluster for software analysis. Interestingly, they used cheap low gain antenna. I'm thinking of proper antenna and emailed German company who specialise in this stuff.

I appreciate horse wants to drink, but bare with me -- if I started to bite a bone it won't easily fall off my mouth.

You're being very thorough and it's appreciated. +++
Sorry for "jumping the gun". :o

I'm very tempted to split the lead on mine and plug the lead into the back of the instruments, leaving a connector somewhere accessible (near driver's knees or even in the glovebox) so that the receiver can be moved to wherever I want.

Knee panel is easy to remove. And you can drive without it. I now drive without it no problem.

There are several candidate locations available in that area, where we can mount receiver with a stock bracket or just use cable tire, etc.

I think stock bracket is actually used as spacer. It seems antenna doesn't like other large objects (no matter steel or plastic) in immediate vicinity. This is why installation in visor didn't work I think.

Mounting antenna properly spaced takes time, i.e. if we want to mount on a bracket to structural beam from under knee panel we need to drill a small hole for screw, and/or use adhesives i.e. putty.

Cutting cable in half and adding extra length in the middle is no problem. Like I said, Audi now route same 3 wires to rear bumper. However, with standard cable length you can get pretty much everywhere in driver's footwell. Another interesting location is under driver's footrest. It is completely hollow inside and there's loads of space in it. I'm only worried it may not be high enough.

Inserting connector into back of cluster is very easy with knee trim out. No need to remove cluster for that. Pulling it back is easy too. I see no need for additional connector in the middle. BTW, 3 wires are: Black is ground, Red is power +5V from cluster, yellow is clock data pulse.

Here are articles how to space and shield clock receivers for good reception:

http://www.fact4ward.com/blog/meteotime/
http://duinolab.blogspot.co.uk/2009/...d-cmmr-6p.html