Tomtom TMC antenna -- horizontal or vertical?

fmfm20j · Occasional Visitor Joined: Oct 27, 2004 Posts: 21

Allan,

there may be something in that. I have a TT 720. I drove from Camberley to Bristol via the M4 on Tuesday and got a signal off and on for some of the way. The best section was within 10 miles of Bristol. That was with the unit running along the base of the dashboard.

On the return trip, having established something of a reference, I stuck the top sucker just under the mirror and dangled the rest of it vertically down the dash. Between Bristol and Membury I got an almost continuous signal. Having stopped at Membury and stuck it vertically in an L shape on the front windscreen and then having played with the position periodically on the rest of the journey home, the reception was just as bad as it was driving down.

My less than scientific approach would suggest that keeping the unit away from the metalwork and suspended in largely 'free air' gives better reception.

I'll certainly give this placement another go when I travel over a distance next time. The reception where I live in Camberley is never very good so I cannot really road test it locally.

Ian

Allan_whoops · Frequent Visitor Joined: Feb 18, 2006 Posts: 369

If the Tom-Tom has a std mini-jack as the connector, then I found that doubling the length of the cable improved things substantially as it allowed me to run it both vertically and horizontally. This was with a Sony 70T (never again as they never upgraded the maps etc, just brought out a replacement system).

mikealder · Posted: Fri Dec 21, 2007 9:02 am Post subject:

It is far from a standard 4 pole connector, the actual number of connections on the plug is 6, there are 4 on the center pin and two others on the inner surfaces of the outer ring surrounding the center pin.
I have never seen one of these connectors (plug or socket) available for sale as yet - Mike

carl_w · Lifetime Member Joined: Mar 13, 2004 Posts: 242

6 connexions for serial data when TX, RX and GND would have sufficed? The connector must be available from somewhere -- I doubt Tomtom are having them custom-made. I'll have a poke around.

mikealder · Posted: Sat Dec 22, 2007 1:27 pm Post subject:

If/ When you locate the connectors both male and female please let us know where from as there are a few things I would like to try, I have spent quite some time looking for them and found nothing as yet - Mike

Hoppy · Posted: Thu Jan 03, 2008 8:25 pm Post subject:

I agree with the 2 that said before the best reception I found by mistake when one of the suckers unstuck and about a foot of aerial was dangeling from the top right corner of the windscreen good signal and stayed locked on with updates had to look at the whole uk map as there were no problems in my area, but it was reporting road works and narrow lanes on the A1 and M1

fmfm20j · Occasional Visitor Joined: Oct 27, 2004 Posts: 21

This may be of interest to those with a similar car to mine:

I have a 5 series BMW touring (E39 2002 model). The best place that I have found for TMC reception is to hang the aerial off the rear view mirror and let it drape over the top of the dashboard (uncoiled).

I've tried the following places with less, limited or no success:

1. stuffed along the front of the dashboard between the interior trim (wood or aluminium depending upon the model) and then up the side and on to the windscreen.

2. from the centre of the dash to the windscreen then left, across the base of the windscreen (suckered to the glass) to the A pillar and then up the screen (about 2" in from the pillar)

3. as in 2 but going right and along the top of the dash either horizontally or at a slight angle upwards.

4. diagonally from the centre of the dash, along the drivers binacle , on to the screen and then , on reaching the A pillar, upwards for the remainder of the length but about 2" in on the windscreen.

I have my 720 mounted on a Brodit universal centre vent mount. The nice thing with this approach is that I can remove all traces of the sat nav and TMC when not in use. True, it's a bit fiddly to connect and the wire is a slight distraction. Funnily enough, however, it seems to be less of a distraction than when I had it permanently mounted in any of the 4 scenarios mentioned above.

In my car it seems that the A pillars inhibit the signal. I have airbags in the pillars. Perhaps the mechanisms or the sensor electronics attenuate the weak TMC signals?

Ian

carl_w · Lifetime Member Joined: Mar 13, 2004 Posts: 242

fmfm20j · Occasional Visitor Joined: Oct 27, 2004 Posts: 21

Hi Carl,

If I hadn't admitted to owning a touring I could have pretended that I had an M5. Alas, the E39 doesn't offer an M5 touring. Short pockets prevent me from having an E61.

Regarding the cornering forces and obscurity of vision: can I assume that the version of TMC antenna that you have is the black one. Perhaps you should have ordered the fibre optic version (which is totally transparent) Wink

Seriously, if you drape the top over the mirror and sucker the wire at the bottom of the dashboard it will work just as well (I have tried this too). The downside is that it leaves a small sucker mark and is one additional connection that needs to be removed.

If you don't already have it, the air vent Brodit is a very professional way of mounting a TomTom.

carl_w · Lifetime Member Joined: Mar 13, 2004 Posts: 242

fmfm20j · Occasional Visitor Joined: Oct 27, 2004 Posts: 21

I've no idea what the Brodit mount for the Z4 would be like (my wife would love to have a Z4... but auditioning a Brodit mount isn't sufficient justification to buy one). I'm sure that a Spartanburg car will be just as good as something out of Bavaria.

On the E39 the mount is excellent. It's a solid bit of plastic which perfectly clips on to the vent and doesn't show any signs of coming off. If you simply buy the ProClip with a universal mount and then buy the TomTom holder and bolt this to the other half of the universal mount you can attach the TomTom in seconds. The best thing of all is the fact that the Proclip and half of the universal mount when left permanently on show doesn't advertise the fact that you have a satnav at all. That's a major benefit as all UK drivers know only too well.

carl_w · Lifetime Member Joined: Mar 13, 2004 Posts: 242

fmfm20j · Occasional Visitor Joined: Oct 27, 2004 Posts: 21

I cannot comment too much about those. Of the ones that I have seen in motorway service stations, they are far from ideal and may prove to be a problem.

Looks like you might need to buy yourself an E39 Smile

ddingbat · Occasional Visitor Joined: Jan 05, 2008 Posts: 2

Having tried the various ideas here I've abandoned the TMC device and obtained a full refund - good old John Lewis shops!
After some testing I found that on my TomTom One XL - with latest SW level and latest TMC device level.
Worked when running on internal battery, would locate and hold station best although not impressively, would auto search and re-locate station, would manually tune to known frequency with TMC. However, that's not a lot of use on a journey longer than battery life and plain inconvenient.
Miserable when running on any external power, whether USB source in the house or car power supply. Would not locate station and hold it, auto search just searches for ever and on random occasions finds a station. Manual tuning to known frequency throws up a message ""no station at this frequency."
The diagonal aerial idea, that I also stumbled across by chance, seemed to help but far from perfect.
My conclusion is that, apart from the less than uniform coverage from iTIS, the TomTom device and software are a large part of the problem. I've written them a complaint letter suggesting they let us all know when they have a version hw and sw etc that actually works in the UK!

carl_w · Lifetime Member Joined: Mar 13, 2004 Posts: 242

How bizarre. The only explanation I have for that effect is that the charging circuit is somehow interfering with the RDS receiver.

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