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Re: LF: LF "Mobile" ( was : "NM" on 136177 )

To: [email protected]
Subject: Re: LF: LF "Mobile" ( was : "NM" on 136177 )
From: Stefan Schäfer <[email protected]>
Date: Tue, 04 Jan 2011 12:50:30 +0100
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John,

Why don't you just disconnect the battery when the car is standing still in the field? :-) Well, i was thinking about investments into this old car and if it is still worth or not. But having not such a nerving CANBUS is one argument for investing into this car! Why the hell do i need a sensor that shows me if the door is open? If it is open i see it or hear it. Just useless inventions by the automobile industry!
73, Stefan


Am 04.01.2011 10:25, schrieb John Rabson:
Hello Stefan, Wolf , LF,

I have a  diesel Renault Kangaroo [no - KANGOO - obviously an Australian 
designed this dictation software].  I have found it impossible to make 
weak-signal field strength measurements on 136 from the vehicle.

There appears to be some kind of data bus to communicate between a central 
control unit and sensors which indicate (for example) whether the doors are 
open or closed.  Something seems to be running even when the engine is switched 
off. My solution is going to be a portable receiver and antenna which can be 
carried a few metres away from the car, otherwise I cannot measure field 
strengths with any usefulness at a distance of more than about 2 km from the 
transmitter.

There is even a problem on some longwave broadcast stations.

73 John F5VLF

On 30 Dec 2010, at 16:34CET, Stefan Schäfer wrote:

Hello Wolf,

Nice email ;-)
Well, no it is a benzine car, an almost 22 years old VW Golf II !! ;-) You 
could know it from the VLF pictures, HI :-) So there is no internal electric 
bus! And i have a car radio (ALDI!) that receives on VHF/MF/LF and i do not 
have QRM by the ignition coil! Once i made holidays at the Nordsee (JO33) i 
drove with the car and listened to DLF/153 kHz during the whole tour without 
problems. Only HV transmission lines above 110 kV cause QRM.

So maybe i have a little better situation to receive DF6NM on LF /m. Otherwise i 
have to drive on the highway, lets say 180 km/h (the maximum of this car) and have 
to switch off the engine during Markus' transmission that must be short then until i 
have to accelerate again at 90 km/h :-)). If this will not work i have to drive to a 
highway near Nürnberg :-)

The magnet foot antenna is already ordered and i am curious about the results 
;-) Mostly i need it for receiving LF during the VLF experiments, e.g. to the 
xband QSO 9/137 with DF6NM, and maybe DF0WD? :-)

73, Stefan

Am 30.12.2010 12:03, schrieb wolf_dl4yhf:
Hi Stefan,


you wrote:
This should allow me to easily receive 137 kHz while driving the car!
Hopefully there is not to much QRM during engine is running.
So maybe i can try a crossband QSO with DF6NM TXing on 137 and me answering on 
30m while beeing on the highway :-)
Maybe, it's a Diesel engine, and the alternator properly low-pass filtered. I tried this 
years ago, and the QRM from the ignition coil, and / or the alternator was horrible. No 
big surprise that car radios with AM LF broadcast receivers have disappeared. And 
weak-signal reception "LF mobile" is even more a challenge.

In my Corolla, I would even have to disconnect the battery (!) if I was to 
receive VLF (and, most likely,  LF too) because some internal digital bus (most 
likely CAN or LIN) remains active, with the ignition and everything else turned 
off. For temporary V(!)LF operation on a remote site, I use a simple FM 
oscillator at the transmitter now, and listen to the VLF signals in the car's 
radio, using a distance of 10 m or so.


Cheers and a happy new year,
   Wolf DL4YHF .







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