[time-nuts] Antenna problems

[David Bobbett]

  Mark is absolutely right about this Peter, the Tbolt receiver is 
'deaf' by modern standards. In fact I seem to remember the Tbolt 
documentation specifically mentions the use of a +26dB aerial. I use a 
+16dB Lucent unit on top of the TV pole here in Central England and 
although there is enough signal, the mapping feature of Lady Heather 
shows that I am operating about 10dB below the expected signal level. 
I'll be buying a +26dB aerial very shortly so that I can upgrade the 
installation when it next gets serviced.

You can get them from eBay for less than 30 Euros, they are purpose 
designed for use outside and I have never had any problem buying from 
China. I bought all my Tbolt gear from 'fluke.l' without a hitch and 
would recommend him.

David




On 22/08/2010 03:35, Mark J. Blair wrote:
> On Aug 21, 2010, at 7:15 PM, Peter Krengel wrote:
>> Warren found out that the signals  TB gets out of my small ceramic typ
>> antenna are too weak. They are too noisy.
>>
>> So I had a look for a good antenna and found some commercial typs called
>> choke-ring antenna. As they are really expensive is there any DIY solution
>> avaliable?
> I think that the TBolt wants a fair amount of gain up at the antenna, based on the signal levels it reported from the roof antenna feed at work (we're in the GPS industry) compared to what I normally see from our "normal" GPS receivers. Mine is installed at home with a Lucent/Alcatel +26dB antenna which I believe was primarily intended for use at cellular base stations, and my TBolt sees nice, strong signals from it with about 9m of feedline. These antennas are all over eBay, both used and unused, and with or without the pole mount. The TBolt will power them with its +5V bias. An eBay search for "lucent gps antenna" should turn up a few antennas and several mounts at the moment.
>
> There are probably many other antennas that will work fine. I'd suggest looking around for active GPS antennas meant for outdoor fixed installations (they'll generally have a somewhat pointy radome to keep snow, birds, etc. from accumulating on them), powered by +5VDC, and with at least 20dB of gain. Used ones can be cheap.
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