[time-nuts] HP/Symmetricom 58535A and 58536A
bg at lysator.liu.se
bg at lysator.liu.se
Wed Nov 4 20:40:13 UTC 2009
Total gain, noise, VSWR are all factors in getting a good signal from the
antenna into the receiver. Here all components matter - antenna, the
antenna LNA, connectors, type and length of coax cable, splitters and
inline LNAs and the receiver spec.
Good passive splitters behave well, but they will attenuate your signal by
say 6dB (for a 4 output splitter.).
Older receivers (always) have a tighter allowance for which total gain
they will accept. Moderns high sensitivity receivers give much less
trouble in this area.
I did not find the numbers from the Tbolt manual. But look at the vintage
Oncore receivers, and you will find that legacy receivers sometimes only
give you a sub 20dB gain band of total gain. (table 4.1 in below url)
Adding (or) substracting 12dB or even 6dB might put your total antenna
(antenna, connector, cable, splitter, etc) system out of spec for your
Thunderbolt. A HS receiver might not even notice this.
Further 6dB extra or less gain does not imply a linear relationship with
signal to noice ratio.
> Hi Bjoern,
> Yes. On our FireFly series GPSDO I get up to 45dB signal to noise ratio
> with a passive 1-to-4 splitter following the Agilent active splitter.
> I think there is something going on with the Thunderbolts such as the
> antenna sense circuit not working properly etc, please also see my other
> following this one.
> In a message dated 11/1/2009 04:04:11 Pacific Standard Time,
> bg at lysator.liu.se writes:
> Hi Said,
>> I think the added noise of the Amp may play funny with the
>> receiver, and there may not be anything wrong with your splitter.
>> M12M's and uBlox receiver's don't have a problem at all, even if two
>> are cascaded. They do start to have issues with three splitters in
> Did you check that you have enough signal power for the Tbolt, when
> cascading (passive) splitters?
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> and follow the instructions there.
More information about the time-nuts