Hi > On Jul 31, 2017, at 3:32 PM, Didier Juges <shali...@gmail.com> wrote: > > The Thunderbolt is well known for not having the best sensitivity among GPS > receivers. It seems that timing receivers in general, particularly those of > the same generation as the Thunderbolt are not as sensitive as navigation > (possibly newer) GPS receivers. It may be because they are expected to run > with amplified antennas?
The newer the receiver, the more horsepower in the silicon. In the case of GPS, that gives you more correlators to do DSP. The sensitivity improvement is a direct result of that. If you take a look at the guts of a TBolt, they date to the late 1990’s. That’s a long time in silicon years …. Bob > > Based on the spec you wrote, it looks like your antenna has no gain, so > definitely I would expect less than good performance. > > My 3 Thunderbolts have been running with inside antennas (2 pucks and one > Trimble Bullet) but my ham shack is upstairs and other than the ceiling and > the shingle roof, there are no other obstructions and they are doing OK not > great (all 3 go on holdover somewhat regularly). I am now running one > downstairs (while I work on the new software for the TB Monitor) with 50 > feet of RG-58 going to a HP 58532A antenna somewhat in the clear but only 8 > feet above ground with significant obstructions in pretty much all > directions due to the low height and the Thunderbolt is happy as a clam in > spite of the significant losses in the cable. The HP antenna works much > better than the Trimble Bullet antenna. > > On Mon, Jul 31, 2017 at 12:19 PM, Jerry <jster...@att.net> wrote: > >> Due to access problems, I run my Thunderbolt with a Symmetricom 58532A >> antenna placed indoor near a window facing South… can’t get much worse but >> most of the time it will be locked onto 3 or 4 satellites. I recently >> bought a www.leobodnar.com <http://www.leobodnar.com> GPSDO for my SDR >> ham >> radio setup. I was very surprised to find that this minimalist GPSDO using >> a small patch antenna with internal LNA placed near my window had satellite >> & PPL lock within a few seconds. It requires 3-4 satellite locks for its >> PPL. However, when I attached the patch antenna to my Thunderbolt – >> satellite signal strength were zero or minus for all satellites. The specs >> for the patch antenna are listed below. >> >> >> >> I would appreciate any advice understanding this behavior. >> >> >> >> Jerry NY2KW >> >> >> >> Center Frequency 1575.42MHz±3 MHz >> >> V.S.W.R 1.5:1 >> >> Band Width ±5 MHz >> >> Impendence 50 ohm >> >> Peak Gain >3dBic Based on 7×7cm ground plane >> >> Gain Coverage >-4dBic at –90°<0<+90°(over 75% Volume) >> >> Polarization RHCP >> >> LNA/Filter >> >> LNA Gain (Without cable) 28+/-3dB >> >> Noise Figure 1.5dB Typ. >> >> Filter Out Band Attenuation (f° =1575.42MHz) >> >> 7dB Min f0+/-20MHZ >> >> 20dB Min f0+/-50MHZ >> >> 30dB Min f0+/-100MHZ >> >> V.S.W.R <2.0 >> >> DC Voltage 2.7V/3.0V/3.3V/5.0V/3.0V to 5.0V/other >> >> DC Current 5mA /11mA/15mA Max >> >> >> >> >> >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.