I am new to the topic of time measurement, freq. standards and GPSDO etc. but would like to share my experience.
I have quite a bad location for a GPS/GNSS antenna, inside an apartment and looking to the north, and I need ~20m of cable to get it to my desk (using RG58). The only good thing is I have a pretty open view almost from the west to the east. Directly in the north direction, there is literally no GPS/GNSS orbit (it is fun to confirm this with an astronomy program), but I catch the ones on the sides. I have a DIY GPSDO made in Japan (as far as I know it is different from BG7TBL), LeoBodnar dual output GPSDO, and ublox M8T and F9T modules. The DIY Japanese one has a ublox 7th gen receiver, and it cannot lock most of the time. I believe the sensitivity is too low. LeoBodnar has a ublox 8th gen receiver. It was mostly working but sometimes losing the lock, so I installed an inline amplifier and then it is working pretty OK (Japanese one does not work well with the inline amplifier also), I never see the LEDs blinking so I guess it never loses the lock. It is a nice device but 1) you cannot use ublox u-center software, 2) it does not have a PPS output. I tried M8T and F9T modules also, and they also work pretty fine. F9T is dual freq. and I can use it in Time mode so actually I am planning to use it to discipline a RbXO. A puzzling question is I have C/N0 values maximum around 35, usually between 20-30. My understanding is normally it has to be more than 40. I did not understand yet why it is low but my current guess is it is due to interference etc. because the antenna is not at the roof. (further complications, I think my building is a steel construction, the window is a little inside with a surrounding steel structure like a very large diameter but small length tube). So if you have a limited sky view or dont have an antenna on the roof, I recommend getting a GPSDO having at least a ublox 8th gen receiver or equivalent. I would like to try a Thunderbolt for example but not sure about their sensitivity, not even sure if the sensitivity of Thunderbolt E would be OK for my location. Mete On Wed, Mar 2, 2022 at 1:45 AM Wes <[email protected]> wrote: > I just acquired my second Bodnar GPSDO, a single frequency model. I have > the > two frequency model already. They don't do 1pps. They are sold in the US > by > Airspy but I have had better luck buying from SDR-Kits in the UK. Not > much > difference in price, they are friendlier and the delivery is just as fast. > > Wes N7WS. > > On 3/1/2022 4:11 PM, Tom Holmes wrote: > > John... > > > > If you haven't already, look into the Leo Bodnar GPSDO. It is a couple > hundred bucks US, and the people I know who have them > > are pretty happy with them. Not sure off the top of my head if they > make a PPS, however. And, he is in the UK. > > > > Tom Holmes, N8ZM > > > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send > an email to [email protected] > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
