Long cable for satellite antenna or for radio antenna?

Just setting up my base station for my farm. I have a 60ft tower beside my house, plan was to setup satellite antenna on house and put the radio to send out the rtk to my rover on the top of the tower 900mhz. Plan to do another one with a similar setup at another tower. Just curious as to whether anyone has tested which is better.
1)setup the f9p on the roof and have a short cable to satellite receiver and long cable to 900mhz antenna at top of tower, or
2)setup the f9p at top of tower and have short cable to 900mhz antenna and long one to satellite receiver mounted on roof of house.

Option 1. Keep the GPS antenna cable as short as practicable. The GPS the weaker signal and the less cable loss the better. You can always amplify the 900Mhz broadcast signal to overcome cable loss.

I would say option 2 or maybe a combination of the two. I’ve added a long SMA coax extension (lmr195) to the ublox’s already long ant cable without any problem. I’d say a stable location with good view of the sats is most important for the GPS ant as it has a signal amplifier built-in. If you can transport the rtcm correction data from your roof to the tower with ethernet or Wi-Fi you can get the best of both. I don’t think 20-30’ of coax for the 900mhz will hurt much either as long as it’s not too thin.

I wouldn’t use either option, I’d keep both coax cables short.

Is the 60 ft tower not stable enough for a GNSS base antenna? If not, I’d use some digital transmission from the GNSS base to the radio (serial, LAN, WIFI or even a separate low power radio link…).

no top of tower moves more than most figure. We used to own and operate and WISP so we installed many antennas on towers and it is amazing how much they move around at the top in the wind.

So thought about this more. I already have poe power switches in the house running other items and have Ethernet cable strung up the tower already. Is there any boards or shields already out there that would allow me to power the f9p with poe through the ethernet line and this way I could have my server running in the house. The other ethernet line would shoot power up to the top of the tower where the xbee and radio antenna would be located and through the switch the rtk correction would be transmitted. This way I would have an ntrip server if I wanted and the radio as well.
I already have the f9ps, the ant antenna, the xbee xb pro development kit on way with three xbees and a 8dbi external antenna for the base station. I have the AIO v2.5 board here as well for the rover. What other boards would you recommend for connecting the xbee and f9p via poe.

One other question, with respect to the ethernet conversion, has there been any problems with accuracy given the way in which ethernet sends groups of packets out and any delay?

The corrections are only send at 1hz (every second) typically, and you can slow that down further if needed so I don’t expect ethernet packets will be a problem.

I’m using a Piksi Multi dev board (bought pre f9p release) for my base and it already has ethernet built-in but you’ll need a PoE ethernet serial server with 5v power to share with the simplertk2b f9p or PoE midspan with 5V output. You can also use a non-poe ethernet serial server and send power passively with a cheap passive injector and then regulate it down in the box on the roof with for the serial server and f9p. I don’t think anyone has a shield for this yet except something like the wifi master (esp32) from arduSimple or the rPi systems which are both ntrip servers in themselves.

Then for your tower you’d need a 2nd ethernet serial server to connect to the Xbee. I like these from PUSR. They’ve been reliable for me.

I suggest getting a module with 2 TTL ports so that you can connect to both F9P UARTs. One can serve your RTCM needs and you can configure/monitor the F9P on the other or setup two RTCM streams. Up on the tower you’d only need a single TTL connection to the Xbee.

Another program I’ve found quite handy for tweaking my RCTM stream is the STRSVR program found in RTKLIB_bin-2.4.2p13 (I’m sure there’s a new version by now) but I think the F9P’s config allows you to set everything quite precisely.

Thanks I had been looking at those options, I was hoping to find an ethernet ttl converter that would work on digikey or mouser to speed things up and order some of these as well. I am thinking I will try

And get some poe splitters to split out the power and ethernet.

If I understand things somewhat. If I get the ethernet ttl converter, and an ethernet splitter, I should be able to put a box with these and my f9p on my roof with the satellite antenna there or nearby. Similarly I should be able to use the same setup replacing the f9p with an xbee and its radio antenna at the top of the tower. All this would be connected back to my switch at the house. I could then send rtcm out my radio and have a server running ntrip in the house if I want.
Or am I missing something?
Thanks and Happy New Year

A well tested solution with power over Ethernet here:

Includes the NTRIP caster too and serial output for your radio if you need that.

It sounds like you have a handle on things. Maybe the f9p’s 3.3v regulator can also power the wiz750 so you just need a 5v PoE midspan there. In the tower/xbee box you’ll need a 3.3v midspan. Some ethernet serial servers can only accept one client connection at a time per serial port and some can handle multiple. Depending on what you want it might work better to UDP broadcast the rtcm and just listen when whatever needs the data.