Can I use an Eggfinder TRS Mounted Horizontally for Tracking?

[OverTheTop]

Can anyone let me know if I can use an Eggfinder TRS system for tracking only with it mounted across the rocket rather than the usual vertical mounting orientation parallel to the central axis? I only need the tracking function, and none of the deployment or logging.

I want to use it in the booster of my half-scale Nike Apache project to fly in April 2019. There is a nice location in the ISC where it would nuzzle in with the structure.

 

[vance2loud]

Looking at both the TRS manual and the spec sheet for the individual components, I can’t see any reason for it to need to be mounted in any particular orientation.
The only concern I would have would be the RF antenna placement.
Personally I would mount an SMA plug and use a bulkhead pigtail to move the antenna and give you options for better antennas.

 

[Eric]

As I understand it, the TRS like most baro only items can be mounted in any orientation. You just want the GPS panel antenna to have a view of the sky. Both antennas are moving and facing different directions on descent anyways. And I haven't lost signal with all that movement.

On the other hand, your straight up facing GPS patch antenna during launch. Could be facing straigh down while under recovery. Just depends how you set it up.

 

[OverTheTop]

Thanks guys.

Vance: My TRS is already fitted with an SMA connector to give me options for the antenna, but I still need to know if the TRS can be mounted horizontally and will still track. I am not sure if the firmware has any expectations about orientation in regards to tracking function.

Eric: The way GPS units are these days with pulling in satellites in ridiculous concrete-canyon situations I have no great concern about achieving lock during and after flight.

 

[cerving]

The altimeter part of the TRS doesn't care about orientation, as long as it's vented properly (1/4" dia hole or the equivalent per 100 cubic inches of AV bay volume is the general rule). In practice, the GPS antenna almost never gets to point "up"... it's usually pointing to the side, and it's very likely to be moving around during boost and especially during descent. The patch antennas that we use have a pretty wide beamwidth, almost 180 degrees, so if you get a decent fix (5 or more satellites) you're probably not going to have a problem during flight.

 

[ksaves2]

Ditto to the above. You could consider a patch cable to a vertically aligned 1/4 to 1/2 wave vertical dipole for better performance.
https://linxtechnologies.com/wp/wp-content/uploads/ant-916-cw-qw.pdf
https://linxtechnologies.com/wp/wp-content/uploads/ant-916-cw-hw.pdf

Be aware, the SMA connectors buyable from Cris are RP-SMA. I have a pile of plain SMA connectors so I use those on all my Egg Stuff. Try and tune the Egg transmitter to the lowest VSWR for the given antenna to wring out all the
performance that you can. Do not expect to receive "every single" position from these low powered 900Mhz trackers. Once the rocket is under the main chute and the descent settles down, that is the time where most of the
positions are decodeable. If fact, if one can afford to blow the main up higher, the chances of better reception is much higher.

If your rocket is expected to stay close by or within sight most of the flight, you shouldn't have an issue. Why bother with a GPS tracker then? If there is a lot of high vegetation it can be a rocket saver even if you get a visual on where it landed.
In that case, best to attach a screamer to the harness too. A GPS tracker is a bit of insurance and peace of mind if one's rocket flies off the expected profile and stays out of sight a little too long Kurt

 

[OverTheTop]

The altimeter part of the TRS doesn't care about orientation, as long as it's vented properly (1/4" dia hole or the equivalent per 100 cubic inches of AV bay volume is the general rule). In practice, the GPS antenna almost never gets to point "up"... it's usually pointing to the side, and it's very likely to be moving around during boost and especially during descent. The patch antennas that we use have a pretty wide beamwidth, almost 180 degrees, so if you get a decent fix (5 or more satellites) you're probably not going to have a problem during flight.

Thanks Cris. I didn't think I would have any problems, but I did want some confirmation as it is a big project. I have no concerns about GPS acquisition.

Ditto to the above. You could consider a patch cable to a vertically aligned 1/4 to 1/2 wave vertical dipole for better performance.
https://linxtechnologies.com/wp/wp-content/uploads/ant-916-cw-qw.pdf
https://linxtechnologies.com/wp/wp-content/uploads/ant-916-cw-hw.pdf

Be aware, the SMA connectors buyable from Cris are RP-SMA. I have a pile of plain SMA connectors so I use those on all my Egg Stuff. Try and tune the Egg transmitter to the lowest VSWR for the given antenna to wring out all the
performance that you can. Do not expect to receive "every single" position from these low powered 900Mhz trackers. Once the rocket is under the main chute and the descent settles down, that is the time where most of the
positions are decodeable. If fact, if one can afford to blow the main up higher, the chances of better reception is much higher.

If your rocket is expected to stay close by or within sight most of the flight, you shouldn't have an issue. Why bother with a GPS tracker then? If there is a lot of high vegetation it can be a rocket saver even if you get a visual on where it landed.
In that case, best to attach a screamer to the harness too. A GPS tracker is a bit of insurance and peace of mind if one's rocket flies off the expected profile and stays out of sight a little too long Kurt

Thanks Kurt. GPS reception should not be a problem with the very capable correlators in them these days and the number of satellites in the sky, and I doubt 900MHz at the booster altitude will be a problem.

I usually blow the main at about 1800' for a couple of reasons: One is to give it extra time to pull up from a sub-optimal drogue deploy, and two is to give the GPS more time to lock for the recovery location if it lost lock during flight.