1.3 GHz Ground Station Initial Setup

2/15/18: See updated schematic here.

Today I mounted all the equipment onto the back of the Crosshair antenna. My plan is to use the Crosshair as the base, because it attaches directly to the tripod. With all the gear attached to the back of the Crosshair on the tripod, it is easy to make setup changes, such as changing the video receiver antennas.

The idea is that if I am flying far, I'll manually aim the Crosshair (the tripod) in the direction of the flight, and swap back to the Airblade for flying around in closer.

This is what is wired up on the back of the tripod now.

The Setup without the Battery

With the Battery

Mounted on the Tripod

Front View

New 1.3 GHz Video Antennas

I received my omni-directional antennas for the Sabre and for the ground station. I got a pair of the IBcrazy Airblades, as well as a TrueRC Singularity. The Airblades are both for the receiving end, as well as the video transmitting side (on the plane). The Singularity is to try in place of the Airblade on the plane, because it has a much smaller form.

The pair of Airblades

Singularity (Left), vs. Airblade (Right)

Ground Station Progress & Updated Schematics

I made some minimal progress on my ground station. I got a tripod to mount things to as well as the 1.3 GHz Crosshair video receiver antenna.

Those are both shown here:

Pardon the mess! This is what the reality of working with
this much stuff in a one bedroom apartment looks like.

In doing more reading and learning, as well as taking suggestions from people on RCGroups, I also modified my ground station plan. Rather than have all the gear on the single tripod, powered by one battery, I have separated out the control portion of the repeater from the video portion. This physical separation will be the simplest way to ensure my UHF signal doesn't cause video issues. It also means that the way I have my control repeater set up now can still be used as-is. That schematic is here:

UHF Control Repeater Schematic

Here is the updated ground station schematic.

Video Receiver Schematic. This is exactly what will be 
on the ground station when it is done in its simplest form

Schematic/Block Diagram for the Sabre

I also decided to visually document all of the physical connections for the components that are onboard the Sabre. The only level of detail that I left out is that it does not show the use of servo extensions.

1.3 GHz Ground Station Schematic

In order to keep my head straight for when I start cutting wires and soldering this new gear together, I find it necessary to plan in a high level of detail. It's not very complicated at all, but when my work bench has 5 components that all need to get connected together properly, it quickly gets overwhelming. Once I have everything, I'll need to figure out the physical layout to determine wire lengths. This part may be tricky because I don't want the Dragon Link transmitting antenna to interfere with either of the video signals, or the 2.4 GHz receiver. It may be trial and error to get enough spacing between components.

I'll post an update once I've built the setup, but I attached a screen capture of my schematic. It is fully comprehensive, including the relevant connector types, and male/female designations.

Microphone in the Sabre

I did a bit of soldering today and got the microphone set up in the Sabre. It required another set of wires to be plugged in to the Vector flight controller. It also required soldering to the audio input wire of the video transmitters. I added the plug to both the 5.8 GHz and 1.3 GHz video transmitters so I can use audio either way. I tested it out and after turning the volume gain way down to get rid of feedback, it works great. It may need some tweaking after test flying to get the volume control set to a good value, but audio definitely comes through clearly on the Headplay.

The whole point is to be able to hear the motor so if I am ever far from home and something doesn't seem like it's behaving right, I can just turn the volume up on the Headplay to make sure the motor is responding properly.

Here's some of the new wiring that went in the Sabre.
The microphone is the tiny green circuit board.

Audio cable is plugged in to the Vector, right next to the Dragon Link receiver.

This is the battery compartment of the Sabre. Now after the wing goes on, the microphone will have to be plugged in the the "AUD" wire, just like the video transmitter has always been plugged in to its own wire that goes to the Vector.

Here's where I currently have the microphone mounted. It's in the aft portion of the payload bay where the other mass of wiring is. I taped it up so it's out of the way, and won't wiggle during flight.

Vortex 230 Mojo

I've been somewhat interested in the modern "race drones" (multirotors or quad copters is all I will call them from now on, because drone is incorrect, and has a negative connotation thanks to the media).

Anyway, since becoming more and more involved with FPV, I decided to try the newest member of ImmersionRC's Vortex lineup, the Vortex 230 Mojo. These race style quad copters are designed to be flown FPV. It comes with everything already installed, including the flight controller, camera, and video transmitter. It will be significantly more convenient to fly than the Sabre, since it is small and portable, and will be able to be flown in smaller places. In general, quads like this are sort of the opposite experience compared to long range FPV. That is, it's high energy and short duration flights, low to the ground.

It came complete as a Bind-N-Fly (directly compatible with my DX20), and ready to fly with modern electronics. I received it in the mail today, and was able to get it set up and did two flights. I'm happy to say it flies amazing. I was pretty intimidated at first but it is truly easy to fly, even in Acro (non-self leveling) mode. My experience with collective pitch helicopters is beneficial, as the controls are similar. I did a few flips in the second flight. The most amazing thing overall is just how much power it has. A split second jab to full throttle pulls over 100 amps and brings it up to 100 feet or so nearly instantly. I'm currently using China Hobby Line 1300mAh, 4S, 100C batteries. Pictures and links to  (boring) videos follow. While I did have the Headplay powered on for the fights, I have not flown the quad FPV yet. I just used it to record on the DVR.

First Flight Ground Video

First Flight DVR

Second Flight DVR

1.3 GHz FPV Gear, Microphone

My intent with my long range FPV setup has always been to eventually switch from 5.8 GHz to 1.3 GHz video frequency. This is due to better long range ability, due to the lower frequency. This is the go-to frequency band for long range FPV pilots. I took advantage of some Black Friday online sales and started getting the equipment to do this.

I have a now have 400 mW 1.3 GHz video transmitter, a 1.3 GHz video receiver, as well as a 5.8 GHz repeater (to allow me to use my Headplay's built-in 5.8 GHz video receiver wirelessly). I also have a Crosshair antenna for use at the ground station, which I will need to do some serious modifications to, since the equipment is bigger and heavier compared to the 5.8 GHz gear.

The ground station will likely consist of a tripod to mount everything to. This will allow for convenient adjustments to the directional antenna, as well as having an elevated, and consolidated place for all the support equipment.

1.3 GHz Video Transmitter (New is Green)

My Bench Test Setup

I don't have all this stuff set up yet, but made some progress. I rigged up the equipment on the bench successfully and it all works just fine. The picture above shows the test bench setup. The video transmitter (green) is rigged up to a battery an FPV camera. The video receiver (silver) is rigged up to power, and to the video input on the repeater. The repeater (smaller and green) is rigged up to the video output from the 1.3 GHz receiver.

433 MHz / 1.3 GHz Notch Filter
This filter is recommended for use at the Dragon Link transmitter. It goes between the transmitter and the transmitter antenna, and is supposed to filter out the frequencies in the range that can affect the video signal.

Ground Station Repeater with The Filter Installed

Microphone
I decided to try to get audio working on my setup. The Headplay SE supports audio so I figured why not experiment with it. The microphone was inexpensive and should be very straightforward to wire in to the Vector and video transmitter. (12/3/17: Updated here.)

I'll post more progress as progress is made.

New Batteries for the Ground Station

I recently picked up two new batteries to power ground equipment with my FPV setup.

First, I got a 2s 2200 mAh battery for the Headplay headset. This will power both the headset itself, and the head tracker module. I have 3s batteries that will work for this, but 2s will make the voltage regulators in the components last longer, because they won't have to work as hard.

Battery for Headplay

I also bought 2s 5000 mAh battery. This will be used to power the "ground station." I set up the wiring so that I plug in the Deans to the BEC, and the Dragon Link transmitter and the OrangeRx receiver will always get clean, stable voltage from the dual output BEC. The 5000 mAh battery should be able to power this setup for hours more than I currently would ever need in a single session.

Battery for Repeater Setup

Size Comparison

New Wheels for the Sabre

The last time out with the Sabre I had an issue where I actually couldn't get it to take off in grass. The stock wheels are fairly small and they tended to dig into the grass instead of pushing it down and going over it. This prevented the plane from building enough speed for takeoff, even at full throttle.

The wheels tended to dig in on landings as well. This hasn't really been an issue ever since I upgraded the nose gear strut (as outlined here). However, it does cause the plane to decelerate excessively fast, and most of the weight during deceleration is transferred to the nose wheel. This causes an undesirable effect where the plane rocks right and left on the nose wheel and each main wheel until the plane comes to rest, rather than a controlled deceleration with nose gear steering to keep it straight. A good example of the this behavior is seen at the end in the Flight 42 onboard video.

In a simple effort to reduce this rocking effect, I upgraded the wheels. The Sabre came with 2.25" wheels all around, and now it has DuBro Super Lites all around, 2.75" for the mains, and 3" for the nose gear. I'm fairly certain this will prove to be an upgrade. I just hope the extra height added to the plane (and therefore CG above the ground) doesn't counter the advantage gained from the lower rolling resistance wheels.

Old vs. New Main Wheel (2.25" vs. 2.75")

Old vs. New Nose Wheel (2.25" vs. 3")

Head Tracker (Pan/Tilt) Demonstration

I put together a quick video to show what the setup is like to use with the pan/tilt and the head tracker on the Sabre.

Youtube Link

Sabre Setup Updates

 I fell a bit behind on updates to the Sabre and the ground station setup, so this is a long and detailed post.

Anyway, here is a list of updates since the last post:

1. Up to 50 flights now
2. New FPV camera, the Runcam Eagle 2
3. Ground station UHF control repeater has been refined
4. Head tracker. It causes the pan/tilt function to correspond to my head movements
5. I tried the pan/tilt setup with the Mobius in forward module, looking out the clear "bubble"
6. After limited success of the pan/tilt in the forward module, I updated it to be used on top of the fuselage
7. I've been trying several new antennas

Here are a few pictures that I like from the last time out:

A preparation shot from the last time out with the Sabre.

Ready for Takeoff

Ready for Takeoff

FPV Camera (Runcam Eagle 2):
The Runcam Eagle 2 is considered one of the best FPV cameras currently available. It's a CMOS sensor instead of a CCD, which traditionally, has some bad effects, but this camera has improved those bad effects to the levels of CCD cameras. The dynamic range of this camera is exceptional, resulting in excellent light handling abilities. For example, if the view is facing the sun, the ground doesn't completely black out as a result of the compensation for the bright sun. It is also very customizable, and came with a convenient cable and button setup that plugs into the camera to access its internal settings menus. I'm still working on the settings, but the view is a noticable improvement over my previous camera.

The Runcam Eagle 2 Installed on the Old Pan/Tilt Setup

Ground Station Repeater:
I added a BEC to power the ground station repeater. This device is basically nothing more than a voltage regulator. It has two outputs, so I set the output going to the receiver to 5 volts and the output going to the Dragon Link transmitter to 7.2 volts. The advantage of using the BEC is that I can hook up any 2 cell, 3 cell, or 4 cell battery to the input and it will provide the correct (and stable) voltages. In addition, I will be adding a voltage sensor to the ground station, which will be sent to the DX20 live telemetry screen. This will allow me to monitor the voltage of the ground station battery.

Repeater, Back

Repeater, Front

Head Tracker (Trinity):
I bought the Trinity External Head Tracker from Fat Shark. This device mounts on the Headplay and interfaces with the DX20 through the trainer port. Through some programming and configuring, The head tracker can control the pan and tilt to follow my head movements, for a very immersive FPV experience. It is very fun to use when landing FPV. When I'm flying my downwind and base legs of my approach for landing, it's very useful to be able to look out to the side to look at where I am relative to where I will be landing. Using the levers on the back of the transmitter to control pan/tilt while flying the airplane down low for landing is too risky and cumbersome, so the head tracker really adds to the experience here.

Trinity Head Tracker. It's the black box that says "Fat Shark" on it.

Pan/Tilt Bubble Module:
In addition, I had the head tracker set up to control a new pan/tilt on the plane. The Sabre came with a "module" for the nose that includes a pan/tilt setup. It's designed for the GoPro Hero camera footprint, and it looks downward out of a clear plastic bubble. I modified the mount to accept my Mobius HD camera. The idea is neat, and it looks cool in my opinion, but unfortunately, the views through the bubble were intolerably distorted. There was an obvious rippling effect, and the overall clarity of the video was reduced.

The Mobius on the Pan/Tilt Inside the Bubble

In order to use this pan/tilt in addition to the FPV camera pan/tilt, I had to use 2 additional channels. That means that 4 channels were being consumed by pan and tilt, and the programming got pretty complicated between setting the head tracker up to control the 4 channels correctly.

Pan/Tilt Refinement:
I decided to reduce the complexity by putting both the Eagle 2 and the Mobius on the same pan/tilt. I modified the one that was in the bubble to mount to the location on top of the fuselage where just the Eagle was mounted before. Both the Mobius and the Eagle fit on there reasonably well. The standard size servo for pan is much smoother than the previous setup with the micro servo. Overall, it's a much more robust, and simpler setup. To top it off, it's also lighter weight than the two separate pan/tilt setups. It will also make for much more interesting HD onboard videos because the Mobius will always be pointing where the FPV view is pointing. My intent is to provide a ground video demonstration of the pan/tilt, as well as the head tracker.

New Pan/Tilt Setup, Front

New Pan/Tilt Setup, Side

New Pan/Tilt Setup, Rear

FPV Video Antennas:
I've been experimenting with different video antennas. With all the other changes, it has been difficult to focus on experimenting with the antenna combinations, so it's hard to tell if I have gained any improvement yet. I have the following new antennas, all from Video Aerial Systems:

• Ion (RHCP pair)
• Ion (LHCP)
• Airblade (LHCP pair)
• 3 turn helical (LHCP)
• 10 dBi Crosshair (LHCP)

Video Aerial Systems 5.8 GHz Antenna Assortment

I haven't tried the Crosshair or the LHCP Ion yet, but I have yet to go beyond about 2.1 miles before the video becomes unflyable and I have to turn back. So far, I preferred the pair of Airblades over the pair of Ions, but the flights were done in separate locations on different days, so it's not a good comparison. When flying with the pair of Airblades, I was able to notice better clarity at about 1.5 miles when switching the receiver to the helical. Using the Crosshair should improve on that result further. 

Repeater "Stand"

I finished a quick and somewhat crude stand for my repeater. The main idea was to have a way to keep the Dragon Link transmitter antenna vertical and have it be easily portable.

I made it out of foam board. I used magnets on the bottom so that I can use the heavy ammo can that I always have with me at the field as the base. The Dragon Link transmitter just sits in place, and is held by the rubber band and a dowel, much like how I've done Dragon Link Transmitter mounts for radios.
For now, I will be using one of my 2S 4,000 mAh batteries from my RC monster truck (Traxxas Summit) to power the ground station. That way, I will never have to worry about the amount of battery left, as it is way more than it could consume in a flying session. In the future I will upgrade to a BEC to power the ground station. That way, I can just plug in any battery I want and it will give the correct voltage to the OrangeRX and the Dragon Link transmitter.

The Setup, Front.

The Setup, Back.

The Bottom of the stand, showing the 3 magnets.

New FPV Antennas for the Sabre/Headplay

I had previously been using a really cheap (and bad) set of video antennas on my setup. I just ordered a pair of Video Aerial Systems's (VAS) Ion antennas. One goes on the video transmitter on the plane, and the other goes on the video receiver on the Headplay head set.

The Ion is a very compact omnidirectional antenna, which claims to have the highest gain of any omnidirectional antenna on the market for FPV. This means that the radiation pattern is compressed into more of a disk shape, rather than a sphere. This is ideal for extending my video range because it means the radiation pattern isn't getting wasted in the vertical direction, and instead can extend further horizontally.

The Ion also has a very high standing wave ratio (SWR), which means more energy is sent in the signal that would otherwise be lost to heat due to internal reflections in the antenna.

I may find that they increase the video clarity as well. I'm really looking forward to giving them a try.

The cheap pair of antennas. I couldn't even find any name or
polarization designation on the package.

Headplay SE with the Ion Antenna

The Ion Antenna mounted to the Video Transmitter in the Sabre Wing

Repeater Setup for Dragon Link

I posted a "Mini How-To" on my RCGroups blog, located here.

The Dragon Link UHF transmitter is designed to interface with the trainer port of the radio (in my case, the DX20). The trainer port outputs a PPM data stream, which (I didn't know until I was configuring my DX20) is limited to 8 channels. The solution to be able to use more channels (up to 12) is to use a repeater setup.

To make a repeater setup, I'm using an OrangeRX receiver that can output an SBUS data stream (digital) to the Dragon Link. So now I will be using the Spektrum DSMX protocol of the DX20 to communicate on 2.4 GHz (as designed for normal range aircraft) to the OrangeRx. The OrangeRx's SBUS output is wired to the input of the Dragon Link transmitter, which has been reconfigured from PPM to SBUS. Now I have a separate "repeater" (takes the 2.4 GHs data and repeats it as the output from the Dragon Link transmitter) station on the ground with the OrangeRx and Dragon Link transmitter, rather than having the Dragon Link plugged directly in the DX20.

This means it's a far less bulky setup for moving around at the field while flying. It also means I don't have to remember to try to hold the Dragon Link antenna vertical for maximum signal reception, because the module will be fixed in place to be vertical. I finished the 12 channel setup tonight, and verified that either failsafe condition (2.4 GHz  or Dragon Link failsafe) will trigger the return to home flight mode in the Vector flight controller. I still need to make some kind of stand or container to mount the components to.

Dragon Link Transmitter, OrangeRX Receiver, and 2 Cell Lipo to Power Both

Sabre Flights 44 and 45, Headplay, DX20, Pan/Tilt

All the gear, getting ready. There's a lot of setup that does into
flying with this much equipment!

Flight 44 Onboard Video

Flight 45 Onboard Video

Sunday was another good day with the Sabre, with several firsts:

1. First time flying with the DX20
2. First time flying with pan and tilt on the FPV camera
3. First time flying with the Headplay SE headset
4. First time flying FPV with a DVR for the FPV feed

Overall, having the pan and tilt operating on the FPV camera greatly enhances the FPV experience. It was very enjoyable to be flying in 2D hold mode, while just looking around. It's really neat to be able to look all the way back see either wingtip. Also, looking down while in loiter mode was neat.

The Headplay video monitor was great. I was able to wear it as long as I felt like flying FPV without ever getting uncomfortable. There were no hotspots or areas of discomfort at all. The FPV experience is greatly enhanced as well because the screen is just so much better than what I was using. I was able to see enough detail on the ground to be more confident to land both flights while flying FPV. 

The Headplay came with a DVR so I was able to get some recordings of the flights, which is nice to have, but also is great for peace of mind. If the plane goes down, I should be able to review DVR footage to get an idea of what went wrong and where it went down.

The DX20 was fantastic as expected. The slow operation of the flaps was great to smooth out their application. One unexpected minor annoyance happened though. There are certain functions you do with the Vector that involve rapidly toggling the mode switch a certain number of times. Due to the way I programmed my mode switch, this wasn't working without also toggling my second mode switch. I have since reprogrammed the mode switch mixes in the DX20, and reran the Vector's receiver analysis tool, to be able to access the menus normally.

DX20 with Dragon Link Mount

I spent some time the other day and set up the DX20 for the Sabre. Now I have pan and tilt on sliders, which will be really nice for "looking around" and just enjoying the FPV experience.

Now with that task done, I had to figure out a way to mount the Dragon Link transmitter module to the DX20. It was a challenge because of the dual antenna orientation on the DX20. The horizontal one is also a carrying handle, with a center pylon, which was the main reason it was tricky to find a suitable mounting location. I also needed to leave space for the Dragon Link power battery.

The result isn't pretty, but it's functional, and very quick and easy to install.

The final configuration. Front view.

The final configuration. Rear view.
The single dowel is used to attach rubber bands to the radio's
horizontal antenna, which holds the entire assembly on. The same
dowel is where the single rubber band also holds the Dragon Link transmitter.

The Velcro is where the battery attaches. The small square opening
is where the vertical antenna goes. That's the main mounting interface.
Then the rubber bands stabilize the assembly against the horizontal antenna.

 

Battery mounted.