The Eachine Pro58 diversity module is designed for Fatshark FPV Goggles, and it’s only $26! With the custom Achilles Plus firmware, how does this module compare to other high end diversity options in the FPV market?
Affordable Diversity Module – The Eachine Pro58
Most existing diversity modules on the market for the Fatshark FPV Goggles can cost over $90, the Eachine Pro58 is certainly very tempting at only $26 a piece. ($29 including the cover)
It looks similar to the Furious True-D: two separate receivers stacked together as one module, so there is no messy wiring and it’s plug and play in any Fatshark Goggles, including the Dominator V3, HD3 and Attitude V4.
Further Reading: Here is my review of the FuriousFPV True-D module.
As you can see, the pins are shorter than other modules such as the True-D, so it can easily fall out of the Goggles if you don’t have a cover to hold it in place.
The cover only costs a couple of bucks, or you can 3D print it with designs on Thingiverse. To get good 3D printing result, I have to scale the design to 100.2%, and I also had to enlarge the holes flighty for the antenna connectors.
The two receivers/connectors are labelled as A and B. You are supposed to use different antennas on them:
- A – onmi-directional, such as pagoda or cloverleaf
- B- direction such as patch or helical
Further Reading: Learn the basics of FPV Antennas.
One complain I have about this module is the button. It’s the same multi-directional button on the first version of the True-D which I didn’t like at all. It’s fragile, and it’s hard to use. I wish they use the same 3-button design like the latest True-D V3.
On the back there is the 3M double sided foam tape that can help secure it in the module bay.
What’s special about the Pro58 with Achilles firmware?
The Eachine Pro58 comes with a factory firmware, it works, but it’s not great. The good news is there is a custom firmware you can install on the Pro58 module to turn it into a truly amazing product.
The Achilles Plus firmware is developed specifically for the Eachine Pro58 hardware, by George Chrysostomos. It optimizes the module’s performance and introduces some cutting-edge features that aren’t even available yet on other more expensive modules.
In fact, the Pro58 has a much better processor than what’s used on the Laforge and True-D, that’s why it can handle more complex and advanced features.
Apart from the usual diversity module stuff, the Achilles firmware can also do:
- OSD Menu – allows you to change settings in the goggles without taking them off
- Lap timer – tracks your lap time using your VTX signals
- Model Searching – help you find your crashed RC model using VTX signal by determining which direction the signal is coming from
- Easy to use menu, and really cool animation
- You can also use the buttons on the goggles to change channels
George, the developer, is currently working on some new features and improving the performance. I can’t wait to see what he comes up with next!
How to get Achilles firmware?
And you will need this tool to flash the firmware, the ST-Link V2 Tool:
In order to enable OSD menu in the goggles, you have to do a little bit of DIY, and solder a resistor on the module which is pretty easy to do. Instructions can be found on achillesfpv.eu.
But at the moment when using the OSD menu, the whole screen goes into black background. It only returns to your camera when you quit the menu. I hope one day they can improve this and allows OSD text to overlay on top of the camera image. This will allow lap timers to be displayed during racing.. how cool would that be?!
Pro58 Achilles Performance Testing
In this test, I was flying my 3″ micro quad in the forest.
I had two pairs of goggles recording DVR at the same time, one with the True-D v3.6 module, and the other with the Pro58 Achilles. Both Goggles were using the exact same antennas (Spironet + Menace Invader) and facing the same direction.
The FPV setup of the quad is:
Disclaimer, this test doesn’t represent how good these modules and firmware are. There are simply too many factors can affect the results. This test is just to show you what the Pro58 Achilles module is capable of.
Anyway, from this test the Pro58 performed on par with the true-D, if not better. The signal quality was more consistent and had less break-up in some situations. Very impressive for what it does and the low cost!
Modes/Functions in Achilles
Here is a list of currently available modes in the Achilles firmware:
- Ultra Search
- Fast Mode
- Manual Search
- Event Mode
- Lap Timer
- Model Find
- Kerveros mode
- Band Scan
I have to say the naming is not the most intuitive about what these modes do, so I will try to explain what they are and how they work.
Ideally this is what you will be using the most.
Ultra Search mode scans the entire 5.8GHz band for any available channels extremely quickly (within a second). You can press the down button for the next available channel.
Sometimes due to the antenna or the environment, the actual broadcasting frequency can be slightly off. In this mode it can check the RSSI for frequencies +/-2MHz around the channel you are listening to, and choose the new frequency for the channel.
For example, if your quad is on F4 (5800MHz), but it has stronger RSSI at 5802MHz, the module will select 5802MHz as the new F4 channel.
Fast Mode & Manual Search
The two modes are similar but also different.
Manual mode is the same as fast mode if you only hit the button one time, it will move to the next channel. But if you hold down the button in manual mode, the frequency changes incrementally by 1MHz. In Fast mode, holding down the button will scroll through the channels quickly.
I find myself using Fast Mode a lot. I hardly use Manual Search mode, I guess it would be useful if you have a VTX that is using a custom frequency that doesn’t have a name :)
Event mode scans the entire 5.8GHz band and stores all the available channels, then you can switch back and forth between these channels. Great for spectating in racing events.
The lap timer uses receiver B, the patch antenna, to check the signal strength. The timer can record up to 12 laps and maximum 59 seconds for each lap.
Parameters in the lap timer:
- RSSI TRIGGER: set this value as the RSSI MAX that will trigger a LAP
- Threshold Pass: this is a delay in milliseconds. If the RSSI TRIGGER becomes true (RSSI is equal to or greater than RSSI TRIGGER), then the module has to make sure that RSSI TRIGGER stays true for this delay before adding 1 to the lap count. This prevents RSSI spikes and error
It’s recommended to race with 200mW VTX for best result, and point the patch antenna into a spot that the drone always pass through in every lap (e.g. the gate in front of you). It can take 2 to 3 laps to set it up correctly for the first time.
You can locate your crashed quadcopter with Model Find mode. I tested it a couple of times and it did work well! :) Especially if your quad doesn’t have a buzzer installed. However your quad must have the battery connected, and the VTX is still working after the crash for this to work…
This function basically uses your directional antenna on receiver B to check the signal strength. Because directional antenna has a narrow beam width, it can fairly accurately detect which direction your quad may have crashed.
The Kerveros Mode is an experimental feature, aims to give you the best possible signal when you are suffering from a low quality VTX that have poor RF performance, bad antennas or environment. Here is how it works:
The two receivers on the module are working independently, Receiver A will focus on the primary channel frequency, while receiver B will be wandering around frequencies around the channels, i.e. +/- 1MHz. And the module will choose the best signal for you.
For example, if you are on F4 (5800MHz), receiver A will stay on 5800MHz, while receiver B will scan 5799MHz and 5801MHz and see which frequency has the best signal.
It scans and draws a RSSI graphs of the entire 5.8GHz band.
You can permanently save up to 10 channels or custom frequencies in this list.
This determines how much higher RSSI has to be for antenna switching to happen. When Filtering is set to FAST, antenna switching happens more often; When it’s set to SLOW, switching happens less often; Default is NORMAL.
Frequent antenna switch can be annoying, but if it’s too slow the switching becomes irresponsive.
The Pro58 module is capable of checking RSSI 1000+ times per second. These RSSI values are stored, and we can get an average every now and then to decide if we should switch antenna.
This setting determines how many values you want to get the average from. The higher value, the slower switching will be. It might be slower to respond, but you can sometimes get a clearer and more stable result.
This setting depends a lot on the environment. For flying in open fields, or long range flying, it’s better to use larger value. For close distance flying with lots of obstacles, it’s better to use lower value.
Alarm level is the RSSI level in percentage. Every time the signal reaches critical level, your goggle beeps. You can turn it off if you find it annoying.
DIVS is the number of antenna changes – With the statistics, the two numbers with % you get a picture how much usage per antenna.
After flashing the firmware, the first thing you want to do is to calibrate it. Here are the instructions how.
Don’t worry about the calibration values, if something is wrong, the Achilles firmware will notify you. For example, if you do the calibration without a working VTX, the module won’t even start until you complete the calibration properly.
The Pro58 Achilles module have been reported working well with all sorts of Fatshark Goggles, except the Fatshark DomV1, because it has auto-contrast and this feature fades the OSD text.