Earlier this year an engineer by the name of Shea Ivey released an exciting new aftermarket upgrade for the popular FatShark Dominator FPV goggles: the La Forge FPV Diversity Pro receiver module (or rx5808-pro for short). This 5.8GHz module sports a bright OLED display, spectrum analyzer, automatic channel scanner, infrared VTX programmer and optional diversity receiver module. I was lucky enough to snag an initial run version of the module through U Buy A Drone (“UBAD”) earlier this year. Read on to find out how I have been getting on with this exciting bit of kit.
Historically FatShark have never offered any diversity receiver capability on their FPV goggles. This has often been a missed feature on what are otherwise market leading products. With the Dominator range of FPV goggles, FatShark added a replaceable video receiver module, allowing 3rd party products like the La Forge FPV diversity module to be created. Signal diversity is a desirable FPV feature whereby two (or more) receivers - usually with different types of antennae - can be teamed up to provide improved video quality and range.
FatShark competitors such as SkyZone have been selling FPV goggles with diversity capability for some time now, so this is a great time to launch such a product. There are also other options for adding on-board diversity reception to the FatShark Dominator goggles: the Flying Lemon 2Pineapples module and the original RX5808-Pro DIY module which this product is derived from. External receivers (such as the eye-wateringly expensive Iftron Tech ClearView Pro) have always been an option for diversity but this necessitated the use of extra equipment like a tripod. The La Forge FPV product offers features which the competition does not: an easily readable OLED screen, spectrum analyser and IR transmitter. The IR transmitter is for configuring the La Forge FPV transmitter which is sold separately.
The main La Forge FPV diversity module is available for $69.99 (USD), while the optional diversity receiver costs $39.99. To take full advantage from the system both parts are recommended, and can be bought in a combo pack for $99.99. Shea Ivey has partnered with UBAD to manufacture and sell the La Forge FPV products. I bought the modules being reviewed here from UBAD for approximately £70 not including international delivery.
The product page for the module gives a good overview of the system:
The LaForge Pro module is a 5.8GHz spectrum scanner with OLED display and a load of features that will forever change the way you FPV. Designed exclusively for the Fat Shark module bay. With this main module you will immediately have the power to quickly tune into your crafts channel, or scan the spectrum to find a free channel, or even tune into a friends channel. But it doesn’t stop there; add the diversity module for an even more reliable FPV experience or get the video transmitter (April 2016) that can quickly bind to the LaForge Pro Module.
The main module sports a small three-way ‘jog wheel’ providing navigation through the various menu screens shown on the brilliantly bright OLED screen. During normal operation the screen shows the current channel, call sign and RSSI (signal strength) for the video downlink. Three LEDs (and a buzzer on the diversity module) provide further user feedback on the module’s status. A large tantalum capacitor and dual antenna filter provide clean power and video signals.
The optional diversity receiver is a simpler module which contains another 5.8GHz rx-5808 receiver, status LEDs, buzzer and connector to interface to the main module. As the FatShark Dominator goggles were never designed to take two receiver modules, the diversity module must be attached to the outside of the goggles, usually over the head-tracker module bay door. The La Forge FPV website states:
Adding a secondary receiver gives another layer of reliability and allows for different types of antennas to be used simultaneously so you can feel confident you are getting the best signal.
The diversity module is simply connected to the main module with the supplied cable harness and works right out of the box.
I pre-ordered my La Forge FPV diversity combo set from UBAD two days before the 10th March release date, and it arrived from the USA in a large anonymous looking cardboard box on the 22nd March. Knowing that the modules are in short supply, after placing my order I sent a website enquiry to UBAD to ask if my order would be included in the initial first shipment or whether I would end up waiting a few weeks, but there was never a response to this message. I also enquired why my order status was apparently stuck on ‘pending’ about ten days after the release date (and payment), with no reply. I’d like to give the guys at UBAD the benefit of the doubt here given the popularity of these new products.
Both the main module and the diversity module are packed in these nifty hard plastic cases which make great storage boxes for when not in use. Also included in the package were UBAD and La Forge FPV stickers. No printed instructions were included, but these are available on the UBAD website.
The main module pack contains the receiver module, the diversity module wiring harness and a double-sided adhesive pad.
The receiver module appears to be assembled and soldered to a good standard. The OLED screen ships with a protective film which can be optionally removed by the user. In the lower left corner of the module is the pin header for the ICSP programming interface, which is how the firmware on the module is updated using a PC and special cable. No 3x2 male header is provided with the module, so this must be obtained separately and then soldered on by the customer. If you’d prefer not to take a soldering iron to the board, Shea Ivey has posted a YouTube video demonstrating how to upgrade the firmware by push-fitting the pin header on the board.
The rear of the main module has a metal RF shield and male header pins for connecting the module to the FatShark goggles. The shield is push-fit on to the receiver and will be pulled off by the strong adhesive pad when removing the module from the goggles - therefore you may want to consider adding a little hot glue to the shield to keep it intact.
This side view of the La Forge FPV diversity module shows the infrared transmitting LED (for wireless programming of the La Forge VTX), jogwheel and OLED screen. The OLED screen is attached to the main circuit board with only a 4-pin header along the top edge which makes the unit quite fragile. There was also no metal surround provided to protect the glass edges of the screen, but these are being included on the latest manufacturing batch.
One good feature of Shea Ivey’s module over and above the DIY module referenced above is the use of a dual filter on the antenna which helps in the overall quality of the video.
The optional diversity module is not quite as exciting to look at as the main module, with just a buzzer and another 5.8GHz receiver module. A self-adhesive foam pad is also included to fix the module to the exterior of the FatShark goggles.
Both the main module and the diversity module are only available with SMA antenna connectors, which is the standard for official FatShark receiver modules. The red plastic protective boots are provided to keep the connectors clean and safe when not in use.
I had been baffled by the “Remove seal after washing” sticker on the buzzer, but then found out this is in reference to the solvent washing process during manufacturing where the solder flux is cleaned from the PCB.
The back of diversity receiver simply sports the La Forge FPV logo.
The overall concept of the La Forge FPV diversity system is a good one - a slave receiver module is attached to the head-tracker bay door with an adhesive pad and connects to the main module with a cable. As there is no space inside the FatShark goggles for a secondary module to be fitted, this is as good as it gets, but works well.
Installation is very straightforward and simply involves removing your existing RF module from the Dominator goggles, plugging in the new La Forge FPV module, and (optionally) connecting and affixing the slave receiver to the outside of the goggles. The OLED screen protrudes from the main circuit board to an extent where the RF module bay door will not fit back on. 3D printed replacement bay doors are available to download from Thingiverse or to buy from Great3D.
The white interconnecting cable sits on the outside of the goggles by default, optionally being secured with some adhesive tape (not included) or the included La Forge ‘visor’ sticker. Alternatively the FatShark goggles can be disassembled and the cable routed inside the goggles - however this requires taking a Dremel tool to the goggles to create an opening for the cable and disconnecting the tiny PFC ribbon cables inside the goggles to get them open. The beta version of this system did not have a white coloured wiring harness (it was red and black) so it’s good to see La Forge FPV have made this aesthetic change for the better.
The main La Forge FPV diversity module has the same footprint as other FatShark RF modules, but is taller due to the OLED screen.
Before picking up my La Forge module I had been using this FatShark Raceband 40-channel 5.8GHz module released last year. The FatShark module changes bands via a physical DIP switch, so the La Forge module will make changing FPV bands much easier.
Dropping the module in to the Dominator’s RF bay was a breeze and it readily slotted in to the pin header at the back of the module bay. Every module I have fitted to these Dominator goggles have had some ‘play’ or looseness in the pin header connection, including this La Forge module. Thankfully the included adhesive pad which goes on the back of the module is very strong and keeps it secure even with a large antenna attached.
The La Forge modules use FatShark compatible SMA connectors for the antennas. The La Forge products do not include any 90-degree SMA adapters so these will need to be purchased separately (if required). For now I’m just bending the coaxial cable on this ImmersionRC SpiroNet antenna which works fine.
The diversity receiver module is then stuck to the headtracker bay door using another self-adhesive foam pad.
I was initially dubious that an adhesive pad would be strong enough to support the module with an antenna attached, but it is actually very secure as the adhesive pad is very strong. A little care is needed when fitting the slave module to make sure that the 3.5mm port on the goggles is not blocked by the PCB. The module also needs to be positioned along the curve of the goggles so that the back of the SMA connector doesn’t stop the adhesive pad from making complete contact with the door.
In the long-term, I plan to use a Video Aerial Systems IBCrazy 5-turn helical antenna on the slave module, but I have been testing the system so far with this comically oversized 13dBi ImmersionRC patch antenna. The patch antenna provides longer range in a forward facing direction, while the cloverleaf antenna provides good omni-directional reception for close range flying.
The La Forge module boots up when power is connected to the goggles. The user is greeted with this amusing Star Trek Geordie LaForge picture and the firmware version. This module from the first production run was shipped with version 1.4 of the firmware but current modules are shipping with version 1.5. The module firmware can be upgraded using the six pin connector shown earlier. More information about firmware updates and improvements can be found here.
The diversity module has some great features. This section will show most, if not all, of the user interface screens available on the unit.
After displaying the boot logo screen a power on check screen show’s the module status. The diversity mode will show ‘disabled’ when the slave module is not connected (there was nothing on the other end of the wiring harness in this example).
A customisable ‘call sign’ can be entered in the settings screen, which will then be displayed on the above boot screen. Presumably the purpose of this feature is to automatically configure a La Forge IR-programmable video transmitter with this call sign.
Visible in the upper right corner of the module are the three status LEDs. From top to bottom these are power, status and receiver-active. The last LED shows whether or not the diversity system is using this receiver module at the moment. There is no buzzer on the main module, but if a diversity module is connected, the buzzer will sound when the status LED is illuminated.
After the bootup sequence has finished - which takes about three seconds - the module is ready to use and enters ‘auto’ mode. In ‘auto’ mode, the jog wheel is pushed up or down to start a scan which locks on to the nearest good signal (just like most car radios). The number in the top right corner of the screen shows the currently selected frequency (in MHz). In this photo there are no transmitters nearby and as such there is no spectrum analyser output in the lower part of the screen.
The OLED screen on the module is superb and is easily viewable in the dark or full sun. Using a OLED screen rather than an LED backlit LCD was a great choice given most people will be using the product outdoors on sunny days.
After a short while the display switches to this ‘screen saver’ mode which shows the currently selected FPV channel, callsign, frequency and RSSI level. Depending on whether a diversity module is connected, the lower part of the display will show one or two RSSI bar graphs.
In addition to navigating up and down, the jog wheel control can be pushed inwards as a selection button for navigating the menus. Pressing the wheel inwards when the module is at the ‘screen saver’ display will bring up the main menu.
From the main menu automatic or manual frequency selection modes can be accessed, as can the band scanner feature. The gap in the menu will offer a diversity menu whenever the diversity module is connected. Lastly, a setup menu offers some configuration options such as setting the callsign parameter.
In the band scanner mode, which accessed from the main menu, the module continually scans the 40 FPV channels in the 5.8GHz band. The results of the scanning are plotted in a graph as seen above. The channel with the strongest reception is shown at the top of the screen. This is a fantastic feature which is normally only available with very expensive specialist radio equipment. Having a band scanner available lets FPV pilots select an unused channel with the lowest background noise for optimum performance. It’s very useful to have on hand at race/club meets where there are several transmitters in use at any one time.
In the photo above, the only transmitter in the vicinity is an Aomway 200mW VTX (fitted to a Mini Skywalker plane). I was surprised to see that the La Forge module displayed this as ‘maximum’ across approximately 50MHz of the spectrum. It is not possible to determine the exact output frequency of a given VTX using just the band scanner function. I wonder whether the scanner would be more helpful showing a logarithmic scale graph, assuming it doesn’t already.
In the remainder of these user interface photos, the diversity module has been connected. This subtly changes some of the screens to show extra diversity information.
In addition to the default ‘auto’ mode, a manual receiver tuning mode can be selected from the main menu. This allows sequential channel selection using the jog wheel. There is an option in the settings screen to switch between using the frequency or the channel letter/number for both the auto and manual tuning modes.
The setup menu can be accessed from the main menu and offers a few customisation options. The order setting alternates between tuning using the frequency or the channel number. The beeps setting enables/disables the buzzer on the diversity module. The callsign setting has been explained earlier in this review and can be up to 10 characters long. The VTX setting allows the user to remotely change the power output level of the La Forge FPV video transmitter (if being used) between 25mW, 200mW and 400mW. Calibrate RSSI switches to another screen (below) where the two receivers can be calibrated for proper diversity switching.
This is the RSSI Setup screen which is accessed through the settings menu. In this screen the module determines the minimum and maximum signal strength levels for each receiver. The instructions recommend carrying out the calibration procedure at the start of every flying session, to account for varying levels of background noise.
When the La Forge diversity module is connected, this extra ‘diversity’ screen becomes available from the main menu. This screen shows the current signal strength (RSSI) on both receivers and allows forcing the use of only one receiver. The instructions make no reference to which receiver is A or B, so presumably receiver A is the main module and B is the diversity slave module.
With the diversity module active, the ‘screen saver’ screen now shows two RSSI bar graphs.
I have been using the La Forge FPV diversity system with the FatShark Dominator V2 goggles for a couple of months now and despite a couple of minor niggles, I’m thoroughly pleased with it. La Forge FPV and UBAD have brought some great additional functionality to the world’s most popular range of FPV goggles.
The OLED screen and jog-wheel combine to provide a crisp and readily accessible user interface which can still be used to switch channels with the goggles on. The user interface screens are well thought out and relatively self-explanatory.
Performance of the video receivers is very good, being subjectively better than the standard FatShark NexwaveRF based modules. When the diversity system is active, signal switching is unnoticeable during FPV flying.
If you’re comfortable working with electronics and a soldering iron, a similar solution can be home-brewed using the open source software and original rx-5808 diversity design that this product is based upon. However for £70 I think the La Forge diversity modules offer superb bang-per-buck considering all of the extra features which the system provides. It’ll also be difficult to get a DIY system to be compact enough to fit on the goggles rather than on a ground station.
There are a few minor issues with the La Forge diversity module though. The module does not boot up to the last used channel so it must be re-tuned at every power-on, which can be inconvenient at best and could result in a crash in the worst case scenario. The spectrum analyser and auto channel tuning appear to be too sensitive, making the analyser screen difficult to interpret and the auto tuner locking on to the wrong channel when only one transmitter is active. I expect that these types of issues will be addressed by Shea Ivey in future firmware updates - but then an Arduino is needed to update the firmware.
On the hardware side, the module protrudes out of the RF module bay, putting the glass on the OLED at risk of accidental damage. Whilst the latest versions of the module include a small protective metal surround for the screen, it would have been good to see the module ship from day one with a replacement module bay door. Lastly, the supplied mega-grippy adhesive pad makes removing the module difficult, usually resulting in the RF shield on the back getting pulled off and/or bent.
These drawbacks are relatively minor though, and don’t really take away much from what is overall a brilliant and innovative product for the FatShark Dominator goggles. I expect that many of the above issues will be addressed by La Forge FPV as the product is further refined over time. Whether you’re flying FPV planes or racing drones, If you want to add portable 5.8GHz diversity reception to your Dominator goggles, this is the product to get. Act quickly though, as these are in short supply and you’ll probably need to wait it out on a pre-order list at one of the approved retailers.
- La Forge FPV Homepage
- RCGroups Forum Thread on Original DIY Diversity Project
- rx-5808 Project on GitHub
- 3D Printed Module Bay door for La Forge Module
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