ARRI RF900 Radio Modules

ARRI’s RF-900 Radio Module 900 MHz FHSS is now finally shipping. I caught up with Tobias from ARRI at Cine Gear 2023 to talk about the RF-900.

RF-900 Radio Module 900 MHz FHSS

The RF-900 is only for use in the USA and Canada as it works on the 900 MHz spectrum (902-928 MHz). It also uses a frequency hopping system and as it isn’t operating on the heavily congested 2.4GHz spectrum, you should, in theory, get a lot better range and less interference. This radio module will be better at sending the signal through walls and other solid objects.

The transmission power is 100mW in Standard Mode, but there is also a Hi-power Mode with is 1W.

Radio Modules

ISM bands have so much wireless traffic on them that coming up with wireless modules that have good range and good immunity from interference is no easy task. ISM bands are used for low-power and short-range telecommunications, such as WiFi, Bluetooth, Zigbee, wireless telephones, RFID, and NFC.

Given all of these challenges, ARRI decided to do away with the inbuilt antenna that was used on the WCU-4 and move to a new modular radio system. In addition, instead of having the radio module at the top of the hand controller, like it was on the WCU-4, ARRI has now moved the position to the back of the Hi-5 controller.

The chipset in all of these modules is the same one as those that are in the ERM external radio modules that ARRI uses in products such as the SH-3.

The chipsets on RF-900 and RF-2400 are related to the ones used in the ERM radio modules used for ARRI SRH-3.

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There are three different Radio Modules available:

  • RF-EMIP Radio Module 2400 MHz DSSS
  • RF-2400 Radio Module 2400 MHz FHSS
  • RF-900 Radio Module 900 MHz FHSS

At launch, only the RF-EMIP Radio Module 2400 MHz DSSS was available.

The modules are incredibly small and ARRI has been able to shrink them down to the size of a matchbox.

RF-EMIP Radio Module 2400 MHz DSSS

Instead of using the FHSS system like the RF-2400, the RF-EMIP utilizes DSSS (direct sequence spreading spectrum). With this radio module, you need to physically choose from 14 different channels to operate on.

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The RF-EMIP is directly compatible with the in-built radio modules that are already found in the ALEXA 35, ALEXA MINI LF, ALEXA LF, and the cforce Mini RF motors. Depending on what region you are in, the transmission power varies from 8.9-70.8mW. This radio module works with up to three handsets.

RF-2400 Radio Module 2400 MHZ FHSS

If you are not familiar with the letters FHSS they stand for frequency hopping spread spectrum. As the name suggests this means that the RF-2400 has the ability to automatically hop around between 99 channels so that you get the least amount of possible interference.

The RF-2400 transmission power is 100mW.

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