RFD900, RFD900+ - New long range radio modem - Discussions

Hi All,

I would like to introduce you to a new radio modem that we developed for very long range datalinks!

http://rfdesign.com.au/RFD900.php

Some of the key features of the RFD900 are as follows:

Multi point and point to point link capability.
Long range >40km depending on antennas and GCS setup.
2 x RP-SMA RF connectors, diversity switched.
1 Watt (+30dBm) transmit power.
Transmit low pass filter.
> 20dB Low noise amplifier.
RX SAW filter.
Passive front end band pass filter.
Open source firmware / tools, field upgradeable, easy to configure.
Small (30 x 57 x 13 mm), light weight (14.5g).
Compatible with 3DR / Hope-RF radio modules.
License free use in Australia, Canada, USA, NZ.

These modems are designed to support long range applications, while being easy to use and affordable.

These modems have been flying in various platforms and have demonstrated excellent performance in real applications.

RFD900 modems are now available at: http://store.rfdesign.com.au

Support within APM planner and the radio configurator from Michael Oborne is already available.

It works seamlessly with APM planner, all radio Mavlink parameters are available.

Update, December 2014: The RFD900+ with improved specifications is available now at:

http://store.rfdesign.com.au/rfd-900p-modem/

Seppo Saario

rfdesign.com.au

Hi Seppo,

I'm an user of the RFD900+ modem and I'm currently in the process of homologating this product in respect to the brazilian radio emission regulations, so I can use this modem here, but I'm facing a problem that I think you maybe can help me with.

The brazilian regulation allows the use of the 915-928MHz range, similar to that of Australia.

The problem I'm current facing is that the modem is emiting spurious frequency (909.966MHz) which is not under conformity with the local regulation (which denies the 907-915MHz range).

I'm sending the spourious frequency analysis attached so you can see the problem.

I'm configuring the modem to use the 915-928MHz range, and this problem occure while the modem is finding a link. When it links to the other modem, the problem stop.

Did you already see this problem before?

Thank you in advance.

unnamed.png

Replies

Michael Shanaher August 30, 2016 at 4:32am

Hi all. I am using the RFD900+ modems for my high altitude UAV project and am about to conduct a range test. The goal is determine the maximum range afforded by the dipoles and see if I need to use a directional antenna to meet the requirements.

Part of this testing will involve changing some of settings and seeing how the radios perform in our environment, the aim being to find a balance between power consumption, telemetry rate and range.

I have a few questions:

Does anyone have any experience with experimenting with the number of FHSS bins? The obvious choice is the maximum number available in order to minimise the effects of noise. However, is there any advantage in selecting fewer bins? I could see there being an advantage of increased data rate if the dwell time is increased as the number of bins is decreased but I'm not sure if that's how it works. On that note, can anyone tell me what chip is being used so I can get a data sheet and look at how FHSS is implemented and how the number of frequency bins parameter affects the link.

I'll be sure to post back with the test set up and results.

FYI: we're aiming for 50 to 100 km.

Regards,
Mike
Mike Mac August 29, 2016 at 9:58am

I have several 900+ units that i run in multi-point mode. The problem is that RSSI does not work. I really like to have TM RSSI recorded by the ground station. They said that it was a know problem and the nest firmware update would fix that bug. That's been way over a year ago. Seams like they spend time selling us new products and not fixing bugs on there current products.

Looks like that Graph above is an example of another bug that's probably existed for a very long time.

.
3qs7z40lxxok2 August 29, 2016 at 6:26am

Mike Mac said:

Why are we getting zero support from the manufacturer?

Have look at this setup i have just removed my RD900+ for this setup

http://www.rcgroups.com/forums/showthread.php?t=2037442&pp=100
Developer

davidbuzz August 29, 2016 at 3:25am

please explain what you've tried, and why you fee that way..?

Mike Mac said:

Why are we getting zero support from the manufacturer?
Mike Mac August 29, 2016 at 3:21am

Why are we getting zero support from the manufacturer?
Developer

davidbuzz August 28, 2016 at 8:08pm

the RFD900 is not open hardware, so the complete diagram isn't available.

lixiaoming said:

do you have a circuit diagram of RD900
lixiaoming August 28, 2016 at 7:37pm

do you have a circuit diagram of RD900
Rafael Araújo Lehmkuhl August 19, 2016 at 11:53am

Hi Seppo,

I'm an user of the RFD900+ modem and I'm currently in the process of homologating this product in respect to the brazilian radio emission regulations, so I can use this modem here, but I'm facing a problem that I think you maybe can help me with.

The brazilian regulation allows the use of the 915-928MHz range, similar to that of Australia.

The problem I'm current facing is that the modem is emiting spurious frequency (909.966MHz) which is not under conformity with the local regulation (which denies the 907-915MHz range).

I'm sending the spourious frequency analysis attached so you can see the problem.

I'm configuring the modem to use the 915-928MHz range, and this problem occure while the modem is finding a link. When it links to the other modem, the problem stop.

Did you already see this problem before?

Thank you in advance.

unnamed.png
Moderator

Alexandre Mainardi (Nuvem UAV) August 15, 2016 at 8:17am

Thanks Davidbuzz, but even using the "AT Commands" the Min value for NUM_CHANNELS is 5. Do you think the module would accept me to put the value 1 ?

davidbuzz said:

check the AT commands. there's one for setting the number of hopping channels. if you set the number of channels to 1, you should get what you are after. be aware thoogh that using the radio in this configuration and at full power almost certainly violates US and australian emissions regulations, so you are best to insert an attenuator in the antenna line, or do the tests in a sheilded environment. etc.

Alexandre Mainardi said:

Hi everyone,

We are trying to put RFD900+ in a single channel (non-hopping) mode to execute some frequency tests, does anybody have a hint to put the module in "Test-Mode"?
Developer

davidbuzz August 15, 2016 at 7:30am

check the AT commands. there's one for setting the number of hopping channels. if you set the number of channels to 1, you should get what you are after. be aware thoogh that using the radio in this configuration and at full power almost certainly violates US and australian emissions regulations, so you are best to insert an attenuator in the antenna line, or do the tests in a sheilded environment. etc.

Alexandre Mainardi said:

Hi everyone,

We are trying to put RFD900+ in a single channel (non-hopping) mode to execute some frequency tests, does anybody have a hint to put the module in "Test-Mode"?

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