SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jun 16, 2012, 10:18 PM
Registered User
Mesa Falcon Fld, Arizona, United States
Joined Sep 2004
426 Posts
Discussion
Any thoughts on a "universal" radio module (software defined radio transceiver)?

I have been looking through the threads seeing people that have been able to reverse engineer the various protocols that are being used in these proprietary 2.4 GHz radios and then doing a diy module, but has anyone thought about making a module that would be able to have a mode for all/most of the current 2.4 protocols out there? Perhaps even add 72 and 75 MHz (or other similar UHF frequencies). If this could be built into a single software upgradable module, then this would make for a great little unit. I am tired of seeing a new model come out that I am interested in only to find out that I need to buy another module. Also an rf module like this would facilitate a diy transmitter with much more capability. I am still in the learning stage of doing PIC microchip projects, so I recognize that this project is currently out of my reach, but what about the others that have done the single protocol diy modules, what are your thoughts about the viability of a project like this?

Adam
Aeroengineer1 is offline Find More Posts by Aeroengineer1
Last edited by Aeroengineer1; Jun 16, 2012 at 10:52 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 17, 2012, 05:28 AM
Registered User
Romania, Dolj, Craiova
Joined Sep 2007
14,945 Posts
Not sure how many people have so many receivers of various manufacturers to feel the need for such module. When this happens, they usually already have dedicated radios for each system, like a 9C for FPV LRS, a DX7 for their BnF "toys" and so on. Ask them if they feel the need to have only one radio for all, I might have a guess of what they reply.
To do such module for those not having any system atm, and not decided what to get... hmmm... not sure if this kind of buyers are the right target for a DIY hacking module :unsure:
For already existing modular radios, the limitation is mechanical, the module shell, before the protocol. There are already some chinese module makers showing is possible to transmit any protocol from any module type.
renatoa is offline Find More Posts by renatoa
Reply With Quote
Old Jun 17, 2012, 06:15 AM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
43,312 Posts
You can't switch frequency bands with software alone. The broader the required spectrum, the less sensitive the device will be.

One universal Rx for multiple Tx types in a band (i.e. 2.4GHz) might be viable, but it's really wasted effort given the relatively low cost of receivers these days.
..a
Andy W is offline Find More Posts by Andy W
Reply With Quote
Old Jun 17, 2012, 07:12 AM
Registered User
Mesa Falcon Fld, Arizona, United States
Joined Sep 2004
426 Posts
As I understand it, you can switch frequency bands with software alone, it is just that there is a loss of sensitivity proportional to the total bandwidth that you are trying to cover. The reason that I said transceiver as opposed to transmitter is I think that Spectrum and other 2.4 GHz systems require a 2 way transmission for binding. Basically this is a transmitter module.

As to who would use it. I have some Spektrum gear, 72 and 75 MHz, I have looked at some of the 9 Eagles stuff, and some of the Tower stuff, but I have not gotten any of those others because it is another $40-60 module to have to take out and store, hoping that I do not break the pins on my transmitter. It would be great to have a small selector switch to choose the protocol and run. As to having enough sensitivity to cover the desired bandwidth, I would think to have 2 rf ic's and switch between the two of them as needed.

Adam
Aeroengineer1 is offline Find More Posts by Aeroengineer1
Last edited by Aeroengineer1; Jun 26, 2012 at 10:54 AM. Reason: correcting errors from being done on my phone
Reply With Quote
Old Jun 17, 2012, 12:20 PM
Stuart
srnet's Avatar
UK, Cardiff
Joined Dec 2008
3,267 Posts
I would imagine that if someone was to produce a 'universal' radio, the manufacturers might just start encrypting the signals.

If such a universal receiver was 'open source' and easily modifiable, and you were an RC event organiser would you be happy to let people use 'universal' receivers they may have modified themselves to control fast moving aircraft ?
srnet is offline Find More Posts by srnet
Reply With Quote
Old Jun 17, 2012, 01:28 PM
Registered User
Mesa Falcon Fld, Arizona, United States
Joined Sep 2004
426 Posts
I am sure that they could end up encripting the data, but that would require an investment in hardware causing people to once again to have to upgrade their gear. As to the issue of people showing up at the flying field with these, well there are people that are coming to the field already with their reverse engineered modules for a single protocol. The number is low, and I would expect that you would not see thousands of these either. Just my thoughts, I think that I am going to at least search out what protocols have been reverse engineered and do some of the initial homework.

Adam
Aeroengineer1 is offline Find More Posts by Aeroengineer1
Reply With Quote
Old Jun 18, 2012, 09:23 AM
Radio? Screwdriver!
United Kingdom, England, Bristol
Joined Aug 2011
960 Posts
Quote:
Originally Posted by Aeroengineer1 View Post
As to the issue of people showing up at the flying field with these, well there are people that are coming to the field already with their reverse engineered modules for a single protocol. The number is low, and I would expect that you would not see thousands of these either.
Not many out there? I would say the opposite. All those OrangeRX/etc clones of Spektrum use a reverse engineered protocol - of which there are many thousands sold.

Changing the frequency is only part of the problem. Different 2.4GHz systems use different RF chipsets from different manufacturers. Each different chipset has a certain amount of modulation formats that they support. So a Texas Instrument chipset (CC2500 - used in FrSky, Graupner, Futaba S-FHSS, Hitec, etc) supports different modulation formats to a Cypress Chipset (used in Spektrum, Multiplex and others). Now some of these modulation formats may be the same across chipsets, but there is no guarantee that the implemented protocol uses that same modulation format.

However its not completely impossible to have a universal transmitter (or receiver) module. You'd probably have to have the different chipsets all on the same board, but its possible. After all the Futaba 18MZ has both chipsets on its RF board and switches between the two, depending if your using FASST or S-FHSS. Now these additional chipsets would push up the cost and complexity of the RF section. Also every protocol supported would have to be reverse engineered and tested, pushing up development costs.

Possible? Yes. Likely to happen? Maybe sometime in the future. I'm not certain how big the market will be though.

What is more achievable is to have a receiver on one Chipset that supports multiple protocols. So for example the TI chipset CC2500 is used by a number of RC manufacturers, hence all those that use it could potentially be supported. This is what I'm slowly pushing towards in the work I'm doing. Currently now I have done the Hitec protocol, the FrSky is detailed on here and the next in my firing line will be the Futaba S-FHSS protocol (when funds permit me to purchase the system).

Si.
SimonChambers is offline Find More Posts by SimonChambers
RCG Plus Member
Reply With Quote
Old Jun 18, 2012, 10:24 AM
Registered User
Mesa Falcon Fld, Arizona, United States
Joined Sep 2004
426 Posts
Simon,

I appreciate your constructive comments. I guess that I should clarify when I say not too many reverse engineered units out there; by that I mean in the context of DIY. I do understand that there are other units that are being sold by manufacturers that are clones. This would be strictly a DIY/Open Source venture.

I had not thought about the need for multiple chipsets, I would guess that it could be done with a single supplier chipset, but at the expense of having to manually reverse not only the communication protocol to the rf chipset, but also the encoding of the chipset itself. I would imagine that the multi chipset would not be difficult to accomplish, though added cost.

I will try and go back and look at your threads. This is something that interests me, so I figure that I though the learning curve may be steep, there is no better time to jump in. Two years ago I could not push code to a microchip, now I am writing simple programs using interrupts. Next on my list to learn are SPI, I2C, and USB communication protocols.

Adam
Aeroengineer1 is offline Find More Posts by Aeroengineer1
Reply With Quote
Old Jun 18, 2012, 10:49 PM
Registered User
Joined Apr 2012
14 Posts
"universal" radio module (software defined radio transceiver)

Aero,

"universal" radio module (software defined radio transceiver)

I am working on exactly this project right now, for fun and learning. This at a very early stage of planning/hacking. A quick brain/notes dump below, most of this is probably wrong and confusing and hard to follow. I will try to check back in a few days.


My rough plan is to prototype in gnuradio with a USRP. Then down the road I would like to implement a universal module for the 9x similar to the neTX project. The module would most likely contain a FPGA and a direct conversion transceiver. The exact hardware specs will be based on price (cheap) and the minimum specs required to hit most of cheap ISM chips used in RC. My main concern is current/future obfuscation/encryption of the data and/or hopping patterns/speed.

My initial hardware/protocol targets are based on the toys I own. From my initial RF captures of these all look possible, time will tell.

flysky
-amiccom a7105
-used in v911 and 9x

old nine eagles
- nordic nrf2401

new nine eagles, this may be a clone of another protocol
-j6pro
-cyrf6936


As of right now I have a very rough sdr transceiver talking to a nrf2401connected though a buspirate. I am calling this gr-nordic.

This is based on
https://github.com/kevinmehall/nRF24L01-buspirate
http://gr-clicker.sourceforge.net/


Tonight I am working on getting scavenged a7105 module talking to a buspirate in a similar setup. This will be used for prototyping gr-amiccom. I came to the forum to looking for the spi dumps posted a little while ago.


Next I am planning on implementing gr-flysky, running the flysky protocol on top of gr-amiccom. The hopping speed may be an issue here. After binding on channel 1 at 2.40ghz the TX immediately goes to 2.48x-ish and sequentially loops down though the band. This is beyond the 25mhz of TX bandwidth of the USRP/SBX and manual says to wait a few seconds for the PLL to lock after changing frequencies(>1e1 SECONDS). The datasheet for the ADF4350, other then hurting my head, looks like it has a quick locking mode(~10e-6 sec) at the cost of phase accuracy. There was a recent discussion on the usrp-users on this topic. Doing a non-hackish flysky implementation may require a custom firmware, I am just going to see what happens and what mood I am in when I cross that bridge.

The nine eagles j6pro with the cyrf6936 looks like it only uses three adjacent channels with are within the USRP/SBX bandwidth. I have not so much as opened the cyrf6936 datasheet, so I have no other thoughts here.

I am planning on putting all of my work up on github once I am further along.
zeza is offline Find More Posts by zeza
Reply With Quote
Old Jun 24, 2012, 01:14 PM
Registered User
Joined Mar 2009
1,088 Posts
Don't know if it can be what you're looking for, but the openlrs project is an open source RC TX-RX. I played a lot with it and can say it's easy to program and to modify. It supports frequency hopping, and bidirectional (telemetry) sending. It's range is a few kilometers, but it can be extended with a 7 W booster sent on the same site.

http://www.flytron.com/openlrs/146-o...ceiver-v2.html

forum :

http://forum.flytron.com/viewforum.p...1231bf6d96f73b
flipflap is offline Find More Posts by flipflap
Reply With Quote
Old Jun 24, 2012, 03:40 PM
Registered User
Joined Jan 2012
682 Posts
If you look at the Devo thread and Flysky thread, you'll see I'm working on this exact problem.
We (basically) understand the Walkera Devo protocol and the Flysky 9x protocol. And will start work on the DSM2 soon (which others on this forum have already decoded). We're working on an open Transmitter platform that will provide a standard API to interface with all known protocols.

The Devo telemetry module that can be had for ~$10 should be sufficient to talk to all CYRF6936 based receivers (Devo, DSM2, DSMX, Nine Eagles J6, etc) we just need to know the protocols, and that requires hooking up a logic analyzer to the SPI ports of a given module (not always a trivial task), and some guess-work/luck.

Additionally, an A7105 based board can be had for $3-$5, and that can be used for Flysky receivers. Both modules can be connected to the same SPI bus (though would need different enable pins). That is my plan for the Deviation firmware.

A universal system would require design and manufacture of a new board incorporating multiple RF chips, as I am not aware of any single chip that would be able to speak all protocols even in 2.4GHz much less at the 18/27/72MHz range. Designing such a board is probably not that difficult, but populating it would not be easy as many of these chips cannot be hand-soldered, which puts such a project out of range of most hobbyists.
PhracturedBlue is offline Find More Posts by PhracturedBlue
Reply With Quote
Old Jun 24, 2012, 05:35 PM
Stuart
srnet's Avatar
UK, Cardiff
Joined Dec 2008
3,267 Posts
Quote:
Originally Posted by PhracturedBlue View Post
Designing such a board is probably not that difficult, but populating it would not be easy as many of these chips cannot be hand-soldered, which puts such a project out of range of most hobbyists.
You can manage the QFNs packages at home, but getting just the right amount of solder past down is tricky. Too much and it bridges pads which can be quite a challenge to remove.
srnet is offline Find More Posts by srnet
Reply With Quote
Old Jun 25, 2012, 11:04 PM
Registered User
Joined Apr 2012
14 Posts
Quote:
Originally Posted by PhracturedBlue View Post
A universal system would require design and manufacture of a new board incorporating multiple RF chips, as I am not aware of any single chip that would be able to speak all protocols even in 2.4GHz much less at the 18/27/72MHz range. Designing such a board is probably not that difficult, but populating it would not be easy as many of these chips cannot be hand-soldered, which puts such a project out of range of most hobbyists.

First I would like to point out the "Direct Mode" of the A7105. IMHO of all the chips you are currently working with it is the most probable of working with a different vendors protocol.


Climbs on to soap box...

The problem with interoperability with all these cheap proprietary 2.4ghz ISM transceivers is that they integrate layer 1 and layer 2 functionality in an inseparable package. The layer 1, or PHY, is the (g)fsk/psk/msk mod/demod. The layer 2, or MAC, is the address, framing, ecc... everything above the bit level. This is a very rough description, but the concept is right.

The easy (relative), and cheap(< used car) solution to this is just to integrate all of the different proprietary chips into a single tx like PhracturedBlue describes. This works! They have stuff that works and I am just sitting here talking. The downside to this, is that it is a never ending battle to add new hardware every 2 years when the manufactures change the transceivers.

A real software defined radio would avoid most of the new hardware problems, and once you have the SDR hardware it is really easy. The hardware would work below the PHY level, use the right mod/demod library you are done. The problem is that the price for capable commercial hardware is not cheap (>= decent used car). However things are changing fast, with the right design scope and proper tradeoffs I think a real RC oriented SDR could be made for well under $200 by a hobbyist in single quantities. I think RC is one of the perfect applications for SDR technology due to the large number of similar but incompatible standards, and the modular nature currently deployed hardware base.


Example of SDR awesomeness (using decent used car priced hardware)-
Raw frame dumps from V911 tx binding ( first try, losing sync, dropping bits after the sync sequence)
Time to acquire - ~20 lines of python @ 80wpm.... <<5 min
Number of wires soldered == 0
Number of warranties voided == 0 (but I did these last two anyway)
Time to convert code to dump nine eagles - ~30 seconds

----------|--preamble--|-address1-|---|-address2-|-------------------payload------------| cksum| ----crap-to-crop-off-------
Frame=55 55 55 55 54 75 c5 22 39 92 4 0 20 67 8b 97 3a 3b aa e0 e1 5b 58 c8 0 0 0 6 1a 55 94 69 c5 dc e7 a0 b9 2d 78 8c 94 dd
Frame=55 55 55 55 54 75 c5 35 55 24 10 0 81 9e 2e 5c e8 ee ab 83 85 6d 63 20 3 fc 3c 18 68 c8 1a b0 2b 6d f4 db 76 66 59 c9 c3 38
Frame=55 55 55 55 54 75 c5 3f e5 24 8 0 40 cf 17 2e 74 77 55 c1 c2 b6 b1 90 1 fe 1e c 34 64 d 49 99 8a 3e 93 29 d3 8c 31 1e 26
Frame=55 55 55 55 54 75 c5 35 55 28 10 0 81 9e 2e 5c e8 ee ab 83 85 6d 63 20 3 fc 3c 18 68 c8 1a ff 8f c0 d4 63 9e b2 2 9f 92 c4
Frame=55 55 55 55 54 75 c5 36 aa 92 4 0 30 4 3 6c 82 f4 1 ef 2 ad ac 2d 81 12 0 0 0 32 1d 6c 11 8c 8e db 2a d9 83 64 95 c9
Frame=55 55 55 55 54 75 c5 2a d6 92 4 0 20 8 6 d9 5 e8 3 de 5 5b 58 5b 2 fe f 0 0 8e 84 49 e5 af 9b a1 11 1c 47 93 cf f0
Frame=55 55 55 55 54 75 c5 25 55 24 c 0 20 8 6 d9 5 e8 3 de 5 5b 58 5b 2 fe f 0 0 8e 84 39 31 3b b7 bd 35 be 53 eb 80 35
Frame=55 55 55 55 54 75 c5 25 55 24 8 0 40 20 1b 64 17 a0 f 78 15 6d 61 6c b f8 3c 0 2 3a 10 98 9a ec 61 9e 65 5f 19 8d f8 bc
Frame=55 55 55 55 54 75 c5 2a aa 92 4 0 20 8 6 d9 5 e8 3 de 5 5b 58 4f 2 48 0 0 0 fc 70 c9 6c 6b d8 1 8c 79 8c 14 c4 2
Frame=55 55 55 55 54 75 c5 22 aa 92 4 0 20 8 6 d9 5 e8 3 de 5 5b 58 4f 2 32 0 0 0 42 6 9b c7 91 a1 9f a9 9d a 1f dc 2
Frame=55 55 55 55 54 75 c5 3a aa 92 4 0 40 10 5 b2 b d0 7 bc a b6 b0 9e 5 fe 1e 0 1 c8 2a b6 e6 53 4b 2d 26 6a 2e 9f c 3b
Frame=55 55 55 55 54 f5 c5 3b d6 92 4 0 20 8 6 df 5 e8 3 de 5 db 5e 4f 2 ff f 0 0 e4 15 3b 4a cd ec db 73 f6 a6 13 db 32
Frame=55 55 55 55 54 75 c5 2b f9 92 4 0 20 8 6 d9 5 e8 3 de 5 5b 58 4f 2 ff 7 0 0 e4 15 71 cc 68 8e 65 65 7f 2 ee 24 1b
zeza is offline Find More Posts by zeza
Last edited by zeza; Jun 25, 2012 at 11:08 PM. Reason: added dashes
Reply With Quote
Old Jun 29, 2012, 04:15 PM
Registered User
Mesa Falcon Fld, Arizona, United States
Joined Sep 2004
426 Posts
Zeza,

Would it be possible to give a brief introduction to how you are going about your analysis. Things such as the tools that you are using, and the software? It would be interesting to see.

Adam
Aeroengineer1 is offline Find More Posts by Aeroengineer1
Reply With Quote
Old Jul 02, 2012, 12:11 AM
Registered User
Joined Apr 2012
14 Posts
Quote:
Originally Posted by Aeroengineer1 View Post
Zeza,

Would it be possible to give a brief introduction to how you are going about your analysis. Things such as the tools that you are using, and the software? It would be interesting to see.

Adam
I am planning on doing a write up after I have a system working. I have been trying to take pictures/videos/notes as I go.


I am using gnuradio and a usrp/sbx.
The standard gnuradio blocks filter and demodulate the signal. From this I get a binary stream of the signal or static, which needs to be parsed.

At this point I am pretty much finished with the rx side of the flysky protocol. The next time I sit down on this project it is tx time



http://gnuradio.org/
https://www.ettus.com/product/details/UN210-KIT
https://www.ettus.com/product/details/SBX
zeza is offline Find More Posts by zeza
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Is there an adapter to change modules on a non-module radio aeajr Radios 2 Jun 07, 2012 10:14 PM
Discussion Realtek chip can be used as a Software Defined Radio 64Mhz to 1700Mhz NorCalMatCat FPV Talk 5 Apr 03, 2012 08:46 PM
Help! How should I do? Spektrum JR modul to be used on a Sanwa/Airtronics radio??? marell01 DIY Electronics 0 Mar 22, 2012 05:37 AM
Help! Spektrum JR modul to be used on a Sanwa/Airtronics radio??? Suggestions please!!! marell01 Radios 0 Mar 15, 2012 09:00 AM
Help! Futaba Radio with TM-7 FASST Module - Any tips aeajr Radios 12 Jan 18, 2012 05:16 PM