Radio control binding

[WB4JFI]

I have some Spektrum RC gear, a DX7 transmitter and several receivers.  It does work rather nicely.

>From what I have read, it relies on specific RF chips, made for the 2.4GHz ISM band.  It is also direct sequence spread spectrum, not frequency hopping.  I’m not sure how or what we could use it for.  Syncing direct sequence and frequency hopping can be totally different animals.

There are also several clock oscillators for computer CPUs that use spread spectrum so they don’t constantly interfere with other devices.  The good news is that they only interfere some of the time – with potentially more devices.

I think we are/were looking to use FHSS on VHF/UHF frequencies, not at 2.4GHz.  That’s too much like broadband, HSMM, or whatever it’s being called this week.  I have a pile of WRT-54Gs that are not doing anything already, and with folks moving up to 5GHz, it seems like they were yet another waste of funds.

IIRC, the renewed interest in FHSS was because Andre wanted to do something with simpler hardware (Arduino Uno & DDS modules), that could be duplicated by the average ham without difficulty.  If pre-built devices CAN be hacked into a simple ham-related project, that would certainly fulfill his goal.  I don’t think the Spektrum RC stuff and be, but I’m willing to learn otherwise!!
73, Terry, WB4JFI


From: Mark Whittington 
Sent: Tuesday, January 20, 2015 4:47 PM
To: Alex Fraser 
Cc: tacos at amrad.org 
Subject: Re: Radio control binding

I looked into this myself a while back.  One of the more popular RC protocol families is Spektrum DSM2 and DSMX.  Apparently it's been completely reverse engineered and there are example implementations out on the net.  The official radios are based on the Cypress CYWUSB6953 PSoC+Radio chip. 

http://datasheet.octopart.com/CYWUSB6953-48LFXC-Cypress-Semiconductor-datasheet-17723564.pdf


http://www.cgsy.com.au/archives/215 discusses the DSMX protocol


This post in a larger thread has links to a bunch more info: http://www.rcgroups.com/forums/showpost.php?s=07273ba7d35902817e79bbdf30110409&p=7916481&postcount=6



On Tue, Jan 20, 2015 at 2:26 PM, Alex Fraser <beatnic at comcast.net> wrote:

  It used to be that in radio control you picked a frequency for your transmitter and for your receiver.  There were channels on 6 meters and at 72 and 75 MHz. You depended on being the sole user of a frequency to guarantee that you were in control.  Back then you would tie a ribbon to your antenna which told every one which channel you were on so no one would accidentally jam your signal and cause you to lose control.

  These days the frequency used has has changed to 2.4 gig.  You turn on your receiver and your transmitter and Bind them.  The Transmitter handshakes with the receiver and they create a unique link.  Everyone using the field can use the same band and the radios don't interfere with each other.

  There has been some threads on this reflector about spread spectrum (ha, an understatement for sure!) and recently been some talk on syncing signals.   I wonder if folks here have looked at what is happening with modern RC radios?  BTW as I understand it these new transmitters have flash-able bios and considerable programing capability so there is a possibility of re purposing the gizmo.

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