Thursday, November 19, 2009

eXRS? Anyone try it?

So, I was looking in the store today and ran across this walkie talkie that caught my attention.  It's by a company called Tri Square but that's not what caught my eye.  It is like FRS, but it's digital and uses frequency hopping technology to help make it secure.  This is pretty exciting technology and its been around for years.  The radios have to be sync'd together beforehand and decide on a number.  Then, when you want to talk, you put in that number and it calls the other radio.  Once you start talking, the radios start changing frequencies based on a common algorithm- so, even if someone else does find out a frequency your on, it changes in a less than a second, so they don't get the whole conversation.  We used similar radios when I was in the police department to stop citizens from using scanners to listen in on us. Also, with this higher end model it will record the last transmission from the other person so if you miss their radio call- they can leave a message!  I'm not trying to advertise for them- I don't care if you buy one or not, but from a COMSEC point of view, this could be a very valuable tool for communicating with those in your group.  This was advertized for $100 and includes 2 units, batteries, wireless headsets and a base charging unit.  They also make it in real-tree.

This is from their site:

eXRS (eXtreme Radio Service) is the new digital two-way radio service operating in the 900 MHz band [Jimmy: this means it can travel through building better than the HF waves but requires more line of sight]. eXRS goes beyond FRS and GMRS. eXRS uses frequency hopping to make it possible to have private and secure communications. eXRS puts an end to annoying interference from other users on the same channel. Because eXRS radios constantly hop from one frequency to another, your conversation cannot be overheard on a scanner or another radio. In addition, eXRS radios, unlike FRS/GMRS radios are license free and are legal for all users of all ages and for personal and business purposes.




That’s a bold statement and true, but of little practical value to the user.

The truth about Radio Range on the planet Earth

The actual range of eXRS and all other UHF two-way radios including FRS and GMRS (walkie-talkies) is effectively the same, regardless of transmit power. The total range is greatly diminished by the effects of the atmosphere, trees, buildings, hills and all other environmental conditions in the area of use.

Portable UHF radios are effectively straight-line communications devices. It is the path that establishes usable range, not the transmit power.

The Earth is not flat.

Even the curvature of the Earth limits the straight-line path. The average curvature of the Earth dictates an average maximum range of 6 miles.

There are certain conditions that will extend the straight-line path to more than one hundred miles (mountain top to valley, for example) and there are many conditions that will obstruct the straight-line path to less than one mile.

Shorter Range Conditions

Longer Range Conditions

Beware of advertised range claims. Advertised range has grown over the last few years from a couple of miles to 30 miles and more in an effort to distinguish product pricing. All good quality portable UHF radios, regardless of range claims, will perform essentially the same under the same conditions. It is unlikely a user will normally experience a set of conditions conducive to long range operation, but under those conditions, radios with advertised range of 2 miles will perform equally as well as those advertising greater than 30 miles.

Realistically, under most conditions, typical range for all eXRS, FRS and GMRS radios will be a few thousand feet to several miles.

eXRS radios have been independently tested head to head with the top of the line GMRS/FRS radios and up to five Watt commercial radios and the results demonstrate that they are all range equivalent.

1 comment:

Gadgeteer said...

I own 4 of these eXRS radios and I was a little disappointed to read this from a Radio forum...

Receiving 900MHz Trisquare eXRS FHSS Radios On Your Scanner

A few years ago a couple of manufacturers introduced digital frequency hopping spread spectrum radios for the consumer market; the Motorola DTR and the Trisquare eXRS 900MHz frequency hopping radios. One claim is that they cannot be monitored by scanners. For the most part, that is not true (except for the DTR). Others have discovered the Trisquare can be monitored with an Optoelectronics R-10 linked to a scanner. This is true. (Note: The Trisquare does NOT use digital audio, it is analog frequency hopping) I have discovered a poor mans method of monitoring these radios. I don't have an R-10 linked to a scanner so I just used my signal stalker and wrote down every frequency it stopped on while tx'ing. This yielded about 30 unique freq's. All the channels are 25KHz spaced. I entered all the freq's into a scanner bank, turned off the delay and hit SCAN. What do ya know I heard audio, albeit choppy, but mostly readable. I am still missing a few of the hopping freq's obviously. I just have to spend more time with the freq. counter. I am going to use my Scout instead of the signal stalker when I get some more time. With some refining this should work really good.

If you have a Trisquare eXRS radio and want to try this here is some additional info:

- The eXRS radios all have a maximum of 400 possible hopping frequencies, however for each TX the radio selects a set of 50 frequencies to perform hopping on. The 50 freq. set is determined by the channel number you select.

- The hop rate is 400mS.

- This crack will not work for the Motorola DTR radios because they use digital audio (VSELP). So, even if you could track the DTR with a near field receiver you would still have to be able to demodulate VSELP.I believe the hop rate for the DTR is 90mS.

This is just an information piece. Of course these radios were not made for true COMSEC, they do however provide much more privacy than virtually all consumer grade radios. However I have seen numerous web sites hawking these radios as "secure" and "unmonitorable". That is simply not the case. Anyone who wants to listen to this radio service just has to try.

I would like to get a complete list of all 400 possible frequencies. One initial problem I am noticing is the scanner stopping on a synchronization signal. Deleting these should solve that problem. They seem to be all in the 922MHz+ range. Most of the voice so far has been in the 906-919MHz range.
Motorola Systems Saber Net
Last edited by Ray_Air; 08-13-2009 at 02:54 PM..

The discussion continues on, but this is the gist of it...