RFConsultant Posted March 21, 2011 Share Posted March 21, 2011 Hi, I am an electronic engineer and work for a company that specialises in wireless communications equipment including perimeter security and remote sensors. I am looking at electromagnetic compatibility between transmitters and wireless and wired alarm systems. I also have some previous experience of installing both wired and wireless alarm systems. I am looking to specify an alarm system that will work in close proximity to some of our transmitting equipment. Currently, I am considering the Texecom ricochet system. I understand that wireless alarms generally use the 868 MHz IMS band and that CE marked equipment 'should' have undergone EMC testing and so should have some level of immunity to interference. I would be interested to get some feedback from installers or users on false triggering due to radio frequency interference from local transmitters, either fixed or mobile/portable. I am really looking for advice on which alarm systems seem to have a good level of immunity. I believe that there are 4 potential mechanisms that would cause false triggering; 1) The wireless alarm panel believing that it is being jammed by unintentional transmissions. 2) RF interference causing a sensor (especially a PIR) to false alarm. 3) RF interference causing the alarm panel to false alarm. 4) RF interference causing the bell box to false alarm. Any advice, feedback or suggestions gratefully received. , John Link to comment Share on other sites More sharing options...
AdrianMealing Posted March 21, 2011 Share Posted March 21, 2011 Our Ricochet equipment has been independently EMC tested, and is currently going through EN approval at a European test house, it operates on the 868-868.6 Frequency, and so far i have no reports of interference from or too our equipment by other radio devices. The only rel chance of interference is within the same frequency band, however the kit wil choose the exact operating frequency at install, if jamming occurs the reciever will choose another frequency if powered of and back on again. amealing@texe.com Head of Industry Affairs Visit Our Website Texecom Link to comment Share on other sites More sharing options...
RFConsultant Posted March 27, 2011 Author Share Posted March 27, 2011 Thanks Adrian. I guess that it may be better for me to request this information again in one of the specific forums. Link to comment Share on other sites More sharing options...
hpotter Posted March 29, 2011 Share Posted March 29, 2011 John, i assume you mean uk based? is your kit licence exempt, on broadcast or intermitent? also what band is your kit working on? Link to comment Share on other sites More sharing options...
RFConsultant Posted April 2, 2011 Author Share Posted April 2, 2011 John, i assume you mean uk based? is your kit licence exempt, on broadcast or intermitent? also what band is your kit working on? Thanks hpotter These systems could go anywhere but I am currently considering a UK installation. The comms kit is not generally licence exempt but could conceivably be close to an ISM band. The comms systems can be very varied and can work over a number of bands from HF up to a couple of GHz. It would be difficult to be precise. Power levels can be quite high though if the site is remote. The transmissions are intermitent. Any Ideas ? Link to comment Share on other sites More sharing options...
RFConsultant Posted April 2, 2011 Author Share Posted April 2, 2011 Our Ricochet equipment has been independently EMC tested, and is currently going through EN approval at a European test house, it operates on the 868-868.6 Frequency, and so far i have no reports of interference from or too our equipment by other radio devices. The only rel chance of interference is within the same frequency band, however the kit will choose the exact operating frequency at install, if jamming occurs the reciever will choose another frequency if powered of and back on again. Adrian, do you know which EN the system is tested against ? It would help me to understand which frequencies and field strengths it has been tested against. Link to comment Share on other sites More sharing options...
AdrianMealing Posted April 2, 2011 Share Posted April 2, 2011 The Ricochet system has been tested obviously for CE, but accredited, not non accredited as some will do, and against EN50131-5-3, and of course any other standards called up by same, such as EN60950 and the like. We are currently submitting for FCC and UL & CUL. if you need more detail let me know. amealing@texe.com Head of Industry Affairs Visit Our Website Texecom Link to comment Share on other sites More sharing options...
hpotter Posted April 4, 2011 Share Posted April 4, 2011 my understanding of kit designed for the 868 band is that it was expected to get interference so should be accounted for in design. i can only go on what we fit (scantronic). goes without saying if there were issues, we wouldnt fit. that said, (again only me saying), rx/tx approved to en50131-5-3 must operate with one of 3 bands (868.6-868.7)(869.2-869.3) both max 10mW & (869.65-869.7) @25mW max (in france?) scanny use 868.6625. think max bandwidth allowed 25KHz, scanny use +/-20KHz, but the max duty cycle (xmitting) is 0.1% ie 3.6s/hr. so to supervision.. pip comes with supervision (think thats what you was looking at aswell as other stuff), signalled approx every 4 mins, fault generated if 3 lost in 20 mins. so guessing your kit might saturate for 12mins/20? tbo very 1st scanny i-on16 we fitted wasnt worried but had naggin in me sleep, was half mile from c.palace xmitter & few hundred yards from 2 different taxi firms. had no issues & many reckys in the area since. attached conformity sheet as has list of regs you might want to follow up. plenty more on their webby :'( http://www2.coopersecurity.co.uk/ I-ON_16_20_english_2008_10_20.pdf Link to comment Share on other sites More sharing options...
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