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[Technology] How well do your RF systems operate in the presence of other wireless devices and avoid interference?

Extremely well, mainly because our special circuit designs and patented radio protocols are thoughtfully designed for that purpose.

We build two kinds of systems: licensed and unlicensed. Obviously, our licensed systems operate far away from the clutter of Wi-Fi, cell phones, and even competitive audience response keypad products. On the other hand, our unlicensed systems must operate in close proximity with a variety of similarly unlicensed RF products – wireless network hubs, cordless phones, Bluetooth equipped PCs and peripherals, and other commercial wireless devices. But that’s not a problem for either Reply-brand or OEM-brand systems that Infowhye designs and manufactures. And here’s why.

All of our new wireless products that operate in unlicensed frequency bands (2.4 GHz, for example) employ proprietary spread spectrum communication protocols. What we’re doing for our Reply and OEM customers is innovative to say the least, and recent patent awards – plus several more patents pending – support that claim. Moreover, our specialized communications methods are proven to be exceptionally tolerant of the interference that commonly occurs in unlicensed bands. That’s because:

  • Reply systems set up a secure network that doesn’t talk or listen anything like commercial devices that use standardized radio protocols. That means other RF devices don’t mess with our systems, and our systems are designed -- and certified by competent major regulatory agencies -- not to mess with them.
  • Reply systems also use a unique frequency hopping spread spectrum (FHSS) method that is certified by the world’s major radio communications certification bodies. FHSS is highly immune to interference and aerial interception. Basically, we’re not talking or listening on an interfering frequency long enough to either be bothered or cause any bother.

  • Reply devices are synchronized so that a vote/response sent is indeed a vote/response received. This orderly method of communications has several advantages over asynchronous methods (even when those disorderly alternative methods are standards-based). Also, visual displays on each keypad we build acknowledge data transfer success to the user.

  • Here's another important point. There really are two kinds of RF interference to be concerned about. One is what we just discussed, that is, something caused by other RF devices. Another is self-induced interference. This is common to products that do not use time division multiplexing (TDM) methods. TDM methods assign a private communications 'time slot' to each response device. That 'time slot' is defined, repeatable, and predictable to make a TDM system inherently reliable. That's pretty important if a system wishes to avoid collisions of radio signals that are generated by its own multiple devices trying to send data simultaneously.

    Our products use patented Reply polling methods in combination with TDM to avoid data collisions when keypads are trying to talk to base stations (and vice versa). When thousands of pads are in a room, and all are trying to respond to a question in a couple of seconds, you don’t want congested airways or log jams at the base station that delay response collection. Those kinds of compromising situations can affect RF group response devices that do not use TDM. (And the greater the number of simultaneously transmitting keypads, the greater the potential for such problems.)

    So if you’re concerned about interference, remember that not all RF is the same. Make sure your audience response system frequency hops to avoid the interference posed by other RF devices. Also, look for one the uses a TDM method to prevent it from interfering with itself.

    And don’t blindly trust in commercial RF protocols, since many of those protocols were standardized for low volume networking and/or are not synchronized. Many of those alternatives depend on multiple transmissions to send data in hopes of that critical data eventually getting through to the base station. Their implementation might be characterized as follows: the more devices, the more retransmissions, the more data, the more potential for self-interference. That makes them inherently noisy, and it adds an element of chance to their solution.

    We’d like you to avoid both of these interference problems. You can with the systems we build. Give us a call. Let’s interact.

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