Are the keypads reliable? What about interference?

If your keypads are slow to vote or frequently timing out, this could be due to either WiFi interference, sub-optimal positioning of the receiver (base station) or both. First check that your receiver(s) are at a good height. Also look at their positions. Are any areas of the room particularly problematic in terms of voting? If so, can you adjust the position of the nearest receiver? 

Assuming you are happy with the positioning of your receivers, move on to checking for potential interference. 

We recommend checking which channels are in use in your meeting room. By default CLiKAPAD systems use channel 75 but this can be changed. It is generally easier to change the channel of a single WiFi router than changing your who voting system though, so we recommend discussing options with the IT administrator before choosing a course of action. 

WiFi Channel	Recommended CLiKAPAD Channel If Clear	Interferes With CLiKAPAD Channels
1	6	6 to 23
2	17	6 to 28
3	22	11 to 33
4	27	16 to 38
5	32	21 to 43
6	37	26 to 48
7	42	31 to 53
8	47	36 to 58
9	52	41 to 63
10	57	46 to 68
11	62	51 to 73
12	67	56 to 75
13	75	61 to 75

 

The first column shows the WiFi channel.

The second columns shows the recommended CLiKAPAD Channel to use if there is no WiFi on that channel (n.b. WiFi channels are very wide and overlap, so if WiFi channel 3 is clear, but WiFi channel 4 is in use avoid using .CLiKAPAD Channel 22 as WiFi on channel 4 will interfere with this).

The third column show the range of CLiKAPAD channels that a WiFi hotspot on this channel will interfere with, so avoid using these channels if possible if you see WiFi on these channels.

 

You will sometimes find WiFi in use on all channels, in this scenario you need to find you which WiFi is likely to be used - i.e. which WiFi hotspots are for use by the delegates/guests in the room and avoid using a CLiKAPAD channel that corresponds with this.  A WiFi hotspot in itself does not cause interference, it is the WiFi hotspots that are in use that are the ones that will cause interference.

 

The CLiKAPAD keypads operate on the 2.4GHz frequency band at a very lower power output (1 to 2 mW of transmit power), this means they are safe to use around any other equipment but does mean they are susceptible to interference - mainly from WiFi.

 

Some general information about interference follows. 

 

The keypads have 70 channels to choose from, so in a well managed WiFi environment it is quite easy to select a clean channel (or channels) to use with the keypads.

 

The keypads use a fixed channel selection, so they do not wander off onto any other channel and do not rely on a synchronisation or handshake protocol like frequency-hopping devices use to find out which channel to use.  Frequency hopping is a scheme that some keypads use and is similar to bluetooth - which when works is very good however if you get any sort of interference during the synchronisation process it can result in a lot of attempts to the devices to connect to one another, something you can see when trying to connect up a bluetooth device which on occassion simply fails.

 

Although frequency hopping does sell the promise of avoiding interference this runs into problems when there are no completely "clean" channels.  One of the challenges of frequency-hopping systems is to synchronize the keypad and receiver. One approach is to have a guarantee that the transmitter will use all the channels in a fixed period of time. The receiver can then find the transmitter by picking a random channel and listening for valid data on that channel.  However if it chooses a random channel that is full of interference, or there are no channels available without some level of interference, this can prevent the keypads from ever getting a chance to vote.

 

With the few seconds available for a vote, even with interference, the CP3 keypads simply attempt to vote on the channel that they have been set to.  More often than not the vote will still get through even with some interference.  The keypads auto retry the vote if they don't receive an acknowledgement and so are quite robust.

 

The key with a fixed channel approach is selecting the best channel(s) to use, the best approach is to use a combination of WiFi scanning software and a dedicated 2.4GHz RF scanning device to check for any potential interference.  You can also position multiple receivers around the room to cater for any unforeseen interference (which is always a possibility).  Mild interference simply results in a reduced range (from the max of 140m) so multiple receivers caters for this scenario.

 

Even with all this planning and foresight, any wireless system (fixed or channel hopping) is susceptible to random local interference that has the potential to knock out a few votes.  This is why we would never guarantee a 100% return rate of votes for any event, and any vendor who does offer this is either unaware of the consequences of radio interference or is not being fully honest. 

 

There are other articles within the knowledge base regarding setting up for maximum range and changing the system's radio channel.