Installation of Receivers in the Wireless System (M. Abrahamson)

Mounting receivers: Receivers are normally mounted high in the front two corners of a lecture hall. This works because:

1. The receivers need to substantially distanced from one another so that a single student transmission isn't received by both receivers. Nothing breaks if this happens but it defeats the purpose of having two receivers. Two receivers are used to increase the speed at which answers can be received. Each receiver can only read one response at a time so if students happen to transmit within the same 18ms interval only one signal will be received and the other student will have to try again.

2. The teacher can easily divide the class into two halves, specifying that everyone seated in the left side of the room should aim at the left receiver and everyone in the right at the right.

3. It is almost always possible to get a good line of sight(mount high).

4. There are not usually projectors or other sources of bright light aimed directly at the corners. Intense light can cause a decrease in performance.

5. Reflect the signals well making it easy for students to hit their target but unlikely that a signal will be reflected in the direction of the other receiver.

Receiver(s), cables, hub and the transformer:

· The receiver looks like a flying saucer (Charles and Art each has one) with a camera mount on the bottom.

· The cables connecting the receivers to the hub and the hub to the teacher’s computer are standard CAT 5 cables. Each cable can be several feet in length to a maximum of 100 feet.

· The hub is approx: 5.25" wide by 5.25" deep by 2" tall. It is powered by a small transformer of which Charles and Art also has an example. Since the transformer power involved is small, the power for the hub can be left on all the time.

· Two-receivers-hub system: For a two receiver system, the cables make a "T" running from each receiver to the hub and then home to the teacher’s computer. The length of each of the 3 cables can be anywhere between a few feet to 100 feet. The length of each cable may be independent of the lengths of the other two.

Pads: Distance from student transmitters (pads) to the receiver is almost never a problem in lecture halls of this size. The manufacturers specs are as follows although we always get better results.

· Range of the pads: Straight line - over 18 meters (about 54 feet.)

· Angle of Transmission of the pads: Both Vertical & Horizontal angles of approx. 45 degrees

· Angle of Reception of the receiver:

o Vertical angle of approx 60 degrees

o Horizontal angle of approx 120 degrees

Mounting the receiver: I suggest mounting the receiver on the wall with a simple "L" Bracket and facing it diagonally towards the opposite corner of the room.

Please give me a call to discuss your plan and testing. Look forward to working with you!

Marty Abrahamson, eConsultant

Interactive Classroom Consulting

Voice - 804-642-9131, Cell - 804-815-4444