Group SD0612

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Contents 1 SD0612 Wireless Referee Horn Indicator (Daktronics, Inc.) 2 Introduction 3 Previous Work: 4 Design Options: 5 Benefits of operation within the 902-928 MHz Bands 6 Drawbacks to the 902-928 MHz Bands 7 Summary: 8 PHOTOS

SD0612 Wireless Referee Horn Indicator (Daktronics, Inc.)

Group Members are

Kai Wai Ho & Brandon Goltz

Introduction

The wireless Referee Horn Indicator is a wireless device that can communicate by transmitting and receiving radio signals to and from the referee and score keeper other over a short range of about 150-200ft. The problem this devise solves the hassle of the referee having to watch the score clock and the sporting event at the same time. This will enable him to make the correct calls and be able to communicate with the scorekeeper effectively. Currently Daktronics holds the patent on this device and is looking to improve on it’s design. Some of the specifications of this device are as follows: the transmitter needs to read the clock signal given out by the All SPORT CONTROL COUNSIL, the receiver end needs to vibrate at 10 seconds left, 5 seconds left, and time is out, the receiver unit needs to be small approximately 1.5in by 1.5in and to be worn on the wrist or arm.

Previous Work:

Daktronics currently owns the patent on the wireless Referee horn indicator. The only sport related similar existing project known to us is a wireless soccer ball. This device has a chip in the soccer ball that will trigger another device to go off if it crosses the goal line.

Design Options:

The major design option for the wireless referee horn indicator was what transceiver we would use. The major factors in selecting the transceiver are: Price, size, range, capability, frequency, voltage. We had the decision to choose a transceiver DR3000 the TR-916-SC-PA and the LT5506, and TR-916-SC-PA, However we have discovered that these chips are now obsolete and we are going with an Applied wireless FM transmitter and Reciever T900AU-A and R900AU-922 respectivly.

Benefits of operation within the 902-928 MHz Bands

1 The band is free of the tight FCC restrictions which limit the applications for which other bands can be used. In the 902-928 MHz band virtually any analog or data signal can be sent without restrictions on content or duration.

2 Higher legal output power yields longer transmission distances than many other bands.

3 The propagation of frequencies in the 900MHz range is better than at higher frequencies, 2.4GHz. Therefore, lower output power is needed to attain any particular distance. Since less output power is needed, transmitter power consumption is reduced.

4 Antenna compactness. A useful byproduct of higher frequency is shorter wavelength. This allows a 1/4-wave antenna in the 900 MHz range to be typically less than 3.25 inches in length, allowing for easy concealment in compact portable products.

Drawbacks to the 902-928 MHz Bands

The lack of restriction on the band has caused it to become increasingly popular and thus congested. Many products that transmit continuous data at high rates are now migrating to higher frequencies but the popularity of the band makes it likely to remain crowded. Higher level interferers: in addition to its allocation for narrow-band devices the 902 to 928 MHz frequency range is also allocated for and surrounded by potentially higher-level interferers such as spread spectrum devices. Linx modules employ a variety of techniques including SAW filtration, uncommon frequency allocation, channel qualification and constant carrier modulation techniques to minimize the possible impact to a user from such interference. Difficulty of export: most countries outside the US do not allow similar operation in the 900MHz band; thus, it is usually impractical to export a device which operates in this range. Fortunately, nearby frequencies are being standardized in large market areas such as Europe. Linx will offer pin- and function-compatible products allowing accommodation of both domestic and export requirements with just a change of modules and antennas.

As you can see the operating frequency range is a key factor and the 902-928 band seems to be the best to work with.

Summary:

The main goal of the Wireless Referee Horn Indicator is to build a transceiver that can be programmed to communicate to another transceiver with ease. The options that this device will include are an audio buzzer or speaker, a Vibration unit for hand free notification, and an LCD screen so the operators know what is going on. It will also be able to connect to a computer for different Sporting events. The goal is more for general purpose transmitting and receiving not just for sporting events.

PHOTOS

(This is our prototype transciever with a speaker for auidio)

This is a prototype of the Transmitter connected to the Daktronics Score console.

This is a prototype of the Reciever in PCB form

This is the Reciever in its enclosure and the Guts of the Reciever and finally the Motor for vibration mounted in the corner.

This is The power circuit on top and the Reciever Circuit on Bottom to be sent out to make a PCB. The 3D modle of what it may look like on the right.

The top circuit is the Transmitter 3D precview and the bottom is the layout on Ultraboard.