AN-101 FCC Certification1

Application Note AN-103 High Speed Data Transmission Using T900V/R900V

The following guidelines are provided here for using the R900V and T900V video modules for high-speed (<5 mbpS) data links.

Figure 1 shows the transmitter setup, and Figure 2 is the receiver setup for 1 mbpS data rates. The additional receiver circuitry is necessary as the output of the video module is AC coupled and of inappropriate voltage levels for a digital interface.

Data Encoding- Manchester encoding is preferred; otherwise avoid long strings of zero’s or ones. Target a long-term duty cycle of 45 to 50%. See AN-102 for further information on Data Encoding Formats.

AN-102 Data Encoding

Application Note AN-0102 Data Encoding Formats
The following guidelines are provided here for optimizing your wireless system design for maximum range and reliability. Many tradeoffs must be considered when selecting an off the shelf encoder/decoder or designing custom software.

If your wireless design incorporates an off the shelf encoder/decoder combination, the only parameter that might vary is the data rate. As a rule, it is best to minimize the data rate as much as possible while balancing this with transmitter power consumption and system latency. Also select an encoder/decoder that has little or no overhead in terms of “1”s or “0”s. The optimal encoding format will have an average value for Ton and Toff equal to 50 percent. This condition places the data slicer threshold halfway between the peak signal level and the noise floor, which will provide the best performance.

If your wireless system incorporates microprocessors for encoding and decoding, some additional factors may be considered in the design of the data encoding scheme. The following is a list of items to consider when selecting the encoding format and decoding algorithm:

1. Transmitter power consumption.-To minimize average transmitter current use the shortest possible transmission interval. For high security applications, the decoder must recognize two or more consecutive words for validation. Design the transmitter such that it automatically stops transmitting regardless of whether the button is depressed.

2. Peak vs. Average Transmitted RF Power. –The FCC Part 15 regulations specifies average power levels which allows a higher than the limit peak power. This is true for the fundamental and harmonic radiated power. To take advantage of this, the transmission must be less than 100 milliseconds and have the smallest number of bits possible. In other words, the average transmitted duty cycle over a millisecond interval should be minimized.

3. Decoder Tolerances. –The decoder algorithm should tolerate some amount of noise spikes within the data stream that might be received is some applications (i.e. ignition noise). Also, allowances should be made for pulse width distortion and jitter. Self-locking schemes are necessary when the data rate s not accurately controlled at the encoder or the clock in the decoder is not crystal controlled. Asynchronous transmission is acceptable for short words and will work for long words if the encoder and decoder clocks are accurate with respect to each other.

AN-103 Data Transmission with Video Modules

Application Note AN-103 High Speed Data Transmission Using T900V/R900V

The following guidelines are provided here for using the R900V and T900V video modules for high-speed (<5 mbpS) data links.

If your wireless design incorporates an off the shelf encoder/decoder combination, the only parameter that might vary is the data rate. As a rule, it is best to minimize the data rate as much as possible while balancing this with transmitter power consumption and system latency. Also select an encoder/decoder that has little or no overhead in terms of “1”s or “0”s. The optimal encoding format will have an average value for Ton and Toff equal to 50 percent. This condition places the data slicer threshold halfway between the peak signal level and the noise floor, which will provide the best performance.

If your wireless system incorporates microprocessors for encoding and decoding, some additional factors may be considered in the design of the data encoding scheme. The following is a list of items to consider when selecting the encoding format and decoding algorithm:

1. Transmitter power consumption.-To minimize average transmitter current use the shortest possible transmission interval. For high security applications, the decoder must recognize two or more consecutive words for validation. Design the transmitter such that it automatically stops transmitting regardless of whether the button is depressed.

2. Peak vs. Average Transmitted RF Power. –The FCC Part 15 regulations specifies average power levels which allows a higher than the limit peak power. This is true for the fundamental and harmonic radiated power. To take advantage of this, the transmission must be less than 100 milliseconds and have the smallest number of bits possible. In other words, the average transmitted duty cycle over a millisecond interval should be minimized.

3. Decoder Tolerances. –The decoder algorithm should tolerate some amount of noise spikes within the data stream that might be received is some applications (i.e. ignition noise). Also, allowances should be made for pulse width distortion and jitter. Self-locking schemes are necessary when the data rate s not accurately controlled at the encoder or the clock in the decoder is not crystal controlled. Asynchronous transmission is acceptable for short words and will work for long words if the encoder and decoder clocks are accurate with respect to each other.

KTX-RCR A-Series Data Addressing

Application Note AN-0104 KTX/RCR A-Series Addressing Using T900V/R900V

The following guidelines are provided here for addressing KTX keychain transmitters and RCR receivers. .

The encoders and decoders used in these products allow for tri-state addressing. That is, each of the 8 address nodes may be set in either ground, +Vcc or open states.

As shipped from the factory, the address nodes for both products are set to ground, and it is not necessary to modify these address for the products to work together. However, if a different address is desired, address nodes on both transmitter and receiver must be set to the same configuration.

The following describes how to set an address node to a particular state:

Open State

To configure a node in the open state, the trace connecting the address node to ground must be cut.


+Vcc State

To configure a node in the +Vcc state, the trace connecting the address node to ground must be cut AND a connection must be made from the address node to the +Vcc node. A dab of solder is typically used to short across the solder bridge.

Ground State

As configured from the factory.

Choosing a Receiver Antenna

Choosing a Receiver Antenna

Want greater reception range? Choose a directional antenna for your receiver. For example…

Flat Panel

Yagi