TR-916-SC-PA Linx Technologies Inc, TR-916-SC-PA Datasheet - Page 10

• Manufacturer Part Number: TR-916-SC-PA
• Description: TRANSCEIVER RF 916MHZ 1/2-DUPLEX
• Manufacturer: Linx Technologies Inc
• Series: SCr

Specifications of TR-916-SC-PA

• Frequency: 916MHz
• Data Rate - Maximum: 33.6kbps
• Modulation Or Protocol: FM, FSK
• Applications: ISM, Garage Door Opener, Remote Controls, 2-way RKE
• Power - Output: -10dBm
• Sensitivity: -94dBm
• Voltage - Supply: 2.7 V ~ 13 V
• Current - Receiving: 15mA
• Current - Transmitting: 19mA
• Data Interface: PCB, Through Hole
• Antenna Connector: RP-SMA
• Operating Temperature: 0°C ~ 70°C
• Package / Case: Module
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Memory Size: -
• Other names: TR-900-SC-PA; TR-900-SC-PA

USING THE TR-XXX-SC-PA FOR AUDIO APPLICATIONS
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6)
The procedure here is protocol-dependent but to illustrate, let’s consider the
packet format outlined above being sent to a UART. A UART interprets the start-
bit of a byte as a 1-0 transition. When the incoming data is 101010 or hash... it is
hard to actually find the start bit. This problem is solved by the UART Sync Byte.
The purpose of the Sync Byte is to create a high marking period of at least a byte
length so that the start bit of the following Start Byte can be correctly recognized.
The Start Byte following the Sync Byte is used by the receiving computer or
microcontroller to intelligently identify the beginning of a data packet. The Start
Byte value should be chosen so that it does not appear in the data stream.
Otherwise, a receiver may “wake up” in the middle of a packet and interpret data
in the packet as a valid Start Byte. There are many other, more complicated ways
to organize the protocol if this restriction cannot be met.
There is always a possibility of bursting errors from interference or changing
signal conditions causing corruption of the data packet, so some form of error
checking should be employed. A simple checksum or CRC could be used. Once
an error is detected the protocol designer may wish to simply discard the corrupt
data or to develop a scheme for correcting it or requesting its retransmission.
The preceding steps indicate the general events involved in using the transceiver
for a half-duplex communication application. To summarize, the system controller
will basically run through the steps in order and then return to step 1, flipping
back and forth between transmit and receive modes. As discussed, the designer
must take into account the timing considerations of both the transmitting and
receiving sides and carefully think through protocol issues to ensure product
reliability under field conditions.
The SC-PA is optimized for the transmission of serial data; however, it can also
be used very effectively to send a variety of simple and complex analog signals
including audio. The SC-PA is an excellent choice for applications requiring audio
quality comparable to a radio or intercom. The ability of the SC-PA to send
combinations of audio and data also opens new areas of opportunity for creative
design. In applications which require high-quality audio, the SC-PA may be used
with a compandor to further improve SNR. In the cases where truly high fidelity
audio is required, the SC-PA will probably not be the best choice. For such
applications, consider devices which have been optimized for audio.
The audio source should provide a 3V P-P maximum waveform and should be
AC-coupled into the TXDATA pin. The size of the coupling capacitor should be
large enough to insure the passage of all desired frequencies. Since the
modulation voltage applied to the TXDATA pin determines the carrier deviation,
distortion can occur if the TXDATA pin is over-driven. The actual level of the input
waveform should be adjusted to achieve the optimum results for your application
in your circuit.
The RXAUDIO output of the transceiver should be filtered and buffered to obtain
maximum audio quality. For voice, a 3-4KHz low-pass filter is often employed. For
broader-range sources such as music, a 12-17KHz cutoff may be more appropriate.
The SNR of the audio will depend on the bandwidth you select. The higher the
SNR, the less “hiss” you will hear in the background. For the best SNR, choose
the lowest filter cutoff appropriate for the intended signal.
Receive a packet