X7000 Datasheet, PDF (5/9 Pages) rfsolutions.ltd – 458MHZ RF SYNTHESISED TRANSCEIVER

TXON
RSSI
DIN
MIN
AOUT
DOUT
RFADJ
SIX
458MHZ RF SYNTHESISED TRANSCEIVER
X7000
50 H Power Down Mode
The module will disable the transmitter and receiver
thereby reducing the current consumption to
approximately 2rnA.
54H Transmit Mode.
Enables the transmitter. Data on DIN, AIN or MIN
will be broadcast.
52H Receiver Mode.
Enables the Receiver. Received data will appear on
AOUT and DOUT
53H Status Report.
Four bytes wilt be transmitted by the module
indicating the current status:
1st Byte
Acknowledge 53H
2nd Byte
Transmission channel number
3rd Byte
Receiver channel number
4th Byte
Module Status:
00H Module powered down
02H Receive mode
04H Transmit mode
22H Receiver synthesiser not locked
32H Transmitter synthesiser not locked
The TXON input is set low to switch on the transmitter stage.
The relative signal strength indication provides a voltage which is logarithmically
proportional to the RF signal strength:
0.0V = No RF signal strength
0.7V = 1µV RF signal. strength
1.6V = 10µV RF signal strength
2.4V = 100µV RF signal strength
2.7V = 1mV RF signal strength
The digital modulation input accepts digital serial data from DC to 10kbps. It has a
threshold of 2.5V with an input impedance of 100kΩ.
The MIN input can be used to directly modulate the transmitter. A 3V p-p signal on a
2.5V bias voltage will produce full deviation of ± 3KHz. There is no filtering on the
input therefore care must be taken not to infringe the MPT1 329 specification on
adjacent channel power limits. If this input is used the equipment might have to be
type approved again.
A demodulated analogue signal is presented. A full deviation of +1-3KHz will
produce a I.8Vp-p signal on a 2.8V DC bias.
The DOUT output signal is a digitised version of the AOUT analogue signal. The
peak and trough limits of AOUT are measured and a midway level is generated. A
comparator compares the level with AOUT and the digitised DOUT signal is
produced.
When transmitting a long data stream it is important to transmit an equal mark and
space ratio if possible. A long stream of either marks (FFH) or spaces (00H) can
cause problems. In addition a preamble such us 55H. AA or CCH is required at the
start of each data, stream so that the midway level can be established before the
data is received.
The RF output level can be regulated from this input. An open circuit will produce
the maximum output power or 500mW. If 0V is applied to RFADJ then the minimum
output power of 5mW will be set.
The RF output power can be adjusted between the maximum and minimum by
setting a voltage of between 0.4V to 0.5V. This adjustment will be affected by both
component tolerance and temperature.
The SIX output is set low when data is present on the STX output.
DS007_2
Oct 00
©2000 REG No 277 4001, ENGLAND.
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