Radiometrix Ltd

SHX1 Data Sheet (preliminary)

page 3

Pin Description

1.

No inversion occurs between TXD and RXD. However, AF out is inverted relative to TXD.

2.

PGM, P0 - P3 (parallel channel selects) and TXE are active LOW and have internal 47K pullups to

4v.

3.

Open collector output RXD has a 47K pullup to 4V.

4.

The software incorporates a 1200baud dumb modem, compatible with that implemented in other

Radiometrix narrowband units ( i1200 tones and format ). Modem operation is selected by a serial

command.

5.

Main serial port (PGM) operates at 2400 baud. (Command set is the same as SMX (USA) version).

The unit is capable of operating in 'basic' parallel channel select only mode, or in serial controlled

'expanded' mode.

6.

If analogue transmit modulation is needed, then connect a series 1uF cap + 500K trimmer (a

multiturn is advised) in the 'baseband TXD' circuit. Adjust trimmer for 90% of peak deviation (+/-

2.7kHz) at mean input level.

7.

The high current (280mA max.) transmitter supply (5v regulated) is fed to a separate pin, on the RF

out connector (pin 6A).

The Vcc (pin 4 on the user connector) can tolerate 4.1 - 15v, and draws up to 25mA. Both pins must

be supplied at all times (most users connect them to a common +5v supply)

Pins

Normal mode

Modem mode

RF

1A

NO PIN

2A

RF in/out

To the antenna

3A

RF Gnd

RF ground

4A

GND

0V

5A

GND

0V

6A

VCCTX

+5V regulated supply for TX

7

User

1

TXD

DC coupled input for TTL / CMOS logic

NC

2

TXE

Transmit enable.

Low = TX mode

NC

3

GND

0V

4

Vcc

DC supply input (+5V regulated)

8

5

P3

Parallel channel select

BUSY

6

P2

Parallel channel select

MOD TXD

7

P1

Parallel channel select

MOD RXD

8

PGM in

Serial programming/control input (inverted logic level RS232)

PGM in

9

RSSI

DC level between 0.5V and 2.5V. 60dB dynamic range

10

RXD

Open collector output of data slicer. 47K pullup to 4V

NC

11

AF out

500mV p-p audio. DC coupled, approx 0.8V bias

NC

Figure 3: SHX1 footprint (Top) view