User manual

18
Fig.10 Template for positioning the
parts for a car antenna (glass-mounting
type) on the inside and outside of the
case
The Home-base Modem
The home-base modem should be set up as described in the Standard
Modems — Home-base Modem section.
The SLM
The 2236 or the 2260 should be set up as as described in the Setting
up the 2236 for Modem Transfer and Setting up the 2260 for Modem
Transfer sections, except that the baud rate must be set to 9600.
APPENDIX 1: Selection of Field Modem
The modem used in the field is critical, because it must be intelligent
enough to provide error correction, but dumb enough not to interpret
any of the communication nor to add anything by sending messages
such as »CONNECT« to the sound level meter.
The requirements for the field modem can be summed up as follows:
❍ Error correction must be supported
❍ The baud rate towards the SLM must be fixed without any relation
to the baudrate used on the phoneline
❍ Hardwire handshake (RTS/CTS) must be supported
❍ The modem must not interpret any commands
❍ The modem must not send any status messages to the SLM
❍ The DCD line must indicate the actual connection state
❍ The modem must disconnect when the carrier signal disappears
❍ The modem must be able to work over an extended temperature
range
Testing a number of modems in the field, Brüel&Kjær has found the
Multitech MT2834ZDX modem to be the best choice, and recommends
that only this modem is used for field use. Brüel&Kjær does not provide
technical support for any other modem.
Case lid,
internal view
105 mm
95 mm
External brace
Antenna
cable
970559e