APPLICATION NOTE Using Modems with Sound Level Meters Sound Level Meters are often used for monitoring in remote places, and you may want to “monitor the monitor” or transfer measured data to your homebase PC, without going to the measurement site. A telephone connection — wired or wireless — is a convenient way to transfer measurement data. And modems are a vital link in the chain of transmission. This application note explains what equipment you need and how to use it.
Using Modems with Sound Level Meters 2260 Semi-permanent Monitoring Kit A sound level meter for monitoring in the field needs protection against weather and tampering, and it needs a power supply other than its internal batteries. Also, you need space and power for the modem. For the Investigator Sound Level Analyzer Type 2260, the 2260 Semipermanent Monitoring Kit is available.
Standard Modems This section shows how to capture sound measurements from a remote Sound Level Analyzer (Investigator Type 2260) via telephone lines and standard modems. Precision Integrating Sound Level Meter Type 2236 may also be used. The field equipment is illustrated in Fig. 2. Fig. 2 Field equipment shown with standard modem.
Fig. 3 Standard modem set-up B&K 2236 or 2260 Hayes ¤ Compatible Modem PC running Evaluator Type 7820 Dumb Auto Answer Modem (Multitech MT 2834ZDX) 980001e Fig. 4 shows the complete system including the home-base modem.
Equipment Table 1 Equipment Type Available From PC operating system Windows 95®, Windows NT4.0®, Windows® 3.10 or 3.11 PC supplier PC-modem cable Depends on modem and PC Modem or PC supplier Home-base modem Hayes® compatible e.g.
Click on the Test the connection… button to launch the Serial Communications Tool. If your modem is properly connected to the PC, all the status indicators except DCD should show ✓. To verify that the modem is recognized enter the letters A and T in the String to be transmitted box and click on the Enter button. The modem should then reply OK. If your modem has reacted as described above, you can go on with the programming of the modem.
Table 2 Commands for the Multitech modem Enter command Significance ATM0 Speaker off ATE0 No Echo AT%E0 No Escape Sequence ATS0=1 Answer incoming calls after first ring AT$SB19200 Lock the baud rate to the SLM to 19200 bits/sec ATQ1 No Result codes AT&W0 Write the new configuration to the modem non volatile memory female 25-pin/9-pin cable with all lines in 1– 1 connection) — Do not use the Brüel & Kjær AO 1386 cable in this case! Setting up the 2236 for Modem Transfer 1.
Setting up the Home-base Modem After connecting the modem to your PC using the modem-PC cable, you can configure the PC software. If you use Windows 95 or Windows NT4.0, you must install the modem via the control panel in Windows first. Start the Evaluator Type 7820. Choose Options… on the Tools menu. Next select the Modem tab. Again if you use Windows 95 or NT4.0, your modem is already known by the system, so all you have to do is select it on the drop-down list.
Select the COM-port and Baud Rate. In the INIT command and in the DIAL command you can insert any string that the software should send to the modem during initialization and dialing. Start by putting ATZ in the init command and ATDT in the dial command. If more than one command is needed for initialization just put (4 letters) in as separator, for example: ATATZATM0 Please consult your modem manual for details on the command parameters.
Once the PC has connection to the remote site, the rest of the download process is the same as if the SLM was connected to your PC via the AO 1386 cable. Wireless Modem Using a GSM dataphone, your field system becomes truly mobile and wireless — no power line and no phone line is required. There is an extra team player in the communication chain: the GSM network operator. But once you have got the settings right, it works as smoothly as the data transfer via normal telephone lines.
Field Modem Siemens M1 Microphone Extension Cable AO 0441 (3m) AO 0442 (10m) 5 MB FLASHDISK MAGS STORAGE SYSTEM Lightweight Tripod UA 0801 Sun isk Tripod UA 0587 Br el & Kj r ? dB 0 Case Type 3592 Outdoor Microphone Kit UA 1404 Sound Level Analyzer (Preamplifier ZG 0026 and Type 2260 Microphone 4189, from 2260) Type 2260 Fig. 6 System diagram.
Equipment Table 3 Equipment 12 Type Available From PC operating system Windows 95 Windows NT4.0 Windows 3.10 or 3.11 PC supplier PC-modem cable Depends on modem and PC Modem or PC supplier Home-base modem Hayes compatible e.g.
Wireless Modems — Siemens M1 Mobile Dataphone Fig. 8 Siemens M1 Mobile Dataphone At the field end we need a device which is a combination of a mobile phone and a modem. A suitable device is the Siemens M1 — it runs on 12 V external DC supply, and it has a 9–pin RS –232 interface to the built-in modem which “talks” directly to the built-in GSM phone unit. It includes a split cable for power supply and antenna connection.
Then click on the Test the connection… button. By entering AT and clicking on the Enter button the M1 should answer OK. The command AT+CSQ indicates the signal quality (a number between 0 and 31, where 31 is the best). The command AT+COPS? shows whether you have been registered on the network or not. It should reply with the name of your network operator. Now the M1 should be programmed to be in auto-answer mode with a non-transparent error correction protocol and the result codes should be disabled.
Table 5 Siemens M1 programming commands Enter Command Significance ATS0= 1 Answer after 1st ring AT\N6 Operating mode: Non-Transparent, with RLP protocol ATB98 Operating mode: Autobauding Modem, 9600 Baud ATQ1 No Result codes AT&Y0 Load User Profile 0 at power-up AT&W0 Write the new configuration to nonvolatile memory as User Profile 0 If you the enter AT\S you should get this status screen: Now you can switch off the M1, position it on the remote site and connect it to the SLM with an AO 14
Wireless Modems — Modem Hand-switch ZH 0457 The Modem Hand-switch ZH 0457 serves to supply power from the 12 V Battery QB 0051 to the Siemens M1 Mobile Dataphone. Fig. 9 Modem Hand-switch ZH 0457 The M1 is supplied with a split cable for supply from 12 V power (and for the antenna). The power supply cable ends in three wires: a red (+12 V), a brown (0 V) and a violet (called “ignition”).
7. Wait until the green power indicator on the M1 stops flashing (it may take up to 10 s). 8. Now the M1 cable or the 12 V connection may be disconnected. Warning: The above sequence should always be followed, otherwise damage may result to the M1 or the SIM card. Battery Life The M1 will typically consume 70 mA when in the standby mode (which it will be most of the time). During transmission the consumption increases as indicated in the table below.
Fig. 10 Template for positioning the parts for a car antenna (glass-mounting type) on the inside and outside of the case Case lid, internal view 95 mm 105 mm External brace Antenna cable 970559e The Home-base Modem The home-base modem should be set up as described in the Standard Modems — Home-base Modem section.
APPENDIX 2: Software Update for Siemens M1 When ordering the Siemens M1, make sure it supports NON-TRANSPARENT data transfer. This means that the M1 firmware must be version 4.02 or later. If not, you can get it from Siemens. Also you can get a description of the new software features (Word file M1-nt2.doc) from Siemens. The Siemens instructions to download the new software are the following: Downloading New Software The M1 consists of two hardware parts, the DSA (Data Service Adapter) and the Mobile.
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