Outdoor Sound Level Meter environmental monitoring kits
These kits are for the ‘30’, ‘33’ & ‘60’ series
Sonomètres Pulsar 
Lärmmessgeräte Pulsar Outdoor kits WK1 and WK2
These kits are for the ‘30’, ‘33’ & ‘60’ series and are typically used for environmental monitoring.
The two basic models MK1 and MK2 both have the same waterproof case that has a large internal battery giving about 5 days (150hr) operation. The kits essentially vary only in their microphone and they both have two waterproof connectors to connect to a microphone and an optional computer. Included is the basic software to acquire data and download the sound level meter,
Both ‘waterproof’ kits contain the following-
| Microphone | (either M100 in WK1 or M120 in WK2) |  |
| Kit case inc battery, calibrator & all accessories (with shaped foam to hold parts) | The data logging slm (series 60 or 30) | |
5m Cable to connect the microphone Type ZB1 or ZB11 |
(included) | |
| Cable to connect the case to a computer | (included) | |
| Software to take data and display it | (basic software included) | |
| Manuals | (for all parts) | |
| Battery Charger | (battery charged externally) |
Application Overview
Environmental monitoring usually takes place out of doors and with the problems of weather, especially in the United Kingdom; this means that at least the microphone must be waterproof. However, for many measuring tasks, there is no suitable shelter for the sound level meter, so this really needs a weatherproof case as well. Since about 1970, there have been many attempts to make a weatherproof system but in the main, they have either been incredibly expense or simply did not work. “Did not work” encompasses everything from not keeping the water out to having an acoustic response that did not meet the requirements of IEC 60651, many not even at Type 2 level.
As well, most of the available systems were very complex indeed - leading to the joke that the user had to be better qualified than the designer. The two Pulsar kits are intended to be simple to use and WK1 is the simplest version. The ‘microphone unit’ is simply a waterproof mount and cable which takes the pre-amplifier and microphone capsule normally fitted to the instrument and provides wind and rain protection. It can be fitted onto a standard camera tripod (not included) and is suitable for overnight use, but not for long term measurements.
The ‘strong’ unit, WK2 uses a full outdoor microphone, which is a complete system and does not use the instrument’s own microphone capsule and pre-amplifier. It is similar to the long-term airport monitor microphone and models have been outside for up to 5 years without problems. It comes complete with its own built-in tripod and for transport fits into a shipping tube. These microphones (Type M120) are also available for sale to competitors who use them for their outdoor kits and are loosely based on a Cirrus MK: 437.
Usage
For both units the summary of the process is:-
- One of the two microphones is connected to the case and the instrument is turned ON.
- The sound level meter is calibrated with Model 100 calibrator and the case shut.
- Data can be collected while the system is running by using the second connector or the whole unit can be taken back to base to download.
- For measurements longer than the battery life, the internal re-chargeable battery can be ‘hot-swapped’ and re-charged without stopping a measurement.
- Batteries MUST be charged outside the kit case for safety and a charger is provided.
WK1 - in detail
The microphone is removed - with its pre-amplifier - and the microphone cable plugged on to the bottom of the pre-amplifier. The microphone and pre-amplifier are now fitted inside the weatherproof mount and this is screwed up to provide a watertight seal. The windshield and it’s frame is now fitted onto the microphone base and the whole assembly screwed onto a standard camera tripod.
The other end of the cable is then screwed onto the waterproof case, the sound level meter, 60 or 30 series is placed into the foam support and the internal ‘microphone’ cable is fitted where the preamplifier was originally. The power and RS232 connectors are then fitted into the base of the sound level meter and these go to the internal battery and the external RS232 port respectively. Close the case - you have completed the task.
If the instrument is to be calibrated, as it should be before a measurement, the calibrator model 100 is fitted over the microphone - with the windshield temporarily removed and the CAN button on the sound level meter is pressed. Obviously, this would normally be done just before the measurement started..
WK2 - in detail
In many ways this is easier as the microphone assembly is already complete. One end cap from the microphone transport case is removed and the microphone assembly slid out. The tripod legs are clipped to the side of the microphone mast and are simply screwed into place. One is telescopic to allow it to be used on un-even ground. The cable is now connected to the microphone assembly and to the case. The sound level meter is fitted in the case exactly as with WK1.
Application Details and FAQ’s
Because the 30 and 60 series use different connectors for their RS232, power and microphone, the model of sound level meter to be used MUST be specified and they are not interchangeable. They also use different battery types, a single 9v battery for models 30 and 60 series and single pen cells for model 33. The original model 30 had rather a high power consumption and after user requests, the newer 33 was fitted with more powerful batteries.
It follows that the operating life of each instruments is different and they are in the order 60, 33 and 30, with a typical operating time of 5 days. The EXACT time depends on the functions selected, especially on model 30 and the signal level being recorded, so precision of data is not possible. Simply put, the more data you choose to store, the shorter the operating time for both battery and a full store.
Both cases have clips locks over the handles and they can both be ‘chained to a tree’, or more correctly, fixed to some solid object. It is recommended that a small padlock is fitted through one hole so that the case cannot be opened at all. If this is not done, a vandal may not be able to steal the system, but they could leave it open a millimetre or so and water may get in.
WK2 also has a hook system below the microphone to allow this to be chained down. The hook is on a standard 20mm conduit thread so that all the standard electrical fittings can be utilised to fasten the system in place. Indeed, some users mount the microphone on a vertical threaded conduit tube to place it at a special height.
Special features and functions
The battery inside the case MUST be charged outside and no attempt should be made to charge it in situ. This is because it is a lead-acid battery and while charging oxygen and hydrogen can be given off. These are an explosive mixture in almost any concentration and in the days when radios operated from these batteries many people were hurt by explosions on charging. The sealed ‘gel’ units used in the Pulsar kits are not prone to ‘gassing off’ as the release of O2 and H is known, but even so, they MUST be charged in the open.
One facility is that the system can ‘hot swap’ the batteries. That is a discharged battery can be exchanged for a fully charged on without stopping the data acquisition. This allows the kit to be used for taking say a whole month of data. As well, an external 12V battery - for example a car battery can be connected externally, although a 12V caravan ‘Leisure’ battery is better for this application.
Data can be taken out of the sound level meter without opening the case as the RS232 connector on the case is waterproof to IP66. It is important to remember to re-fit the connector cap after use.