Figure 1. The SARSound Unit.
SARSound
A Sound Sweep Coordinator
User's Manual
Rev. 1.1
Table of Contents
SARSound is a small electronic unit that connects between the base radio and microphone. Its purpose is to send a tone over the radio at regular intervals to coordinate searchers performing a Sound Sweep Method search.
The name SARSound is actually an acronym made by combining Search And Rescue and Sound.
Overview of SARSound
SARSound is built in a rugged steel enclosure. The "U" bracket allows it to be mounted on any horizontal or vertical surface. See the figure below.
Figure 1. The SARSound Unit.
A power switch; an external power connector; and two cables that connect to the radio are located on the rear panel. The unit is powered from an internal alkaline 9V battery (supplied) or can be connected to an external 12VDC power source. The 3 1/2 digit display shows the time and the operating mode, four key switches set the time and mode. The display and switches are made splash resistant by a tough mylar label overlay.
The internal timer, manually set by the user, counts down and when it times out keys the radio and transmits an audio tone. The timer is free-running and the tone is generated every interval automatically and continuously while the unit is switched on. At five seconds before the end of the interval, the unit transmits a warning tone which consists of four short beeps. At the end of the interval the unit transmits a 1.5 second long continuous tone.
The unit can operate intermittently from an alkaline 9V battery for several weeks. Battery life can be extended if an external 12VDC power source is connected to the standard coaxial power connector.
On the front panel are the time and mode setting switches and the display. See the figure below for the parts of the front panel.
Figure 2. The front panel.
The TX key sets the mode of operation, and the SET key allows the time interval to be set by the user. The MIN and SEC keys are used in conjunction with the SET key to set the minutes and seconds digits of the display.
On the rear panel are located the power switch, external power connector and the radio and microphone cables, see the figure below.
Figure 3. The rear panel.
The battery is located under the rear panel, to replace it, see the section Battery Replacement below.
The liquid crystal display (LCD) shows the time and operating mode of the SARSound unit. The sections of the display are shown in the figure below.
Figure 4. The parts of the display.
The time remaining in the interval is shown in the digits, one digit to the left of the colon shows the minutes and the two digits to the right show the seconds. For example, the time shown in the figure is three minutes and fifty-two seconds (3:52) left in the interval. The "Speaker Enabled" indicator, the left pointing arrow in the upper left of the display, when showing indicates that the internal speaker will sound when the tones are transmitted. The transmit enabled indicator, the bar or 'minus sign' to the left of the digits, when showing indicates that the tones will be sent out over the radio. When the SARSound unit is actually sending the tones, the "Transmitting" indicator will show, making a 'plus sign' to the left of the digits. The colon blinks on and off every second to indicate that the unit is operating.
How to Use SARSound
Although the display and switches are made splash resistant by a tough mylar label overlay, the SARSound unit is by no means waterproof.
Rain or water spray can get inside the case and permanently dammage the circuitry. SARSound is intended only for use in dry environments such as a radio room or inside a rescue truck.
Some precautions:
Always mount the unit away from doors or windows that open to the outside where rain or water spray can get in.
The temperature of the operating environment should not go below freezing, otherwise the display will become unreadable (although no dammage will result).
Avoid direct sunlight on the unit especially the display. Keep the maximum temperature below 40C.
If an external power source is used, ensure the maximum voltage is less than 18VDC (but at least 9VDC) and observe the polarity of the cable. The positive or '+' end is marked with a tag or if that is missing, the wire is marked with a white line.
When the SARSound unit is installed, it becomes part of the microphone circuit of the base radio. With the unit correctly connected, operation of the radio is unaffected.
To connect the SARSound unit to the radio:
The microphone will operate normally through the SARSound unit except when the tone is generated. At these times, the microphone is disabled until the signal finishes.
The power switch is located on the back panel. Reach over the upper right top of the unit and slide the switch up. The unit runs through a brief power up sequence where all the display segments are turned on and the tone is sounded for one second (the unit will not transmit the test tone into the radio). After the test sequence ends, the display shows 1:00 and the timer starts down-counting from one minute.
The internal battery will power the unit for several weeks of intermittent operation. Should the operation time need to be extended, the unit can be connected into an external power source with the supplied external power cable. The cable is terminated at one end with a standard power connector. The other end is not terminated and it is up to the end user to connect it to a battery, power supply, automobile cigarette lighter adapter or other suitable 12VDC power source. The polarity of the external connection must be observed (it is marked on the wires), although SARSound is protected from reversed polarity, it will not work if wired incorrectly.
After the SARSound unit is powered up, a default time interval of one minute (1:00) is displayed. The time interval can be manually set by the following procedure:
The length of the time interval is determined by the Sound Sweep Method. Please refer to the appropriate SAR manuals for this information.
There are four distinct modes of operation. The modes cycle through in the order shown below each time the TX key is pressed.
The speaker mode is indicated by the left-pointing arrow in the upper left of the display. If the arrow is on the speaker is on. The transmit mode is indicated by the minus sign to the left of the minutes digit. If the minus sign is on then the SARSound unit will key the radio and broadcast a tone. To change the mode, repeatedly press and release the TX key until the desired indicators are on or off. When the SARSound unit is first turned on, the speaker is on and the transmit mode is enabled.
Note: Ensure the power switch is in the off position before changing the battery.
The battery is in a holder on the inside of the rear panel. To change it, the rear panel must be removed. The panel is held in place by two half-shear dimples so no screws are required. To remove the panel, place a small screwdriver into the hole on the bottom edge of the panel. Pry up the edge of the panel until the dimple comes clear and lift the panel off.
Remove the battery by sliding it straight back out of the holder, a small screwdriver may be required to pry it out if the terminals are tight. Install the new battery by snapping it down into the holder and then sliding it onto the terminals. Make sure it is in the correct orientation before sliding it onto the terminals.
To replace the back panel, line up one dimple over its corresponding hole and snap the panel over the other edge of the enclosure. Check that you have the panel oriented correctly or it won't go into place because the battery will interfere with some of the components on the board.
Installation Procedure
The following instructions are for first-time installation of the SARSound unit. It is assumed that connectors have been correctly attached to the cables coming from the SARSound unit. If no connectors are attached, please refer to the Appendix at the end of this manual.
SaRSound is designed to be secured to any flat surface such as a table, a wall, a radio bracket, or even a ceiling or bulkhead. There are four #8 screw holes in the base of the mounting bracket. The mounting bracket allows the unit to be swiveled to any angle and then held in place by tightening the two thumb screws. The bracket is also stable enough for SARSound to be set on a table instead of being screwed down. A set of rubber feet is available for this purpose.
Remove the thumb screws (be careful not to lose the washers) and slide SARSound out of the bracket. Use four #6 or #8 screws to secure the bracket to the surface near to the base radio. Re-assemble SARSound in the bracket, tilt it to the desired angle and tighten the thumb screws. Unplug the microphone from the base radio and connect it to the short cable marked "Microphone" on the SARSound unit. Take the longer cable marked "Radio" and connect it to the microphone connector on the radio.
SARSound has a 'volume' control that must be adjusted so that the tones sent to the radio do not overload the transmitter or are loud enough to modulate the transmitter properly. If this control is not adjusted properly, searchers in the field may not be able to hear the tones. The control is accessed through a small hole on the edge of the unit below the key switches, a jeweler's screwdriver will be required to adjust it.
To adjust the volume control follow these steps:
Appendix
Radio and Microphone Cable Termination
SARSound comes standard with un-terminated (no connectors installed) cables for attachment to the microphone and radio. Because of the large number and variety of radios in the market today, it is impossible to supply a set of connectors that could connect to every radio. A set of standard microphone connectors can be supplied attached to the cables if requested at time of purchase. Additionally an optional set of matching in-line connectors can be supplied (for an additional fee) which can be cut into the microphone cable of your radio. A qualified technician will have to be employed to install these connectors. Alpen Engineering can provide this service for an additional fee if the microphone cable is sent to the factory. Contact Alpen Engineering for the costs of the connectors and the installation service.
There are four wires in each cable. The function of each is described below.
"Microphone" cable:
"Radio" cable:
Each wire is individually shielded and the shields must be connected to ground.
Alpen Engineering
E-Mail: craigh@netidea.com
last updated: March 6, 2005
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